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Poudel P, Joshi P, Tuladhar S, Ghimire A, Baidya M, Howard G, Sharma S. Groundwater implications on methane emission from non-sewered sanitation systems in Nepal. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024:124248. [PMID: 38810674 DOI: 10.1016/j.envpol.2024.124248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 04/16/2024] [Accepted: 05/26/2024] [Indexed: 05/31/2024]
Abstract
Non-sewered sanitation systems (NSSS) are identified as a significant contributor of greenhouse gases (GHGs), primarily due to biological processes within the containment systems. In unsealed or unlined containment systems like pit latrines, the emissions are influenced by moisture. This work quantified the GHG emission occurring from unlined or unsealed containments prevalent in Nepal and compared it with sealed containment-like septic tanks, where the chances of groundwater (GW) inundation are low. The modeled GW data extracted from the secondary sources were validated with available national data. The emissions were quantified using the Intergovernmental Panel for Climate Change (IPCC) model for different ecological divisions and provincial divisions of Nepal. Spatial representation for the results was done using the Geographical Information System (GIS) tool. The total methane (CH4) emission occurring from the various NSSS was determined to be 2,618 Gg CO2 e per year which is almost twice the emission from the waste sector, as reported by the recent national communication submitted to the United Nations Framework Convention on Climate Change (UNFCC). Variation of the CH4 emission was found to be prominent in lowlands (Terai region) with total national emissions of 1,329.37 Gg CO2e per year. The lowland has a shallow GW table that can easily inundate the unlined containments like pit latrines thus contributing to more anaerobic conditions which may lead to higher CH4 emissions compared to containments in mid and highlands. This study concludes that the GHG emissions occurring from NSSS are substantial and addressing these emissions can help fulfil the Nationally Determined Contributions (NDCs) in the waste sector.
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Affiliation(s)
- Prativa Poudel
- Department of Environment Science and Engineering, Kathmandu University, Nepal; Aquatic Ecology Centre, School of Science, Kathmandu University
| | | | - Sarana Tuladhar
- Aquatic Ecology Centre, School of Science, Kathmandu University
| | - Anish Ghimire
- Department of Environment Science and Engineering, Kathmandu University, Nepal; Environmental Engineering Program, Department of Energy, Environment and Climate Change, Asian Institute of Technology, Pathum Thani 12120, Thailand.
| | - Manish Baidya
- Aquatic Ecology Centre, School of Science, Kathmandu University
| | - Guy Howard
- Department of Civil Engineering, Cabot Institute for the Environment, University of Bristol, UK
| | - Subodh Sharma
- Department of Environment Science and Engineering, Kathmandu University, Nepal; Aquatic Ecology Centre, School of Science, Kathmandu University
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Guo D, Li B, Yu W, Han JC, Zhou Y, Ye Z, Wu X, Young B, Huang Y. Revisiting China's domestic greenhouse gas emission from wastewater treatment: A quantitative process life-cycle assessment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 876:162597. [PMID: 36871740 DOI: 10.1016/j.scitotenv.2023.162597] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 01/24/2023] [Accepted: 02/27/2023] [Indexed: 06/18/2023]
Abstract
The wastewater treatment industry could alleviate water pollution but consume a large amount of energy and resources. China has over 5000 centralized domestic wastewater treatment plants and produces an unignorable amount of greenhouse gases (GHG). By considering the wastewater treatment, wastewater discharge, and sludge disposal processes, and employing the modified process-based quantification method, this study quantifies wastewater treatment's on-site and off-site GHG emissions across China. Results showed that the total GHG emission was 67.07 Mt CO2-eq in 2017, with approximately 57% of on-site emissions. The top seven cosmopolis and metropolis (top 1%) emitted nearly 20% of the total GHG emission, while their emission intensity was relatively low due to the huge population. This means that a high urbanization rate may be a feasible way to mitigate GHG emissions in the wastewater treatment industry in the future. Furthermore, GHG reduction strategies can also focus on process optimization and improvement at WWTPs as well as the nationwide promotion of onsite thermal conversion technologies for sludge management.
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Affiliation(s)
- Dengting Guo
- Water Research Center, Tsinghua Shenzhen International Graduate School, Tsinghua, Shenzhen 518055, China; Department of Chemical & Materials Engineering, University of Auckland, 0926, New Zealand
| | - Bing Li
- Water Research Center, Tsinghua Shenzhen International Graduate School, Tsinghua, Shenzhen 518055, China.
