This paper deals with the problem of chromium recovery from chrome-tanned waste and thus with reducing the environmental impact of the leather industry. Chrome-tanned waste was transformed by alkaline enzymatic hydrolysis promoted by magnesium oxide into practically chromium-free, commercially applicable collagen hydrolysate and filtration cake containing a high portion of chromium. The crude and magnesium-deprived chromium cakes were subjected to a process of thermal decomposition at 650°C under oxygen-free conditions to reduce the amount of this waste and to study the effect of magnesium removal on the resulting products. Oxygen-free conditions were applied in order to prevent the oxidation of trivalent chromium into the hazardous hexavalent form. Thermal decomposition products from both crude and magnesium-deprived chrome cakes were characterized by high chromium content over 50%, which occurred as eskolaite (Cr2O3) and magnesiochromite (MgCr2O4) crystal phases, respectively. Thermal decomposition decreased the amount of chrome cake dry feed by 90%. Based on the performed experiments, a scheme for the total control of chromium in the leather industry was designed.
The aim of this study was to use the life cycle assessment tool to assess, from an environmental point of view, the different possible municipal solid waste (MSW) management scenarios for the island of Mauritius. The scenarios include landfilling with energy recovery (S1), incineration with energy recovery (S2), composting, incineration and landfilling (S3) and finally composting, recycling, incineration and landfilling (S4). The MSW generated in 2010 was selected as the functional unit. Foreground data were collected through surveys and literature. Background data were obtained from ecoinvent data in SimaPro 8 libraries. The scenarios were compared both through the CML-IA baseline–midpoint method and the ReCiPe end-point method. From the midpoint method, the results obtained indicates that landfilling (S1) has the greatest impact in all the analyzed impact categories except ozone layer depletion and human toxicity, while incineration (S2) has the least impact on almost all the analyzed damage categories except in global warming potential and human toxicity. The collection and transportation of waste has a significant impact on the environment. From the end-point method, S4 reduces the damage impact categories on Human Health, Ecosystems and Resources due to the recycling process. S3 is not favorable due to the impact caused by the composting process. However, it is also very important to emphasize that for incineration, the best available technology with energy recovery shall be considered. It is recommended that S2 and S4 are considered for strategic planning.
Municipal solid waste generation is huge in growing cities of developing nations such as India, owing to the rapid industrial and population growth. In addition to various methods for treatment and disposal of municipal solid waste (landfills, composting, bio-methanation, incineration and pyrolysis), aerobic/anaerobic bioreactor landfills are gaining popularity for economical and effective disposal of municipal solid waste. However, efficiency of municipal solid waste bioreactor landfills primarily depends on the municipal solid waste decomposition rate, which can be accelerated through monitoring moisture content and temperature by using the frequency domain reflectometry probe and thermocouples, respectively. The present study demonstrates that these landfill physical properties of the heterogeneous municipal solid waste mass can be monitored using these instruments, which facilitates proper scheduling of the leachate recirculation for accelerating the decomposition rate of municipal solid waste.
Vegetables waste is generally utilized through a bioconversion process or disposed of at municipal landfills, dumping sites or dumped on open land, emitting a foul odor and causing health hazards. The presents study deals with an alternative way to utilize solid vegetable waste through a thermochemical route such as briquetting and gasification for its energy recovery and subsequent power generation. Briquettes of 50 mm diameter were produced from four different types of vegetable waste. The bulk density of briquettes produced was increased 10 to 15 times higher than the density of the dried vegetable waste in loose form. The lower heating value (LHV) of the briquettes ranged from 10.26 MJ kg–1 to 16.60 MJ kg–1 depending on the type of vegetable waste. The gasification of the briquettes was carried out in an open core downdraft gasifier, which resulted in syngas with a calorific value of 4.71 MJ Nm–3 at the gasification temperature between 889°C and 1011°C. A spark ignition, internal combustion engine was run on syngas and could generate a maximum load up to 10 kWe. The cold gas efficiency and the hot gas efficiency of the gasifier were measured at 74.11% and 79.87%, respectively. Energy recovery from the organic vegetable waste was possible through a thermochemical conversion route such as briquetting and subsequent gasification and recovery of the fuel for small-scale power generation.
Climate change remains one of the biggest threats to life on earth to date with black carbon (BC) emissions or smoke being the strongest cause after carbon dioxide (CO2). Surprisingly, scientific evidence about black carbon emissions reduction in healthcare settings is sparse. This paper presents new research findings on the reduction of black carbon emissions from an observational study conducted at the UN Peacekeeping Operations (MINUSTAH) in Haiti in 2014. Researchers observed 20 incineration cycles, 30 minutes for each cycle of plastic and cardboard sharps healthcare waste (HCW) containers ranged from 3 to 14.6 kg. The primary aim was to determine if black carbon emissions from healthcare waste incineration can be lowered by mainstreaming the use of cardboard sharps healthcare waste containers instead of plastic sharps healthcare waste containers. Similarly, the study looks into whether burning temperature was associated with the smoke levels for each case or not. Independent samples t-tests demonstrated significantly lower black carbon emissions during the incineration of cardboard sharps containers (6.81 ± 4.79% smoke) than in plastic containers (17.77 ± 8.38% smoke); a statistically significant increase of 10.96% smoke (95% Confidence Interval (CI) [4.4 to 17.5% smoke], p = 0.003). Correspondingly, lower bottom burner temperatures occurred during the incineration of cardboard sharps containers than in plastic (95% Cl [16 to 126°C], p = 0.014). Finally, we expect the application of the new quantitative evidence to form the basis for policy formulation, mainstream the use of cardboard sharps containers and opt for non-incineration disposal technologies as urgent steps for going green in healthcare waste management.
Understanding waste flows within an urban area is important for identifying the main problems and improvement opportunities for efficient waste management. Assessment tools such as material flow analysis (MFA), an extensively applied method in waste management studies, provide a structured and objective evaluating process to characterize the waste management system best, to identify its shortcomings and to propose suitable strategies. This paper presents the application of MFA to municipal solid waste management (MSWM) in Maputo City, the capital of Mozambique. The results included the identification and quantification of the main input and output flows of the MSWM system in 2007 and 2014, from the generation, material recovery and collection, to final disposal and the unaccounted flow of municipal solid waste (MSW). We estimated that the waste generation increased from 397x103 tonnes in 2007 to 437x103 tonnes in 2014, whereas the total material recovery was insignificant in both years – 3x103 and 7x103 tonnes, respectively. As for collection and final disposal, the official collection of waste to the local dumpsite in the inner city increased about threefold, from 76x103 to 253x106 tonnes. For waste unaccounted for, the estimates indicated a reduction during the study period from 300x103 to 158x103 tonnes, due to the increase of collection services. The emphasized aspects include the need for practical waste reduction strategies, the opportunity to explore the potential for material recovery, careful consideration regarding the growing trend of illegal dumping and the urgency in phasing-out from the harmful practice of open dumping.
Bituminous pavement can be recycled – even multiple times – by reusing it in new bituminous mixtures. If the mechanical properties of the binder get worse, this reclaimed asphalt is often used in the sub-structure of the road. Apparently, up till now, no end-of-life phase exists for the material. Actually, defining the end-of-life and the end-of-waste stage of a material is important for life cycle assessment modelling. Various standards and scientific studies on modelling life cycle assessment are known, but the crucial stages are not yet defined for reclaimed asphalt pavement. Unlike for iron, steel and aluminium scrap, at this moment, no legislative end-of-waste criteria for aggregates are formulated by the European Commission. More research is necessary in order to develop valuable end-of-life criteria for aggregates. This contribution is a mini-review article of the current regulations, standards and studies concerning end-of-life and end-of-waste of reclaimed asphalt pavement. The existing methodology in order to define end-of-waste criteria, a case study on aggregates and the argumentation used in finished legislative criteria are the basis to clarify some modelling issues for reclaimed asphalt material. Hence, this contribution elucidates the assignment of process environmental impacts to a life cycle stage as defined by EN15804, that is, end-of-life stage (C) and the supplementary information Module D with benefits and loads beyond the system boundary.
Degradation of polychlorinated dibenzo-p-dioxins and dibenzofurans in municipal solid waste incinerator fly ash is beneficial to its risk control. Fly ash was treated in a full-scale thermal degradation system (capacity 1 t d–1) to remove polychlorinated dibenzo-p-dioxins and dibenzofurans. Apart from the confirmation of the polychlorinated dibenzo-p-dioxin and dibenzofuran decomposition efficiency, we focused on two major issues that are the major obstacles for commercialising this decomposition technology in China, desorption and regeneration of dioxins and control of secondary air pollution. The toxic equivalent quantity values of polychlorinated dibenzo-p-dioxins and dibenzofurans decreased to <6 ng kg–1 and the detoxification rate was >=97% after treatment for 1 h at 400 °C under oxygen-deficient conditions. About 8.49% of the polychlorinated dibenzo-p-dioxins and dibenzofurans in toxic equivalent quantity (TEQ) of the original fly ash were desorbed or regenerated. The extreme high polychlorinated dibenzo-p-dioxin and dibenzofuran levels and dibenzo-p-dioxin and dibenzofuran congener profiles in the dust of the flue gas showed that desorption was the main reason, rather than de novo synthesis of polychlorinated dibenzo-p-dioxins and dibenzofurans in the exhaust pipe. Degradation furnace flue gas was introduced to the municipal solid waste incinerator economiser, and then co-processed in the air pollution control system. The degradation furnace released relatively large amounts of cadmium, lead and polychlorinated dibenzo-p-dioxins and dibenzofurans compared with the municipal solid waste incinerator, but the amounts emitted to the atmosphere did not exceed the Chinese national emission limits. Thermal degradation can therefore be used as a polychlorinated dibenzo-p-dioxin and dibenzofuran abatement method for municipal solid waste incinerator source in China.
In-vessel composting of agricultural waste is a well-described approach for stabilization of compost within a short time period. Although composting studies have shown the different combinations of waste materials for producing good quality compost, studies of the particular ratio of the waste materials in the mix are still limited. In the present study, composting was conducted with a combination of vegetable waste, cow dung, sawdust and dry leaves using a 550 L rotary drum composter. Application of a radial basis functional neural network was used to simulate the composting process. The model utilizes physico-chemical parameters with different waste materials as input variables and three output variables: volatile solids, soluble biochemical oxygen demand and carbon dioxide evolution. For the selected model, the coefficient of determination reached the high value of 0.997. The complicated interaction of agricultural waste components during composting makes it a nonlinear problem so it is difficult to find the optimal waste combinations for producing quality compost. Optimization of a trained radial basis functional model has yielded the optimal proportion as 62 kg, 17 kg and 9 kg for vegetable waste, cow dung and sawdust, respectively. The results showed that the predictive radial basis functional model described for drum composting of agricultural waste was well suited for organic matter degradation and can be successfully applied.
This paper studies the recyclability of construction and household plastic waste collected from local landfills. Samples were processed from mixed plastic waste by injection moulding. In addition, blends of pure plastics, polypropylene and polyethylene were processed as a reference set. Reference samples with known plastic ratio were used as the calibration set for quantitative analysis of plastic fractions in recycled blends. The samples were tested for the tensile properties; scanning electron microscope–energy-dispersive X-ray spectroscopy was used for elemental analysis of the blend surfaces and Fourier transform infrared (FTIR) analysis was used for the quantification of plastics contents.
The influences of temperature and residence times on the conversion and product distribution during hydrothermal carbonisation of municipal solid wastes were investigated. Analysis of variance and reaction severity were used to comprehensively analyse the experimental results. Analysis results showed both reaction temperature and residence time had varying degrees of impact on production distribution and hydrochars characteristic, while the effect of combine temperature and time was negligible. It is novel to find that the products yield was a linear function of the logarithm of the reaction ordinate. Base on comprehensive consideration, 240 °C to 260 °C and 50 min to 60 min would be the optimised reaction region to achieve relatively better economic benefits for hydrothermal carbonisation of municipal solid waste. By employing the analysis results and estimated models of high heating value and solid yield established in this article, predicting the product characteristics that have not been explored experimentally become possible.
Stricter regulatory requirements concerning end-of-life vehicles and rising disposal costs necessitate new ways for automobile shredder residue utilisation. The shredder granulate and fibres, produced by the VW-SICON-Process, have a high energy content of more than 20 MJ kg–1, which makes energy recovery an interesting possibility. Shredder fibres have a low bulk density of 60 kg m–3, which prevents efficient storing and utilisation as a refuse-derived fuel. By mixing fibres with plastic-rich shredder granulate and heating the mixture, defined granules can be produced. With this ‘ReGran’ process, the bulk density can be enhanced by a factor of seven by embedding shredder fibres in the partially melted plastic mass. A minimum of 26–33 wt% granulate is necessary to create enough melted plastic. The process temperature should be between 240 °C and 250 °C to assure fast melting while preventing extensive outgassing. A rotational frequency of the mixing tool of 1000 r min–1 during heating and mixing ensures a homogenous composition of the granules. During cooling, lower rotational frequencies generate bigger granules with particles sizes of up to 60 mm at 300 r min–1. To keep outgassing to a minimum, it is suggested to melt shredder granulate first and then add shredder fibres. Adding coal, wood or tyre fluff as a third component reduces chlorine levels to less than 1 wt%. The best results can be achieved with tyre fluff. In combination with the VW-SICON-Process, ReGran produces a solid recovered fuel or ‘design fuel’ tailored to the requirements of specific thermal processes.
Dumping of municipal solid waste into uncontrolled dumpsites is the most common method of waste disposal in most cities of India. These dumpsites are posing a serious challenge to environmental quality and sustainable development. Mumbai, which generates over 9000 t of municipal solid waste daily, also disposes of most of its waste in open dumps. It is important to analyse the impact of municipal solid waste disposal today and what would be the impact under integrated waste management schemes. In this study, life cycle assessment methodology was used to determine the impact of municipal solid waste management under different scenarios. Six different scenarios were developed as alternatives to the current practice of open dumping and partially bioreactor landfilling. The scenarios include landfill with biogas collection, incineration and different combinations of recycling, landfill, composting, anaerobic digestion and incineration. Global warming, acidification, eutrophication and human toxicity were assessed as environmental impact categories. The sensitivity analysis shows that if the recycling rate is increased from 10% to 90%, the environmental impacts as compared with present scenario would reduce from 998.43 kg CO2 eq t–1 of municipal solid waste, 0.124 kg SO2 eq t–1, 0.46 kg PO4–3 eq t–1, 0.44 kg 1,4-DB eq t–1 to 892.34 kg CO2 eq t–1, 0.121 kg SO2 eq t–1, 0.36 kg PO4–3 eq t–1, 0.40 kg 1,4-DB eq t–1, respectively. An integrated municipal solid waste management approach with a mix of recycling, composting, anaerobic digestion and landfill had the lowest overall environmental impact. The technologies, such as incineration, would reduce the global warming emission because of the highest avoided emissions, however, human toxicity would increase.
The expressive generation of construction and demolition waste is stimulating several studies for reusing this material. The improvement of soft soils by concrete compaction piles has been widely applied for 40 years in some Brazilian cities. This technique is used to improve the bearing capacity of soft soils, allowing executing shallow foundations instead of deep foundations. The compaction piles use a high volume of material. This article explored the possibility of using recycled aggregates from construction waste to replace the natural aggregates in order to improve the bearing capacity of the soft soil, regarding its compressive strength. Construction wastes from different stages of a construction were used in order to make samples of concrete with recycled aggregates. The strength of concretes with natural aggregates was compared with the strength of concretes with recycled (fine and coarse) aggregates. Results show that all samples met the minimum compressive strength specified for compaction piles used to improve the bearing capacity of soft soils. The concrete with recycled aggregate from the structural stage had even higher resistances than the concrete with natural aggregates. This behaviour was attributed to the large amount of cementitious materials in the composition of this type of concrete. It was also observed that concrete with recycled fine aggregate has a superior resistance to concrete with recycled coarse aggregate.
Knowledge about the total waste generated by the production of consumer goods can help raise awareness among policy-makers, producers and consumers of the benefits of closing loops in a future circular economy, avoiding unnecessary production and production steps and associated generation of large amounts of waste. In strict life cycle assessment practice, information on waste outputs from intermediate industrial processes of material and energy transformation is translated into and declared as potential environmental impacts, which are often not reported in the final results. In this study, a procedure to extract available intermediate data and perform a systematic pre-consumer waste footprint analysis was developed. The pre-consumer waste footprint concept was tested to analyse 10 generic products, which provided some novel and interesting results for the different product categories and identified a number of challenges that need to be resolved in development of the waste footprint concept. These challenges include standardised data declaration on waste in life cycle assessment, with a separation into waste categories illustrating the implicit environmental and scale of significance of waste types and quantities (e.g. hazardous waste, inert waste, waste for recycling/incineration) and establishment of a common definition of waste throughout sectors and nations.
