Review of LCA studies of solid waste management systems – Part I: Lessons learned and perspectives

The continuously increasing solid waste generation worldwide calls for management strategies that integrate concerns for environmental sustainability. By quantifying environmental impacts of systems, life cycle assessment (LCA) is a tool, which can contribute to answer that call. But how, where and to which extent has it been applied to solid waste management systems (SWMSs) until now, and which lessons can be learnt from the findings of these LCA applications? To address these questions, we performed a critical review of 222 published LCA studies of SWMS. We first analysed the geographic distribution and found that the published studies have primarily been concentrated in Europe with little application in developing countries. In terms of technological coverage, they have largely overlooked application of LCA to waste prevention activities and to relevant waste types apart from household waste, e.g. construction and demolition waste. Waste management practitioners are thus encouraged to abridge these gaps in future applications of LCA. In addition to this contextual analysis, we also evaluated the findings of selected studies of good quality and found that there is little agreement in the conclusions among them. The strong dependence of each SWMS on local conditions, such as waste composition or energy system, prevents a meaningful generalisation of the LCA results as we find it in the waste hierarchy. We therefore recommend stakeholders in solid waste management to regard LCA as a tool, which, by its ability of capturing the local specific conditions in the modelling of environmental impacts and benefits of a SWMS, allows identifying critical problems and proposing improvement options adapted to the local specificities.     

Review of comparative LCAs of food waste management systems – Current status and potential improvements

Twenty-five comparative cycle assessments (LCAs) addressing food waste treatment were reviewed, including the treatment alternatives landfill, thermal treatment, compost (small and large scale) and anaerobic digestion. The global warming potential related to these treatment alternatives varies largely amongst the studies. Large differences in relation to setting of system boundaries, methodological choices and variations in used input data were seen between the studies. Also, a number of internal contradictions were identified, many times resulting in biased comparisons between alternatives. Thus, noticed differences in global warming potential are not found to be a result of actual differences in the environmental impacts from studied systems, but rather to differences in the performance of the study. A number of key issues with high impact on the overall global warming potential from different treatment alternatives for food waste were identified through the use of one-way sensitivity analyses in relation to a previously performed LCA of food waste management. Assumptions related to characteristics in treated waste, losses and emissions of carbon, nutrients and other compounds during the collection, storage and pretreatment, potential energy recovery through combustion, emissions from composting, emissions from storage and land use of bio-fertilizers and chemical fertilizers and eco-profiles of substituted goods were all identified as highly relevant for the outcomes of this type of comparisons. As the use of LCA in this area is likely to increase in coming years, it is highly relevant to establish more detailed guidelines within this field in order to increase both the general quality in assessments as well as the potentials for cross-study comparisons.     

Part II – The effect of data on waste behaviour: The South African waste information system

Combining the process of learning and the theory of planned behaviour into a new theoretical framework provides an opportunity to explore the impact of data on waste behaviour, and consequently on waste management, in South Africa. Fitting the data to the theoretical framework shows that there are only three constructs which have a significant effect on behaviour, viz experience, knowledge, and perceived behavioural control (PBC). Knowledge has a significant influence on all three of the antecedents to behavioural intention (attitude, subjective norm and PBC). However, it is PBC, and not intention, that has the greatest influence on waste behaviour. While respondents may have an intention to act, this intention does not always manifest as actual waste behaviour, suggesting limited volitional control. The theoretical framework accounts for 53.7% of the variance in behaviour, suggesting significant external influences on behaviour not accounted for in the framework. While the theoretical model remains the same, respondents in public and private organisations represent two statistically significant sub-groups in the data set. The theoretical framework accounts for 47.8% of the variance in behaviour of respondents in public waste organisations and 57.6% of the variance in behaviour of respondents in private organisations. The results suggest that respondents in public and private waste organisations are subject to different structural forces that shape knowledge, intention, and resultant waste behaviour.     

