Anaerobic Digestion Of Municipal Solid Waste Research Articles

Enhancing biogas production in anaerobic digestion of MSW with addition of bio-solids and various moisture sources

This study aimed to investigate the influence of moisture content on the anaerobic digestion of municipal solid waste (MSW) with the addition of leachate, tap water, wastewater, and sewage sludge. To accomplish this, ten sets of batch experiments were conducted to examine the impact of these various moisture sources on the rate of degradation, indicated by cumulative biogas yield, volatile solids (VS) and total solids (TS) removal. The addition of sludge with leachate and wastewater to MSW resulted in biogas yields that were approximately 30 % higher than the biogas yield from MSW and wastewater alone. Based on the observations of VS removal, it was observed that the addition of sludge degraded about half of the substrate. Therefore, it was observed that the addition of 10 % sludge with leachate and wastewater to MSW provides the best outcomes. The lowest biogas yield was observed with the mixing of tap water with MSW. Further, it was determined that the optimal moisture content for MSW degradation should be greater than 75 % of field capacity (FC). The cumulative biogas yield decreased by more than 50 % when the moisture contents decreased from 100 % to 50 % of FC. The reduction in biogas production at low moisture contents is attributed to limited mass transfer, and the hydrolysis rate also slightly decreases with an increase in total solids. The kinetic study was also carried out using the first order, modified Gompertz, Transference, and Logistic models, and the predicted cumulative biogas yield was compared with the experimental data. The modified Gompertz and Logistic models showed the best fit (R2 ≥ 0.994) with the experimental data for all the sets. The sludge, leachate, and wastewater are produced in large quantities in developing countries, and this study may provide a possible utilization strategy of these wastes for accelerated degradation of MSW.

Development of a MSW-fueled sustainable co-generation of hydrogen and electricity plant for a better environment comparing PEM and alkaline electrolyzers

Efficient conversion of Municipal Solid Waste (MSW) into useful energy by anaerobic digestion is a sustainable method which received growing interest, particularly for small-scale decentralized energy systems. This paper aims at development of an efficient combined cogeneration cycle for production of electricity and hydrogen from biogas generated using anaerobic digestion of MSW. When it comes to the topping cycle, the proposed system makes use of a micro gas turbine, whose waste heat is converted to electricity by an absorption power cycle. This additional electricity is provided to a water electrolyzer, which uses it to generate hydrogen. Two types of electrolyzers, including the Proton Exchange Membrane Electrolyzer (PEME) and the Alkaline Electrolyzer (AE) are considered, and their performances (as a component of the overall suggested combined systems) are compared from economic and thermodynamic viewpoints. The CO2 emission index is also addressed, and tri-objective optimization based on exergy, cost, and emission indices is carried out to compare the two systems. Obtained results indicated important outcomes, including that the system integrated with PEME is superior in terms of exergetic performance and emissions, whereas the system with AE is superior in terms of economics. The former has a 3.0% greater efficiency and a 3.3% lower emissions at optimal point established by tri-objective optimization, while it has a 9.3% higher levelized product cost.

Mesophilic batch co‐digestion of municipal solid waste and food waste: improved digester performance and stability at optimum organic loading rates

AbstractBACKGROUNDThe accumulative municipal solid waste (MSW) production calls for emerging efficient technology for its handling. Anaerobic digestion (AD) of MSW provides effective waste volatilization. The high C/N ratio of MSW and increasing organic loading rates (OLRs) are central AD restrictions that affect the AD process performance, inhibition due to aggregation of volatile fatty acids (VFAs), and rapid fall in pH.RESULTSThis study examines the consequence of OLRs on AD of MSW with a high C/N ratio of 406 in food waste (FW) to have a balanced C/N ratio of 30. Three batch scale digesters investigate under mesophilic conditions (35 °C) with OLRs of 10, 15, and 20 gVS L−1 to assess the digester performance and stability in biogas yield, methane yield, and volatile solids (VS) reduction. The cumulative biogas and methane yield are observed to be 1336 and 776 mL gVS−1, respectively, with a VS reduction rate of 78%, at 10 gVS L−1. VFA/alkalinity ratio ranges from 0.02 to 0.01 at OLR of 10 and 15 gVS L−1, which designates a higher buffering capability of the digester. While VFA/alkalinity ratio of 0.48 observes at OLR of 20 gVS L−1. A rapid deprivation in digester performance and stability finds at ORL of 15 and 20 gVS L−1. The cumulative biogas yield and methane yield decrease with the increase in OLR from 10 to 20 gVS L−1.CONCLUSIONThis study provided sufficient information for better AD processes and operational circumstances that are an optimum and effective method to convert organic matter to biogas fuel. © 2021 Society of Chemical Industry (SCI).