Bioreactor landfills use leachate recirculation to enhance the biodegradation of municipal solid waste and accelerate landfill stabilisation, which can provide significant environmental and economic benefits. Vertical wells are operated as a major method for leachate recirculation systems. The objectives of this article are to analyse the leachate migration in bioreactor landfills using vertical wells and to offer theoretical basis for the design of leachate recirculation systems. A three-dimensional numerical model was built using FLAC-3D, and this model can consider the saturated and unsaturated flow of leachate within anisotropic waste to reflect the actual conditions. First, main influence factors of leachate migration were analysed, including the vertical well height, hydraulic conductivity, and anisotropic coefficient, in a single-well recirculation system. Then, the effects of different configurations of a group-well system were studied and the optimal well spacing was obtained. Some key design parameters (e.g. the recirculation flow rate, volume of impact zone, radius of impact zone and time to reach steady state) were also evaluated. The results show that the hydraulic conductivity has a great impact on the optimal height of vertical wells and uniform configuration is the best option in terms of both volume of impact zone and time to reach steady state.
In a number of energy-poor nations, peel from cassava processing represents one of the most abundant sources of lignocellulosic biomass. This peel is mostly discarded indiscriminately and eventually constitutes a problem to the environment. However, energy can be extracted from this peel in a microbial fuel cell. In this study, the viability of cassava peel extract as a substrate in a single-chamber air cathode microbial fuel cell is demonstrated, and optimum performance conditions are explored. The effects of different pretreatments on the extract are also discussed in the context of observed changes in the internal resistances, conductivity and Coulombic efficiencies. At the best conditions examined, the extract from cassava peel fermented for 168 h and adjusted to a pH of 7.63 attained a peak voltage of 687 mV ± 21 mV, a power density of 155 mW m–3 of reactor volume and a Coulombic efficiency of 11 %. Although this energy is limited to direct use, systems exist that can effectively harvest and boost the energy to levels sufficient for supplementary energy usage in cassava producing regions.
Holistic environmental policies, which emerged from a mere combination of technical activities in waste management some 40 years ago, constitute the most advanced level of environmental policies. These approaches to environmental policy, among them the policies in integrated waste management, attempt to guide economic agents to an environment-friendly behaviour.
Nevertheless, current holistic policies in waste management, including policies on one-way drinks containers and waste electrical and electronic equipment, and implementations of extended producer responsibility with further applications to waste electrical and electronic equipment, reveal more or less severe deficiencies – despite some positive examples. This article relates these policy failures, which are not necessarily the result of an insufficient compliance with the regulations, to missing constitutive elements of what is going to be called an ‘integrated environmental policy’.
This article therefore investigates – mostly from a practical point of view – constitutive elements, which are necessary for a holistic policy to serve as a well-functioning allocation mechanism. As these constitutive elements result from a careful ‘integration’ of the environmental commodities into the economic allocation problems, we refer to these policies as ‘integrated environmental policies’. The article also discusses and illustrates the main steps of designing such a policy – for waste electrical and electronic equipment and a (possible) ban of Glyphosat in agriculture.
As these policies are dependent on economic and political stability with environmental awareness sufficiently developed, the article addresses mostly waste management policies in highly industrialised countries.
Material recycling of post-consumer bulk plastics made up of polyolefins is well developed. In this article, it is examined which effects on waste sorting and treatment processes influence the qualities of polyolefin-recyclats. It is shown that the properties and their changes during the product life-cycle of a polyolefin are defined by its way of polymerisation, its nature as a thermoplast, additives, other compound and composite materials, but also by the mechanical treatments during the production, its use where contact to foreign materials is possible and the waste sorting and treatment processes. Because of the sum of the effects influencing the quality of polyolefin-recyclats, conclusions are drawn for the material recycling of polyolefins to reach high qualities of their recyclats. Also, legal requirements like the EU regulation 1907/2006 concerning the registration, evaluation, authorisation and restrictions on chemicals are considered.
The availability and distribution of biomass resources are important for the development of the bioenergy industry in a region. Biomass resources are abundant in China; however, the raw material is severely deficient, which makes the Chinese bioenergy industry an embarrassment and a contradiction. Unclear reserves and distribution and changing trends of biomass resources are the reason for this situation. A collection coefficient model of Chinese agricultural residue resources was established and the spatial and temporal pattern dynamics of agricultural residue resources in the last 30 years were analyzed. The results show that agricultural residue resources increased in stages from 1978 to 2011, including a rapid increase from 1978 to 1999, a significant fall from 2000 to 2004, and a slow increase from 2004 to 2011. Crops straw and livestock manure are the main ingredients of agricultural residue resources with proportions of 53–59% and 31–38%, respectively. However, the former has gradually decreased, while the latter is increasing. This mainly resulted from the strategic reorganization of the Chinese agriculture structure and the rapid development of large-scale livestock breeding and agricultural mechanization. Large regional differences existed in Chinese agricultural residue resources, and three distribution types formed, including resource-rich areas in North China, Northeast and Inner Mongolia, resource-limited areas in Central and Southwest China, and resource-poor areas along Northwest and Southeast coasts. This pattern is a reverse of the distributions of climatic conditions, water resources, economic development, human resources, and technological levels. Finally, it can be predicted that livestock manure and biomass conversion technology at low temperature will play increasingly significant roles in bioenergy industry development.
In France, domestic waste production is estimated at c. 350 kg year–1 per person and landfilling still represents a predominant way of municipal solid waste management, with 39% of waste dumped in 2007. Waste characterization campaigns were conducted at different stages of a mechanical–biological treatment process in order to evaluate its efficiency. Waste samples were sorted by size (>100 mm, <100–20 mm and <20 mm) in order to assess the opportunity for mechanical and aerobic degradation and to reduce the volume of waste landfilled. The monitoring of parameter characteristics of waste stabilization highlighted a decrease in both organic matter and oxidizable organic matter, and an increase in fine particles <20 mm. The respirometric index after 4 days performed on waste samples from the pre-treatment stage showed a decrease in the biological activity compared with the samples taken upstream in the process. The biochemical methane potential of the waste is above the German limit of acceptance in landfills. This intermediate phase of stabilization is confirmed by the results of the leaching tests and hydrophobic fractionation.
The push for creating a more competitive and liberalized system for traditional public services, including waste management, has been on the European agenda since the late 1980s. In 2008, changes were made in EU waste legislation allowing source-separated industrial/commercial waste that is suitable for incineration to be traded within the European market. This change has had broad implications for the Danish waste sector, which is characterized by institutionalized municipal control with all streams of waste and municipal ownership of the major treatment facilities allowing the municipal sector to integrate combustible waste in local heat and power generation. This article, applying an institutional approach, maps the institutions and actors of the Danish waste sector and analyses how the regulatory as well as normative pressure to liberalize has been met and partly neutralized in the institutional and political context. The new Danish regulation of 2010 has thus accommodated the specific requirement for liberalization, but in fact only represents a very small step towards a market-based waste management system. On the one hand, by only liberalizing industrial/commercial waste, the Danish Government chose to retain the main features of the established waste system favouring municipal control and hence the institutionalized principles of decentralized enforcement of environmental legislation as well as welfare state considerations. On the other hand, this has led to a technological and financial deadlock, particularly when it comes to reaching the recycling targets of EU, which calls for further adjustments of the Danish waste sector.
Food waste is a stream that becomes increasingly important in terms of its prevention potential. There is a large number of behaviours that can be associated with food waste generation and the efforts towards food waste prevention. A questionnaire study was carried in order to study consumer behaviour related to food provision and wastage in Greece. Proper practices of the respondents that can prevent the generation of food waste were investigated using nine behavioural scales, which were defined on the basis of similar studies in other countries. A structured questionnaire was utilised in order to test those behaviours against the socio-demographic characteristics of respondents. The results of the study indicate that in terms of inferential statistical analysis, among the numerous variables examined, those that enhance food waste prevention are the involvement of the respondent in cooking, the annoyance towards food waste generation and the education level.
The present research studies the characterisation and the physico-chemical properties of an excavated fine fraction (<10 mm) from a Swedish landfill, the Högbytorp. The results showed that the fine fraction represents 38% by mass of the total excavated wastes and it contains mainly soil-type materials and minerals. Higher concentrations of zinc, copper, barium and chromium were found with concentrations higher than the Swedish Environmental Protection Agency (EPA) for contaminated soil. The found moisture and organic contents of the fine fraction were 23.5% and 16.6%, respectively. The analysed calorific value (1.7 MJ kg–1), the potential of CH4 (4.74 m3 t–1 dry matter) and Total Organic Carbon (TOC) (5.6%) were low and offer low potential of energy. Sieving the fine fraction further showed that 80% was smaller than 2 mm. The fine represents a major fraction at any landfill (40%–70%), therefore, characterising the properties of this fraction is essential to find the potential of reusing/recycling or safely redisposing.
It is important to determine the contaminant retention characteristics of materials when assessing their suitability for use as liners in landfill sites. Sand–bentonite mixtures are commonly used as liners in the construction of landfill sites for industrial and hazardous wastes. Sand is considered to be a passive material with a negligible chemical retention capacity; fly ash, however, offers the additional advantage of adsorbing the heavy metals present in landfill leachates. There have been few studies of the contaminant retention characteristics of fly ash–bentonite mixes. The study reported here determined the contaminant retention characteristics of different fly ashes, bentonite and selected fly ash–bentonite mixes for Pb2+ using 24 h batch tests. The tests were conducted by varying the initial concentrations of metal ions under uncontrolled pH conditions. The efficiency of the removal of Pb2+ by the different types of fly ash and fly ash–bentonite mixes was studied. The influence of multiple sources of fly ash on the retention characteristics of fly ash–bentonite mixes was investigated.
Pyrolysis is an attractive thermochemical conversion technology that may be utilised as a safe disposal option for acid tar waste. The kinetics of acid tar pyrolysis were investigated using thermogravimetry coupled with mass spectrometry under a nitrogen atmosphere at different heating rates of 10, 15 and 20 K min-1. The thermogravimetric analysis shows three major reaction peaks centred around 178 °C, 258 °C, and 336 °C corresponding to the successive degradation of water soluble lower molecular mass sulphonic acids, sulphonated high molecular mass hydrocarbons, and high molecular mass hydrocarbons. The kinetic parameters were evaluated using the iso-conversional Kissinger–Akahira–Sunose method. A variation in the activation energy with conversion revealed that the pyrolysis of the acid tar waste progresses through complex multi-step kinetics. Mass spectrometry results revealed a predominance of gases such as hydrogen, methane and carbon monoxide, implying that the pyrolysis of acid tar waste is potentially an energy source. Thus the pyrolysis of acid tar waste may present a viable option for its environmental treatment. There are however, some limitations imposed by the co-evolution of corrosive gaseous components for which appropriate considerations must be provided in both pyrolysis reactor design and selection of construction materials.
In recent years, increased light has been shed on the large amounts of food wasted along the food supply chain (FSC). As lifecycle assessments (LCAs) are commonly used for estimations of environmental impacts from food production, it is relevant to investigate and discuss how such wastage is reflected in foodstuff LCAs. The objective of the present paper is to review a larger set of LCAs of foodstuff in order to (1) investigate if and how wastage along the FSC is addressed and (2) explore the importance of including wastage accumulated along the FSC in terms of environmental impacts. Twenty-eight LCA case studies and two review papers, focusing on tomatoes, were reviewed and greenhouse gas (GHG) emissions chosen as indicator for the second objective. Only one third of the studies consider wastage at some part of the supply chain, in many cases in an inconsistent manner, and only in nine cases were GHG emissions from wastage included in overall systems GHG emissions. In these, wastage accounts for between 2 and 33% of total contribution to climate change. Omitting wastage when conducting LCA of foodstuff could result in underestimations of environmental impacts. Occurrence of wastage along all phases of the supply chain should be acknowledged in order to estimate environmental benefits from prevention and to identify areas where strategies with the aim of reducing wastage could be most efficient.
An often suggested method for waste prevention is substitution of currently-used materials with materials which are less bulky, contain less hazardous components or are easier to recycle. For policy makers it is important to have tools available that provide information on the impact of this substitution on the changes in total amounts of waste generated and managed. The purpose of this paper is to see how much changes in the mix of 15 waste streams generated in eight economic sectors from 30 European countries have influenced the amounts of waste generated and managed in the period 2004–2012. In order to determine these impacts, two variations of the logarithmic mean Divisia index (LMDI) analysis model were developed and applied. The results show that the changes in the mix of waste streams in most cases did not have a considerable influence on the changes in the amounts of generated waste. In the analyses of waste sent for landfill, incineration without energy recovery, incineration with energy recovery and recovery other than energy recovery, the results also show that the changes in the mix of waste streams in most cases did not have the expected/desired influence on the changes in the amounts of managed waste. This paper provides an example on the possibilities of applying the LMDI analysis as a tool for quantifying the potential of effects which implemented or planned measures could have on the changes in waste management systems.
Government agencies have implemented regulations to reduce the volume of waste electrical and electronic equipment to protect the environment and encourage recycling. The effectiveness of systems through which waste electrical and electronic equipment is collected and recycled depends on (a) the development and operation of new programmes to process this material and (b) on information dissemination programmes aimed at manufacturers, retail sellers, and the consuming public. This study analyses these two elements. The main focus is to better understand household residents’ behaviour in regards to the proper methods of handling waste electrical and electronic equipment and possible storage of the obsolete equipment that brings disturbances with collection of the waste equipment. The study explores these issues depending on size of municipality and the household residents’ knowledge about legal methods of post-consumer management of waste electrical and electronic equipment in Poland, where the collection rate of that type of waste is about 40% of the total mass of waste electrical and electronic equipment appearing in the market.
The research was informed by various sources of information, including non-government organisations, Inspectorate of Environmental Protection and Central Statistics Office in Poland, questionnaires, and interviews with the household residents. The questionnaires were distributed to daytime and vocational students from different universities and the customers of an electronic equipment superstore. The results show that a resident’s behaviour in regards to the handling of obsolete waste electrical and electronic equipment can significantly reduce the collection rate, especially when the waste is discarded improperly – mixed with municipal waste or sold in scrapyards. It is possible to identify points that are necessary to be improved to achieve a higher collection rate.
Lagos is one of the fastest growing cities in Africa, which is grappling with the challenges of poorly managed urbanisation. With an estimated population of about 17.5 million, solid waste management is one of the most pressing environmental challenges currently faced in the city. It is estimated that more than 9071847.4kg of urban waste is generated every day in the city. The city lacks the capacity to deal with such magnitude of waste. Consequently, the city has involved the private sector (private sector participation) in its waste management drive. This article examines the effectiveness of this public–private sector collaboration model in waste management in informal settlements in Lagos using empirical data. Major findings of the article include the irregularity of waste collection owing to a poor road network, an inadequate transport infrastructure and the desire to maximise profit, as well as poor waste handling and disposal methods by the private sector participation operators who are not chosen based on competence and capacity to perform. Another major finding is the lack of cooperation from residents evidenced in non-payment of bills and poor packaging of wastes, resulting in wastes being littered. The article concludes on the need to restructure the scheme through proper sensitisation of residents, selection of operators with demonstrable delivery capacity and provision of a well-maintained road network to facilitate access of operators to settlements.
Vulnerability assessment of simple landfills was conducted using the multimedia, multipathway and multireceptor risk assessment (3MRA) model for the first time in China. The minimum safe threshold of six contaminants (benzene, arsenic (As), cadmium (Cd), hexavalent chromium [Cr(VI)], divalent mercury [Hg(II)] and divalent nickel [Ni(II)]) in landfill and waste pile models were calculated by the 3MRA model. Furthermore, the vulnerability indexes of the six contaminants were predicted based on the model calculation. The results showed that the order of health risk vulnerability index was As > Hg(II) > Cr(VI) > benzene > Cd > Ni(II) in the landfill model, whereas the ecology risk vulnerability index was in the order of As > Hg(II) > Cr(VI) > Cd > benzene > Ni(II). In the waste pile model, the order of health risk vulnerability index was benzene > Hg(II) > Cr(VI) > As > Cd and Ni(II), whereas the ecology risk vulnerability index was in the order of Hg(II) > Cd > Cr(VI) > As > benzene > Ni(II). These results indicated that As, Hg(II) and Cr(VI) were the high risk contaminants for the case of a simple landfill in China; the concentration of these in soil and groundwater around the simple landfill should be strictly monitored, and proper mediation is also recommended for simple landfills with a high concentration of contaminants.
Landfilling is the most preferred solid waste disposal method in Turkey owing to both economic and technical reasons. However, beside the sanitary landfills there are also hundreds of uncontrolled waste sites located throughout Turkey, which are often left either abandoned or burning. Because there is a lack of legislative guidelines governing the closure and rehabilitation of these dumpsites, the municipalities that are responsible for waste management do not initiate the proactive strategies required for the closure of these sites. In this study, a method based on a multi-criteria analysis is conducted for different dumpsites in Turkey to evaluate the level of negative impacts on the environment. This method is based on the use of environmental indices for a quantitative assessment of the landfills, such as environmental interaction between the source and the receptors, environmental values of the receptors, and operational conditions. It was possible to assess the robustness of the proposed methodology since the pre- and post-groundwater quality monitoring data was available from the study sites that were closed and rehabilitated in 2014. The results of this study show that the method based on a multi-criteria analysis is an effective tool while in the preliminary planning stages of closure and rehabilitation activities of uncontrolled waste landfills.
