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The opportunity cost concept refers to quantifying the opportunities lost upon choosing one investment option over a more economical alternative. The present study applies the concept to the process of choosing the best investment option for managing municipal solid waste. In a case study in Brazil, the options on the table are bulk collection and tipping versus reverse logistics with selective collection and sale of recovered components. The use of relative monetary values renders the results general and applicable in other scenarios. The bulk tipping option represents the reference cost of 100. The research postulates a linear relation between the opportunity cost of bulk tipping (y) and the efficiency of reverse logistics operations (x). Zero efficiency means bulk collection and tipping of all waste. Full efficiency means capture of all recyclable items, which in the case study amount to 80% of waste. Various intermediate points confirm the relationship that takes the form y=0.968x. The result shows that opportunity cost is dynamic in as much as changes of technologies and administrative procedures move it along that line. It also illustrates to municipal administrations the immediate economic effect of implementation and stepwise improvement of reverse logistics.

This study presents solid waste management planning in an urban green area, Bangkok, Thailand based on the material flow analysis (MFA) and life cycle assessment (LCA). Global warming potential (GWP) of four scenarios for handling solid waste generated in Chulalongkorn University Centenary Park, 2018 was assessed concerning the different ratios of waste recycling, composting, incineration, and landfilling. The results show that alternative systems proposed will result in lower GWP than the existing waste management strategy. The MFA results reveal that the final weights of solid waste ending up in a landfill are 98.8, 101.9, 68.2, and 44.8 t yr− 1 for scenarios 1, 2, 3, and 4, respectively. Increased rates of landfill diversion by increased recycling, composting, and incineration decreased the quantity of solid waste disposed to the landfill and improved the environmental profile of the park waste management system. The LCA results found landfilling to be the dominant source of greenhouse gas (GHG) burdens, while waste recycling was found to result in the reduction of GHG. The results highlight that the use of MFA and LCA as a combined tool to evaluate the environmental performance of solid waste management systems provides valuable information for policy and decision-makers.

When assessing the environmental and human health impact of a municipal food waste (FW) management system waste managers typically rely on the principles of the waste hierarchy; using metrics such as the mass or rate of waste that is 'prepared for recycling,' 'recovered for energy,' or 'sent to landfill.' These metrics measure the collection and sorting efficiency of a waste system but are incapable of determining the efficiency of a system to turn waste into a valuable resource. In this study a life cycle approach was employed using a system boundary that includes the entire waste service provision from collection to safe end-use or disposal. A life cycle inventory of seven waste management systems was calculated, including the first service wide inventory of FW management through kitchen in-sink disposal (food waste disposer). Results describe the mass, energy and water balance of each system along with key emissions profile. It was demonstrated that the energy balance can differ significantly from its' energy generation, exemplified by mechanical biological treatment, which was the best system for generating energy from waste but only 5th best for net-energy generation. Furthermore, the energy balance of kitchen in-sink disposal was shown to be reduced because 31% of volatile solids were lost in pre-treatment. The study also confirmed that higher FW landfill diversion rates were critical for reducing many harmful emissions to air and water. Although, mass-balance analysis showed that the alternative end-use of the FW material may still contain high impact pollutants.

The city of Makkah in the Kingdom of Saudi Arabia (KSA) hosts millions of Muslim worshippers every year. As a consequence, the municipal solid waste (MSW) quantities become enormous. City landfills receive about 2.4 thousand tons of MSW every day, whilst during the months of fasting (Ramadan) and Pilgrimage (Hajj), these quantities become 3.1 and 4.6 thousand tons per day respectively. Currently, there is no waste-based biorefinery or waste-to-energy (WTE) facility existing in KSA to treat different fractions of MSW as a source of renewable energy production and a solution to landfill waste problems. Therefore, the waste-based biorefinery, if developed in Makkah city, including WTE technologies such as anaerobic digestion (AD), transesterification, pyrolysis and refuse derived fuel (RDF) can be able to treat around 87.8% of the total MSW. The remaining 12.2% of MSW fraction can be recycled. The waste-based biorefinery, along with the recycling approach, can generate savings of about 87.6 million Saudi Arabian Riyal (SAR) from carbon credits. Similarly, a total net revenue of 758 million SAR can be generated from landfill diversion (530.4 million SAR) and electricity generation (288.5 million SAR). Moreover, 1.95 million barrels of oil and 11.2 million MCF of natural gas can be saved with a cost savings of 485.5 million SAR. Collectively, the waste-based biorefinery and recycling can reduce the global warming potential (GWP) of 1.15 million Mt.CO2 eq.

