Greenhouse gas emissions from waste management--assessment of quantification methods

A critical review on global CO2 emission: where do industries stand?

Global CO2 emissions from different industries have been increasing at an alarming rate. This growth is outpacing the efforts, nations are putting in place to reduce their carbon footprints. In this topical review, we critically analyze the level of CO2 emissions on a global scale and across various industries and activities within them and the dominant anthropogenic forcing instability. The global CO2 emission from various economic sectors such as industries, transportation and variety of waste sources were traced globally and regionally. To contextualize our review, the sector wise CO2 emission trends data for a period more than a decade is reviewed which highlighted the main sources of emissions. The data shows the overall reduction of carbon footprints and its progress across various sectors is very limited. The governing factors for this continued global pattern can be ascribed to two main factors: high consumer demands, and poor efforts towards shifting low and zero carbon services across all sectors. Some efforts have been witnessed to shift towards clean fuels and renewables, particularly in Europe and North America. However, rapid growth in industrialization limits the shifting of fossil-based energy systems towards less harmful systems. In Asia, particularly in eastern, southern, and south-eastern regions, the carbon footprints were found to increased owing to a huge demand for materials production, travelling and energy services. Therefore, it is of utmost importance to identify, understand and tackle the most persistent and climate-harmful factors across all industries and drive such policies to substitute the fossil fuels with renewables.

Spatiotemporal patterns and drivers of carbon emissions from municipal solid waste treatment in China

Reducing carbon emissions from municipal solid waste (MSW) treatment is non-negligible for China to meet its "carbon peaking and carbon neutrality" targets. It is critical to objectively evaluate the spatiotemporal patterns and drivers of carbon emissions from MSW treatment. This study estimates the carbon emissions from MSW treatment across 30 Chinese provinces from 2011 to 2020. The joint approach LMDI-PDA model is further used to refine the impact of policy on carbon emission changes from technical and efficiency perspectives, while considering the socio-economic factors. The results showed that carbon emissions from MSW treatment grew significantly until peaking at 202.05Mt CO2e in 2017 and then stabilized, finally dropping to 165.10 Mt CO2e in 2020 due to the impact of COVID-19. Compared with the "12th Five-Year Plan" period, the MSW emissions intensity declined significantly during the "13th Five-Year Plan" period, indicating the effective implementation of waste emission control measures. Furthermore, the slowdown in the growth of national emissions was primarily driven by technological advances in waste treatment. Technical efficiency change effect, MSW generation intensity effect, economic scale effect, and population scale effect impeded national emissions decline. Since the performance of various drivers varied greatly in different provinces, a cluster analysis was conducted to provide policy recommendations in provinces with similar characteristics. Both the methods and results of this study can provide better decision-making support for national and provincial carbon emissions control policies targeting MSW treatment.

Organic Waste Generation and Its Valorization Potential through Composting in Shashemene, Southern Ethiopia

Composting organic waste and human excreta could significantly reduce the amount of waste dumped and increase soil fertility and agricultural yields. However, studies focusing on the replacement of mineral fertilizer with compost from these resources are rare. The presented study quantifies the potential of human excreta and other organic waste for compost production. During wet and dry seasons, the generation and composition of household solid waste (HSW) was measured from three wealth categories: poor, medium, and rich, as well as the organic waste generated from 20 commercial facilities. Furthermore, the amount of human excreta, when converting unimproved into ecological sanitation facilities, was assessed. The HSW generation was significantly higher in the wet (0.77 ± 0.07 kg fresh weight (FW) cap−1 day−1) compared to the dry season (0.54 ± 0.04 kg FW cap−1 day−1). Organic waste was the main component of HSW in the dry and wet seasons, accounting for 84% and 76% of the total HSW, respectively. Annually, about 6824 Mg of organic dry matter could be collected from households, 212 Mg from commercial units, and 12,472 Mg from ecological sanitation. With these resources, 11,732 Mg of compost could be produced annually and used for fertilizing 470 ha of farmland, completely replacing mineral fertilizer.