Construction and demolition waste continues to sharply increase in step with the economic growth of less developed countries. Though the construction industry is large, it is composed of small firms with individual waste management practices, often leading to the deleterious environmental outcomes. Quantifying construction and demolition waste generation allows policy makers and stakeholders to understand the true internal and external costs of construction, providing a necessary foundation for waste management planning that may overcome deleterious environmental outcomes and may be both economically and environmentally optimal. This study offers a theoretical method for estimating the construction and demolition project waste generation rate by utilising available data, including waste disposal truck size and number, and waste volume and composition. This method is proposed as a less burdensome and more broadly applicable alternative, in contrast to waste estimation by on-site hand sorting and weighing. The developed method is applied to 11 projects across Malaysia as the case study. This study quantifies waste generation rate and illustrates the construction method in influencing the waste generation rate, estimating that the conventional construction method has a waste generation rate of 9.88 t 100 m–2, the mixed-construction method has a waste generation rate of 3.29 t 100 m–2, and demolition projects have a waste generation rate of 104.28 t 100 m–2.
In Macao, about 7200 t yr–1 of bottom ash (BA) is generated and conventionally landfilled with construction waste. Because the properties of BA are similar to those of natural aggregates, it is suitable to be recycled as construction material. However, pre-treatment processes for BA reuse may require more resource input and may generate additional environmental impacts. Life cycle assessment, multi-media transport model analysis, cost–benefit analysis and the analytical hierarchy process were conducted to evaluate the impacts of current and potential BA management scenarios regarding environmental, economic, social and regulatory aspects. The five analysed scenarios are as follows: (0) BA buried with construction and demolition waste (current system); (1) pre-treated BA used to replace 25% of the natural aggregate in asphalt concrete; (2) pre-treated BA used to replace 25% of the natural aggregate in cement concrete; (3) pre-treated BA used to replace 25% of cement in cement concrete; and (4) pre-treated BA sent to China, blended with municipal solid waste for landfill. The results reveal the following ranking of the scenarios: 3 > 2 > 0 > 1 > 4. Scenario 3 shows the best conditions for BA recycling, because the quantity of cement concrete output is the highest and this brings the greatest economic benefits. Our use of integrated analysis provides multi-aspect investigations for BA management systems, particularly in accounting for site-specific characteristics. This approach is suitable for application in other non-western regions.
Solid waste management is a complex domain involving the interaction of several dimensions; thus, its analysis and control impose continuous challenges for decision makers. In this context, multi-criteria decision-making models have become important and convenient supporting tools for solid waste management because they can handle problems involving multiple dimensions and conflicting criteria. However, the selection of the multi-criteria decision-making method is a hard task since there are several multi-criteria decision-making approaches, each one with a large number of variants whose applicability depends on information availability and the aim of the study. Therefore, to support researchers and decision makers, the objectives of this article are to present a literature review of multi-criteria decision-making applications used in solid waste management, offer a critical assessment of the current practices, and provide suggestions for future works. A brief review of fundamental concepts on this topic is first provided, followed by the analysis of 260 articles related to the application of multi-criteria decision making in solid waste management. These studies were investigated in terms of the methodology, including specific steps such as normalisation, weighting, and sensitivity analysis. In addition, information related to waste type, the study objective, and aspects considered was recorded. From the articles analysed it is noted that studies using multi-criteria decision making in solid waste management are predominantly addressed to problems related to municipal solid waste involving facility location or management strategy.
Existing waste disposal sites are being strained by exceeding their volumetric capacities because of exponentially increasing rates of municipal solid waste generation worldwide, especially in densely populated metropolises. Over the past 40 years, six well-documented and analyzed disposal sites experienced catastrophic failure. This research presents a novel analysis and design method for implementation of a series of in-situ earth berms to slow down the movement of waste material flow following a catastrophic failure. This is the first study of its kind that employs a dynamic landslide analysis model, DAN-W, and the Voellmy rheological model to approximate solid waste avalanche flow. A variety of single and multiple berm configuration scenarios were developed and tested to find an optimum configuration of the various earth berm geometries and number of berms to achieve desired energy dissipation and reduction in total waste material runout length. The case study application of the novel mitigation measure shows that by constructing a series of six relatively inexpensive 3 m high earth berms at an optimum distance of 250 m from the slope toe, the total runout length of 1000 m and associated fatalities of the Leuwigajah dumpsite catastrophic failure in Bandung, Indonesia, could have been reduced by half.
The effect of six additives (CaCO3, HZSM-5, CaO, Al2O3, FeOOH and Ca(OH)2) on the generation, migration, transformation and escaping behaviours of typical gaseous pollutants in the pyrolysis process were studied by vacuum pyrolysis experiments on epoxy resin powder from waste printed circuit boards with tube furnace. The results show that the additives Al2O3, CaO, Ca(OH) 2 and FeOOH could reduce the yield of the gas phase. The removal rates of pollutants, such as benzene, toluene, ethyl benzene, phenol, p-xylene, HBr, NO2 and SO2 in the gaseous products, has changed variously with the increasing percentage of the above additives. Judging from the control of gas-phase pollutant discharge, the calcium-base additives are superior to the others. Ca(OH)2 has the best inhibition effect among them. The increase of the pyrolysis temperature and vacuum degree enhanced the volatility of organic pollutants and weakened the Ca(OH)2 inhibition effect on organic pollutants, while it improved the removal rate of SO2. Under the condition of 500 °C pyrolysis temperature and 0.09 MPa vacuum degree, when the additive proportion of Ca(OH)2 was one-fifth, the average removal rate of pollutants in gas phase is up to 66.4%.
This study employed a set of quantitative criteria to analyse the three parameters; namely policy, process, and practice; of the respective e-waste management systems adopted in Thailand, Laos, and China. Questionnaire surveys were conducted to determine the current status of the three parameters in relation to mobile phones. A total of five, three, and six variables under Policy (P1), Process (P2), and Practice (P3), respectively, were analysed and their weighted averages were calculated. The results showed that among the three countries surveyed, significant differences at p<0.01 were observed in all the P1, P2, and P3 variables, except P305 (sending e-waste to recovery centres) and P306 (treating e-waste by retailers themselves). Based on the quantitative method developed in this study, Laos’ e-waste management system received the highest scores in both P1 average (0.130) and P3 average (0.129). However, in the combined Ptotal, China scored the highest (0.141), followed by Laos (0.132) and Thailand (0.121). This method could be used to assist decision makers in performing quantitative analysis of complex issues associating with e-waste management in a country.
The pyrolytic characteristics of tyre powder treated under different microwave powers (300, 500, and 700 W) were studied via microwave thermogravimetric analysis. The product yields at different power levels were studied, along with comparative analysis of microwave pyrolysis and conventional pyrolysis. The feedstock underwent preheating, intense pyrolysis, and final pyrolysis in sequence. The main and secondary weight loss peaks observed during the intense pyrolysis stage were attributed to the decomposition of natural rubbers and synthetic rubbers, respectively. The total mass loss rates, bulk temperatures, and maximum temperatures were distinctively higher at higher powers. However, the maximum mass loss rate (0.005 s-1), the highest yields of liquid product (53%), and the minimum yields of residual solid samples (43.83%) were obtained at 500 W. Compared with conventional pyrolysis, microwave pyrolysis exhibited significantly different behaviour with faster reaction rates, which can decrease the decomposition temperatures of both natural and synthetic rubber by approximately 110 °C–140 °C.
Waste management is an important issue all over the world and it will become even more urgent in the near future due to the increase of global volumes of waste. Waste prevention is at the top of the European waste hierarchy, followed by reuse, recycling, other recovery (including energy recovery), and safe disposal. In Italy, municipalities are the authorities that concretely choose the prevention actions to be applied in their territory and therefore they are crucial in promoting a decrease in waste amounts. In our research we investigated costs and benefits of prevention actions in three small municipalities in the north of Italy. We found that the "Pay as You Throw" (PAYT) scheme is an effective action in preventing waste production, with many instances, on analyzing the collection data. The specific effect of the other actions (such as the awareness raising campaigns) is difficult to isolate, even if we found positive impacts. We analyzed some external drivers, such as the migration effect, in order to understand the real effectiveness of the implemented actions. One of the objectives of the study was to comprehend the consequences of political choices at a bigger scale than the individual municipality. Analyzing the results obtained in three typical small Italian municipalities, this study suggests that local authorities, with their choices, can greatly affect the efficacy of selected waste collection and waste prevention.
Today, the impending stringent environmental norms and concerns about the depletion of fossil fuel reserves have added impetus on development of cutting edge technologies for production of alternative fuels from renewable sources, like biomass. The concept of biomass pyro-gasification offers a platform for production of (a) hydrogen, (b) hydrocarbons and (c) value added chemicals, etc. In this context, there exists potential for hydrogen production from biomass by superheated steam gasification. Apart from H2, gaseous products of biomass steam gasification contain CO, CH4 and other hydrocarbons that can be converted to hydrogen through cracking, steam reforming and water gas shift reactions. In the present work, the characteristics of biomass steam gasification in an indigenously designed rotary tubular coiled-downdraft reactor for high value gaseous fuel production from rice husk was studied through a series of experiments. The robust reactor system enhances biomass conversion to gaseous products by improved mass and heat transfer within the system induced by a coiled flow pattern with increased heat transfer area. Also, the system has improved upon the reliability of operation and offered greater continuity of the process and easier control in comparison with a conventional process by making use of an innovative gas cooler assembly and efficient venturi-mixing system for biomass and steam. Subsequently, the effects of reactor temperature, steam-to-biomass ratio and residence time on overall product gas yield and hydrogen yield were investigated. From the experimental results, it can be deduced that an optimum reactor temperature of 750 °C, steam-to-biomass ratio of 2.0 and a residence time of 3.0 min contributed highest gas yield (1.252 Nm3 kg-1 moisture-free biomass). Based on the obtained experimental results, a projected potential hydrogen yield of 8.6 wt% of the moisture-free biomass could be achieved, and is also practical for production of pure hydrogen.
This study highlights the economic and environmental challenges of recycling in Ontario, specifically examining the effect of attempting to increase the emissions target for the province’s household recycling programme. The findings from the cost model analysis found that Ontario’s Blue Box programme reduces overall carbon emissions by approximately 1.8 million tonnes every year. This study also found that targeting specific materials for recovery could result in a scenario where the province could improve both overall diversion and emissions offsets while reducing material management costs. Under our modelled scenario, as the tonnes of greenhouse gases (GHGs) avoided increases, the system cost per tonne of GHG avoided initial declines. However, after avoiding 2.05 million tonnes of GHGs, the system cost/tonne GHG avoided increases. To achieve an emissions target in excess of 2.05 million tonnes, the province will have to start recycling higher cost non-core materials (composite materials, other plastics, etc.).
Open municipal solid waste (MSW)-burning is a major source of particulate matter emissions in developing world cities. Despite a legal ban, MSW-burning is observed ubiquitously in Indian cities with little being known about the factors shaping it. This study seeks to uncover social and infrastructural factors that affect MSW-burning at the neighborhood level. We couple physical assessments of the infrastructure provision and the MSW-burning incidences in three different neighborhoods of varying socio-economic status in Delhi, with an accompanying study of the social actors (interviews of waste handlers and households) to explore the extent to which, and potential reasons why, MSW-burning occurs. The observed differences in MSW-burning incidences range from 130 km–2 day–1 in low-income to 30 km–2 day–1 in the high-income areas. However, two high-income areas neighborhoods with functional infrastructure service also showed statistical differences in MSW-burning incidences. Our interviews revealed that, while the waste handlers were aware of the health risks associated with MSW-burning, it was not a high priority in the context of the other difficulties they faced. The awareness of the legal ban on MSW-burning was low among both waste handlers and households. In addition to providing infrastructure for waste pickup, informal restrictions from residents and neighborhood associations can play a significant role in restricting MSW-burning at the neighborhood scale. A more efficient management of MSW requires a combined effort that involves interplay of both social and infrastructural systems.
In household waste matters, the objective is always to conceive an optimal integrated system of management, where the terms ‘optimal’ and ‘integrated’ refer generally to a combination between the waste and the techniques of treatment, valorization and elimination, which often aim at the lowest possible cost. The management optimization of household waste using operational methodologies has not yet been applied in any Algerian district. We proposed an optimization of the valorization of household waste in Tiaret city in order to lower the total management cost. The methodology is modelled by non-linear mathematical equations using 28 variables of decision and aims to assign optimally the seven components of household waste (i.e. plastic, cardboard paper, glass, metals, textiles, organic matter and others) among four centres of treatment [i.e. waste to energy (WTE) or incineration, composting (CM), anaerobic digestion (ANB) or methanization and landfilling (LF)]. The analysis of the obtained results shows that the variation of total cost is mainly due to the assignment of waste among the treatment centres and that certain treatment cannot be applied to household waste in Tiaret city. On the other hand, certain techniques of valorization have been favoured by the optimization. In this work, four scenarios have been proposed to optimize the system cost, where the modelling shows that the mixed scenario (the three treatment centres CM, ANB, LF) suggests a better combination of technologies of waste treatment, with an optimal solution for the system (cost and profit).
The objective of this study was to assess the limonene removal efficiency of three pre-treatment methods when applied to citrus waste and to evaluate their effects on the biochemical methane potential and the methane production rate using batch anaerobic tests. The methods tested were based on removal (biological pretreatment by fungi) or recovery (steam distillation and ethanol extraction) of limonene. All the treatments decreased the concentration of limonene in orange peel, with average efficiencies of 22%, 44% and 100% for the biological treatment, steam distillation and ethanol extraction, respectively. By-products from limonene biodegradation by fungi exhibited an inhibitory effect also, not making interesting the biological pretreatment. The methane potential and production rate of the treated orange peel increased significantly after applying the recovery strategies, which separated and recovered simultaneously other inhibitory components of the citrus essential oil. Apart from the high recovery efficiency of the ethanol extraction process, it presented a favourable energy balance.
Vertical liquids addition systems have been used at municipal landfills as a leachate management method and to enhance biostabilization of waste. Drawbacks of these systems include a limitation on pressurized injection and the occurrence of seepage. A novel vertical well system that employed buried wells constructed below a lift of compacted waste was operated for 153 days at a landfill in Florida, USA. The system included 54 wells installed in six clusters of nine wells connected with a horizontally-oriented manifold system. A cumulative volume of 8430 m3 of leachate was added intermittently into the well clusters over the duration of the project with no incidence of surface seeps. Achievable average flow rates ranged from 9.3 x 10–4 m3 s–1 to 14.2 x 10–4 m3 s–1, which was similar to or greater than flow rates achieved in a previous study using traditional vertical wells at the same landfill site. The results demonstrated that pressurized liquids addition in vertical wells at municipal solid waste landfills can be achieved while avoiding typical operational and maintenance issues associated with seeps.
Although thermal recovery of waste plastics is widely practiced in many European countries, reliable information on the amount of waste plastics in the feed of waste-to-energy plants is rare. In most cases the amount of plastics present in commingled waste, such as municipal solid waste, commercial, or industrial waste, is estimated based on a few waste sorting campaigns, which are of limited significance with regard to the characterisation of plastic flows. In the present study, an alternative approach, the so-called Balance Method, is used to determine the total amount of plastics thermally recovered in Austria’s waste incineration facilities in 2014. The results indicate that the plastics content in the waste feed may vary considerably among different plants but also over time. Monthly averages determined range between 8 and 26 wt% of waste plastics. The study reveals an average waste plastics content in the feed of Austria’s waste-to-energy plants of 16.5 wt%, which is considerably above findings from sorting campaigns conducted in Austria. In total, about 385 kt of waste plastics were thermally recovered in all Austrian waste-to-energy plants in 2014, which equals to 45 kg plastics cap-1. In addition, the amount of plastics co-combusted in industrial plants yields a total thermal utilisation rate of 70 kg cap-1 a-1 for Austria. This is significantly above published rates, for example, in Germany reported rates for 2013 are in the range of only 40 kg of waste plastics combusted per capita.
Biogas production from food waste has been used as an efficient waste treatment option for years. The methane yields from decomposition of waste are, however, highly variable under different operating conditions. In this study, a statistical experimental design method (Taguchi OA9) was implemented to investigate the effects of simultaneous variations of three parameters on methane production. The parameters investigated were solid content (SC), carbon/nitrogen ratio (C/N) and food/inoculum ratio (F/I). Two sets of experiments were conducted with nine anaerobic reactors operating under different conditions. Optimum conditions were determined using statistical analysis, such as analysis of variance (ANOVA). A confirmation experiment was carried out at optimum conditions to investigate the validity of the results. Statistical analysis showed that SC was the most important parameter for methane production with a 45% contribution, followed by F/I ratio with a 35% contribution. The optimum methane yield of 151 l kg–1 volatile solids (VS) was achieved after 24 days of digestion when SC was 4%, C/N was 28 and F/I were 0.3. The confirmation experiment provided a methane yield of 167 l kg–1 VS after 24 days. The analysis showed biogas production from food waste may be increased by optimization of operating conditions.