Environmental analysis of a construction and demolition waste recycling plant in Portugal – Part II: Environmental sensitivity analysis

Part I of this study deals with the primary energy consumption and CO₂eq emissions of a 350 tonnes/h construction and demolition waste (CDW) recycling facility, taking into account incorporated, operation and transportation impacts. It concludes that the generated impacts are mostly concentrated in operation and transportation, and that the impacts prevented through material recycling can be up to one order of magnitude greater than those generated.However, the conditions considered for the plant’s operation and related transportation system may, and very likely will, vary in the near future, which will affect its environmental performance. This performance is particularly affected by the plant’s installed capacity, transportation fuel and input CDW mass. In spite of the variations in overall primary energy and CO₂eq balances, the prevented impacts are always higher than the generated impacts, at least by a factor of three and maybe even as high as 16 times in particular conditions. The analysis indicates environmental performance for variations in single parameters, except for the plant’s capacity, which was considered to vary simultaneously with all the others. Extreme best and worst scenarios were also generated to fit the results into extreme limits.     

Municipal solid waste management in India: From waste disposal to recovery of resources?

Unlike that of western countries, the solid waste of Asian cities is often comprised of 70-80% organic matter, dirt and dust. Composting is considered to be the best option to deal with the waste generated. Composting helps reduce the waste transported to and disposed of in landfills. During the course of the research, the author learned that several developing countries established large-scale composting plants that eventually failed for various reasons. The main flaw that led to the unsuccessful establishment of the plants was the lack of application of simple scientific methods to select the material to be composted. Landfills have also been widely unsuccessful in countries like India because the landfill sites have a very limited time frame of usage. The population of the developing countries is another factor that detrimentally impacts the function of landfill sites. As the population keeps increasing, the garbage quantity also increases, which, in turn, exhausts the landfill sites. Landfills are also becoming increasingly expensive because of the rising costs of construction and operation. Incineration, which can greatly reduce the amount of incoming municipal solid waste, is the second most common method for disposal in developed countries. However, incinerator ash may contain hazardous materials including heavy metals and organic compounds such as dioxins, etc. Recycling plays a large role in solid waste management, especially in cities in developing countries. None of the three methods mentioned here are free from problems. The aim of this study is thus to compare the three methods, keeping in mind the costs that would be incurred by the respective governments, and identify the most economical and best option possible to combat the waste disposal problem.     

Municipal solid waste management—An example of a partnership between five municipalities

Throughout the 1970s and 1980s many joint municipal partnerships were established in Denmark to take responsibility for the planning and handling of waste on behalf of municipalities in the partnership. RENO SYD is a typical joint municipal partnership, established to handle the municipal solid waste of five municipalities with a total of 65,000 inhabitants. The paper reviews the by-laws and organization of RENO SYD; the facility financing ownership or leasing; the collection of the various waste types; the reception at recycling cites; the refuse treatment, energy recovery, waste separation, treatment and landfill disposal; recycling; and economics, including tipping fees and taxation.     

Possibilities and limitations of life cycle assessment (LCA) in the development of waste utilization systems – Applied examples for a region in Northern Germany

Against the background of increasing concerns about climate change, the reduction of greenhouse gas emissions has become an integral part of processes in both the waste management and the energy industries. This is reflected in the development of new waste treatment concepts, in which domestic and commercial waste is treated with the aim of utilizing its energy content, while at the same time recycling as much of its material content as possible. Life cycle assessment (LCA) represents a method of assessing the environmental relevance of a waste management system, the basis of which is a material flow analysis of the system in question. GHG emissions from different options for thermal treatment and energy recovery from waste as applied to a region in Northern Germany have been analyzed by the LCA approach and an indicative LCA, which only considers those emissions resulting from operating stages of the system. Operating stages have the main share of emissions compared to pre-processing stages. Results show that through specific separation of waste material flows and highly efficient energy recovery, thermal treatment and energy generation from waste can be optimized resulting in reduction of emissions of greenhouse gases. There are also other areas of waste utilization, currently given little attention, such as the solar drying of sewage sludge, which can considerably contribute to the reduction of greenhouse gas emissions.     