This study presents a preliminary assessment of biodiesel production from waste sources available in the Kingdom of Saudi Arabia (KSA) for energy generation and solution for waste disposal issues. A case study was developed under three different scenarios: (S1) KSA population only in 2017, (S2) KSA population and pilgrims in 2017, and (S3) KSA population and pilgrims by 2030 using the fat fraction of the municipal solid waste. It was estimated that S1, S2, and S3 scenarios could produce around 1.08, 1.10 and 1.41 million tons of biodiesel with the energy potential of 43423, 43949 and 56493 TJ respectively. Furthermore, annual savings of US $55.89, 56.56 and 72.71 million can be generated from landfill diversion of food waste and added to the country's economy. However, there are challenges in commercialization of waste to biodiesel facilities in KSA, including waste collection and separation, impurities, reactor design and biodiesel quality.

Diverting organics from landfills to compost piles is generally recognized as a means to reduce greenhouse gas emissions. This article provides a detailed review of the Climate Action Reserve (CAR) and the U.S. EPA Waste Reduction Model (WARM) protocols on landfill diversion and composting for food scraps and yard waste. The primary benefits associated with diversion are methane avoidance. The equations used to quantify methane avoidance include first-order decay rate constants for different feedstocks to predict how quickly organics will decay. The total methane generation potential of the different feedstocks is also included. The equations include estimates of gas collection efficiencies in landfills. The decay rate constants have been determined from laboratory incubations and may not be representative of decomposition within a landfill. Estimates of gas capture efficiency have been improved and more closely reflect actual landfill conditions. Gas capture efficiency will vary based on landfill...

Business opportunities in the household waste sector in emerging economies still evolve around the activities of bulk collection and tipping with an open material balance. This research, conducted in Brazil, pursued the objective of shifting opportunities from tipping to reverse logistics in order to close the balance. To do this, it illustrated how specific knowledge of sorted waste composition and reverse logistics operations can be used to determine realistic temporal and quantitative landfill diversion targets in an emerging economy context. Experimentation constructed and confirmed the recycling trilogy that consists of source separation, collection infrastructure and reverse logistics. The study on source separation demonstrated the vital difference between raw and sorted waste compositions. Raw waste contained 70% biodegradable and 30% inert matter. Source separation produced 47% biodegradable, 20% inert and 33% mixed material. The study on collection infrastructure developed the necessary receiving facilities. The study on reverse logistics identified private operators capable of collecting and processing all separated inert items. Recycling activities for biodegradable material were scarce and erratic. Only farmers would take the material as animal feed. No composting initiatives existed. The management challenge was identified as stimulating these activities in order to complete the trilogy and divert the 47% source-separated biodegradable discards from the landfills.

The European Union Landfill Directive (1999/31 EC) promotes more environmental friendly waste management options, by reducing the amount of wastes and more specific of biodegradable wastes, disposed of in landfills. The EU member states are adopting the mechanical-biological treatment process for municipal solid waste and non-hazardous industrial wastes to comply with the abovementioned Directive's targets on landfill diversion, and produce waste derived fuels such as refuse derived fuel and solid recovered fuel. Waste derived fuels present high calorific values depending on their synthesis and are being used both in dedicated waste-to-energy plants and as fuel substitutes in industrial processes. In this paper the refuse derived fuel and solid recovered fuel production and utilisation options in European Union are presented, and the possibilities in Greece based on the waste production and National Plan for Waste Management of the Ministry of Environment is attempted. The existing and ongoing studies on co-combustion and co-gasification with brown coal support the use of refuse derived fuel and solid recovered fuel as fuel on Hellenic Power Sector, adopting in the existing lignite power plants adequate Air Pollution Control systems. If the co-combustion or co-gasification of these alternative fuels is adopted from the Hellenic Power Sector a reduction on emissions is expected that cannot be neglected.