In Austria, the first basic technological and economic examinations of mass-waste landfills with the purpose to recover secondary raw materials have been carried out by the ‘LAMIS – Landfill Mining Österreich’ pilot project. A main focus of its research, and the subject of this article, is the first conceptual design of a comprehensive assessment method for landfill mining plans, including not only monetary factors (like costs and proceeds) but also non-monetary ones, such as the concerns of adjoining owners or the environmental impact. Detailed reviews of references, the identification of influences and system boundaries to be included in planning landfill mining, several expert workshops and talks with landfill operators have been performed followed by a division of the whole assessment method into preliminary and main assessment. Preliminary assessment is carried out with a questionnaire to rate juridical feasibility, the risk and the expenditure of a landfill mining project. The results of this questionnaire are compiled in a portfolio chart that is used to recommend, or not, further assessment. If a detailed main assessment is recommended, defined economic criteria are rated by net present value calculations, while ecological and socio-economic criteria are examined in a utility analysis and then transferred into a utility-net present value chart. If this chart does not support making a definite statement on the feasibility of the project, the results must be further examined in a cost-effectiveness analysis. Here, the benefit of the particular landfill mining project per capital unit (utility-net present value ratio) is determined to make a final distinct statement on the general benefit of a landfill mining project.
The increase in the quantity of municipal solid waste generated as a result of population growth in most urban areas has resulted in the difficulty of locating suitable land areas to be used as landfills. To curb this, waste transfer stations are used. The Kumasi Metropolitan Area, even though it has an engineered landfill, is faced with the problem of waste collection from the generation centres to the final disposal site. Thus in this study, multi-criteria decision analysis incorporated into a geographic information system was used to determine potential waste transfer station sites. The key result established 11 sites located within six different sub-metros. This result can be used by decision makers for site selection of the waste transfer stations after taking into account other relevant ecological and economic factors.
All available data on asbestos consumption in Australia were collated in order to determine the most common asbestos-containing materials remaining in the built environment. The proportion of asbestos contained within each material and the types of products these materials are most commonly found in was also determined. The lifetime of these asbestos containing products was estimated in order to develop a model that projects stocks and flows of asbestos products in Australia through to the year 2100. The model is based on a Weibull distribution and was built in an excel spreadsheet to make it user-friendly and accessible. The nature of the products under consideration means both their asbestos content and lifetime parameters are highly variable, and so for each of these a high and low estimate is presented along with the estimate used in the model. The user is able to vary the parameters in the model as better data become available.
This paper aims to ascertain the efficacy and acceptability of five incentive schemes for the take-back of waste electrical and electronic equipment in Portugal, focusing in consumers’ perspectives. It assesses users’ perception of these items, evaluating the motivations and interests they have concerning the market of waste electrical and electronic equipment. Results indicate, on one hand, a lack of awareness by consumers about the process of take-back of their equipment. On the other hand, results show that information conditions and socio-demographic factors affect consumers’ motivations for returning the electrical and electronic equipment at the end of life. In this context, it can be concluded that, in Portugal, the market for the recovery of waste electrical and electronic equipment is still in its infancy.
The European Union hosts some of the world’s most developed waste management systems and an ambitious policy commitment to the circular economy. The existence of informal recycling and re-use activities in Europe has been vigorously denied until quite recently, and remains a very challenging subject for the European solid waste management sector, as well as for European government and private institutions. In countries ranging from Malta to Macedonia and from France to Turkey, informal recyclers excluded from legal recycling niches increasingly collide with formalised and controlled European Union approaches to urban waste management, packaging recovery schemes, formal re-use enterprises, and extended producer responsibility systems.
This review focuses on the period from 2004 through the first half of 2016. The 78 sources on European (and neighbouring) informal recycling and re-use are contextualised with global sources and experience. The articles focus on informal recovery in and at the borders of the European Union, document the conflicts and collisions, and elaborate some constructive approaches towards legalisation, integration, and reconciliation. The overarching recommendation, to locate the issue of informal recovery and integration in the framework of the European circular economy package, is supported by four specific pillars of an integration strategy: Documentation, legalisation, occupational and enterprise recognition, and preparation for structural integration.
The design of waste management systems rarely accounts for the spatio-temporal evolution of the demand. However, recent studies suggest that this evolution affects the planning of waste management activities like the choice and location of treatment facilities. As a result, the transport structure could also be affected by these changes. The objective of this paper is to study the influence of the spatio-temporal evolution of the demand on the strategic planning of a waste transport structure. More particularly this study aims at evaluating the effect of varying spatial parameters on the economic performance of hierarchical structures (with one transfer station). To this end, three consecutive generations of three different spatial distributions were tested for hierarchical and non-hierarchical transport structures based on costs minimization. Results showed that a hierarchical structure is economically viable for large and clustered spatial distributions. The distance parameter was decisive but the loading ratio of trucks and the formation of clusters of sources also impacted the attractiveness of the transfer station. Thus the territories’ morphology should influence strategies as regards to the installation of transfer stations. The use of spatial-explicit tools such as the transport model presented in this work that take into account the territory’s evolution are needed to help waste managers in the strategic planning of waste transport structures.
Brazil, as a result of economic development and strengthening of the construction industry in recent years, is generating an increasing amount of construction and demolition waste (CDW). Hence, environmental assessment of the management systems is vital. A life cycle assessment (LCA) is presented of CDW management in a medium-sized municipality located in the southeast region of Brazil, where the impacts of leaching were not considered due to absence of consistent data. Six different proposed scenarios for the current CDW management situation have been considered. These scenarios comprised the combined use of landfilling, sorting, and recycling, and the use of CDW as paving material for landfill roads, in different percentages. Considering 0.8 ton of waste as the functional unit, the life cycle inventory was performed using primary data obtained from field survey and secondary data from the database Ecoinvent version 3.1, and from the literature. The method CML 2 baseline 2001 was used for environmental impacts evaluation. The results highlight that recycling is beneficial when efficient CDW sorting takes place at construction sites, avoiding the transport of refuse to sorting and recycling facilities, and the distance between the generation source and the recycling unit is within 30 km. Thus, our results are helpful to ensure that the decision-making processes are based on environmental and technical aspects, and not only on economic and political factors, and also provide data and support for other LCA studies on CDW.
The usage of old equipment (over 10-year-old diesel-fuelled waste collection vehicles, WCVs) for municipal solid waste (MSW) collection in Ludbreg for longer than a decade has had a negative environmental impact, which has been reduced by replacing an old diesel WCV with a new diesel WCV. This study aims to assess the share of air emissions of two old WCVs (FAP 1990 and MAN 2003) and one new (MAN 2015), expressed in CO2 emissions. In addition, these vehicles have been found easily to reach the limit of 100 dB, which can cause hearing damage in their surroundings. Furthermore, their average fuel consumption is more than 80 l per 100 km, which makes them ineffective in terms of fuel consumption. Generally, higher fuel consumption results in more emissions and for a more eco-friendly operation, the MAN 2003 from Ludbreg WCV fleet should be technically amended and adjusted, and the FAP 1990 should be retired. Although the MAN 2015 is diesel fuelled, the best solution for replacement, according to Maimoun et al. (Waste Management 33: 1079–1089, 2016), would be the use of hydraulic-hybrid vehicles, which provide the best environmental benefits over other alternatives. According to Maimoun et al., hybrid is better environmentally, diesel is the best environmental–economical option and landfill gas-sourced natural gas is the best alternative when accessible because it significantly (up to 80%) reduces emissions of hazardous gases as well as noise levels (50–98%).
Those responsible for developing sustainable solid waste management programmes must consider the impacts of programme elements on everyone involved. This paper focuses on identifying the effects of waste management activities and assessing their overall impact on stakeholders. Collaborating with four focus groups and 36 experts, 19 effects were identified and nine questionnaires were designed to evaluate them, one for each stakeholder group. All told, 1805 people took part in the survey. The results show that the effects most important to the survey participants are: (a) recycling solid urban waste, (b) pollution and (c) corporate social responsibility.
The politically preferred solution to fulfil legal recycling demands is often implementing separate collection systems. However, experience shows their limitations, particularly in urban centres with a high population density. In response to the European Union landfill directive, mechanical biological waste treatment plants have been installed all over Europe. This technology makes it possible to retrieve plastic waste from municipal solid waste. Operators of mechanical biological waste treatment plants, both in Germany and the Netherlands, have started to change their mechanical separation processes to additionally produce plastic pre-concentrates. Results from mechanical biological waste treatment and separate collection of post-consumer packaging waste will be presented and compared. They prove that both the yield and the quality of plastic waste provided as feedstock for the production of secondary plastic raw material are largely comparable. An economic assessment shows which conditions for a technical sorting plant are economically attractive in comparison to separate collection systems. It is, however, unlikely that plastic recycling will ever reach cost neutrality.
Local waste management has so far been characterised by end-of-pipe solutions, landfilling, incineration, and recycling. End-of-pipe solutions build on a different mind-set than life cycle-based approaches, and for this reason, local waste managers are reluctant to consider strategies for waste prevention. To accelerate the transition of waste and resource management towards a more integrated management, waste prevention needs to play a larger role in the local waste management. In this review article, we collect knowledge from the scientific community on waste prevention of relevance to local waste management. We analyse the trends in the waste prevention literature by organising the literature into four categories. The results indicate an increasing interest in waste prevention, but not much literature specifically concerns the integration of prevention into the local waste management. However, evidence from the literature can inform local waste management on the prevention potential; the environmental and social effects of prevention; how individuals in households can be motivated to reduce waste; and how the effects of prevention measures can be monitored. Nevertheless, knowledge is still lacking on local waste prevention, especially regarding the methods for monitoring and how local waste management systems can be designed to encourage waste reduction in the households. We end the article with recommendations for future research. The literature review can be useful for both practitioners in the waste sector and for academics seeking an overview of previous research on waste prevention.
Brazil, Russia, India, China and South Africa (BRICS) nations account for one-quarter of the world’s land area, having more than 40% of the world’s population, and only one-quarter of the world gross national income. Hence the study and review of waste electrical and electronic equipment management systems in BRICS nations is of relevance. It has been observed from the literature that there are studies available comparing two or three country’s waste electrical and electronic equipment status, while the study encompassing the BRICS nations considering in a single framework is scant. The purpose of this study is to analyse the existing waste electrical and electronic equipment management systems and status of compliance to Basel convention in the BRICS nations, noting possible lessons from matured systems, such as those in the European Union EU) and USA. The study introduced a novel framework for a waste electrical and electronic equipment management system that may be adopted in BRICS nations and revealed that BRICS countries have many similar types of challenges. The study also identified some significant gaps with respect to the management systems and trans-boundary movement of waste electrical and electronic equipment, which may attract researchers for further research.
Waste collection and transport can generate up to 70% of the total costs of the system. Separated collection of recyclables implies additional costs for which the sale of recycled waste often does not compensate, but there is increased pressure to reach the long-term recycling objectives set by law. The proper estimation and monitoring of waste collection costs are essential to define the most cost-effective waste collection system. The aim of this study is to propose and implement a management tool to determine waste collection costs for different waste collection schemes. Based on input data, such as waste quantity and composition, the number of waste bins, the location of collection points, the type of collection vehicle, crew, collection route, etc., the developed tool can calculate the time and costs of waste collection (per vehicle, collection point or tonne of collected waste). This tool uses Excel spreadsheets and it was tested on a district in the central area of the city of Kragujevac to calculate the costs of waste collection for two scenarios: Collecting all waste as mixed waste, and collecting separately recyclables and residual waste. The developed tool can be useful for municipal solid waste management companies, since it allows benchmarking and variance analysis.
Trametes versicolor is a white-rot fungus known to be efficient in lignin removal due to its complex extracellular lignocellulolytic enzymatic system. Therefore, it can be used in the treatment of lignocellulose waste from agro, food, and wood industries. In a first experiment, corn forage treatment with T. versicolor was investigated in laboratory jars. In a second experiment, the process was scaled up to a tray bioreactor. In the tray bioreactor, the process of lignin degradation was improved, resulting in an increase in lignin conversion of up to 71% during seven days’ treatment.
The aim of this study was to investigate the possibility of measuring methane emission fluxes, using surface methane concentration and gauge pressure, by analyzing the influence of gauge pressure on the methane emission flux and the surface methane concentration, as well as the correlation between the methane emission flux and surface methane concentrations. The surface methane concentration was measured using a laser methane detector. Our results show a positive linear relationship between the surface methane concentration and the methane emission flux. Furthermore, the methane emission flux showed a positive linear relationship with the gauge pressure; this implies that when the surface methane concentration and the surface gauge pressure are measured simultaneously, the methane emission flux can be calculated using Darcy’s law. A decrease in the vertical permeability was observed when the gauge pressure was increased, because reducing the vertical permeability may lead to a reduced landfill gas emission to the atmosphere, and landfill gas would be accumulated inside the landfill. Finally, this method is simple and can allow for a greater number of measurements during a relatively shorter period. Thus, it provides a better representation of the significant space and time variations in methane emission fluxes.
To investigate the potential use of tobacco stems as feedstock for biochar production, a variety of pyrolysis conditions were studied to determine their effects on the distribution of pyrolysis products, as well as the physicochemical properties, energy yield and porosity characteristics of the biochar. The results showed that a moderate temperature of 400–450°C, a retention time of three hours and a slow heating rate of 5°C min–1 was better to get high energy yield from biochar. In this study, the highest calorific value of biochar was 28.128 MJ kg–1. The highest biochar yield occurred at a moderate retention time of three hours. The heating rate had an important influence on the characteristics of biochar, and the physiochemical properties of biochar produced at a heating rate of 10°C min–1 were better than other levels. Also, the oil yield decreased and gas yield increased as retention time and heating rate increased. Biochar produced at a high temperature of 600°C, a retention time up to four hours and a heating rate of 10–15°C min–1 had a larger BET surface area and cumulative pore volume than that of others. The highest change rate of pore volume of biochar almost occurred at the pore size of 2–5 nm.
This paper outlines the approach that can assist decision makers to have first preliminary insights regarding costs of complying with requested European Union municipal waste management goals in transition and developing countries. Serbia, as a joining member of European Union, must confront itself with the challenges resulting from European Union waste management directives. Implementation of waste separation units and the construction of sanitary landfills is already in place in Serbia. However, new waste management practice will need additional transformation and will require implementation of waste treatment technologies for additional management of generated waste. Implementation of analyzed best available technology/techniques for waste treatment can support the country’s effort in reaching the policy goals. However, the question here is how much will the implementation of additional waste treatments influence the overall waste management costs? Results of the scenario’s financial viability show that composting and sanitary landfill are the most viable solutions regarding the costs, even under increasing discount rates. Although different discount rates influence the overall gate fees and net present values, the level of affordability for different scenarios remains the same.
Sustainability assessment of a waste management system is a very complex problem for numerous reasons. Firstly, it is a problem of environmental assessment, economic viability and social acceptability, and also a choice of the most practical waste treatment technique, taking into account all the specific areas in which a waste management system is implemented. For these reasons, among others, it is very important to benchmark, cooperate and exchange experiences in areas with similar characteristics. In this study, a comparison of waste management scenarios in the Cities of Niš and Sofia was performed. Based on the amount and composition of municipal solid waste, and taking into account local specifics (economic conditions, social acceptance, etc.), different scenarios were developed: landfilling without energy recovery, landfilling with energy recovery, mechanical-biological treatment, anaerobic digestion with biogas utilization and incineration with energy recovery. Scenario ranking was done using multi-criteria analysis and 12 indicators were chosen as the criteria. The obtained results show that the most sustainable scenario in both case studies is the mechanical-biological treatment (recycling, composting and Refuse Derived Fuel production). Having in mind that this scenario is the current waste management system in Sofia, these results can help decision-makers in the City of Niš in choosing a successful and sustainable waste management system.
Solid waste management is one of the subjects essentially addressing the current interest today. Due to the scarcity of land filling area, utilization of wastes in the construction sector has become an attractive proposition for disposal. Ferrochrome ash (FA) is a dust obtained as a waste material from the gas cleaning plant of Ferro alloy industries. It possesses the chemical requirements of granulated slag material used for the manufacture of Portland cement. Ferrochrome slag (FS) is another residue that is obtained as a solid waste by the smelting process during the production of stainless steel in Ferroalloy industries. FS possesses the required engineering properties of coarse aggregates. The possibility of using FA with lime for partial replacement of ordinary Portland cement (OPC) and FS for total replacement of natural coarse aggregates is explored in this research. The combined effect of FA with lime and FS-addition on the properties of concrete, such as workability, compressive strength, flexural strength, splitting tensile strength and sorptivity, were studied. Results of investigation revealed improvement in strength and durability properties of concrete on inclusion of FA and FS. Concrete mix containing 40% FA with 7% lime (replacing 47% OPC) and100% of FS (replacing 100% natural coarse aggregate) achieved the properties of normal concrete or even better properties at all ages. The results were confirmed by microscopic study such as X-ray diffraction and petrography examination. Environmental compatibility of concrete containing FA and FS was verified by the toxicity characteristic leaching procedure test.