MSW A Potential Energy Resources: A Two Stage Anaerobic Digestio

Present investigation reveals the biodegradability of municipal solid wastes (MSW) in context of Jabalpur city [1] (at 23˚10 North latitude and 79˚57 East longitude, at an altitude of 393 meters above mean sea level) and harnessing energy through two stage anaerobic digestion. A critical study of various process parameters affecting the anaerobic digestion has been analyzed. During the anaerobic digestion of MSW it has been seen that the retention time of the process increases as compared to other waste such as fruits and vegetable waste, cow dung, agricultural residues etc. With the use of suitable bio-methanization technology the twin objectives (a) waste reduction and (b) the environmental problems can be achieved. The present work will help all academicians, rural and urban energy industry people in generating eco-friendly energy and maintaining environment too. In this study the biodegradability of the MSW organic fraction has been tested and in particular a comparison between the production of biogas from landfills and organic wastes in anaerobic conditions has been performed. Two stage digestion of this kind of wastes were proved a better efficiency than single stage digestion.

Promoting circular economy in the surroundings of an organic fraction of municipal solid waste anaerobic digestion treatment plant: Biogas production impact and economic factors

The Anaerobic Digestion and Composting Plant of the Vallès Oriental Waste Treatment Centre processes source-selected organic fraction of municipal solid wastes generated in its surrounding area. To promote Circular Economy between Municipal Solid Waste and industrial waste management systems, the Treatment Centre is looking for complementary wastes to be valorised through co-digestion with its main substrate. The study includes waste characterization and a complete treatment cost analysis, that jointly with the biogas potential and the mass balance of the Plant allows to calculate the price of each waste to be treated in the Plant. Up to 13 industrial wastes have been characterised for its biogas potential and its treatment cost calculated. Treatment prices ranged between 83 and 51 € t−1.

Anaerobic digestion of municipal solid waste: Energy and carbon emission footprint

Anaerobic digestion (AD) serves as a promising alternative for waste treatment and a potential solution to improve the energy supply security. The feasibility of AD has been proven in some of the technologically and agriculturally advanced countries. However, development is still needed for worldwide implementation, especially for AD process dealing with municipal solid waste (MSW). This paper reviews various approaches and stages in the AD of MSW, which used to optimise the biogas production and quality. The assessed stages include pre-treatment, digestion process, post-treatment as well as the waste collection and transportation. The latest approaches and integrated system to improve the AD process are also presented. The stages were assessed in a relatively quantitative manner. The range of energy requirement, carbon emission footprint and the percentage of enhancement are summarised. Thermal hydrolysis pre-treatment is identified to be less suitable for MSW (−5% to +15.4% enhancement), unless conducted in the two-phase AD system. Microwave pre-treatment shows consistent performance in elevating the biogas production of MSW, but the energy consumption (114.24–8,040 kWeh t−1) and carbon emission footprint (59.93–4,217.78 kg CO2 t−1 waste) are relatively high. Chemical (∼0.43 kWeh m−3) and membrane-based (∼0.45 kWeh m−3) post-treatments are suggested to be a lower energy consumption approach for upgrading the biogas. The feasibility in terms of cost (scale up) and other environmental impacts (non-CO2 footprint) needs to be further assessed. This study provides an overview to facilitate further development and extended implementation of AD.

Biogas derived from municipal solid waste to generate electrical power through solid oxide fuel cells