The research reported here characterizes municipal solid waste in terms of the quantity produced as a function of time and pre-sorting as well as post-sorting composition in a municipality with 90,000 inhabitants located in Central Brazil. It pursues the objective of identifying the basic strategy of a municipal solid waste management model specific to household waste. It shows that sorted-waste composition, and not raw waste composition, drives reverse logistics. The household waste production rate is 45 tons per day. The research provides data on the base case of progressive annual tipping rates without a diversion target. It goes on to determine a landfill diversion potential of 67 % of domestic waste produced, based on sorted waste composition data. Annual progress indicators required to reach this potential within a chosen timeframe are detailed. Reverse logistics capacity is identified and found sufficient to remove all inert waste items separated at the source. The necessary logistics for biodegradable matter, based on decentralized composting tests, is outlined. The challenge of the municipal administration is identified as the promotion of source separation, and the funds required for this undertaking are shown to derive from the correspondingly reduced landfill maintenance.

A pilot-scale (1800 kg per batch capacity) autoclave used in this study reduces municipal solid waste to a debris contaminated pulp product that is efficiently separated into its renewable organic content and non-renewable organic content fractions using a rotary trommel screen. The renewable organic content can be recovered at nearly 90% efficiency and the trommel rejects are also much easier to sort for recovery. This study provides the evaluation of autoclave operation, including mass and energy balances for the purpose of integration into organic diversion systems. Several methods of cooking municipal solid waste were explored from indirect oil heating only, a combination of oil and direct steam during the same cooking cycle, and steam only. Gross energy requirements averaged 1290 kJ kg−1 material in vessel, including the weight of free water and steam added during heating. On average, steam recovery can recoup 43% of the water added and 30% of the energy, supplying on average 40% of steam requirements for the next cook. Steam recycle from one vessel to the next can reduce gross energy requirements to an average of 790 kJ kg−1.

The use of materials and the generation of waste are linked to economic activities and in many projections these are assumed to be a constant ratio of the economic activities. This may be the case considering detailed economic activities and unchanged technology. However, the assumption of constant coefficients is questionable when linking material use and waste generation to aggregated economic activities. Therefore, in this paper, econometrics is used to test the assumption of constant waste coefficients empirically. The analyses show that an assumption of constant waste coefficients is not supported, generally, and a model allowing for trendwise changing coefficients is developed and used for projections of waste and material flows in 25 European countries.

International audience; Many countries in the European Union (EU) have very developed waste management systems. Some of its members have managed to reduce their landfilled waste to values close to zero during the last decade. Thus, European Union legislation is very stringent regarding waste management for their members and candidate countries, too. This raises the following questions: Is it possible for developing and developed countries to comply with the European Union waste legislation, and under what conditions? How did waste management develop in relation to the economic development in the countries of the European Union? The correlation between waste management practices and economic development was analysed for 27 of the European Union Member States for the time period between 1995 and 2007. In addition, a regression analysis was performed to estimate landfilling of waste in relation to gross domestic product for every country. The results showed a strong correlation between the waste management variables and the gross domestic product of the EU27 members. The definition of the municipal solid waste management development phases followed a closer analysis of the relation between gross domestic product and landfilled waste. The municipal solid waste management phases are characterised by high landfilling rates at low gross domestic product levels, and landfilling rates near zero at high gross domestic product levels. Hence the results emphasize the importance of wider understanding of what is required for developing countries to comply with the European Union initiatives, and highlight the importance of allowing developing countries to make their own paths of waste management development.