The Waste Framework Directive obliged European Union Member States to set up separate collection systems to promote high quality recycling for at least paper, metal, plastic and glass by 2015. As implementation of the requirement varies across European Union Member States, the European Commission contracted BiPRO GmbH/Copenhagen Resource Institute to assess the separate collection schemes in the 28 European Union Member States, focusing on capital cities and on metal, plastic, glass (with packaging as the main source), paper/cardboard and bio-waste. The study includes an assessment of the legal framework for, and the practical implementation of, collection systems in the European Union-28 Member States and an in depth-analysis of systems applied in all capital cities. It covers collection systems that collect one or more of the five waste streams separately from residual waste/mixed municipal waste at source (including strict separation, co-mingled systems, door-to-door, bring-point collection and civic amenity sites). A scoreboard including 13 indicators is elaborated in order to measure the performance of the systems with the capture rates as key indicators to identify best performers. Best performance are by the cities of Ljubljana, Helsinki and Tallinn, leading to the key conclusion that door-to-door collection, at least for paper and bio-waste, and the implementation of pay-as-you-throw schemes results in high capture and thus high recycling rates of packaging and other municipal waste.
Ecological problems arising after the construction and operation of a waste incineration plant generally originate from incorrect decisions made during the selection of the location of the plant. The main objective of this study is to investigate how the selection method for the location of a new municipal waste incineration plant can be improved by using a dispersion modelling approach supported by geographical information systems and multi-criteria decision analysis. Considering this aim, the appropriateness of the current location of an existent plant was assessed by applying a pollution dispersion model. Using this procedure, the site ranking for a total of 90 candidate locations and the site of the existing incinerator were determined by a new location selection practice and the current place of the plant was evaluated by ANOVA and Tukey tests. This ranking, made without the use of modelling approaches, was re-evaluated based on the modelling of various variables, including the concentration of pollutants, population and population density, demography, temporality of meteorological data, pollutant type, risk formation type by CALPUFF and re-ranking the results. The findings clearly indicate the impropriety of the location of the current plant, as the pollution distribution model showed that its location was the fourth-worst choice among 91 possibilities. It was concluded that the location selection procedures for waste incinerators should benefit from the improvements obtained by the articulation of pollution dispersion studies combined with the population density data to obtain the most suitable location.
Multi-criteria decision making (MCDM) is a relatively new tool for decision makers who deal with numerous and often contradictory factors during their decision making process. This paper presents a procedure to choose the optimal municipal solid waste (MSW) management system for the area of the city of Kragujevac (Republic of Serbia) based on the MCDM method. Two methods of multiple attribute decision making, i.e. SAW (simple additive weighting method) and TOPSIS (technique for order preference by similarity to ideal solution), respectively, were used to compare the proposed waste management strategies (WMS). Each of the created strategies was simulated using the software package IWM2. Total values for eight chosen parameters were calculated for all the strategies. Contribution of each of the six waste treatment options was valorized. The SAW analysis was used to obtain the sum characteristics for all the waste management treatment strategies and they were ranked accordingly. The TOPSIS method was used to calculate the relative closeness factors to the ideal solution for all the alternatives. Then, the proposed strategies were ranked in form of tables and diagrams obtained based on both MCDM methods. As shown in this paper, the results were in good agreement, which additionally confirmed and facilitated the choice of the optimal MSW management strategy.
The literature was reviewed with respect to deinking flotation methods with toner samples, specifically emphasizing the speciation of copy machine and laser printing, which produce an increasing quantity of paper that is difficult to recycle. Speciation here refers to the physical-chemical characteristics of the toner, which change because of the polymerization (fusion) and oxidation process, due to exposure to heat, light and oxygen (air) during the printing process. To simulate the deinking flotation, after the ideal disintegration process, samples of toner were prepared in order to provide free toner particles. Synthetic toner has iron content and the same physical-chemical features as free disintegrated printed toner particles.
We report the toner (I) and fibre (Y) recovery and the brightness (B) of laboratory filter pads formed of deinked product as deinking efficiencies. The application of oleic acid as the collector in the flotation stage gives a better flotation recovery in alkaline than in acidic conditions. The highest brightness (BF = 93.66%) and flotation recoveries (I = 90, Y = 92.82%) were achieved during testing at an oleic acid concentration of 3.38·10–6 mol l–1, which is the lowest dose used. This makes the use of oleic acid economical and environmentally friendly.
The mud generated from oil and natural gas drilling, presents a considerable ecological problem. There are still insufficient remedies for the removal and minimization of these very stable emulsions. Existing technologies that are in use, more or less successfully, treat about 20% of generated waste drilling mud, while the rest is temporarily deposited in so-called mud pits. This study investigated in situ bioremediation of a mud pit. The bioremediation technology used in this case was based on the use of naturally occurring microorganisms, isolated from the contaminated site, which were capable of using the contaminating substances as nutrients. The bioremediation was stimulated through repeated inoculation with a zymogenous microbial consortium, along with mixing, watering and biostimulation. Application of these bioremediation techniques reduced the concentration of total petroleum hydrocarbons from 32.2 to 1.5 g kg–1 (95% degradation) during six months of treatment.
The anchovy canning industry has high importance in the Cantabria Region (North Spain) from economic, social and touristic points of view. The Cantabrian canned anchovy is world-renowned owing to its handmade and traditional manufacture. The canning process generates huge amounts of several food wastes, whose suitable management can contribute to benefits for both the environment and the economy, closing the loop of the product life cycle. Life cycle assessment methodology was used in this work to assess the environmental performance of two waste management alternatives: Head and spine valorisation to produce fishmeal and fish oil; and anchovy meat valorisation to produce anchovy paste. Fuel oil production has been a hotspot of the valorisation of heads and spines, so several improvements should be applied. With respect to anchovy meat valorisation, the production of polypropylene and glass for packaging was the least environmentally friendly aspect of the process. Furthermore, the environmental characterisation of anchovy waste valorisation was compared with incineration and landfilling alternatives. In both cases, the valorisation management options were the best owing to the avoided burdens associated with the processes. Therefore, it is possible to contribute to the circular economy in the Cantabrian canned anchovy industry.
The selection of the most feasible strategy for implementation of landfills is a challenging step. Potential implementation options of landfills cover a wide range, from conventional construction contracts to the concessions. Montenegro, seeking to improve the efficiency of the public services while maintaining affordability, was considering privatisation as a way to reduce public spending on service provision. In this study, to determine the most feasible model for construction and operation of a regional landfill, a quantitative risk analysis was implemented with four steps: (i) development of a global risk matrix; (ii) assignment of qualitative probabilities of occurrences and magnitude of impacts; (iii) determination of the risks to be mitigated, monitored, controlled or ignored; (iv) reduction of the main risk elements; and (v) incorporation of quantitative estimates of probability of occurrence and expected impact for each risk element in the reduced risk matrix. The evaluated scenarios were: (i) construction and operation of the regional landfill by the public sector; (ii) construction and operation of the landfill by private sector and transfer of the ownership to the public sector after a pre-defined period; and (iii) operation of the landfill by the private sector, without ownership. The quantitative risk assessment concluded that introduction of a public private partnership is not the most feasible option, unlike the common belief in several public institutions in developing countries. A management contract for the first years of operation was advised to be implemented, after which, a long term operating contract may follow.
This paper analyses waste management on small islands (on a global scale these are micro-islands). In the context of the paper, small islands are islands that have an area less than 50 km2. The study presents an overview of the problems connected with waste transport from islands to the mainland. Waste generation on islands is very much related to tourists. If tourists do not handle waste properly, it will cause problems. Four small Estonian islands in the range of 3–19 km2 are studied in detail. For these and other small islands, the main problem is the waste produced by tourists, or related to tourists and waste transport to the mainland. Currently, the local municipality has to arrange and finance waste transport. In fact, and based on the polluter-pays principle, the tourists should bear the cost of waste management. There are different tax options available in order to collect the money from tourists – waste tax, harbour tax, tourist tax, donations, environmental tax and others. The study results revealed that the best possible solution for Estonian islands may be a non-deposit system – including an additional charge on ferry ticket prices. The extra money should cover the costs of waste management and waste shipping. The tourists arriving in their own boats should pay a harbour tax, which includes a waste tax to compensate for the cost of waste management.
Trying to respond to the latest policy needs, the work presented in this article aims at developing a life-cycle based framework methodology to quantitatively evaluate the environmental and economic sustainability of European food waste management options. The methodology is structured into six steps aimed at defining boundaries and scope of the evaluation, evaluating environmental and economic impacts and identifying best performing options. The methodology is able to accommodate additional assessment criteria, for example the social dimension of sustainability, thus moving towards a comprehensive sustainability assessment framework. A numerical case study is also developed to provide an example of application of the proposed methodology to an average European context. Different options for food waste treatment are compared, including landfilling, composting, anaerobic digestion and incineration. The environmental dimension is evaluated with the software EASETECH, while the economic assessment is conducted based on different indicators expressing the costs associated with food waste management. Results show that the proposed methodology allows for a straightforward identification of the most sustainable options for food waste, thus can provide factual support to decision/policy making. However, it was also observed that results markedly depend on a number of user-defined assumptions, for example on the choice of the indicators to express the environmental and economic performance.
Roma communities represent the main involved actors in the informal activities in the Balkan regions, especially because the state does not formally recognize them as formal inhabitants. The Roma community in Zavidovici, despite being resident since the beginning of the 20th century, is still considered a marginalized and vulnerable group. They are actively involved in and dependent on the informal solid waste sector. Waste collection is a ‘family business’, a kind of self-employment and the main source of income for households. Informal recyclers have a central role in the solid waste management system and they recover a significant amount of materials, especially iron, copper, brass, lead and exhausted batteries. Despite the negative fluctuations of the raw material prices, because of the international economic crisis, informal recyclers remain dependent on the waste recycling sector. They are crucial actors in the value chain of recyclables: though they cannot access the final buyers of recyclables, they provide more than 50% of the market to the middle dealers in the Zenica-Doboj Canton. This research activity consists of a deep socio-economic analysis of the informal recyclers’ community living in Zavidovici city. In particular, this paper describes the composition and welfare status of informal recyclers’ households, the role of informal recyclers in waste collection, the geographical coverage and the related pattern of waste picking, types, volumes and price fluctuations of recyclable materials, and the middle dealers involved in the informal recycling system.
The problems of waste management have become increasingly complex in recent decades. The increasing amount of generated waste, adopted legislation in the field of waste management, administrative issues, economic impacts and social awareness are important drivers in achieving a sustainable waste management system. However, in practice, there are many other drivers that are often mutually in conflict. The purpose of this research is to define the precise driver and their corresponding sub-drivers, which are relevant for developing a waste management system and, on the basis of their importance, to determine which has the predominant influence on the slow development of a waste management system at the national and regional level, within the Republic of Serbia and similar countries of southeast Europe. This research presents two levels of decision making: the first is a pair-wise comparison of the drivers in relation to the goal and the second is a pair-wise comparison of the sub-drivers in relation to the driver and in relation to the goal. Results of performed analyses on the waste management drivers were integrated via the decision-making process supported by an analytic hierarchy process (AHP). The final results of this research shows that the Institutional–Administrative driver is the most important for developing a sustainable waste management system.
Sustainable solid waste management needs more dedicated attention in respect of environmental and human health protection. Solid waste containing persistent organic pollutants is of special concern, since persistent organic pollutants are persistent, toxic and of high risk to human health and the environment. The objective of this investigation was to identify critical points in the Serbian system of solid waste and persistent organic pollutants management, to assure the life cycle management of persistent organic pollutants and products containing these chemicals, including prevention and final destruction. Data were collected from the Serbian competent authorities, and led us to identify preventive actions for solid waste management that should reduce or minimise release of persistent organic pollutants into the environment, and to propose actions necessary for persistent organic pollutants solid waste. The adverse impact of persistent organic pollutants is multidimensional. Owing to the lack of treatment or disposal plants for hazardous waste in Serbia, the only option at the moment to manage persistent organic pollutants waste is to keep it in temporary storage and when conditions are created (primarily financial), such waste should be exported for destruction in hazardous waste incinerators. Meanwhile, it needs to be assured that any persistent organic pollutants management activity does not negatively impact recycling flows or disturb progress towards a more circular economy in Serbia.
Agricultural waste is one of the main renewable energy resources available, especially in an agricultural country such as Serbia. Pyrolysis has already been considered as an attractive alternative for disposal of agricultural waste, since the technique can convert this special biomass resource into granular charcoal, non-condensable gases and pyrolysis oils, which could furnish profitable energy and chemical products owing to their high calorific value. In this regard, the development of thermochemical processes requires a good understanding of pyrolysis mechanisms. Experimental and some literature data on the pyrolysis characteristics of corn cob and several other agricultural residues under inert atmosphere were structured and analysed in order to obtain conversion behaviour patterns of agricultural residues during pyrolysis within the temperature range from 300 °C to 1000 °C. Based on experimental and literature data analysis, empirical relationships were derived, including relations between the temperature of the process and yields of charcoal, tar and gas (CO2, CO, H2 and CH4). An analytical semi-empirical model was then used as a tool to analyse the general trends of biomass pyrolysis. Although this semi-empirical model needs further refinement before application to all types of biomass, its prediction capability was in good agreement with results obtained by the literature review. The compact representation could be used in other applications, to conveniently extrapolate and interpolate these results to other temperatures and biomass types.
The utilisation of municipal solid waste incineration bottom ash has been extensively studied, for example, in the unbound layers of roads and the products of cement and concrete industry. On the other hand, less attention has been given to other innovative utilisation possibilities, such as using the municipal solid waste incineration bottom ash as a component in growing media of plants. The municipal solid waste incineration bottom ash contains useful substances, such as calcium, that can influence plant growth in a positive manner. Therefore, the utilisation of this waste-derived material in the growing media may substitute the use of commercial fertilisers. Since the municipal solid waste incineration bottom ash also contains hazardous substances that can be toxic to plants, the main aim of this study was to add different amounts of recovered municipal solid waste incineration bottom ash in the growing media and to evaluate the effect of this material on plant growth. Based on the obtained results, the concentration of, for example copper and zinc, increased in test plants; ryegrass and barley, when recovered municipal solid waste incineration bottom ash was added in their growing media. On the other hand, this did not have a significant effect on plant growth, if compared with the growth of plants in commercially produced growing medium. Furthermore, the replacement of natural sand with municipal solid waste incineration bottom ash had a positive liming effect in the growing media. Overall, these findings suggest that the utilisation of recovered municipal solid waste incineration bottom ash as a component in growing media is possible and, thus, may allow more widespread and innovative use of this waste-derived material.
The article presents the results of e-waste thermal treatment in a fluidised bed reactor and solid products digestion under acidic conditions. During the processes, measurements of carbon monoxide, carbon dioxide, volatile organic compounds, nitrogen oxides, sulphur dioxide, hydrogen chloride, hydrogen bromide, hydrogen cyanide, ammonia, phenol, aliphatic and aromatic hydrocarbons, hydrogen fluoride and phosgene were carried out. Several digestion tests of the solid residue in sulphuric acid (VI) at 25 °C–65 °C, for 55 min–24 h were conducted. In each case, the dilution method was used, i.e. preliminary digestion in concentrated sulphuric acid (VI) (95%) for 40 min, and then dilution to expected concentrations (30%–50%). Most preferred results were obtained using sulphuric acid (VI) with a target concentration of 40% at 65 °C, where the leaching degrees were 76.56% for copper, 71.67% for iron, 91.89% for zinc and 97.40% for tin. The time necessary to effectively carry out the digestion process was 220 min.
Increasing concern about climate change is prompting organisations to mitigate their greenhouse gas emissions. Waste management activities also contribute to greenhouse gas emissions. In the waste management sector, there has been an increasing diversion of waste sent to landfill, with much emphasis on recycling and reuse to prevent emissions. This study evaluates the carbon footprint of the different processes involved in waste management systems, considering the entire waste management stream. Waste management data from the Royal Borough of Kingston upon Thames, London (UK), was used to estimate the carbon footprint for its (Royal Borough of Kingston upon Thames) current source segregation system. Second, modelled full and partial co-mingling scenarios were used to estimate carbon emissions from these proposed waste management approaches. The greenhouse gas emissions from the entire waste management system at Royal Borough of Kingston upon Thames were 12,347 t CO2e for the source-segregated scenario, and 11,907 t CO2e for the partial co-mingled model. These emissions amount to 203.26 kg CO2e t–1 and 196.02 kg CO2e t–1 municipal solid waste for source-segregated and partial co-mingled, respectively. The change from a source segregation fleet to a partial co-mingling fleet reduced the emissions, at least partly owing to a change in the number and type of vehicles.
The organic content of municipal solid waste has long been an attractive source of renewable energy, mainly as a solid fuel in waste-to-energy plants. This study focuses on the potential to use microbial fuel cells to convert municipal solid waste organics into energy using various operational conditions. The results showed that two-chamber microbial fuel cells with carbon felt and carbon felt allocation had a higher maximal power density (20.12 and 30.47 mW m-2 for 1.5 and 4 L, respectively) than those of other electrode plate allocations. Most two-chamber microbial fuel cells (1.5 and 4 L) had a higher maximal power density than single-chamber ones with corresponding electrode plate allocations. Municipal solid waste with alkali hydrolysis pre-treatment and K3Fe(CN)6 as an electron acceptor improved the maximal power density to 1817.88 mW m-2 (~0.49% coulomb efficiency, from 0.05–0.49%). The maximal power density from experiments using individual 1.5 and 4 L two-chamber microbial fuel cells, and serial and parallel connections of 1.5 and 4 L two-chamber microbial fuel cells, was found to be in the order of individual 4 L (30.47 mW m-2) > serial connection of 1.5 and 4 L (27.75) > individual 1.5 L (20.12) > parallel connection of 1.5 and 4 L (17.04) two-chamber microbial fuel cells . The power density using municipal solid waste microbial fuel cells was compared with information in the literature and discussed.