DISCRISET: A battery of tests for fast waste classification – Application of tests on waste extracts

The Hazardous Waste Directive (HWD, Council Directive 91/689/EC, 1991) provides a framework for classification of hazardous waste, based on 15 Hazard (H)-criteria. For complex wastes the HWD foresees the application of toxicity tests on the waste material itself to assess its toxic properties. However, these proposed test methods often involve mammalian testing, which is not acceptable from an ethical point of view, nor is it feasible economically. The DISCRISET project was initiated to investigate the use of alternative chemical and biological fast screening tests for waste hazard classification. In the first part of the project, different methods were reviewed and a testing strategy was proposed to minimize time and cost of analysis by a tiered approach. This includes as a first tier chemical analysis followed by a general acute toxicity screen as a second tier and as a third tier mechanistic toxicity tests to assess chronic toxicity (genotoxicity, hormone disturbance, teratogenic effects, immunologic activity). In this phase of the project, selected methods were applied to 16 different waste samples from various sources and industries. The first tier chemical tests are recommended for the full characterization of the leachate fraction (inorganics) but not for the organic fraction of samples. Here the chemical characterization is only useful if toxic content is known or suspected. As second tier the fast bacterial test Microtox is validated as a general toxicity screen for the organic fraction (worst case organic extract). Samples that are not classified in tier 1 or 2 are then further investigated in the third tier by the mechanistic toxicity tests and tested for their potential chronic toxicity: immune activity (TNF-α upregulation) is indicative for corrosive, irritating or sensitising effects (H4/H8/H15), reproductive effects (H10) are indicated by hormone disturbance and early life stage abnormalities in fish larvae when exposed to the extracts and mutagenicity and carcinogenicity (H7, H11) are indicated by SOS response induction and increased mutation frequency in the Ames test when exposed to the extracts. Results indicate that the combination of chemical tests and bioassays allows important hazardous properties to be addressed and the tiered approach ensures that the tests are performed quickly and economically. The suggested strategy provides a solid and ethical alternative to the methods described in the HWD and is a vast improvement on the current, arbitrary classification.     

Integration of the informal sector into municipal solid waste management in the Philippines – What does it need?

The integration of the informal sector into municipal solid waste management is a challenge many developing countries face. In Iloilo City, Philippines around 220 tons of municipal solid waste are collected every day and disposed at a 10 ha large dumpsite. In order to improve the local waste management system the Local Government decided to develop a new Waste Management Center with integrated landfill. However, the proposed area is adjacent to the presently used dumpsite where more than 300 waste pickers dwell and depend on waste picking as their source of livelihood. The Local Government recognized the hidden threat imposed by the waste picker’s presence for this development project and proposed various measures to integrate the informal sector into the municipal solid waste management (MSWM) program. As a key intervention a Waste Workers Association, called USWAG Calahunan Livelihood Association Inc. (UCLA) was initiated and registered as a formal business enterprise in May 2009. Up to date, UCLA counts 240 members who commit to follow certain rules and to work within a team that jointly recovers wasted materials. As a cooperative they are empowered to explore new livelihood options such as the recovery of Alternative Fuels for commercial (cement industry) and household use, production of compost and making of handicrafts out of used packages. These activities do not only provide alternative livelihood for them but also lessen the generation of leachate and Greenhouse Gases (GHG) emissions from waste disposal, whereby the life time of the proposed new sanitary landfill can be extended likewise.     

Networks of recyclable material waste-picker’s cooperatives: An alternative for the solid waste management in the city of Rio de Janeiro

The objective of this study is to discuss the role of networks formed of waste-picker cooperatives in ameliorating problems of final disposal of solid waste in the city of Rio de Janeiro, since the city’s main landfill will soon have to close because of exhausted capacity. However, it is estimated that in the city of Rio de Janeiro there are around five thousand waste-pickers working in poor conditions, with lack of physical infrastructure and training, but contributing significantly by diverting solid waste from landfills. According to the Sustainable Development Indicators (IBGE, 2010a, IBGE, 2010b) in Brazil, recycling rates hover between 45% and 55%. In the municipality of Rio de Janeiro, only 1% of the waste produced is collected selectively by the government (COMLURB, 2010), demonstrating that recycling is mainly performed by waste-pickers. Furthermore, since the recycling market is an oligopsony that requires economies of scale to negotiate directly with industries, the idea of working in networks of cooperatives meets the demands for joint marketing of recyclable materials. Thus, this work presents a method for creating and structuring a network of recycling cooperatives, with prior training for working in networks, so that the expected synergies and joint efforts can lead to concrete results. We intend to demonstrate that it is first essential to strengthen the waste-pickers’ cooperatives in terms of infrastructure, governance and training so that solid waste management can be environmentally, socially and economically sustainable in the city of Rio de Janeiro.     