Depleting fossil fuels and the pollution resulting from their consumption indicate an urgent need for clean and dependable alternatives such as renewable energies. Biomass is a free and abundant source of renewable energy. Municipal solid waste (MSW) as one of the main categories of biomass has always been an issue for metropolitan cities. It has, however, a high potential for biogas production. In this study, the technical and economic aspects of generating electrical power through solid oxide fuel cells (SOFCs) powered by injecting biogas derived from Tehran's MSW, as a case study, are investigated. The main objectives of the current study are to identify the power generation capability of the process and find out if it can result in a competitive energy resource. The total amount of obtainable methane through anaerobic digestion of MSW and then the achievable power generation capacity by using the obtained biogas are computed using the electrochemical relations inside the SOFC. The economic calculations are carried out to estimate the final price of the generated electricity, taking into account the major capital and ongoing costs of the required equipment. The effect of variations of MSW composition on the power generation capability and final electricity price is also studied. Moreover, the application of a gas turbine (GT) with the SOFC as a hybrid SOFC–GT system to recover the produced heat by SOFC and its effect on the power generation capability and the final electricity price are investigated. Results indicate that around 997.3 tons day−1 biomethane can be generated using Tehran's MSW. By using the SOFC, the produced biogas can generate 300 MWAC electrical power with a final cost of $0.178 kWh−1. By using the hybrid SOFC–GT, the electrical power capacity is increased to 525 MWAC, and the final electricity cost drops to $0.11 kWh−1, which indicates its competitiveness with other common energy resources in the near future, especially by considering different governmental subsidy policies that support renewable energy resources. The considerable environmental benefits of the proposed procedure, from both MSW management and CO2 emission reduction points of view, make it a promising sustainable energy resource for the future. Copyright © 2016 John Wiley & Sons, Ltd.

Penta- and 2,4,6-tri-chlorophenol biodegradation during municipal solid waste anaerobic digestion

In this study isotopic tracing using 13C labelled pentachlorophenol (PCP) and 2,4,6-trichlorophenol (2,4,6-TCP) is proposed as a tool to distinguish the loss of PCP and 2,4,6-TCP due to biodegradation from other physical processes. This isotopic approach was applied to accurately assess in situ PCP and 2,4,6-TCP degradation under methanogenic conditions in several microcosms made up of household waste. These microcosms were incubated in anaerobic conditions at 35°C (mesophilic) and 55°C (thermophilic) without agitation. The volume of biogas produced (CH4 and CO2), was followed for a period of 130 days. At this stage of stable methanogenesis, 13C6-PCP and 13C6-2,4,6-TCP were introduced anaerobically in microcosms and its monitoring at mesophilic and thermophilic conditions was performed in parallel by gas chromatography mass spectrometry (GC–MS) and gas chromatography isotope-ratio mass spectrometry (GC–IRMS). This study proved the almost total dechlorination of bioavailable PCP and 2,4,6-TCP into 4-CP at 35°C. Nevertheless, high rate adsorption in particular materials of the two compounds was observed. Furthermore, Carbon-13 Nuclear Magnetic Resonance (13C-NMR) Spectroscopy analysis of 13C labelled 2,4,6-TCP mesophilic incubations showed the partial mineralization of 4-CP at 35°C to acetate and then to HCO3−. Consequently, NMR results confirm the biogas isotopic results indicating the mineralization of 13C labelled 2,4,6-TCP into 13C (CH4 and CO2). Concerning 13C labelled PCP mesophilic incubations, the isotopic composition of the biogas still natural until the day 262. In contrast, no dechlorination was observed at 55°C. Thus PCP and 2,4,6-TCP were persistent in thermophilic conditions.

Effect of calcium chloride on abating inhibition due to volatile fatty acids during the start-up period in anaerobic digestion of municipal solid waste

ABSTRACTBiomethanation of municipal solid waste (MSW) is a slow process and the yield of biogas is usually low. The present study was carried out to examine the effect of calcium chloride (CaCl2) on anaerobic digestion of MSW. Three anaerobic digesters with different concentrations of CaCl2, namely sample without additives (Control), sample with 2.5 g/L CaCl2 (R1) and sample with 5 g/L CaCl2 (R2) were studied separately and the significant results are presented. From the experimental results, it was observed that pH decreased with an increase in the dosage of CaCl2. Total solids and volatile solids reduction percentage in digester R2 was considerably lower than Control and R1 digesters. The significant positive correlation with small increments in volatile solids and chemical oxygen demand (COD) reduction were observed with an increase in pH. The cumulative biogas production in all the three digesters (Control, R1 and R2) were observed to be 35.38, 46.46 and 37.56 L, respectively. It was also observed that the volatile fatty acids (VFAs) removal efficiency in digester R1 was the best among all the three digesters. A comparison of the effluent characteristics revealed improvement in the overall performance of the digester R1 amended with 2.5 g/L CaCl2 over the other two digesters.