The most viable option for biostabilisation of old sanitary landfills, filled with raw municipal solid waste, is the so-called bioreactor landfill. Even today, bioreactor landfills are viable options in many economically developing countries. However, in order to reduce the biodegradable component of landfilled waste, mechanical and biological treatment has become a widely accepted waste treatment technology, especially in more prosperous countries. Given that mechanical and biological treatment alters the geotechnical properties of raw waste material, the design of sanitary landfills which accepts mechanically and biologically treated waste, should be carried out with a distinct set of geotechnical parameters. However, under the assumption that ‘waste is waste’, some design engineers might be tempted to use geotechnical parameters of untreated raw municipal solid waste and mechanical and biological pre-treated municipal solid waste interchangeably. Therefore, to provide guidelines for use and to provide an aggregated source of this information, this mini-review provides comparisons of geotechnical parameters of mechanical and biological pre-treated waste and raw untreated waste at various decomposition stages. This comparison reveals reasonable correlations between the hydraulic conductivity values of untreated and mechanical and biological pre-treated municipal solid waste. It is recognised that particle size might have a significant influence on the hydraulic conductivity of both municipal solid waste types. However, the compression ratios and shear strengths of untreated and pre-treated municipal solid waste do not show such strong correlations. Furthermore, another emerging topic that requires appropriate attention is the recovery of resources that are embedded in old landfills. Therefore, the presented results provide a valuable tool for engineers designing landfills for mechanical and biological pre-treated waste or bioreactor landfills for untreated raw waste as well as planning landfill mining projects.
Infection with the hepatitis B and C viruses may occur through contact with infected body fluids, including injury with infected sharps. Collectors of domestic or healthcare wastes are potentially exposed to these infections. The aim of this article is to investigate the risk factors associated with the prevalence of hepatitis B and C viruses (HBV and HCV) infection among domestic and healthcare waste workers in Belo Horizonte, Brazil. A cross-sectional study of hepatitis B and C infection was conducted from November 2014 to January 2015, through blood sample collection and interviews about socio-demographic factors with 61 workers exposed to healthcare waste (‘exposed’) and 461 exposed only to domestic wastes (‘unexposed’). The prevalence of antibodies to HCV (Anti-HCV) antibodies was 3.3% in ‘exposed’ workers and 0.9% in ‘unexposed’, and of antibody to hepatitis B core antigen (Anti-HBc) was 9.8% and 5.6% in ‘exposed’ and ‘unexposed’ workers, respectively. Only 207 (44.9%) of those exposed to domestic waste and 45 (73.8%) of those handling healthcare waste were effectively immunised against hepatitis B virus (HBV). Exposures to domestic waste and to healthcare wastes were associated with similar risks of infection with HBV. The risk of hepatitis C virus (HCV) infection was marginally higher among healthcare waste workers compared with domestic waste workers, probably because of needlestick accidents owing to deficient sharps management systems. Immunisation against hepatitis B and screening tests to ensure the success of vaccination should be a condition for recruitment for both groups of waste workers.
Collection of municipal solid waste is one of the most important elements of municipal waste management and requires maximum fund allocated for waste management. The cost of collection and transportation can be reduced in comparison with the present scenario if the solid waste collection bins are located at suitable places so that the collection routes become minimum. This study presents a suitable solid waste collection bin allocation method at appropriate places with uniform distance and easily accessible location so that the collection vehicle routes become minimum for the city Dhanbad, India. The network analyst tool set available in ArcGIS was used to find the optimised route for solid waste collection considering all the required parameters for solid waste collection efficiently. These parameters include the positions of solid waste collection bins, the road network, the population density, waste collection schedules, truck capacities and their characteristics. The present study also demonstrates the significant cost reductions that can be obtained compared with the current practices in the study area. The vehicle routing problem solver tool of ArcGIS was used to identify the cost-effective scenario for waste collection, to estimate its running costs and to simulate its application considering both travel time and travel distance simultaneously.
The objective of this article is to develop a computerised tool (software) that facilitates the analysis of strategies for waste management on construction sites through the use of indicators of construction and demolition waste generation. The development involved the following steps: knowledge acquisition, structuring the system, coding and system evaluation. The step of knowledge acquisition aims to provide subsidies for the representation of them through models. In the step of structuring the system, it was presented the structuring and formalisation of knowledge for the development of the system, and has two stages: the construction of the conceptual model and the subsequent instantiation of the model. The coding system aims to implement (code) the conceptual model developed in a model played by computer (digital). The results showed that the system is very useful and applicable in construction sites, helping to improve the quality of waste management, and creating a database that will support new research.
The results of this case study are used to argue that waste management planning should follow a detailed process, adequately confronting the complexity of the waste management problems and the specificity of each urban area and of regional/national situations. To support the development or completion of integrated waste management systems, this article proposes a planning method based on: (1) the detailed analysis of waste flows and (2) the application of a life cycle assessment to compare alternative scenarios and optimise solutions. The evolution of the City of Bologna waste management system is used to show how this approach can be applied to assess which elements improve environmental performance. The assessment of the contribution of each waste management phase in the Bologna integrated waste management system has proven that the changes applied from 2013 to 2017 result in a significant improvement of the environmental performance mainly as a consequence of the optimised integration between materials and energy recovery: Global Warming Potential at 100 years (GWP100) diminishes from 21,949 to –11,169 t CO2-eq y-1 and abiotic resources depletion from –403 to –520 t antimony-eq. y-1. This study analyses at great detail the collection phase. Outcomes provide specific operational recommendations to policy makers, showing the: (a) relevance of the choice of the materials forming the bags for ‘door to door’ collection (for non-recycled low-density polyethylene bags 22 kg CO2-eq (tonne of waste)-1); (b) relatively low environmental impacts associated with underground tanks (3.9 kg CO2-eq (tonne of waste)-1); (c) relatively low impact of big street containers with respect to plastic bags (2.6 kg CO2-eq. (tonne of waste)-1).
Basic technical and economic examinations of Austrian mass waste landfills, concerning the recovery of secondary raw materials, have been carried out by the ‘LAMIS – Landfill Mining Austria’ pilot project for the first time in Austria. A main focus of the research – the subject of this article – was the first devotion of a pilot landfill to an integrated ecological and economic assessment so that its feasibility could be verified before a landfill mining project commenced. A Styrian mass waste landfill had been chosen for this purpose that had been put into operation in 1979 and received mechanically–biologically pre-treated municipal waste till 2012. The whole assessment procedure was divided into preliminary and main assessment phases to evaluate the general suitability of a landfill mining project with little financial and human resource expense. A portfolio chart, based on a questionnaire, was created for the preliminary assessment that, as a result, has provided a recommendation for subsequent investigation – the main assessment phase. In this case, specific economic criteria were assessed by net present value calculation, while ecological or socio-economic criteria were rated by utility analysis, transferring the result into a utility–net present value chart. In the case of the examined pilot landfill, assessing the landfill mining project produced a higher utility but a lower net present value than a landfill leaving-in for aftercare. Since no clearly preferable scenario could be identified this way, a cost–revenue analysis was carried out in addition that determined a dimensionless ratio: the ‘utility – net present value quotient’ of both scenarios. Comparing this quotient showed unmistakably that in the overall assessment, ‘leaving the landfill in aftercare’ was preferable to a ‘landfill mining project’ in that specific case.
Vinegar residue is the by-product in the vinegar production process. The large amount of vinegar residue has caused a serious environmental problem owing to its acidity and corrosiveness. Anaerobic digestion is an effective way to convert agricultural waste into bioenergy, and a previous study showed that vinegar residue could be treated by anaerobic digestion but still had room to improve digestion efficiency. In this study, steam explosion at pressure of 0.8, 1.2, and 1.5 MPa and residence time of 5, 10, 15, and 20 min were used to pretreat vinegar residue to improve methane production, respectively. Scanning electron microscopy and X-ray diffraction analyses were applied to validate structural changes of vinegar residue after steam explosion. Results showed that steam explosion pretreatment could destroy the structure of lignocellulose by removing the hemicellulose and lignin, and improve the methane yield effectively. Steam explosion-treated vinegar residue at 0.8 MPa for 5 min produced the highest methane yield of 153.58 mL gVS-1, which was 27.65% (significant, α < 0.05) more than untreated vinegar residue (120.31 mL gVS-1). The analyses of pH, total ammonia-nitrogen, total alkalinity, and volatile fatty acids showed that steam explosion did not influence the stability of anaerobic digestion. This study suggested that steam explosion pretreatment on vinegar residue might be a promising approach and it is worth further study to improve the efficiency of vinegar residue waste utilisation.
Economic instruments provide significant potential for countries with low municipal waste management performance in decreasing landfill rates and increasing recycling rates for municipal waste. In this research, strengths and weaknesses of landfill tax, pay-as-you-throw charging systems, deposit–refund systems and extended producer responsibility schemes are compared, focusing on conditions in countries with low waste management performance. In order to prioritise instruments for implementation in these countries, the analytic hierarchy process is applied using results of a literature review as input for the comparison. The assessment reveals that pay-as-you-throw is the most preferable instrument when utility-related criteria are regarded (wb = 0.35; analytic hierarchy process distributive mode; absolute comparison) mainly owing to its waste prevention effect, closely followed by landfill tax (wb = 0.32). Deposit–refund systems (wb = 0.17) and extended producer responsibility (wb = 0.16) rank third and fourth, with marginal differences owing to their similar nature. When cost-related criteria are additionally included in the comparison, landfill tax seems to provide the highest utility–cost ratio. Data from literature concerning cost (contrary to utility-related criteria) is currently not sufficiently available for a robust ranking according to the utility–cost ratio. In general, the analytic hierarchy process is seen as a suitable method for assessing economic instruments in waste management. Independent from the chosen analytic hierarchy process mode, results provide valuable indications for policy-makers on the application of economic instruments, as well as on their specific strengths and weaknesses. Nevertheless, the instruments need to be put in the country-specific context along with the results of this analytic hierarchy process application before practical decisions are made.
The financial and social contributions of coffee processing industries within most coffee export-based national economies like Ethiopia are generally high. The type and amount of waste produced and the waste management options adopted by these industries can have negative effects on the environment. This study investigated the solid waste management options adopted in wet coffee processing industries in the Gidabo watershed of Ethiopia. A field observation and assessment were made to identify whether the operational characteristics of the industries have any effect on the waste management options that were practiced. The investigation was conducted on 125 wet coffee processing industries about their solid waste handling techniques. Focus group discussion, structured questionnaires, key informant interview and transect walks are some of the tools employed during the investigation. Two major types of wastes, namely hull-bean-pulp blended solid waste and wastewater rich in dissolved and suspended solids were generated in the industries. Wet mills, on average, released 20.69% green coffee bean, 18.58% water and 60.74% pulp by weight. Even though these wastes are rich in organic matter and recyclables; the most favoured solid waste management options in the watershed were disposal (50.4%) and industrial or household composting (49.6%). Laxity and impulsive decision are the driving motives behind solid waste management in Gidabo watershed. Therefore, to reduce possible contamination of the environment, wastes generated during the processing of red coffee cherries, such as coffee wet mill solid wastes, should be handled properly and effectively through maximisation of their benefits with minimised losses.
This work is the first nationwide study in Portugal on pharmaceutical waste generated at households, exploring people’s attitudes and risk perception. The waste audit was carried out from September to November 2014, targeting pharmaceutical products kept by a sample of families (n = 244). This campaign was an assignment of VALORMED, the non-profit association that manages waste and packaging from expired and unused pharmaceutical products collected by the pharmacies. On average, each household kept at home 1097 g of pharmaceutical products, of which 20% were in use, 72% were not in use, and 8% were mostly expired products ready to discard. Face-to-face interviews with householders showed that 69% of the respondents claimed returning pharmaceutical waste to the local pharmacy. However, this figure is overrated, probably owing to a possible ‘good answer’ effect. The barriers identified to proper disposal were mainly established routines and lack of close disposal points. This study also provides an insight into the Portuguese awareness and daily practices concerning pharmaceutical waste, which is the cornerstone of any future strategy to reduce the release of active pharmaceutical ingredients into ecosystems.
Municipal solid waste disposed in landfill sites decomposes under anaerobic conditions and produces so-called landfill-gas, which contains 30%–40% of carbon dioxide (CO2) and 50%–60% of methane (CH4). Methane has the potential of causing global warming 25 times more than CO2. Therefore, migration of landfill-gas from landfills to the surrounding environment can potentially affect human life and environment. Thus, this research aims to determine municipal solid waste generation in Oman over the years 1971–2030, to quantify annual CH4 emissions inventory that resulted from this waste over the same period of time, and to determine the economic and environmental benefits of capturing the CH4 gas for energy production. It is found that cumulative municipal solid waste landfilled in Oman reaches 3089 Giga gram (Gg) in the year 2030, of which approximately 85 Gg of CH4 emissions are produced in the year 2030. The study also found that capturing CH4 emissions between the years 2016 and 2030 could attract revenues of up to US$333 million and US$291 million from the carbon reduction and electricity generation, simultaneously. It is concluded that CH4 emissions from solid waste in Oman increases enormously with time, and capture of this gas for energy production could provide a sustainable waste management solution in Oman.
Earth’s natural resources are finite. To be environmentally sustainable, it may not only be necessary to use them ‘efficiently’ but also ‘effectively’. While we consider ‘repair’, ‘recondition’, ‘refurbish’ and ‘remanufacture’ to be ‘reuse’ options, not all researchers agree. Also, there is lack of clarity between the different options that are likely to be challenging for both; the policy makers who formulate policies aimed to encourage ‘reuse’ of ‘waste’ products and for decision makers to initiate appropriate action for recovering ‘reusable resources’ from ‘waste streams’. This dichotomy could result into more ‘waste’ to landfill. A systematic analysis of peer reviewed literature is conducted to understand inconsistencies and/or lack of clarity that exist between the definitions or descriptions of identified `reuse’ options. This article proposes a ‘hierarchy of reuse options’ that plots the relative positions of identified ‘reuse’ options vis-à-vis five variables, namely work content, energy requirement, cost, performance and warranty. Recommendations are made on how to incentivise original equipment manufacturers (OEMs) to ‘remanufacture’. Finally, an alternative ‘Type II Resource Effective Close-loop Model’ is suggested and a conceptual ‘Type II/2 Model of Resource Flows’ that is restricted to the use of environmentally benign and renewable resources is introduced. These suggestions are likely to help decision makers to prioritise between ‘reuse’ options, drive resource effectiveness and also environmental sustainability.
The illegal dumping of hazardous waste is one of the most concerning occurrences related to illegal waste activities. The waste management process is quite vulnerable, especially when it comes to assuring the right destination for the delivery of the hazardous waste. The purpose of this paper is to present a new system design and prototype for applying the RFID technology so as to guarantee the correct destination for the hazardous waste delivery. The aim of this innovative approach, compared with other studies that employ the same technology to the waste disposal process, is to focus on the certification that the hazardous waste will be delivered to the right destination site and that no inappropriate disposal will occur in the transportation stage. These studies were carried out based on data collected during visits to two hazardous waste producer companies in Brazil, where the material transportation and delivery to a company in charge of the waste disposal were closely monitored.
Waste management in construction is critical for the sustainable treatment of building-related construction and demolition (C&D) waste materials, and recycling of these wastes has been considered as one of the best strategies in minimization of C&D debris. However, recycling of C&D materials may not always be a feasible strategy for every waste type and therefore recycling and other waste treatment strategies should be supported by robust decision-making models. With the aim of assessing the net carbon, energy, and water footprints of C&D recycling and other waste management alternatives, a comprehensive economic input–output-based hybrid life-cycle assessment model is developed by tracing all of the economy-wide supply-chain impacts of three waste management strategies: recycling, landfilling, and incineration. Analysis results showed that only the recycling of construction materials provided positive environmental footprint savings in terms of carbon, energy, and water footprints. Incineration is a better option as a secondary strategy after recycling for water and energy footprint categories, whereas landfilling is found to be as slightly better strategy when carbon footprint is considered as the main focus of comparison. In terms of construction materials’ environmental footprint, nonferrous metals are found to have a significant environmental footprint reduction potential if recycled.
