Greenhouse gases emission control in WWTS via potential operational strategies: A critical review

Quantification and control of the greenhouse gas emissions from a dairy cow system

Carbon footprint analysis and comprehensive evaluation of municipal wastewater treatment plants under different typical upgrading and reconstruction modes

Advanced wastewater treatment processes and novel technologies are adopted to improve nutrient removal from wastewater so as to meet stringent discharge standards. Municipal wastewater treatment plants are one of the major contributors to the increase in the global greenhouse gas (GHG) emissions and therefore it is necessary to carry out intensive studies on quantification, assessment and characterization of GHG emissions in wastewater treatment plants, on the life cycle assessment from GHG emission prospective, and on the GHG mitigation strategies. Greenhouse Gas Emission and Mitigation in Municipal Wastewater Treatment Plants summarises the recent development in studies of greenhouse gases’ (CH4 and N2O) generation and emission in municipal wastewater treatment plants. It introduces the concepts of direct emission and indirect emission, and the mechanisms of GHG generations in wastewater treatment plants’ processing units. The book explicitly describes the techniques used to quantify direct GHG emissions in wastewater treatment plants and the protocol used by the Intergovernmental Panel on Climate Change (IPCC) to estimate GHG emission due to wastewater treatment in the national GHG inventory. Finally, the book explains the life cycle assessment (LCA) methodology on GHG emissions in consideration of the energy and chemical usage in municipal wastewater treatment plants. In addition, the strategies to mitigate GHG emissions are discussed. The book provides an overview for researchers, students, water professionals and policy makers on GHG emission and mitigation in municipal wastewater treatment plants and industrial wastewater treatment processes. It is a valuable resource for undergraduate and postgraduate students in the water, climate, and energy areas; for researchers in the relevant areas; and for professional reference by water professionals, government policy makers, and research institutes. ISBN: 9781780406305 (Print) ISBN: 9781780406312 (eBook) ISBN: 9781780409054 (ePUB)

In recent times, waste management has emerged as a significant environmental challenge, and sewage is among the major contributors due to the rapidly increasing population. Despite sewage treatment plants (STPs) being the solution for the treatment of sewage, they have been identified as sources of greenhouse gas (GHG) emissions. This study aimed to estimate the contribution of STPs to GHG emissions in the state. This was achieved by visiting the sites, filling scientifically designed questionnaires, sample collection as well as computational methods by Intergovernmental Panel on Climate Change. The assessment of direct and indirect emissions from the STPs revealed that emissions were caused by the activated sludge process, electricity consumption, transportation, and sludge storage. Electricity consumption by STPs was responsible for the highest emissions, accounting for 43% of the total emissions, equivalent to 20,823 tCO2 eq. The activated sludge process contributed 31% (14,934 tCO2 eq) of the emissions, while storage of sludge in landfills accounted for 24% (11,359 tCO2 eq). Additionally, transportation contributed 2% (1121 tCO2 eq) of the emissions. In total, the STPs in Himachal Pradesh had the potential to contribute 48,237 tCO2 eq GHG emissions annually. Thus, the study suggests process-level modifications in STPs of Himachal Pradesh to mitigate GHG emissions. This research provides insight into the GHG emissions from STPs and highlights the need for their management to reduce environmental impacts.

Carbon Footprint Drivers in China’s Municipal Wastewater Treatment Plants and Mitigation Opportunities through Electricity and Chemical Efficiency

The energy intensive nature of electric arc furnace (EAF) steelmaking necessitates that efforts to reduce greenhouse gas (GHG) emissions will affect steelmakers directly and/or through electric power producers. A model of GHG emissions from an EAF meltshop has been developed using the life cycle assessment approach. Direct and indirect sources of GHG gas emissions are estimated and ranked. Furnace combustion optimisation was evaluated in case studies conducted on a Canadian conventional EAF and a British scrap preheating `shaft' furnace. The analysis assumed 32 and 68% fossil fuel electricity generation, respectively. These case studies show that indirect GHG emission sources, in particular electricity generation, are more significant than direct emissions from the EAF. For the conventional EAF, offgas analysis and improved combustion control reduced electricity consumption by 40 kWh t-1, costs by US$1·05/t, and GHG emissions by 20 kg CO2-eq./t. For the shaft EAF, real time offgas monitoring and closed loop burner control reduced electricity consumption by 25 kWh t-1, costs by US$3·6/t, and GHG emissions by 15 kg CO2-eq./t. The case studies show that combustion optimisation using an EAF offgas analysis and combustion control system provides greater electricity, cost, and GHG reductions than previously reported in the literature.

Carbon footprint analysis of chemical enhanced primary treatment and sludge incineration for sewage treatment in Hong Kong

Comprehensive assessment of refined greenhouse gas emissions from China's livestock sector

Advancing greenhouse gas emission factors for municipal wastewater treatment plants in China