Technologies for municipal solid waste management: Current status, challenges, and future perspectives

Municipal solid waste (MSW) is a reflection of the culture that generates it and has a negative impact on the health of the humans and the environment. In the global context, people are abandoning increasing volumes of garbage, and the content of that waste is becoming more complicated than it has ever been, as plastic and electronic consumer goods spread. At the same time, the world is rapidly urbanizing. These changes place a burden on cities to manage garbage appropriately on both a social and environmental level. Globally, extensive research has been conducted to develop a comprehensive MSW management system that includes treatment. The primary objective of this article is to examine municipal solid waste in eight of China's eastern coastal regions. With the use of this review, we found that MSW generation is increasing in Shandong, Guangdong, Zhejiang, and Fujian provinces, but declining in other eastern coastal cities, provinces, and special zones. Furthermore, municipal solid waste in China is treated utilizing 52 percent landfill, 45 percent incineration, and 3 percent composting techniques, resulting in significantly lower usage efficiency than in developed countries. The effectiveness of China's municipal waste management system must be improved. In addition, this review examines MSW management issues and prospects in China, as well as recommendations for strengthening the MSW management system.

Quantifying the effects of general waste reduction on greenhouse-gas emissions at public facilities

Global municipal solid waste (MSW) amounts to approximately 1.3 billion tons per year and is expected to increase to approximately 2.2 billion tons per year by 2025. The greenhouse gas (GHG) emissions from landfills contribute to global climate change. Emissions from this sector contribute around 3% of total net emissions in Australia. Although responsible for a minor portion of Australia's emissions, the sector provides the opportunity for low-cost sources of abatement. This research study aimed to identify new opportunities for reducing GHG emissions from the landfill waste stream in public facilities in Blacktown City in New South Wales, Australia. For this purpose, two public facilities of different types were selected, a library and an aquatic center. The results of the study show that removing organic food waste from the landfill stream at 10 public facilities of the Council could reduce GHG emissions compared with landfilling the food waste by about 0.805 tCO2e/year. However, separately transporting that waste would emit 7.13 tCO2e/year. Therefore, the separated food waste would need to be processed on-site, for example, through worm farms. Removing coffee cups from the landfill waste stream could reduce the associated landfill GHG emissions by around 0.275 tCO2e/y for the 10 public facilities. The study also recommended separating plastic bags from the landfill waste stream of these facilities to reduce 1.10 tonnes of plastic bags from landfill each year. Implications: Potential opportunities for general waste reduction and GHG emission mitigation in public facilities has been studied in this paper. Removing coffee cups and organics food from the waste stream are the main potential opportunities for reducing general waste with possible GHG emission reduction of 0.275 tCO2e/y and 0.161 tCO2/y respectively for 10 public facilities. Removing plastic bags from the waste stream would offer another solution for waste reduction by jointing with the large program running in Australia and creating a collection point for them with 1.1 tonne/y mitigation in general waste at 10 studied public facilities.

Mitigation of CO2e Emissions from the Municipal Solid Waste Sector in the Kingdom of Bahrain

Mitigating climate change to limit the global temperature increase (relative to pre-industrial temperatures) to 2 °C is receiving considerable attention around the world. Here, historical and future carbon dioxide equivalent (CO2e) emissions from municipal solid waste (MSW) in Bahrain were calculated using the revised Intergovernmental Panel on Climate Change (IPCC) 1996 and IPCC 2006 methods. The extent to which waste-to-energy (WtE) technologies can contribute to climate change mitigation was assessed by performing a multicriteria analysis. The results indicated that CO2e emissions from MSW in Bahrain have been increasing since the Askar landfill was constructed in 1986. Emission recalculations indicated that CO2e emissions from MSW contribute 6.2% of total emissions in Bahrain rather than the 11.6% reported in the second national communication. Methane emissions from MSW in 2030 are predicted to be 22–63 Gg. The WtE technologies anaerobic digestion and landfill gas recovery gave the best and gasification the worst multicriteria analysis model results. A database of WtE plants around the world should be compiled to allow decisions around the world to be based on best practices. The potential for maximizing energy recovery and decreasing costs needs to be investigated to allow WtE plants to compete better with renewable and nonrenewable energy sources.