Polybrominated diphenyl ethers with persistent organic pollutant properties are required to be controlled by the Stockholm Convention. Recently, polybrominated diphenyl ether contamination has become widespread in Asia, mainly because of the disposal and recycling processes of polybrominated diphenyl ether-containing wastes. The management status, production, usage, import/export, treatment, and disposal, as well as implementation deficiencies for the environmentally sound management of polybrominated diphenyl ethers and polybrominated diphenyl ether-containing materials in ten Asian countries were investigated and assessed in this study. This information could help the participating countries implement the Stockholm Convention and could promote the regional environmentally sound management of polybrominated diphenyl ether-containing articles and products. The results obtained were as follows. (1) Most of the countries studied lacked environmental policies and regulations, or even standards of polybrominated diphenyl ether pollution management and emission control actions. Accurate data on the consumption and importation of polybrominated diphenyl ether-containing materials, however, were not available for all the participating countries. In addition, there were no special treatment or disposal systems for polybrominated diphenyl ether-containing materials, or emission-cutting measures for the treatment of waste in these countries, owing to the lack of sufficient funding or technologies. (2) The improper dismantling of e-waste is a major source of polybrominated diphenyl ether emissions in these countries. (3) Proper e-waste management could result in a breakthrough in the environmentally sound management of this major polybrominated diphenyl ether-containing material flow, and could significantly reduce polybrominated diphenyl ether emissions. Finally, based on the study results, this article puts forward some recommendations for improving the environmentally sound management of polybrominated diphenyl ethers in Asia.
Sustainable waste management was introduced more than ten years ago, but it has not yet been applied to the Thai petrochemical industry. Therefore, under the philosophy of sustainable waste management, this research aims to apply the reduce, reuse, and recycle (3R) concept at the petrochemical factory level to achieve a more sustainable industrial solid waste management system. Three olefin plants in Thailand were surveyed for the case study. The sources and types of waste and existing waste management options were identified. The results indicate that there are four sources of waste generation: (1) production, (2) maintenance, (3) waste treatment, and (4) waste packaging, which correspond to 45.18%, 36.71%, 9.73%, and 8.37% of the waste generated, respectively. From the survey, 59 different types of industrial wastes were generated from the different factory activities. The proposed 3R options could reduce the amount of landfill waste to 79.01% of the amount produced during the survey period; this reduction would occur over a period of 2 years and would result in reduced disposal costs and reduced consumption of natural resources. This study could be used as an example of an improved waste management system in the petrochemical industry.
Municipal solid waste management is not only a contemporary problem, but also an issue at world level. In detail, the tourist areas are more difficult to be managed. The dynamics of municipal solid waste production in tourist areas is affected by the addition of a significant amount of population equivalent during a few months. Consequences are seen in terms of the amount of municipal solid waste to be managed, but also on the quality of selective collection. In this article two case studies are analyzed in order to point out some strategies useful for a correct management of this problem, also taking into account the interactions with the sector of waste-to-energy. The case studies concern a tourist area in the north of Italy and another area in the south. Peak production is clearly visible during the year. Selective collection variations demonstrate that the tourists’ behavior is not adequate to get the same results as with the resident population.
Waste hydraulic conductivity and anisotropy represent two important parameters controlling fluid movement in landfills, and thus are the key inputs in design methods where predictions of moisture movement are necessary. Although municipal waste hydraulic conductivity has been estimated in multiple laboratory and field studies, measurements of anisotropy, particularly at full scale, are rare, even though landfilled municipal waste is generally understood to be anisotropic. Measurements from a buried liquids injection well surrounded by pressure transducers at a full-scale landfill in Florida were collected and examined to provide an estimate of in-situ waste anisotropy. Liquids injection was performed at a constant pressure and the resulting pore pressures in the surrounding waste were monitored. Numerical fluid flow modeling was employed to simulate the pore pressures expected to occur under the conditions operated. Nine different simulations were performed at three different lateral hydraulic conductivity values and three different anisotropy values. Measured flowrate and pore pressures collected from conditions of approximate steady state were compared with the simulation results to assess the range of anisotropies. The results support that compacted municipal waste in landfills is anisotropic, provide anisotropy estimates greater than previous measurements, and suggest that anisotropy decreases with landfill depth.
Elevated Cr and Mo concentrations are often found in leachates of thermally treated solid waste, but there is no general explanation for this so far. Therefore, we studied the leaching behaviour after thermal treatment as a function of heating temperature and residence time for two types of solid waste: contaminated sludge and bottom ash from municipal solid waste incineration. The leaching behaviour of both waste streams was compared with experiments on synthetic samples, allowing deduction of a general mechanism for Cr and Mo leaching. Cr and Mo showed a similar leaching behaviour: after an initial increase, the leaching decreased again at higher temperatures. Oxidation of these elements from their lower oxidation states to chromate and molybdate at temperatures up to 600 °C was responsible for the increased leaching. At higher temperatures, both Mo and Cr leaching decreased again owing to the formation of an amorphous phase, incorporating the newly formed chromate and molybdate salts, which prevents them from leaching.
Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner–subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner.
Performance assessment of membrane bioreactor (MBR) technology for the treatability of high-strength landfill leachate is relatively limited or lacking. This study examines the feasibility of treating high-strength landfill leachate using a hollow-fiber MBR. For this purpose, a laboratory-scale MBR was constructed and operated to treat leachate with a chemical oxygen demand (COD) of 9000–11,000 mg/l, a 5-day biochemical oxygen demand (BOD5) of 4000–6,000 mg/l, volatile suspended solids (VSS) of 300–500 mg/l, total nitrogen (TN) of 2000–6000 mg/l, and an ammonia-nitrogen (NH3-N) of 1800–4000 mg/l. VSS was used with the BOD and COD data to simulate the biological activity in the activated sludge. Removal efficiencies > 95–99% for BOD5, VSS, TN and NH3-N were attained. The coupled experimental and simulation results contribute in filling a gap in managing high-strength landfill leachate and providing guidelines for corresponding MBR application.
Private sector involvement in solid waste management in developing countries has increased, but the effect is not always clear. This study assesses how it has been organized in five cities in Ghana, what has been its effect and what lessons for private sector development in developing countries can be drawn. Data were collected from 25 private companies and a sample of 1200 households. More than 60% of solid waste in Ghanaian cities is now collected by private enterprises. Sometimes, and increasingly, competitive bidding takes place, although sometimes no bidding is organized leading to rendering of this service and no contract being signed. Local governments and local solid waste companies have not changed to more customer-oriented delivery because of the slow pace of charging users and the resulting low rate of cost recovery. The participation of the population has been limited, which contributes to low cost recovery. However, a gradual better functioning of the system put in place is shown. We observed an increasing use of competitive bidding, signing of contracts and city-wide user charging.
This article deals with assessment of the potential health risk posed by carcinogenic and non-carcinogenic substances, namely lead (Pb), cadmium (Cd), copper, chromium (CrVI), zinc, nickel and mercury, present in e-waste. A multi-objective, multi-stakeholder approach based on strategic game theory model has been developed considering cost, as well as human health risk. The trade-off due to cost difference between a hazardous substances-free (HSF) and a hazardous substance (HS)-containing desktop computer, and the risk posed by them at the time of disposal, has been analyzed. The cancer risk due to dust inhalation for workers at a recycling site in Bangalore for Pb, Cr(VI) and Cd was found to be 4, 33 and 101 in 1 million respectively. Pb and Cr(VI) result in a very high risk owing to dust ingestion at slums near the recycling site—175 and 81 in 1 million for children, and 24 and 11 in 1 million for adults respectively. The concentration of Pb at a battery workshop in Mayapuri, Delhi (hazard quotient = 3.178) was found to pose adverse health hazards. The government may impose an appropriate penalty on the land disposal of computer waste and/or may give an incentive to manufacturer for producing HSF computers through, for example, relaxing taxes, but there should be no such incentive for manufacturing HS-containing computers.
This article presents a process of evaluation and selection of the most favourable location for a sanitary landfill facility from three alternative locations, by applying a multi-criteria decision-making (MCDM) method. An incorrect choice of location for a landfill facility can have a significant negative economic and environmental impact, such as the pollution of air, ground and surface waters. The aim of this article is to present several improvements in the practical process of landfill site selection using the VIKOR MCDM compromise ranking method integrated with a fuzzy analytic hierarchy process approach for determining the evaluation criteria weighing coefficients. The VIKOR method focuses on ranking and selecting from a set of alternatives in the presence of conflicting and non-commensurable (different units) criteria, and on proposing a compromise solution that is closest to the ideal solution. The work shows that valuable site ranking lists can be obtained using the VIKOR method, which is a suitable choice when there is a large number of relevant input parameters.
Sustainable waste management requires an integrated planning and design strategy for reliable forecasting of waste generation, collection, recycling, treatment and disposal for the successful development of future residential precincts. The success of the future development and management of waste relies to a high extent on the accuracy of the prediction and on a comprehensive understanding of the overall waste management systems. This study defies the traditional concepts of waste, in which waste was considered as the last phase of production and services, by putting forward the new concept of waste as an intermediate phase of production and services. The study aims to develop a demand forecasting tool called ‘zero waste index’ (ZWI) for measuring the natural resources recouped from municipal solid waste. The ZWI (ZWI demand forecasting tool) quantifies the amount of virgin materials recovered from solid waste and subsequently reduces extraction of natural resources. In addition, the tool estimates the potential amount of energy, water and emissions avoided or saved by the improved waste management system. The ZWI is tested in a case study of waste management systems in two developed cities: Adelaide (Australia) and Stockholm (Sweden). The ZWI of waste management systems in Adelaide and Stockholm is 0.33 and 0.17 respectively. The study also enumerates per capita energy savings of 2.9 GJ and 2.83 GJ, greenhouse gas emissions reductions of 0.39 tonnes (CO2e) and 0.33 tonnes (CO2e), as well as water savings of 2.8 kL and 0.92 kL in Adelaide and Stockholm respectively.
The Canadian construction industry generates 30% of the total municipal solid waste deposited in landfills. Ample evidence can be found in the published literature about rework and waste generation due to ambiguity and errors in contract documents. Also, the literature quotes that disclaimer clauses in contract documents are included in the contractual agreements to prevent contractor claims, which often cause rework. Our professional practice has also noted that there are several disclaimer clauses in standard contract documents which have the potential to cause rework (and associated waste). This article illustrates a comparative study of standard contractual documents and their potential to create rework (and associated waste) in different regions of the world. The objectives of this study are (1) to analyse standard contractual documents in Canada, the USA and Australia in terms of their potential to generate rework and waste, and (2) to propose changes/amendments to the existing standard contract documents to minimise/avoid rework. In terms of construction waste management, all the reviewed standard contract documents have deficiencies. The parties that produce the contract documents include exculpatory clauses to avoid the other party’s claims. This approach tends to result in rework and construction waste. The contractual agreements/contract documents should be free from errors, deficiencies, ambiguity and unfair risk transfers to minimise/avoid potential to generate rework and waste.
Municipal solid waste (MSW) recycling performance, both nationally and in Florida, USA, has shown little improvement during the past decade. This research examines variations in the MSW recycling program performance in Florida counties in an attempt to identify effective recycling programs. After reviewing trends in the MSW management literature, we conducted an empirical analysis using cross-sectional multiple regression analysis. The findings suggest that the convenience-based hypothesis was supported by showing that curbside recycling had a positive effect on MSW recycling performance. Financial (cost-saving) incentive-based hypotheses were partially supported meaning that individual level incentives can influence recycling performance. Citizen environmental concern was found to positively affect the amount of county recycling, while education and political affiliation yielded no significant results. In conclusion, this article discusses the implications of the findings for both academic research and practice of MSW recycling programs.
The purpose of this study was to evaluate the physical and mechanical properties of particleboard made with pruning wastes from Ipê (Tabebuia serratifolia) and Chapéu-de-Sol (Terminalia catappa) trees. Particleboards were prepared with both wood species, using all the material produced by grinding the pruning wastes. The particleboards had dimensions of 45x45 cm, a thickness of approximately 11.5 mm and an average density of 664 kg/m3. A urea–formaldehyde adhesive was used in the proportion of 12% of the dry particle mass. The particleboards were pressed at a temperature of 130°C for 10 mins. The physical and mechanical properties analyzed were density, moisture content, thickness swelling, percentage of lignin and cellulose, modulus of resilience, modulus of elasticity and tensile strength parallel to the grain, accordingly to the standards NBR 14810 and CS 236-66 (1968). The particleboards were considered to be of medium density. The particle size significantly affected the static bending strength and tensile strength parallel to the grain. Ipê presented better results, demonstrating a potential for the production and use of particleboard made from this species.
The bioreactor environment for the mechanically sorted organic fraction (MSOF) of residual municipal solid waste was simulated for a period of 300 days. A closed-loop system was implemented for analysing the leachate purification process due to its recirculation through MSOF. Maximum concentrations of Cu, Zn and Ni in the leachate were about 60, 20 and 15 mg L–1, whereas Pb and Cr were about 5.5 and 7 mg L–1. About 60 days from the start of recirculation these concentrations dropped to < 1 mg L–1. Chemical (COD) and biological oxygen demand (BOD5) dropped, respectively, by about 50 and 80%, achieving a COD-to-BOD5 ratio > 7. Volatile fatty acids, which were about 10 g L–1, fell to about 3.5 g L–1 whereas biomethane production was about 34 NL kg TS–1. As expected, recirculation under strictly anaerobic conditions gave minor benefits in reducing nitrogen and ammonium which reached final concentrations of about 4 and 3.8 g L–1, respectively.
A study was conducted to investigate the levels of plant nutrients, heavy metals, parasites and fecal coliform bacteria in Bangkok-produced sewage sludge and finished compost products for potential agricultural application, as well as to compare the quality of compost under different composting conditions. The results indicated that digested sewage sludge had high fertilizing values for organic matter (19.01 ± 0.09%), total nitrogen (2.17 ± 0.07%), total phosphorus (2.06 ± 0.06%) and total potassium (1.16 ± 0.22%), but it was contaminated with human pathogens, including fecal coliform bacteria, viable helminthes egg and active forms of parasite cysts. Thus, fresh sewage sludge should not be disposed on land unless it has undergone pathogen reduction. It is proven that the quality of the sludge mixed with grass clippings at a ratio of 6:1 volume/volume after having passed a windrow composting process for 8 weeks can be classified as class A biosolids as the levels of remaining fecal coliforms were < 3 most probable number g–1 dry solid and all human parasites were destroyed. Concentrations of organic matter, total nitrogen, total phosphorus and total potassium in the finished compost were 16.53 ± 1.25%, 1.39 ± 0.06%, 0.42 ± 0.10% and 1.53 ± 0.05% respectively. The total copper concentration was rather high (2291.31 ± 121.77 mg kg–1), but all heavy metal concentrations were also well below the United States Environmental Protection Agency pollutant limits for land application. The finished compost products can be considered as a soil conditioner as they have relatively low essential plant nutrient concentrations. It is recommended to be initially used for gardening and landscaping to ensure safety utilization.
The article summarises the main results of the ‘Gestione Rifiuti in Lombardia: Analisi del ciclo di vita’ (Waste management in Lombardia region: Life cycle assessment; GERLA) project. Life cycle assessment (LCA) has been selected by Regione Lombardia as a strategic decision support tool in the drafting of its new waste management programme. The goal was to use the life cycle thinking approach to assess the current regional situation and thus to give useful strategic indications for the future waste management. The first phase of the study consisted of the LCA of the current management of municipal waste in the Lombardia region (reference year: 2009). The interpretation of such results has allowed the definition of four possible waste management scenarios for the year 2020, with the final goal being to improve the environmental performance of the regional system. The results showed that the current integrated waste management of Lombardia region is already characterised by good energy and environmental performances. However, there is still room for further improvement: actions based, on the one hand, on a further increase in recycling rates and, on the other hand, on a series of technological modifications, especially in food waste and residual waste management, can be undertaken to improve the overall system.
Chlorine, sulfur and phosphorus were selected as element donators to investigate their effect on the volatilization behavior of heavy metals in sludge sewage incineration. Principal component analysis indicated that the promotive effect on the volatilization of heavy metals was followed by chlorine, sulfur and phosphorus. This result was proved to be correct by total release of heavy metals in sewage sludge incineration using different element donators. The release of heavy metals was very chlorine dependent, especially cadmium (Cd), lead (Pb) and nickel (Ni). When chlorine content was in the range of 0.1–0.5wt%, the increase of the volatilization rate was 44.9% for Cd, 6.8% for Pb and 4.6% for Ni, respectively. Although sulfur contributed to the promotion of the volatilization of heavy metals, excess oxygen impaired the promotive effect of sulfur on the release of heavy metals from the condensed phase. For phosphorus, solidifying heavy metals was dominant. Energy analysis showed that metal chlorides and sulfides were prone to volatilize or to be decomposed at elevated temperature compared with sulfates and phosphates owing to low binding energy in absolute value (VLFA). It was the difference of binding energy that led to the different volatilization behavior of metal compounds in a high temperature, oxygen-enriched atmosphere.
The recovery of aluminium (Al) scraps from waste incineration bottom ash is becoming a common practice in waste management. However, during the incineration process, Al in the waste undergoes oxidation processes that reduce its recycling potential. This article investigates the behaviour of Al scraps in the furnace of two selected grate-fired waste-to-energy plants and the amount recoverable from the bottom ash. About 21–23% of the Al fed to the furnace with the residual waste was recovered and potentially recycled from the bottom ash. Out of this amount, 76–87% was found in the bottom ash fraction above 5 mm and thus can be recovered with standard eddy current separation technology. These values depend on the characteristics and the mechanical strength of the Al items in the residual waste. Considering Al packaging materials, about 81% of the Al in cans can be recovered from the bottom ash as an ingot, but this amount decreases to 51% for trays, 27% for a mix of aluminium and poly-laminated foils and 47% for paper-laminated foils. This shows that the recovery of Al from the incineration residues increases proportionally to the thickness of the packaging.
