The evaluation of GHG emissions from Shanghai municipal wastewater treatment plants based on IPCC and operational data integrated methods (ODIM)

Characteristics of greenhouse gases emission from wastewater treatment plants operation in China (2009–2016): A case study using operational data integrated method (ODIM)

Analyzing greenhouse gas emissions from municipal wastewater treatment plants using pollutants parameter normalizing method：a case study of Beijing

Assessment of greenhouse gas emission from A/O and SBR wastewater treatment plants in Beijing, China

Quantifying urban wastewater treatment sector's greenhouse gas emissions using a hybrid life cycle analysis method – An application on Shenzhen city in China

Climate-smart livestock production at landscape level in Kenya

Substantial greenhouse gas (GHG) emissions from wastewater treatment plants (WWTPs) increase the global warming potential, underscoring the importance of addressing their role in GHG mitigation. This study proposes a strategy development approach that analyzes unit-process-based energy consumption, direct and indirect GHG emissions, and scenario impacts to create integrated water–energy–GHG solutions. The analysis of four WWTPs in Seoul Metropolitan City (SMC) identified aeration as the most energy-intensive process, consuming over 40% of the total energy. In addition, substantial GHG emissions were observed, with total indirect emissions surpassing direct emissions. To address these challenges, five future scenarios targeting 2050 were developed and analyzed: (1) replacing aeration diffusers, (2) reducing wastewater production, (3) adjusting treatment levels, (4) increasing renewable energy production, and (5) integrating all measures. Scenario 1 proved most effective in reducing energy and GHG emission intensity, Scenario 4 achieved high energy self-sufficiency, and Scenario 5 enabled some plants to achieve net-zero energy and carbon conditions. The approach proposed in this study provides actionable insights to support carbon neutrality through targeted water–energy–GHG strategies.

In this study, the urban CO2 emission based on energy consumption (Coal, Petroleum, Electricity, and City Gas) in 16 provincial and metropolitan city governments in South Korea was evaluated. For calculation of the urban CO2 emission, direct and indirect emissions were considered. Direct emissions refer to generation of greenhouse gas (GHG) on-site from the energy consumption. Indirect emissions refer to the use of resources or goods that discharge GHG emissions during energy production. The total GHG emission was 497,083 thousand ton CO2eq. in 2007. In the indirect GHG emission, about 240,388 thousand ton CO2eq. was occurred, as 48% of total GHG emission. About 256,694 thousand ton CO2eq. (52% of total GHG emissions) was produced in the direct GHG emission. This amount shows 13% difference with 439,698 thousand ton CO2eq. which is total national GHG emission data using current calculation method. Local metropolitan governments have to try to get accuracy and reliability for quantifying their GHG emission. Therefore, it is necessary to develop and use Korean emission factors than using the IPCC (Intergovernmental Panel on Climate Change) emission factors. The method considering indirect and direct GHG emission, which is suggested in this study, should be considered and compared with previous studies.

Whole-farm systems modelling of greenhouse gas emissions from pastoral suckler beef cow production systems

Biological wastewater treatment is linked to direct and indirect greenhouse gases (GHGs) emissions, thus new approaches on design and operation of wastewater treatment plants (WWTPs) must be adopted aiming towards GHGs emissions’ mitigation. This study evaluates the impact of solids retention time (SRT) on GHGs (CO2 and N2O) emissions of activated sludge (AS) wastewater treatment processes with nutrients removal operating at 10, 30 and 180 days SRT. The 180 days SRT represents the complete solids retention AS process (CRAS), which introduces a novel WWTP design and operation approach for excess sludge reduction. The evaluation of GHGs emissions and process performance via ASDM model and Bridle methodology showed that the total N2O emissions increased together with increasing dissolved oxygen and SRT. CRAS process achieved 97,4% and 96,2% excess sludge reduction compared to AS process with SRT of 10 d and 30 d respectively, with total direct emissions in CRAS process being respectively higher by 20,0% and 12,2%. The lower total indirect emissions in CRAS process compensate for the higher direct emissions. At high influent loads, the balance in GHGs emissions tilts in favour of CRAS process due to management of increased excess sludge quantities, rendering CRAS process a more sustainable choice.

Carbon footprint of a conventional wastewater treatment plant: An analysis of water-energy nexus from life cycle perspective for emission reduction

Carbon footprint of a winter wheat-summer maize cropping system under straw and plastic film mulching in the Loess Plateau of China