The role of solid waste composting in mitigating climate change in Jordan

Solid waste composting has never been practised on a full scale in Jordan. However, the National Solid Waste Management Strategy recommended five major composting facilities to be put into operation starting from 2025. According to the Ministry of Environment, the waste sector is contributing to 10.6% of the total greenhouse gas emissions of the country. The main objective of this study was to assess the potential of solid waste composting in mitigating greenhouse gas emissions in Jordan. Applying the upstream-operating-downstream account framework and developing a model that estimates the greenhouse gas emissions, it was possible to estimate the emissions associated with composting of source-segregated bio-waste, which was compared with three other scenarios, including business as usual (dumping and landfilling), sanitary landfilling, and anaerobic digestion. The assessment revealed that composting and anaerobic digestion of the total generated source-segregated bio-waste (Scenarios 3 and 4) have the least net greenhouse gas emissions with 1.1 million Mg CO₂-_eq y^-1, while engineered sanitary landfilling and dumping have net emissions of 2.6 and 3.75 million Mg CO₂-_eq y^-1, respectively. The findings of this research are paving the way to make informed and responsible decisions in the Jordanian solid waste sector to adopt sustainable and integrated management options.

Impact of Alkaline H₂O₂ Pretreatment on Methane Generation Potential of Greenhouse Crop Waste under Anaerobic Conditions

This paper intended to explore the effect of alkaline H₂O₂ pretreatment on the biodegradability and the methane generation potential of greenhouse crop waste. A multi-variable experimental design was implemented. In this approach, initial solid content (3⁻7%), reaction time (6⁻24 h), H₂O₂ concentration (1⁻3%), and reaction temperature (50⁻100 °C) were varied in different combinations to determine the impact of alkaline H₂O₂ pretreatment. The results indicated that the alkaline H₂O₂ pretreatment induced a significant increase in the range of 200⁻800% in chemical oxygen demand (COD) leakage into the soluble phase, and boosted the methane generation potential from 174 mLCH₄/g of volatile solid (VS) to a much higher bracket of 250⁻350 mLCH₄/gVS. Similarly, the lignocellulosic structure of the material was broken down and hydrolyzed by H₂O₂ dosing, which increased the rate of volatile matter utilization from 31% to 50⁻70% depending on selected conditions. Alkaline H₂O₂ pretreatment was optimized to determine optimal conditions for the enhancement of methane generation assuming a cost-driven approach. Optimal alkaline H₂O₂ pretreatment conditions were found as a reaction temperature of 50 °C, 7% initial solid content, 1% H₂O₂ concentration, and a reaction time of six h. Under these conditions, the biochemical methane potential (BMP) test yielded as 309 mLCH₄/gVS. The enhancement of methane production was calculated as 77.6% compared to raw greenhouse crop wastes.

Replacing Recycling Rates with Life-Cycle Metrics as Government Materials Management Targets

In Florida, the passing of the Energy, Climate Change, and Economic Security Act of 2008 established a statewide mass-based municipal solid waste recycling rate goal of 75% by 2020. In this study, we describe an alternative approach to tracking performance of materials management systems that incorporates life-cycle thinking. Using both greenhouse gas (GHG) emissions and energy use as life-cycle indicators, we create two different materials management baselines based on a hypothetical 75% recycling rate in Florida in 2008. GHG emission and energy use footprints resulting from various 2020 materials management strategies are compared to these baselines, with the results normalized to the same mass-based 75% recycling rate. For most scenarios, LCI-normalized recycling rates are greater than mass-based recycling rates. Materials management strategies that include recycling of curbside-collected materials such as metal, paper, and plastic result in the largest GHG- and energy-normalized recycling rates. Waste prevention or increase, determined as the net difference in per-person mass discard rate for individual materials, is a major contributor to the life-cycle-normalized recycling rates. The methodology outlined here provides policy makers with one means of transitioning to life-cycle thinking in state and local waste management goal setting and planning.