As the quantity of municipal solid waste (MSW) increases with economic growth, problems arise in regard to sustainable management solutions. Thermal treatment presents a valid option for reducing the amounts of post-recycling waste to be landfilled. Incineration technology, besides reducing the total volume of waste and making use of the chemical energy in MSW for power generation, has negative environmental impact from high emission of pollutants. Recent policy to tackle climate change and resources conservation stimulated the development of renewable energy and landfill diversion technology, thereby giving gasification technology development renewed importance. In this work a two-dimensional CFD model for MSW gasification was developed and an Eulerian-Eulerian approach was used to describe the transport of mass, momentum and energy for the solid and gas phases. This model is validated using experimental data from the literature. The numerical results obtained are in good agreement with the reported experimental results.

This study evaluated seven different waste management strategies for venue-based events and characterized the impacts of event waste management via waste audits and the Waste Reduction Model (WARM). The seven waste management scenarios included traditional waste handling methods (e.g. recycle and landfill) and management of the waste stream via composting, including purchasing where only compostable food service items were used during the events. Waste audits were conducted at four Arizona State University (ASU) baseball games, including a three game series. The findings demonstrate a tradeoff among CO2 equivalent emissions, energy use, and landfill diversion rates. Of the seven waste management scenarios assessed, the recycling scenarios provide the greatest reductions in CO2 eq. emissions and energy use because of the retention of high value materials but are compounded by the difficulty in managing a two or three bin collection system. The compost only scenario achieves complete landfill diversion but does not perform as well with respect to CO2 eq. emissions or energy. The three game series was used to test the impact of staffed bins on contamination rates; the first game served as a baseline, the second game employed staffed bins, and the third game had non staffed bins to determine the effect of staffing on contamination rates. Contamination rates in both the recycling and compost bins were tracked throughout the series. Contamination rates were reduced from 34% in the first game to 11% on the second night (with the staffed bins) and 23% contamination rates at the third game.

International audience; With the goal to move society toward less reliance on fossil fuels and the mitigation of climate change, there is increasing interest and investment in the bioenergy sector. However, current bioenergy growth patterns may, in the long term, only be met through an expansion of global arable land at the expense of natural ecosystems and in competition with the food sector. Increasing thermal energy recovery from solid waste reduces dependence on fossil- and biobased energy production while enhancing landfill diversion. Using inventory data from pilot processes, this work assesses the cradle-to-gate environmental burdens of plasma gasification as a route capable of transforming construction and demolition (C&D) derived biomass (CDDB) and forest residues into electricity. Results indicate that the environmental burdens associated with CDDB and forest residue gasification may be similar to conventional electricity generation. Land occupation is lowest when CDDB is used. Environmental impacts are to a large extent due to coal cogasified, coke used as gasifier bed material, and fuel oil cocombusted in the steam boiler. However, uncertainties associated with preliminary system designs may be large, particularly the heat loss associated with pilot scale data resulting in overall low efficiencies of energy conversion to electricity; a sensitivity analysis assesses these uncertainties in further detail.

Managing solid waste is one of the biggest challenges in urban areas around the world. Technologically advanced economies generate vast amounts of organic waste materials, many of which are disposed to landfills. In the future, efficient use of carbon containing waste and all other waste materials has to be increased to reduce the need for virgin raw materials acquisition, including biomass, and reduce carbon being emitted to the atmosphere therefore mitigating climate change. At end-of-life, carbon-containing waste should not only be treated for energy recovery (e.g. via incineration) but technologies should be applied to recycle the carbon for use as material feedstocks. Thermochemical and biochemical conversion technologies offer the option to utilize organic waste for the production of chemical feedstock and subsequent polymers. The routes towards synthetic materials allow a more closed cycle of materials and can help to reduce dependence on either fossil or biobased raw materials. This chapter summarizes carbon-recycling routes available and investigates how in the long-term they could be applied to enhance waste management in both industrial countries as well as developing and emerging economies. We conclude with a case study looking at the system-wide global warming potential (GWP) and cumulative energy demand (CED) of producing high-density polyethylene (HDPE) from organic waste feedstock via gasification followed by Fischer–Tropsch synthesis (FTS). Results of the analysis indicate that the use of organic waste feedstock is beneficial if greenhouse gas (GHG) emissions associated with landfill diversion are considered.

