Emission of greenhouse gases from anaerobic digestion processes: comparison with other municipal solid waste treatments

Background, Aim and Scope. Municipal Solid Waste (MSW) management system has an important role to reduce final disposal of MSW. Recently prevention of global warming in MSW transportation and treatment processes is also coming into important. Decision makers in local region should design the MSW management system that solves above issues, and is desirable for the region in cost constraint. But there are few studies taking into account regional MSW discharge and waste treatment properties and their perspective. In this study, we proposed a methodology to design environmentally and economically desirable MSW management systems in local region by applying Life Cycle Assessment (LCA) and cost analysis.Materials and Methods. The central region of Iwate Prefecture was chosen as a case study. Firstly, we surveyed material and energy inputs/outputs in MSW transportation and treatment processes in the case study area. Then, Life Cycle Inventory (LCI) data of each process was calculated. Secondarily, scenarios involving several MSW management systems considering patterns of MSW treatment technologies and/or MSW segregation were designed. Results and Discussion. As a scenario analysis, Greenhouse Gas (GHG) emissions, SOx/NOx emissions, final disposal and the cost was calculated when each scenario would be for the period from FY2005 to FY2030. From the results, we found that the MSW treatment system in which municipalities form communal MSW treatment mostly has an advantage than the municipality-based MSW treatment system in which municipalities treat MSW by themselves. We also found the trade-off relationship in the results; a system giving priority to gasification and melting facilities decreases the amount of final disposal and cost and increases GHG emissions, while another system giving priority to stoker type grate facility decreases GHG emissions and cost and increases the amount of final disposal. However this trade-off relationship is solved by enhancing waste segregation and/or bio-methanation of kitchen garbage. Additionally, we calculated the indicator value of environmental impact by the Distance-to-target method, and we evaluated a relationship between the indicator value and the cost. As the result, scenario involving the region-based MSW treatment system with bio-methanation is selected as a desirable MSW management system if reduction of final disposal is prioritize as the MSW treatment policy. Conclusions. In the actual fields, it is required not only quantatative evaluation environmental impact and cost but also qualitative investigation such as site selection of waste treatment facilities considering NIMBY phenomenon. Nonetheless, the methodology proposed in this paper is effective for local municipalities’ decision support.

China's changing city-level greenhouse gas emissions from municipal solid waste treatment and driving factors

Greenhouse gas emission mitigation potential from municipal solid waste treatment: A combined SD-LMDI model

Landfilling is the most applied solid waste management method in developing countries, which leads to a large amount of greenhouse gas (GHG) emissions. It is thus imperative to develop strategies for evaluating different economically viable waste management scenarios to mitigate GHG emissions. According to the Paris Agreement, Kazakhstan planned to decrease GHG emissions by 25% by 2050 as compared to 1990 levels, while reaching carbon neutrality by 2060. In this context, we herein propose four different scenarios for municipal solid waste (MSW) treatment and three scenarios for sewage sludge (SS) treatment with the aim of evaluating the GHG potential for Astana, the capital city of Kazakhstan, using the (solid waste management) SWM-GHG calculator developed by the Institute for Energy and Environmental Research. The MSW treatment scenarios include: (A) 15% recycling of secondary materials and 85% landfilling of remaining MSW; (B) 30% recycling of secondary materials; 70% sanitary landfilling with biogas collection; (C) 30% recycling and 70% biological stabilization and landfilling without biogas collection; and (D) 30% recycling, 20% composting, and 50% (waste-to-energy) WtE incineration. The sewage sludge management scenarios include (1) 100% landfilling; (2) 100% WtE incineration; and (3) co-incineration of sewage sludge and coal. The results reveal that more complex scenarios lead to extensive ecological benefits; however, there are economic constraints. Based on the analysis of the proposed scenarios, we recommend the optimal strategy for MSW treatment to be 30% recycling with biological stabilization that has a total cost of EUR 16.7 million/year and overall GHG emissions of −120 kt of CO2 eq/year. In terms of sewage sludge management, the addition of coal to sewage sludge simplifies the combustion process due to the higher heat capacity. Considering lower cost and higher energy recovery, it is recommended as a favorable process.