Assessment of the environmental impact of management measures for the biodegradable fraction of municipal solid waste in São Paulo City

There is increasing concern about landfilling of biodegradable wastes. Therefore, biological treatment processes such as composting and biogasification have been considered as alternative strategies for managing those wastes. In this work, life cycle assessment was employed to compare the environmental impacts of landfilling, composting, and biological treatment of municipal solid waste in S?o Paulo City, Brazil. Energy consumption, recovered resources, and emissions to air and water were quantified and analyzed in terms of their potential contribution to global warming, acidification, and nutrient enrichment impact. The results demonstrated that processes that require high levels of energy consumption, such as wastewater treatment, play an important role in the outcome of environmental impact potentials. It was found that the landfilling of all waste is generally the worst strategy from an environmental point of view. However, significant reductions in the resulting impacts can be accomplished through biogasification and composting of the biodegradable fraction. Regarding composting, the application of a biofilter for gas treatment reduced significantly the gaseous emissions.     

Environmental analysis of a construction and demolition waste recycling plant in Portugal – Part I: Energy consumption and CO2 emissions

This work is a part of a wider study involving the economic and environmental implications of managing construction and demolition waste (CDW), focused on the operation of a large scale CDW recycling plant. This plant, to be operated in the Lisbon Metropolitan Area (including the Setúbal peninsula), is analysed for a 60 year period, using primary energy consumption and CO₂eq emission impact factors as environmental impact performance indicators.Simplified estimation methods are used to calculate industrial equipment incorporated, and the operation and transport related impacts. Material recycling – sorted materials sent to other industries, to act as input – is taken into account by discounting the impacts related to industrial processes no longer needed.This first part focuses on calculating the selected impact factors for a base case scenario (with a 350 tonnes/h installed capacity), while a sensitivity analysis is provided in part two. Overall, a 60 year global primary energy consumption of 71.4 thousand toe (tonne of oil equivalent) and a total CO₂eq emission of 135.4 thousand tonnes are expected. Under this operating regime, around 563 thousand toe and 1465 thousand tonnes CO₂eq could be prevented by replacing raw materials in several construction materials industries (e.g.: ferrous and non-ferrous metals, plastics, paper and cardboard).     

Fluid bed gasification – Plasma converter process generating energy from solid waste: Experimental assessment of sulphur species

Often perceived as a Cinderella material, there is growing appreciation for solid waste as a renewable content thermal process feed. Nonetheless, research on solid waste gasification and sulphur mechanisms in particular is lacking. This paper presents results from two related experiments on a novel two stage gasification process, at demonstration scale, using a sulphur-enriched wood pellet feed.Notable SO₂ and relatively low COS levels (before gas cleaning) were interesting features of the trials, and not normally expected under reducing gasification conditions. Analysis suggests that localised oxygen rich regions within the fluid bed played a role in SO₂’s generation. The response of COS to sulphur in the feed was quite prompt, whereas SO₂ was more delayed. It is proposed that the bed material sequestered sulphur from the feed, later aiding SO₂ generation. The more reducing gas phase regions above the bed would have facilitated COS – hence its faster response. These results provide a useful insight, with further analysis on a suite of performed experiments underway, along with thermodynamic modelling.     

From mixed to separate collection of solid waste: Benefits for the town of Zavidovići (Bosnia and Herzegovina)

In Bosnia and Herzegovina only 50% of the municipalities have a well-organized service for (mixed) waste collection and disposal. Illegal dumping is very common, in particular in rural areas, which are not regularly served by any service of collection. This situation leads to serious risks for public health and has dangerous environmental impacts. In Zavidovi?i the municipality is trying to meet high standards in the delivery of services of waste collection, but is constrained by scarce financial and technical resources. Different scenarios for the implementation of a system of separate collection in Zavidovi?i were elaborated in order to provide a useful tool for decision making by comparing costs and environmental & economic benefits of each scenario. Six scenarios were considered, based on different recovery rates for plastic, paper & cardboard, and metals. Benefits resulting from the implementation of each of the proposed scenarios are compared in terms of savings of landfill volume and costs. The study concludes that the adoption of a system of separate collection could generate positive impacts on all the stakeholders involved in the solid waste management sector in Zavidovi?i and could contribute to the compliance of European standards in many Central and Eastern European countries as established by a number of national environmental protection strategies.