Inventories and reduction scenarios of urban waste-related greenhouse gas emissions for management potential

Waste-related greenhouse gas (GHG) emissions have been recognized as one of the prominent contributors to global warming. Current urban waste regulations, however, face increasing challenges from stakeholders' trade-offs and hierarchic management. A combined method, i.e., life cycle inventories and scenario analysis, was employed to investigate waste-related GHG emissions during 1995-2015 and to project future scenarios of waste-driven carbon emissions by 2050 in a pilot low carbon city, Xiamen, China. The process-based carbon analysis of waste generation (prevention and separation), transportation (collection and transfer) and disposal (treatment and recycling) shows that the main contributors of carbon emissions are associated with waste disposal processes, solid waste, the municipal sector and Xiamen Mainland. Significant spatial differences of waste-related CO_2e emissions were observed between Xiamen Island and Xiamen Mainland using the carbon intensity and density indexes. An uptrend of waste-related CO_2e emissions from 2015 to 2050 is identified in the business as usual, waste disposal optimization, waste reduction and the integrated scenario, with mean annual growth rates of 8.86%, 8.42%, 6.90% and 6.61%, respectively. The scenario and sensitivity analysis imply that effective waste-related carbon reduction requires trade-offs among alternative strategies, actions and stakeholders in a feasible plan, and emphasize a priority of waste prevention and collection in Xiamen. Our results could benefit to the future modeling of urban multiple wastes and life-cycle carbon control in similar cities within and beyond China.

Cities' Role in Mitigating United States Food System Greenhouse Gas Emissions

Current trends of urbanization, population growth, and economic development have made cities a focal point for mitigating global greenhouse gas (GHG) emissions. The substantial contribution of food consumption to climate change necessitates urban action to reduce the carbon intensity of the food system. While food system GHG mitigation strategies often focus on production, we argue that urban influence dominates this sector's emissions and that consumers in cities must be the primary drivers of mitigation. We quantify life cycle GHG emissions of the United States food system through data collected from literature and government sources producing an estimated total of 3800 kg CO₂e/capita in 2010, with cities directly influencing approximately two-thirds of food sector GHG emissions. We then assess the potential for cities to reduce emissions through selected measures; examples include up-scaling urban agriculture and home delivery of grocery options, which each may achieve emissions reductions on the order of 0.4 and ∼1% of this total, respectively. Meanwhile, changes in waste management practices and reduction of postdistribution food waste by 50% reduce total food sector emissions by 5 and 11%, respectively. Consideration of the scale of benefits achievable through policy goals can enable cities to formulate strategies that will assist in achieving deep long-term GHG emissions targets.

Greenhouse gas emissions estimation from proposed El Fukhary Landfill in the Gaza Strip

Landfills throughout the world are contributing to the global warming problem. This is due to the existence of the most important greenhouse gases (GHG) in landfill gas (LFG); namely, methane (CH4) and carbon dioxide (CO2). The aim of this paper is quantifying the total potential emissions, as well as the variation in production with time of CH4 from a proposed landfill (El Fukhary landfill) in the Gaza Strip, Palestine. Two different methods were adopted in order to quantify the total potential CH4 emissions; the Default methodology based on the intergovernmental panel on climate change (IPCC) 1996 revised guidelines and the Landfill Gas Emissions model (LandGEM V3.02) provided by the United States Environmental Protection Agency (EPA). The second objective of the study has been accomplished using the Triangle gas production model. The results obtained from both Default and LandGEM methods were found to be nearly the same. For 25 years of disposing MSW, El Fukhary landfill expected to have potential CH4 emissions of 1.9542 ± 0.0037 ×109 m3. Triangle model showed that the peak production in term of CH4 would occur in 2043; 28 years beyond the open year. Moreover, the model shows that 50 % of the gas will be produced approximately at the middle of the total duration of gas production. Proper control of Methane emissions from El Fukhary landfill is highly suggested in order to reduce the harmful effects on the environment.

IMPLICATIONS

Although, GHG emissions are extensively discussed in the developed countries throughout the world, it has gained little concern in the developing countries because they are forced most of the time to put environmental concerns at the end of their priority list. The paper shows that developing countries have to start recognizing their fault and change their way of dealing with environmental issues especially GHG emissions (mainly Methane and carbon dioxide). The authors estimated the potential methane emissions from a proposed central landfill that has been approved to be built in Palestine, a country that is classified as a developing country.