This study empirically evaluates whether the increasingly large numbers of private outpatient healthcare facilities (HCFs) within the European Union (EU) countries comply with the existing European waste legislation, and whether compliance with such legislation affects the fraction of healthcare waste (HCW) classified as hazardous. To that end, this study uses data collected by a large survey of more than 700 small private HCFs distributed throughout Portugal, a full member of the EU since 1986, where 50% of outpatient care is currently dominated by private operators. The collected data are then used to estimate a hurdle model, i.e. a statistical specification in which there are two processes: one is the process by which some HCFs generate zero or some positive fraction of hazardous HCW, and another is the process by which HCFs generate a specific positive fraction of hazardous HCW conditional on producing any. Taken together, the results show that although compliance with the law is far from ideal, it is the strongest factor influencing hazardous waste generation. In particular, it is found that higher compliance has a small and insignificant effect on the probability of generating (or reporting) positive amounts of hazardous waste, but it does have a large and significant effect on the fraction of hazardous waste produced, conditional on producing any, with a unit increase in the compliance rate leading to an estimated decrease in the fraction of hazardous HCW by 16.3 percentage points.
Pollutants put great stress on the environment, especially the aquatic ecosystem; therefore, the ease with which pollutants migrate in water is a subject of global concern. In this study, leachate from landfill that was analyzed with the objective of understanding the potential impact to the environment was tested on Pangasius sutchi. Heavy metals available at various concentrations in raw leachate samples of both closed and active landfills necessitated the determination of their degree of bioaccumulation in this fish species in order to enrich the risk data on toxicity of effluents. Zinc (3.2 µg g-1), iron (2.1 µg g-1) and chromium (0.24 µg g-1) detected in the fish within 96 h of acute exposure is of concern. A histopathology test on excised liver of P. sutchi indicated cellular disruption from normal stain. Heterogeneous effluents like leachate may affect not only groundwater but can endanger aquatic ecosystems, especially in some regions where improper waste disposal and treatment allow the flow of leachate into surface water courses. Though metals might be beneficial to organisms, the extent at which they can accumulate in leachate-exposed fish is a risk and can initiate metal toxicity in aquatic life.
Landfilling is the most common and cost-effective waste disposal method, and it is widely applied throughout the world. In developing countries in Asia there is currently a trend towards constructing sanitary landfills with gas recovery systems, not only as a solution to the waste problem and the associated local environmental pollution, but also to generate revenues through carbon markets and from the sale of electricity. This article presents a quantitative assessment of climate co-benefits from landfill gas (LFG) to energy projects, based on the case of Bangkok Metropolitan Administration, Thailand. Life cycle assessment was used for estimating net greenhouse gas (GHG) emissions, considering the whole lifespan of the landfill. The assessment found that the total GHG mitigation of the Bangkok project would be 471,763 tonnes (t) of carbon dioxide (CO2)-equivalents (eq) over its 10-year LFG recovery period. This amount is equivalent to only 12% of the methane (CH4) generated over the whole lifespan of the landfill. An alternative scenario was devised to analyse possible improvement options for GHG mitigation through LFG-to-energy recovery projects. This scenario assumes that LFG recovery would commence in the second year of landfill operation and gas extraction continues throughout the 20-year peak production period. In this scenario, GHG mitigation potential amounted to 1,639,450 tCO2-eq during the 20-year project period, which is equivalent to 43% of the CH4 generated throughout the life cycle. The results indicate that with careful planning, there is a high potential for improving the efficiency of existing LFG recovery projects which would enhance climate co-benefits, as well as economic benefits. However, the study also shows that even improved gas recovery systems have fairly low recovery rates and, in consequence, that emissions of GHG from such landfills sites are still considerable.
This article presents a water balance equation for predicting leachate generation in municipal solid waste (MSW) landfills located in semi-arid areas, using the Akaider landfill in Jordan as an example. HYDRUS-2D/3D software was used to model the effect of co-disposal of wastewater into the landfill on the leachate production rates and for comparison with the results of the simulation of the proposed water balance equation parameters. A series of simulations was carried out for a 30-year period. The suggested water balance equation predicted that leachate will percolate to a depth of 50 m in the simulated period. The result indicates that the co-disposed wastewater plays a major role in controlling the rate and magnitude of the contaminants that percolate from the MSW leachate. As the initial water content of the waste increases, there is greater mobilisation of salts. The concentration of chloride at a given location increased and the time required for the chloride to reach this location decreased as a consequence. However, eliminating the co-disposed wastewater will significantly minimise leachate generation and decrease possible groundwater contamination. This equation is applicable to areas that have geological and hydrological properties similar to Jordan.
The aim of this study was to determine the methane (CH4) generation factor (k) and CH4 generation potential (L) for bulk waste in order to calibrate a CH4 generation model (USEPA Landgem 3.02) and provide information on the remaining CH4 generation potential in a large (54 ha) municipal solid waste landfill located in a boreal climate. The CH4 generation model was calibrated by actual CH4 recovery and emission measurement data. Moreover, waste characterisation information from a previous study was considered. The appropriate k for bulk waste was 0.18 in the studied landfill, which indicated a higher rate of degradation than proposed by the Intergovernmental Panel on Climate Change as a default k value of 0.09 for wet conditions in boreal and temperate climes, whereas the calibrated L of 100 m3/t was lower than estimated on the basis of a previous waste characterisation study. The results demonstrate the importance of model calibration, as inappropriate model parameters may result in a large discrepancy (approximately 100 % or 119 million m3 having an energy equivalent of nearly 1.2 TWh) in cumulative CH4 generation estimates within a 18-year timescale (2012–30) at the studied landfill.
Heavy fractions resulting from mechanical treatment stages of mechanical–biological waste treatment plants are posing very specific demands with regard to further treatment (large portions of inert and high-caloric components). Based on the current Austrian legal situation such a waste stream cannot be landfilled and must be thermally treated. The aim of this research was to evaluate if an inert fraction generated from this waste stream with advanced separation technologies, two sensor-based [near-infrared spectroscopy (NIR), X-ray transmission (XRT)] and two mechanical systems (wet and dry) is able to be disposed of. The performance of the treatment options for separation was evaluated by characterizing the resulting product streams with respect to purity and yield. Complementing the technical evaluation of the processing options, an assessment of the economic and global warming effects of the change in waste stream routing was conducted. The separated inert fraction was evaluated with regard to landfilling. The remaining high-caloric product stream was evaluated with regard to thermal utilization. The results show that, in principal, the selected treatment technologies can be used to separate high-caloric from inert components. Limitations were identified with regard to the product qualities achieved, as well as to the economic expedience of the treatment options. One of the sensor-based sorting systems (X-ray) was able to produce the highest amount of disposeable heavy fraction (44.1%), while having the lowest content of organic (2.0% Cbiogenic per kg waste input) components. None of the high-caloric product streams complied with the requirements for solid recovered fuels as defined in the Austrian Ordinance on Waste Incineration. The economic evaluation illustrates the highest specific treatment costs for the XRT (23.15 per t), followed by the NIR-based sorting system (15.67 per t), and the lowest costs for the air separation system (10.79 per t). Within the ecological evaluation it can be shown that the results depend strongly on the higher heating value of the high caloric light fraction and on the content of Cbiogenic of the heavy fraction. Therefore, the XRT system had the best results for the overall GWP [–14 kg carbon dioxide equivalents (CO2eq) per t of input waste] and the NIR-based the worst (193 kg CO2 eq per t of input waste). It is concluded that three of the treatment options would be suitable under the specific conditions considered here. Of these, sensor-based sorting is preferable owing to its flexibility.
The goal of this work was to evaluate a washing process that uses organic solutions for polychlorinated biphenyl (PCB)-contaminated soil, and includes an ultrasound pre-treatment step to reduce operational times and organic solvent losses. In a preliminary trial, the suitability of 10 washing solutions of different polarities were tested, from which three n-hexane-based solutions were selected for further evaluation. A second set of experiments was designed using a three-level Taguchi L27 orthogonal array to model the desorption processes of seven different PCB congeners in terms of the variability of their PCB concentration levels, polarity of the washing solution, sonication time, the ratio washing solution/soil, number of extraction steps and total washing time. Linear models were developed for the desorption processes of all congeners. These models provide a good fit with the results obtained. Moreover, statistically significant outcomes were achieved from the analysis of variance tests carried out. It was determined that sonication time and ratio of washing solution/soil were the most influential process parameters. For this reason they were studied in a third set of experiments, constructed as a full factorial design. The process was eventually optimized, achieving desorption rates of more than 90% for all congeners, thus obtaining concentrations lower than 5 ppb in all cases. The use of an ultrasound-assisted soil washing process for PCB-contaminated soils that uses organic solvents seems therefore to be a viable option, especially with the incorporation of an extra step in the sonication process relating to temperature control, which is intended to prevent the loss of the lighter congeners.
In order to study the influence of settlement under gas pressure in bioreactor landfill, the landfill is simplified as a one-way gas seepage field, combining Darcy’s Law, the gas equation of state, and the principle of effective stress and fluid dynamics of porous media theory. First assume that the bioreactor landfill leachate is fully recharged on the basis of gas mass conservation, then according to the changes in gas pressure (inside the landfill and surrounding atmosphere) during the gas leakage time and settlement in the landfill, establish a numerical model of bioreactor landfill settlement under the action of the gas pressure, and use the finite difference method to solve it. Through a case study, the model’s improved prediction of the settlement of bioreactor landfill is demonstrated.
Plastics continue to be a challenge for recovering materials at the end-of-life for vehicles. However, it may be possible to improve the recovery of plastics by exploiting material characteristics, such as shape, or by altering their behavior, such as through temperature changes, in relation to recovery processes and handling. Samples of a 2009 Dodge Challenger front fascia were shredded in a laboratory-scale hammer mill shredder. A 2 x 2 factorial design study was performed to determine the effect of sample shape (flat versus curved) and sample temperature (room temperature versus cryogenic temperature) on the size of the particles exiting from the shredder. It was determined that sample shape does not affect the particle size; however, sample temperature does affect the particle size. At cryogenic temperatures, the distribution of particle sizes is much narrower than at room temperature. Having a more uniform particle size could make recovery of plastic particles, such as these more efficient during the recycling of end-of-life vehicles. Samples of Chrysler minivan headlights were also shredded at room temperature and at cryogenic temperatures. The size of the particles of the two different plastics in the headlights is statistically different both at room temperature and at cryogenic temperature, and the particles are distributed narrowly. The research suggests that incremental changes in end-of-life vehicle processing could be effective in aiding materials recovery.
This study aimed to determine the content of fossil carbon in waste combusted in Sweden by using four different methods at seven geographically spread combustion plants. In total, the measurement campaign included 42 solid samples, 21 flue gas samples, 3 sorting analyses and 2 investigations using the balance method. The fossil carbon content in the solid samples and in the flue gas samples was determined using 14C-analysis. From the analyses it was concluded that about a third of the carbon in mixed Swedish waste (municipal solid waste and industrial waste collected at Swedish industry sites) is fossil. The two other methods (the balance method and calculations from sorting analyses), based on assumptions and calculations, gave similar results in the plants in which they were used. Furthermore, the results indicate that the difference between samples containing as much as 80% industrial waste and samples consisting of solely municipal solid waste was not as large as expected. Besides investigating the fossil content of the waste, the project was also established to investigate the usability of various methods. However, it is difficult to directly compare the different methods used in this project because besides the estimation of emitted fossil carbon the methods provide other information, which is valuable to the plant owner. Therefore, the choice of method can also be controlled by factors other than direct determination of the fossil fuel emissions when considering implementation in the combustion plants.
Waste management policy makers always face the problem of how to predict the future amount and composition of medical solid waste, which, in turn, helps to determine the most appropriate treatment, recycling and disposal strategy. An accurate prediction can assist in both the planning and design of medical solid waste management systems. Insufficient budget and unavailable management capacity are the main reasons for the scarcity of medical solid waste quantities and components historical records, which are so important in long-term system planning and short-term expansion programs. This article presents a new technique, using System Dynamics modeling, to predict generated medical solid waste in a developing urban area, based on a set of limited samples from Jenin District hospitals, Palestine. The findings of the model present the trend of medical solid waste generation together with its different components and indicate that a new forecasting approach may cover a variety of possible causative models and track inevitable uncertainties when traditional statistical least-squared regression methods are unable to handle such issues.
During the last decade, the European Union has enforced the diversion of organic wastes and recyclables to waste management companies operating incineration plants, composting plants and recycling units instead of landfills. The temporary storage sites have been established as a buffer against fluctuations in energy demand throughout the year. Materials also need to be stored at temporary storage sites before recovery and recycling. However, regulations governing waste fuel storage and handling have not yet been developed, and, as a result, companies have engaged in risky practices that have resulted in a high number of fire incidents. In this study, a questionnaire survey was distributed to 249 of the 400 members of Avfall Sverige (Swedish Waste Management Association), which represents the waste management of 95% of the Swedish population. Information regarding 122 storage facilities owned by 69 companies was obtained; these facilities were responsible for the storage of 47% of the total treated waste (incineration + digestion + composting) in 2010 in Sweden. To identify factors related to fire frequency, the questionnaire covered the amounts of material handled and burnt per year, financial losses due to fires, storage duration, storage method and types of waste. The results show that 217 fire incidents corresponded to 170 kilotonnes of material burnt and cumulative losses of 49 million SEK (4.3 million). Fire frequency and amount of material burnt per fire was found to be dependent upon type of management group (waste operator). Moreover, a correlation was found between fire frequency and material recycled during past years. Further investigations of financial aspects and externalities of fire incidents are recommended.
The only option for municipal solid waste (MSW) treatment adopted so far in Serbia is landfilling. Similarly to other south-eastern European countries, Serbia is not recovering any energy from MSW. Fifty percent of electricity in Serbia is produced in coal-fired power plants with emission control systems dating from the 1980s. In this article, the option of MSW incineration with energy recovery is proposed and examined for the city of Novi Sad. A sustainability analysis consisting of financial, economic and sensitivity analyses was done in the form of a cost–benefit analysis following recommendations from the European Commission. Positive and negative social and environmental effects of electricity generation through incineration were valuated partly using conversion factors and shadow prices, and partly using the results of previous studies. Public aversion to MSW incineration was considered. The results showed that the incineration project would require external financial assistance, and that an increase of the electricity and/or a waste treatment fee is needed to make the project financially positive. It is also more expensive than the landfilling option. However, the economic analysis showed that society would have net benefits from an incineration project. The feed-in tariff addition of only 0.03 (KWh)–1 to the existing electricity price, which would enable the project to make a positive contribution to economic welfare, is lower than the actual external costs of electricity generation from coal in Serbia.
The waste and recycling sector has been identified as a green industry and, as such, jobs within this sector may be classed as ‘green jobs’. Many governments have seen green jobs as a way of increasing employment, particularly during the global financial crisis. However, the methods used to define and quantify green jobs directly affect the quantification of these green jobs. In December 2010, Queensland introduced a waste strategy that stated intent to increase green jobs within the waste sector. This article discusses the milieu and existing issues associated with quantifying green jobs within Queensland’s waste and recycling sector, and provides a review of the survey that has sought to quantify the true size of the Queensland industry sector. This research has identified nearly 5500 jobs in Queensland’s private waste management and recycling sector, which indicates that official data do not accurately reflect the true size of the sector.
Landfill monitoring is one of the most important components of waste management. This article presents a case study on landfill monitoring using remote sensing technology. The study area was the Glina landfill, one of the largest municipal waste disposal sites in Romania. The methodology consisted of monitoring the differences of temperature computed for several distinct waste disposal zones with respect to a ground reference area, all of them located within the landfill site. The remote sensing data used were Landsat satellite multi-temporal data. The differences of temperature were computed using Landsat thermal infrared data. The study confirmed the use of multi-temporal Landsat imagery as a complementary data source.
An integrated formal collection and recycling network is a significant concern to achieve efficient management of waste electrical and electronic equipment (WEEE). This study, which aimed to investigate the present problems of WEEE recycling in China, proposes the application of a comprehensive solution approach to address a complete WEEE collection and transportation network in Shanghai, China. The methodologic steps regard three things: identification of WEEE collection sites and transit sites with quadratic optimizing models solved by exact algorithm; vehicle routing planning with a modified ant colony algorithm; and defining of minimum transportation cycles and proper shipping arrangements. The rounded WEEE collection network is presented as technical support and a demonstration of further planning and construction of the WEEE recycling system in China.
The significant amount of waste generated from construction demolition has become a chronic problem in many developing countries. Using data obtained from demolition contractors and various other sources, this paper proposes a framework for proper handling of construction demolition waste (CDW) to serve as a decision support tool in countries suffering from the lack of national CDW management guidelines. The framework is then demonstrated through a case study in the city of Beirut, Lebanon, and a sensitivity analysis is carried out to examine the economic feasibility of developing a recycling facility. The analysis showed that in order for a facility to be feasible, a gate fee should be charged in the presence of a market for recycled aggregates. The results confirm the significance of instigating and implementing legislation to control illegal dumping, constructing, and managing engineered landfills, and establishing markets for recycled CDW.