Global economic development has highlighted the issue of climate change, which is one of the most important environmental issues plaguing human beings. It is widely agreed that excessive greenhouse gas (GHG) emissions are important factors contributing to global warming. Many countries have formulated corresponding GHG emission reduction plans to deal with climate change issues. An important GHG emission source is released from sewage-sludge treatment systems. However, there has not been a comprehensive quantitative GHG emissions evaluation system in the case of sewage-sludge treatment systems, due to multiple emission sources, complex processes, and different standards. In previous studies, the Guidelines for National Greenhouse Gas Inventories (Intergovernmental Panel on Climate Change, IPCC, 2006) and Chinese Greenhouse Gas Inventory (National Center for Climate Change Strategy and International Cooperation, NCSC, 2005) were widely applied to estimate GHG emissions from sewage-sludge treatment. However, IPCC does not consider CO2 emissions from sewage treatment, and NCSC does not consider CO2 emissions from the sewage treatment and N2O emissions from sludge treatment. Therefore, the following have been conducted in this study: (1) A GHG estimation model basing on Life Cycle Thinking (LCT) was constructed, and the research objects were CH4, N2O, and CO2 that were produced by the sewage-sludge treatment system. The estimation model of CO2 and N2O, which were ignored in the IPCC report, were analyzed and discussed. The models of the GHG emission estimation were summarized and improved in the urban sewage-sludge treatment system under the different sewage-sludge treatment process scenarios. (2) The GHG emission load of major urban sewage-sludge treatment processes was analyzed, and the level and key links of environmental impacts generated by different processes were identified. This helps to understand and compare the environmental impacts of different treatment processes and provides suggestions for the sustainable development of wastewater treatment processes. (3) The GHG emission characteristics of nine scenarios of different sewage-sludge treatment processes were analyzed, and the environmental impacts caused by energy consumption and chemicals consumption were studied. Consequently, the sewage-sludge treatment process under low carbonization and low environment impact were proposed.

Taking a sewage treatment plant in Suzhou City, Jiangsu Province, as an example, the greenhouse gas （GHG） emissions generated in the sewage treatment system were calculated using the carbon balance method and the emission factor method. The environmental impacts and economic aspects of different treatment units in wastewater treatment plants were analyzed using life cycle assessment, cost-benefit analysis, and data envelopment analysis models, and emission reduction pathways were proposed. The results indicated that the total GHG emissions （in terms of CO2） from a certain municipal wastewater treatment plant in Suzhou were 6 653.08 kg·（104 m3）-1, with direct and indirect GHG emissions accounting for 29.22% and 74%, respectively. The reuse of treated effluent achieved a reduction of 3.3% in emissions. The biological treatment phase and the sludge treatment phase were the main impact stages for GHG emissions at a certain wastewater treatment plant in Suzhou, where the high-power equipment, specifically the blowers used in the biological treatment phase, and the use of polymeric ferric sulfate agents in the sludge treatment phase were the primary factors contributing to GHG emissions. Life cycle assessment analysis revealed that electricity consumption, direct CO2 emissions, pollutant concentration in the effluent, and the use of chemical agents at wastewater treatment plants had negative impacts on global warming, atmospheric acidification, and eutrophication of water bodies. Calculations indicated that for every 10 000 m3 of wastewater treated, the sewage treatment plant achieved a net benefit of 13 630 RMB. However, from April to May 2023, the scale efficiency of the sewage treatment plant was less than 1. This indicates that during this period, the proportion of output increase was less than that of input increase, demonstrating an irrational structure of input-output. After June, through enhancing the overall operational load, advancing technical improvements, and management efforts, the optimization of scale efficiency was achieved. A sewage treatment plant in Suzhou could achieve the goal of being "green and low-carbon" by installing high-efficiency pumps and fans, utilizing solar photovoltaic and water source heat pump systems, and making process improvements.

Descriptive, prescriptive and second-best approaches to the control of global greenhouse gas emissions

Assessment and modeling of effluent quality, economic benefits, and greenhouse gas reduction for receiving brewery wastewater on A2O by GPS-X

In this study, we performed analysis to identify the effective method for suppression of Green House Gasses(GHGs) emissions from the public swage treatement plants. In particular, according to the IPCC guidelines, GHG emissions from public sewage treatment plants were calculated by dividing them by size and construction method. Among the methods investigated, the standard activated sludge method and the MEDIA method generated the least amount of greenhouse gas 0.000267 kgCO₂-eq/㎥ and 0.000327 kgCO₂-eq/㎥ respectively in the sewage treatment plant size of 10,000 ㎥ to 50,000 ㎥. On the other hand, the A₂O and SBR methods generated the most greenhouse gas emissions at 50,000 ㎥~100,000 ㎥ of sewage treatment plants, respectively, with 254 kgCO₂-eq/㎥ and 248 kgCO₂-eq/㎥. In addition, we verify the BOD load was the largest influencing factor on the quantity of generated greenhouse gas at the sewage treatment plants, and the factor is followed by the facility capacity, the inflow flow and T-N load, and the power consumption.

This study presents a synergic optimization of control for greenhouse gas (GHG) emissions and system cost in integrated municipal solid waste (MSW) management on a basis of bi-level programming. The bi-level programming is formulated by integrating minimizations of GHG emissions at the leader level and system cost at the follower level into a general MSW framework. Different from traditional single- or multi-objective approaches, the proposed bi-level programming is capable of not only addressing the tradeoffs but also dealing with the leader-follower relationship between different decision makers, who have dissimilar perspectives interests. GHG emission control is placed at the leader level could emphasize the significant environmental concern in MSW management. A bi-level decision-making process based on satisfactory degree is then suitable for solving highly nonlinear problems with computationally effectiveness. The capabilities and effectiveness of the proposed bi-level programming are illustrated by an application of a MSW management problem in Canada. Results show that the obtained optimal management strategy can bring considerable revenues, approximately from 76 to 97 million dollars. Considering control of GHG emissions, it would give priority to the development of the recycling facility throughout the whole period, especially in latter periods. In terms of capacity, the existing landfill is enough in the future 30 years without development of new landfills, while expansion to the composting and recycling facilities should be paid more attention.