Taking an economic-geographical perspective, through a panel analysis of Italian municipal solid waste (MSW) data, we show that although decoupling for waste generation from income is absent, there are some signs of absolute decoupling for landfilled waste. Within this general picture, geographical and socio-economic differentiation across Italian provinces seems to matter. Spatial effects at the level of provinces – the institutions that primarily manage waste regulations – seem to be negligible, especially for landfilled waste. This is consistent with the fact that the definition and implementation of landfill policy effectively happened at sub-provincial (even municipal) levels; as a result, the recent waste policy decentralisation process has been characterised by fragmented actions. In light of this fragmentation, we note that although North-South waste performances show some signs of convergence, greater coordination aimed at complete convergence in waste performance, in a decentralised policy scenario, will be needed for the effective achievement of EU national based targets by a federal country.

The evolution of domestic waste management practices in an urban residential condominium complex in Brazil is reported. A sustained effort over 10 years has created a benchmark for landfill diversion by private initiative. The project was initiated in 1998 when the prevailing practice was to tip all waste at the landfill. In the presently attained situation, which is available for imitation elsewhere, 67% of all domestic waste produced in the complex is recycled without cost to the municipal administration. Instead of separating the inert recyclables, the effort was turned to separating the biodegradable material. The management programme derived from waste analyses and the work with people evolved into a two-stage source-separation procedure combined with the participation of handpicked reverse logistics operators. City crews now take only 33% of all waste to the landfill. Although this description is strictly valid only for Brazil, the story in itself might be of wider interest.

International audience; Worldwide, health and environmental considerations encourage landfill diversion of the organic fraction (OW) of municipal solid wastes, through alternative such as home composting. Of poor sanitation, and trace element and toxic hydrocarbon content (PAH) documentation, this study compared against a laboratory composter (LR), the performance (temperature regime and compost quality) of four 300 to 400 L home composting systems (HC), namely the Plastic (P) and Wood (W) Bins, the Rotary Drum (RD) and the Ground Pile (GP). All were batch loaded with the same food waste (FW) and yard trimmings (YT) mixture for uniform testing. The P and GP performed best in terms of temperature regime, followed by W and LR, while all demonstrated similar dry and organic matter and chemical oxygen demand except for RD with a higher dry matter because of poor aeration. All composts respected regulatory pathogen/parasite counts, trace element and PAH levels

As unrestricted landfilling of Municipal Solid Waste is being progressively abandoned, separation and processing of biodegradable material is becoming a basic component of urban waste management. The principal processing technology available is composting in its two basic forms and applications, namely centralised and decentralised composting. The centralised scheme targets biological stabilisation prior to landfilling. The decentralised scheme targets the preparation of a useful product. Experimental results obtained by the author are presented and discussed that confirm decentralised composting as a definite future option in urban waste management. Educational and technical aspects of the corresponding management problem are described.

The author's research and practical experience with municipal solid waste management have shown the urgent need for new thinking models. Present paradigms are stalemate. They do not allow for flexible approaches to solving an extremely dynamic problem. This paper discusses the basic flaws in present thinking models of residents, municipal administrators and even scholars. Fundamental arguments presented on municipal solid waste relate to nomenclature, destinations, definitions, logistics, social dynamics, social assistance programs, education and employment philosophies. In each case, the consequences of the stalemate are explained in terms of the unsustainable situation of constantly growing landfills. In sequence, proactive thinking models are presented and explained that lead to drastic reduction of landfill size. Several of these models have been tested successfully in small communities and are now available for scale-up. Although of necessity the arguments and models apply directly to Brazil, the basic ideas behind the reasoning may be extrapolated.

Recycling is alive and well in many industrial sectors. This article addresses worn or wasted tires and evaluates the extensive recycling already achieved. This study addresses the efforts of the State of California and the US Army Corps of Engineers to stimulate tire recycling, demonstrating the public sector commitment currently necessary. Albeit, private markets are on the verge of commercial viability at the same time they accomplish a significant diversion from landfills.