As a significant source of anthropogenic greenhouse gas emissions, the municipal solid waste sector’s greenhouse gas emission mode remains unknown, hampering effective decision-making on possible greenhouse gas emission reductions. Rapid urbanization and economic growth have resulted in massive volumes of municipal solid trash. As a result, identifying emission reduction routes for municipal solid waste treatment is critical. In this research, we investigate the potential of municipal solid waste treatment methods in lowering greenhouse gas (GHG) emissions in Shenzhen, a typical Chinese major city. The results showed that the combined treatment of 58% incineration, 2% landfill, and 40% anaerobic digestion (AD) had the lowest greenhouse gas emissions of about 5.91 million tons under all scenarios. The implementation of waste sorting and anaerobic digestion treatment of organic municipal solid waste after separate collection can reduce greenhouse gas emissions by simply increasing the incineration ratio.

Greenhouse gas (GHG) emissions are a significant cause of climate change, and municipal solid waste (MSW) is an important source of GHG emissions. In this study, GHG emissions from MSW treatment in Beijing during 2006–2019 were accounted, basing on the Intergovernmental Panel on Climate Change (IPCC) inventory model; the influencing factors affecting GHG emissions were analyzed by the logarithmic mean Divisia index (LMDI) model combined with the extended Kaya identity, and the GHG mitigation potential were explored based on different MSW management policy contexts. The results showed that the GHG emissions from MSW treatment in Beijing increased from 3.62 Mt CO2e in 2006 to 6.57 Mt CO2e in 2019, with an average annual growth rate (AAGR) of 4.68%, of which 89.34–99.36% was CH4. Moreover, the driving factors of GHG emissions from MSW treatment were, in descending order: economic output (EO), GHG emission intensity (EI), population size (P), and urbanization rate (U). The inhibiting factors were, in descending order: MSW treatment pattern (TP) and MSW treatment intensity (TI). Furthermore, compared with the BAU (business–as–usual) scenario, the GHG mitigation potential of the MSW classification and the population control scenario were 35.79% and 0.51%, respectively, by 2030.

There are special requirements for municipal solid waste (MSW) treatment caused by lower oxygen content and atmospheric pressure on the Altiplano. The intention of this paper was to analyse the applicability of various technologies to MSW treatment in the Altiplano and select the best one based on the current MSW collection modes and technical levels, using the Fuzzy Mathematical Decision Method (FMDM). Technologies including landfill, incineration, composting, and anaerobic digestion (AD) were compared. The results of the studies showed that AD technology is a new technology which is attractive in economic terms and helpful for environmental harmony. AD can solve the difficulties caused by a high content of organic matter in the MSW, lower atmospheric pressure and oxygen content on the Altiplano. Moreover, it can achieve reduction and recycling of the waste, thereby saving space for treatment and disposal. Using this technology, renewable energy can be recovered to save conventional fuel consumption and the emission of greenhouse gases can be reduced to improve the conservation of the local ecosystem. Putting AD into practice in the Altiplano may be the preferred method of MSW treatment.

The research is aimed at comparing different methods of municipal solid waste treatment (waste burial, composting, complex recycling) depending on the values of generated greenhouse gases. In order to compare waste burial and composting of municipal solid waste based on amount of generated greenhouse gases the calculation methods used for compiling the National Inventory, were taken. The mass balance method was used to estimate the output of a product of complex recycling. The municipal solid waste components differ by amount of degradable organic carbon and decomposition rate but have the largest mass. The municipal solid waste treatment techniques consist in placing such waste at landfills and dumps which are sources of environmental pollution, for example, by greenhouse gases. There are other organic waste treatment methods, such as composting via different technologies, burning, recycling etc. But all of them are also associated with greenhouse gases emission. Easily decomposed organic waste can be used for production of organic fertilizers, but a mandatory requirement, that is separation from the general municipal solid waste stream at the time of waste production, should be complied with. A complex recycling of easily decomposed organic waste, including anaerobic and aerobic composting is offered as an efficient way of waste management. The article presents a comparative analysis of various methods of municipal solid waste treatment based on the amount of greenhouse gases emitted in the Odessa Region. It considers three waste treatment approaches: all waste mass is to be placed at landfills and dumps, composting of some of park and garden waste and burial of other components, complex recycling of food, park and garden waste and some of paper waste according to the developed scheme. Complex recycling offers the least value of total greenhouse gases emission over a five-year period whereas waste disposal is characterized by the highest value thereof. The complex recovery of components containing bioavailable organic carbon through anaerobic fermentation method excludes emission of greenhouse gases into the atmosphere, as the biogas produced can be collected and extracted. However, over a long period, even after two-stage complex recycling, the total emission of greenhouse gases will be lower comparing to other methods of easily decomposed organic waste treatment. Emission of greenhouse gases in case of waste disposal has a prolonged nature whereas emission of greenhouse gases in case of composting occurs within a short period of time which should be taken into account when analyzing the prospects of solving the municipal solid waste problem.