Fluctuation of dissolved heavy metal concentrations in the leachate from anaerobic digestion of municipal solid waste in commercial scale landfill bioreactors: The effect of pH and associated mechanisms

Heavy metals present in landfill leachate have infrequently been related to complete anaerobic degradation municipal solid waste (MSW) due to discrete ages of deposited MSW layers and leachate channelling in landfills. In this study, anaerobic digestion of MSW was performed in two enclosed 1000 tonne bioreactors using a unique flood and drain process. Leachates were characterised in terms of pH, soluble chemical oxygen demand, volatile fatty acids (VFAs), ammonium nitrogen and heavy metals over the entire course of digestion. All parameters, including pH, fluctuated during acidogenesis, acetogenesis and methanogenesis, which strongly impacted on the dynamics of dissolved heavy metal concentrations. The simulation of dissolution and precipitation processes indicated that metal sulphide precipitation was not a factor as metal concentrations exceeded solubility limits. The correlation of pH and dissolved heavy metal concentrations indicated that other, mechanisms were involved in the homogenised conditions within the bioreactors. Beside dissolution and precipitation, the main processes most likely involved in metal distributions were adsorption (Zn, Cu, Ni, Pb and Cd), complexation (Cr) or combinations of both process (As and Co).

Environmental impact of rejected materials generated in organic fraction of municipal solid waste anaerobic digestion plants: Comparison of wet and dry process layout

Anaerobic digestion of source separated organic fraction of municipal solid waste is an increasing waste valorization alternative instead of incineration or landfilling of untreated biodegradable wastes. Nevertheless, a significant portion of biodegradable wastes entering the plant is lost in pre-treatments and post-treatments of anaerobic digestion facilities together with other improper materials such as plastics, paper, textile materials and metals. The rejected materials lost in these stages have two main implications: (i) less organic material enters to digesters and, as a consequence, there is a loss of biogas production and (ii) the rejected materials end up in landfills or incinerators contributing to environmental impacts such as global warming or eutrophication.The main goals of this study are (i) to estimate potential losses of biogas in the rejected solid materials generated during the pre- and post-treatments of two full-scale anaerobic digestion facilities and (ii) to evaluate the environmental burdens associated to the final disposal (landfill or incineration) of these rejected materials by means of Life Cycle Assessment.This study shows that there is a lost of potential biogas production, ranging from 8% to 15%, due to the loss of organic matter during pre-treatment stages in anaerobic digestion facilities. From an environmental point of view, the Life Cycle Assessment shows that the incineration scenario is the most favorable alternative for eight out of nine impact categories compared with the landfill scenario. The studied impact categories are Climate Change, Fossil depletion, Freshwater eutrophication, Marine eutrophication, Ozone depletion, Particulate matter formation, Photochemical oxidant formation, Terrestrial acidification and Water depletion.

Design and Economic Analysis of a Heating/Absorption Cooling System Operating with Municipal Solid Waste Digester: A Case Study of Gazi University

Abstract Recovering energy from municipal solid waste (MSW) is one of the most important issues of energy management in developed countries. This raises even more interest as world fossil fuel reserves diminish and fuel prices rise. Being one of main processes of waste disposal, anaerobic digestion can be used as a means to reduce fossil fuel and electricity consumption as well as reducing emissions. With growing demand for cooling in Turkey, especially during warm seasons and considering the energy costs, utilizing heat-driven absorption cooling systems coupled with an anaerobic digester for local cooling purposes is a potentially interesting alternative for electricity driven compression cooling. The aim of this article is to study the viability of utilizing biogas obtained from MSW anaerobic digestion as the main fuel for heating facilities of Gazi University, Turkey and also the energy source for an absorption cooling system designed for the central library of the aforementioned campus. The results prove that the suggested system is sustainably and financially appealing and has the potential to replace the conventional electricity driven cooling systems with a reasonable net present worth; moreover, it can notably reduce carbon dioxide emissions.

Elucidation of the thermophilic phenol biodegradation pathway via benzoate during the anaerobic digestion of municipal solid waste

Anaerobic digestion makes it possible to valorize municipal solid waste (MSW) into biogas and digestate which are, respectively, a renewable energy source and an organic amendment for soil. Phenols are persistent pollutants present in MSW that can inhibit the anaerobic digestion process and have a toxic effect on microbiota if they are applied to soil together with digestate. It is then important to define the operational conditions of anaerobic digestion which allow the complete degradation of phenol. In this context, the fate of phenol during the anaerobic digestion of MSW at 55°C was followed using an isotopic tracing approach (13C6-phenol) in experimental microcosms with inoculum from an industrial thermophilic anaerobic digester. With this approach, it was possible to demonstrate the complete phenol biodegradation into methane and carbon dioxide via benzoate. Benzoate is known to be a phenol metabolite under mesophilic conditions, but in this study it was found for the first time to be a phenol degradation product at thermophilic temperature.