The greenhouse gas (GHG) emissions caused by tourism have been studied from several perspectives, but few studies exist that include all direct and indirect emissions, particularly those from aviation. In this study, an input/output-based hybrid life-cycle assessment (LCA) method is developed to assess the consumption-based carbon footprint of the average tourist including direct and indirect emissions. The total inbound tourism-related GHG emissions are also calculated within a certain region. As a demonstration of the method, the full carbon footprint of an average tourist is assessed as well as the total GHG emissions induced by tourism to Iceland over the period of 2010–2015, with the presented approach applicable in other contexts as well. Iceland provides an interesting case due to three features: (1) the tourism sector in Iceland is the fastest-growing industry in the country with an annual growth rate of over 20% over the past five years; (2) almost all tourists arrive by air; and (3) the country has an almost emissions-free energy industry and an import-dominated economy, which emphasise the role of the indirect emissions. According to the assessment, the carbon footprint for the average tourist is 1.35 tons of CO2-eq, but ranges from 1.1 to 3.2 tons of CO2-eq depending on the distance travelled by air. Furthermore, this footprint is increasing due to the rise in average flight distances travelled to reach the country. The total GHG emissions caused by tourism in Iceland have tripled from approximately 600,000 tons of CO2-eq in 2010 to 1,800,000 tons in 2015. Aviation accounts for 50%–82% of this impact (depending on the flight distance) underlining the importance of air travel, especially as tourism-related aviation is forecasted to grow significantly in the near future. From a method perspective, the carbon footprinting application presented in the study would seem to provide an efficient way to study both the direct and indirect emissions and to provide new insights and information to enable the development of appropriate GHG mitigation policies in the tourism sector.

This study uncovered the direct and indirect energy-related greenhouse gas (GHG) emissions of 213 Chinese national-level industrial parks, providing 11% of China's gross domestic product, from a life-cycle perspective. Direct emissions are sourced from fuel combustion, and indirect emissions are embodied in energy production. The results indicated that in 2015, the direct and indirect GHG emissions of the parks were 1042 and 181 million tonne CO2 equiv, respectively, totally accounting for 11% of national GHG emissions. The total energy consumption of the parks accounted for 10% of national energy consumption. Coal constituted 74% of total energy consumption in these parks. Baseline and low-carbon scenarios are established for 2030, and five GHG mitigation measures targeting energy consumption are modeled. The GHG mitigation potential for these parks in 2030 is quantified as 111 million tonne, equivalent to 9.1% of the parks' total emission in 2015. The measures that increase the share of natural gas consumption, reduce the GHG emission factor of electricity grid, and improve the average efficiency of industrial coal-fired boilers, will totally contribute 94% and 98% in direct and indirect GHG emissions reductions, respectively. These findings will provide a solid foundation for the low carbon development of Chinese industrial parks.

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.

It is of great significance to understand the effects of different rice cultivation methods in southeast China on greenhouse gas emission characteristics and carbon footprint of paddy fields during rice cultivation for rice sustainable production. In this study, the popular conventional rice 'Jiafuzhan' and hybrid rice 'Yongyou 2640' were used as materials to establish four rice cultivation patterns suitable for different ecological types in Fujian Province: 1) double-cropping system, early rice and late rice with Jiafuzhan (D-J); 2) early maturing ratooning system, first season rice and ratooning season rice with Jiafuzhan (R-J); 3) middle-maturing ratooning system, first season rice and ratooning season with Yongyou 2640 (R-Y); and 4) single cropping system with Yongyou 2640 (S-Y), which should be synchronized in heading time with the counterpart (the ratooning season rice). Greenhouse gas emissions from paddy soil were measured by the closed static black box observation method and the gas chromatography method, respectively. The total direct and indirect greenhouse gas emissions (carbon footprints) from different rice farming patterns were evaluated by using the life cycle analysis. The results showed that greenhouse gas emissions in different rice cropping systems were lower in the early growth stage, then decreased after reaching the peak at the booting stage, demonstrating a double peak curve in the whole growth stage, in which the first peak was higher in early season or first season than the second peak in the late season or ratooning season in the cropping patterns. Moreover, the total greenhouse gas emissions were significantly different among cropping systems. The global warming potential (GWP) of different cropping patterns was in order of R-Y>D-J>S-Y>R-J, while the annual greenhouse gas emission intensity (GHGI) was D-J>S-Y>R-Y>R-J. GWP and GHGI of the ratooning system decreased by 26.1% and 14.1%, respectively, compared with those of the double-cropping system. The same pattern was observed in the ratooning rice of Yongyou 2640, which were decreased by 74.3% and 56.7%, respectively, compared with the counterpart, Yongyou 2640 in a single-cropping system synchronized heading. Carbon footprint of rice per unit yield ranged from 0.38-1.08 kg CO2-eq.·kg-1 under the different cropping systems, of which the carbon footprint of rice per unit yield was the highest under the double cropping system compared with that under other cropping systems. The reverse was true in the case of carbon footprint of rice per unit yield under the ratooning system with Yongyou 2640. Additionally, the main source of carbon footprint of different rice cropping patterns was CH4, contributing 44.2%-71.5%, suggesting that rice ratooning system could significantly reduce global warming potential and carbon emission intensity of rice in comparison with other cropping patterns. Therefore, it is key to select rice varieties with high yield and low carbon emission and to establish the supporting scientific cultivation techniques for effective reduction of CH4 emission and carbon footprint of paddy fields and promotion of ratooning rice production.