Prediction of carbon emissions from municipal solid waste treatment in 31 provinces and cities in China under the shared socio-economic pathways

Carbon neutrality prediction of municipal solid waste treatment sector under the shared socioeconomic pathways

This study focuses on defining the greenhouse gas (GHG) emissions from treatment of municipal solid waste (MSW) in Ha Noi city. Firstly, the MSW samplings at Nam Son and Xuan Son landfills were collected to identify the components. Based on the statistical data on the amount and ratio of MSW collected, the volume of MSW treated by different technologies was estimated. Then, the GHG emissions were quantified by applying the Intergovernmental Panel on Climate Change (IPCC) 2006 model. The annual GHG released from MSW in Ha Noi in 2017 was 1.1 million tons of CO2e from landfilling, 16.3 thousand tons of CO2e from incineration, and 76,100 tons of CO2e from composting. The GHG emission level from landfills is the highest (327 kg of CO2e per ton of treated waste), followed by composting (189 kg of CO2e per ton), and incineration (115 kg of CO2e per ton). The GHG emissions from landfills comprised nearly 90% of GHG emissions from MSW disposal in Ha Noi. The results also revealed that if there are no measures to recover landfill gas for energy generation, the GHG generated from MSW treatment facilities will also contribute significantly to the greenhouse effect and climate change impact. These research results also supply the basis information for decision-makers to select the appropriate MSW treatment technologies for Ha Noi in the context of increasing population pressure and environmental pollution.

Comparative life cycle environmental impacts of two scenarios for managing an organic fraction of municipal solid waste in Rasht-Iran

Towards sustainable municipal solid waste treatment: Life cycle environmental-economic analysis under waste sorting.

Managing municipal solid waste (MSW) is becoming a more pressing global issue that requires creative and long-lasting solutions due to population expansion and changing consumption habits. Given its capacity to transform organic waste into useful resources like biogas and fertilizers, anaerobic digestion (AD) presents a viable solution to the urgent problems related to waste management in this context. This study investigates the potential of AD, and more specifically the two-stage anaerobic digestion (TSAD) process, as a game-changing technique for the treatment of organic fraction municipal solid waste (OFMSW). The efficiency of TSAD is thoroughly examined in this study, which takes into account a number of variables including temperature, pH, solid retention time, hydraulic retention time, organic loading rate, and carbon to nitrogen ratio. Though TSAD is a promising approach, there is still a significant knowledge gap about its stability, ideal operating parameters, and widespread application, especially when it comes to MSW management. The study highlights the necessity for more investigation to close this knowledge gap and realize TSAD's full promise for handling the difficulties involved in energy production and municipal waste treatment.

The incineration treatment of municipal solid waste is widely used, but gas-phase hydrogen chloride (HCl) generated during the incineration seriously threatens the heating surface of boiler tail, and even causes serious harm to environment. Through incineration experiments, this paper found that many factors (temperature, oxygen concentration, residence time and moisture content) affect the HCl emission characteristics in the process of municipal solid waste incineration treatment. In order to effectively cut back the HCl emission in incineration treatment of municipal solid waste, this paper proposes torrefaction and classification pretreatment of municipal solid waste. Torrefaction pretreatment has a significant inhibitory effect on HCl emission during the incineration of mixed municipal solid waste. At the same time, compared with the incineration treatment of mixed municipal solid waste, sawdust and plastic municipal solid waste of the same quality after classification pretreatment can effectively curb HCl emissions within the entire temperature range. In particular, HCl emissions are reduced by 35% during sawdust incineration treatment at 400°C. Furthermore, by studying the reaction mechanics of HCl generation during combustion at different temperatures, and the reaction rate of HCl generation is: mixed municipal solid waste >plastic >sawdust. Therefore, this paper believes that torrefaction and classification pretreatment of mixed municipal solid waste is beneficial to inhibit the precipitation of chlorine during the incineration process and promotes the resource utilization of municipal solid waste, which is of significant significance for energy conservation and emission reduction.