Anaerobic Digestion of MSW Spiked with BPA

This study aims to investigate the effects of bisphenol A (BPA) on the MSW (municipal solid waste) biodegradation in anaerobic bioreactors. BPA 10 and 100 mg L^(-1) daily fed bioreactors were found to stimulate the biogas production rate after about 126 days' operation while that of BPA 500 mg L^(-1) daily fed ones was inhibited gradually from the beginning. Enhancement or inhibition of MSW biodegradation was thought to be the resulting exposed BPA soluble levels of ~10 - ~13, ~11 - ~30 and ~30 - ~102 mg L^(-1) for 10, 100 and 500 mg L^(-1) daily fed bioreactors compared to control (~4 - ~10 mg L^(-1)). PCR (polymerase chain reaction) and DGGE (denaturing gradient gel electrophoresis) analysis also showed that Methanosarcina sp., Methanosarcina barkeri and Methanomicrobiales archaeon methane producing bacteria could adapt BPA levels (~10 - ~30 mg L^(-1)) at BPA 10 and 100 mg L^(-1) daily fed bioreactors resulting in the improvement of MSW anaerobic digestion and the enhancement of biogas production rates for about ~1 - ~3.5 times that of control between 126 and 305 days' operation.

Evaluation of biodegradability of phenol and bisphenol A during mesophilic and thermophilic municipal solid waste anaerobic digestion using 13C-labeled contaminants

In this paper, the isotopic tracing using 13C-labeled phenol and bisphenol A was used to study their biodegradation during anaerobic digestion of municipal solid waste. Microcosms were incubated anaerobically at 35°C (mesophilic conditions) and 55°C (thermophilic conditions) without steering. A continuous follow-up of the production of biogas (CH4 and CO2), was carried out during 130d until the establishment of stable methanogenesis. Then 13C12-BPA, and 13C6-phenol were injected in microcosms and the follow-up of their degradation was performed simultaneously by gas chromatography isotope-ratio mass spectrometry (GC–IRMS) and gas chromatography mass spectrometry (GC–MS). Moreover, Carbon-13 Nuclear Magnetic Resonance (13C-NMR) Spectroscopy is used in the identification of metabolites. This study proves that the mineralization of phenol to CO2 and CH4 occurs during anaerobic digestion both in mesophilic and thermophilic conditions with similar kinetics. In mesophilic condition phenol degradation occurs through the benzoic acid pathway. In thermophilic condition it was not possible to identify the complete metabolic pathway as only acetate was identified as metabolite. Our results suggest that mineralization of phenol under thermophilic condition is instantaneous explaining why metabolites are not observed as they do not accumulate. No biodegradation of BPA was observed.

Effects of different SRT on anaerobic digestion of MSW dosed with various MSWI ashes

This study investigated different solid retention time (SRT) on municipal solid waste (MSW) anaerobic digestion with various MSW incinerator fly ash (FA) and bottom ash (BA) addition. Results showed that biogas production rates (BPRs, ∼200 to ∼400mL/gVS) with organic loading rate of ∼0.053gVS/gVSreactor (Day 1–435, SRT 20days, SRT20) at FA 1g/d (FA1), BA 12g/d (BA12) and BA 24g/d (BA24) dosed bioreactors increased after adaptation. BPRs with SRT10 and SRT5 decreased while BPRs with SRT40 showed to increase compared to initial BPRs (∼200mL/gVS) with SRT20. SRT5 operation reduced the BPRs (∼10 – ∼90mL/gVS) significantly and only BA12 and BA24 dosed bioreactors could recover the BPRs (∼100 – ∼200mL/gVS) after SRT20 operation (Day 613–617) compared to FA1 and FA3 and control. Released levels of Co, Mo and W at BA12 and BA24 dosed bioreactors showed most potential to improve MSW anaerobic digestion.

Performance study for anaerobic digestion of municipal solid waste in a single phase reactor

Anaerobic Digestion (AD) has been up to now essentially applied to wastewater. However, anaerobic treatment of organic solid waste fits well with the new requirements for waste management. A batch study of vegetable market waste composed at various solid concentrations was studied in a single phase anaerobic reactor. Prior to this, studies were also carried out in aspirator bottles of different capacity to select essential factors influencing the Single Stage High Solid (SSHS) approach with emphasis on C/N ratio. Initially, the maximum total solid concentration was optimised, which gives maximum biogas yield and at maximum total solid concentration, further experiments were carried out with varying C/N ratio to arrive at optimum C/N ratio leading to maximum biogas yield. This paper describes the performance of AD of municipal solid waste in a laboratory-scale reactor for varying solid concentration and C/N ratio.

In search of a reliable technique for the determination of the biological stability of the organic matter in the mechanical–biological treated waste

The biological stability determines the extent to which readily biodegradable organic matter has decomposed. In this work, a massive estimation of indices suitable for the measurement of biological stability of the organic matter content in solid waste samples has been carried out. Samples from different stages in a mechanical–biological treatment (MBT) plant treating municipal solid wastes (MSW) were selected as examples of different stages of organic matter stability in waste biological treatment. Aerobic indices based on respiration techniques properly reflected the process of organic matter biodegradation. Static and dynamic respirometry showed similar values in terms of aerobic biological activity (expressed as oxygen uptake rate, OUR), whereas cumulative oxygen consumption was a reliable method to express the biological stability of organic matter in solid samples. Methods based on OUR and cumulative oxygen consumption were positively correlated. Anaerobic methods based on biogas production (BP) tests also reflected well the degree of biological stability, although significant differences were found in solid and liquid BP assays. A significant correlation was found between cumulative oxygen consumption and ultimate biogas production. The results obtained in this study can be a basis for the quantitative measurement of the efficiency in the stabilization of organic matter in waste treatment plants, including MBT plants, anaerobic digestion of MSW and composting plants.

Use of Wastewater and Compost Extracts as Nutrient Sources for Growing Nursery and Turfgrass Species

Nutrient salts present in liquid by-products following waste treatment are lost resources if not effectively recycled, and can cause environmental problems if improperly disposed. This research compared the growth response and mineral nutrient status of two nursery and two turfgrass species, hydroponically supplied with nutritive by-product extracts derived from anaerobically digested municipal solid waste (MSW) and aerobically composted organic wastes from the mushroom and MSW industries. Forsythia (Forsythia x intermedia 'Lynwood') and weigela (Weigela florida 'Red Prince'), and creeping bentgrass (Agrostis palustris Huds.) and Kentucky bluegrass (Poa pratensis L.), were grown in nutrient solutions/extracts prepared from: (i) half-strength Hoagland's #2 solution (HH; control), (ii) Plant Products liquid fertilizer (PP; g kg(-1): 180 N; 39 P; 224 K), (iii) spent mushroom compost (SMC), (iv) MSW compost (GMC), and (v) intra-process wastewater from the anaerobic digestion of MSW (ADW). Additional nutrient solutions (SMC-A, GMC-A, and ADW-A) were prepared by amending the original solutions with N, P, and/or K to concentrations in HH (mg L(-1): 105 N; 15 P; 118 K). Plants receiving the SMC-A extract grew best or at least as well as those in HH, PP, and the amended GMC-A and ADW-A solutions. This study indicated that, with proper amendments of N, P, K and other nutrients, water-soluble constituents derived from organic waste treatment have potential for use as supplemental nutrient sources for plant production.

Assessing the environmental burdens of anaerobic digestion in comparison to alternative options for managing the biodegradable fraction of municipal solid wastes

Biological treatment processes including anaerobic digestion (biogasification) and composting are increasingly being considered by waste management officials and planners as alternatives for managing the mainly organic residues of municipal solid wastes (MSW). The integrated waste management model which is based upon the application of life-cycle analysis was employed to compare the environmental burdens of landfilling, composting and anaerobic digestion of MSW at a mid-sized Canadian community. Energy consumption (or recovery), residue recoveries and emissions to air and water were quantified. Scenario comparisons were analyzed to demonstrate that the environmental burdens associated with anaerobic digestion are reduced in comparison with the alternative options. The major benefit occurs as a result of the electricity produced from burning the biogas and then supplying the 'green power' to the local electrical grid.