| | - Wei Yu
- Department of Chemical & Materials Engineering, University of Auckland, 0926, New Zealand
| | - Jing-Cheng Han
- Water Science and Environmental Engineering Research Center, College of Chemical and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Yang Zhou
- Water Science and Environmental Engineering Research Center, College of Chemical and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Zhilong Ye
- Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Xiaofeng Wu
- Water Research Center, Tsinghua Shenzhen International Graduate School, Tsinghua, Shenzhen 518055, China
| | - Brent Young
- Department of Chemical & Materials Engineering, University of Auckland, 0926, New Zealand
| | - Yuefei Huang
- Water Research Center, Tsinghua Shenzhen International Graduate School, Tsinghua, Shenzhen 518055, China; State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, Qinghai 810016, China
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Chen W, Zhang Q, Hu L, Geng Y, Liu C. Understanding the greenhouse gas emissions from China's wastewater treatment plants: Based on life cycle assessment coupled with statistical data. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 259:115007. [PMID: 37209571 DOI: 10.1016/j.ecoenv.2023.115007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 04/27/2023] [Accepted: 05/10/2023] [Indexed: 05/22/2023]
Abstract
Wastewater treatment plants (WWTPs) are significant contributors to energy consumption and anthropogenic greenhouse gas (GHG) emissions. For achieving carbon reduction in the wastewater treatment industry, the direct and indirect GHG emissions generated by WWTPs need to be understood from a holistic perspective. This study estimated GHG emissions from WWTPs at the country scale by integrating process-based life cycle assessment and statistical data. On-site data were collected from 17 WWTPs of various regions in China. Uncertainty analysis based on Monte Carlo was also performed, so as to provide more reliable results. The results show that life cycle GHG emissions generated from the wastewater treatment process vary from 0.29 kg CO2 eq/m3 to 1.18 kg CO2 eq/m3 based on 17 sample WWTPs. The key factors contributing to overall GHG emissions are also identified as carbon dioxide (fossil) and methane (fossil) to air mainly generated from electricity generation, and methane (biogenic) and nitrous oxide (biogenic) to air mainly generated from wastewater treatment. National average GHG emissions was evaluated with the value of 0.88 kg CO2 eq/m3, with on-site GHG emissions and off-site electricity-based GHG emissions accounting for 32% and 34%, respectively. The total GHG emissions generated from wastewater treatment are 56.46 billion kg CO2 eq in 2020, with Guangdong province having the dominant contribution. Policy suggestions (e.g., further adjusting the electricity grid toward a low carbon structure, improving technology to promote treatment efficiency and energy recovery) were highly recommended so that national GHG emissions of WWTPs can be reduced. In order to achieve the synergy of pollutant removal and GHG emission reduction, policy-making on wastewater treatment should be tailored to specific local conditions.
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Affiliation(s)
- Wei Chen
- School of Geography and Environment, Shandong Normal University, Jinan 250358, PR China; Antai College of Economics & Management, Shanghai Jiao Tong University, Shanghai 200240, PR China.
| | - Qian Zhang
- School of Geography and Environment, Shandong Normal University, Jinan 250358, PR China
| | - Lulu Hu
- School of Geography and Environment, Shandong Normal University, Jinan 250358, PR China
| | - Yong Geng
- School of International and Public Affairs, Shanghai Jiao Tong University, Shanghai 200240, PR China
| | - Chengqing Liu
- School of Economics, Shandong Normal University, Jinan 250358, PR China; Institute for Carbon Neutrality, Shandong Normal University, Jinan 250014, PR China.
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Ahmad A, Senaidi AS. Sustainability for wastewater treatment: bioelectricity generation and emission reduction. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:48703-48720. [PMID: 36862299 DOI: 10.1007/s11356-023-26063-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 02/16/2023] [Indexed: 04/16/2023]
Abstract
This review covers the technological measures of a self-sustainable anaerobic up-flow sludge blanket (UASB) system compared with an aerobic activated sludge process (ASP) for wastewater treatment plants (WWTPs). The ASP requires a huge amount of electricity and chemicals and also results in the emission of carbon. The UASB system, instead, is based on greenhouse gas (GHG) emission reduction and is associated with biogas production for cleaner electricity. WWTPs including the ASP system are not sustainable due to the massive financial power required for clean wastewater. When the ASP system was used, the amount of production was estimated to be 10658.98 tonnes CO2eq-d- of carbon dioxide. Whereas it was 239.19 tonnes CO2eq-d-1 with the UASB. The UASB system is advantageous over the ASP system as it has a high production of biogas, needs low maintenance, yields a low amount of sludge, and is also a source of electricity that can be used as a power source for the WWTPs. Also, the UASB system produces less biomass, and this helps in reducing costs and maintaining work. Moreover, the aeration tank of the ASP needs 60% of energy distribution; on the other hand, the UASB consumes less energy, approximately 3-11%.
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Affiliation(s)
- Anwar Ahmad
- Civil and Environmental Engineering Department, College of Engineering and Architecture, University of Nizwa, PO 33 Postal Code 616, Nizwa, Sultanate of Oman.
| | - Alaya Said Senaidi
- Civil and Environmental Engineering Department, College of Engineering and Architecture, University of Nizwa, PO 33 Postal Code 616, Nizwa, Sultanate of Oman
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Aryal B, Gurung R, Camargo AF, Fongaro G, Treichel H, Mainali B, Angove MJ, Ngo HH, Guo W, Puadel SR. Nitrous oxide emission in altered nitrogen cycle and implications for climate change. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 314:120272. [PMID: 36167167 DOI: 10.1016/j.envpol.2022.120272] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 08/28/2022] [Accepted: 09/21/2022] [Indexed: 06/16/2023]
Abstract
Natural processes and human activities play a crucial role in changing the nitrogen cycle and increasing nitrous oxide (N2O) emissions, which are accelerating at an unprecedented rate. N2O has serious global warming potential (GWP), about 310 times higher than that of carbon dioxide. The food production, transportation, and energy required to sustain a world population of seven billion have required dramatic increases in the consumption of synthetic nitrogen (N) fertilizers and fossil fuels, leading to increased N2O in air and water. These changes have radically disturbed the nitrogen cycle and reactive nitrogen species, such as nitrous oxide (N2O), and have impacted the climatic system. Yet, systematic and comprehensive studies on various underlying processes and parameters in the altered nitrogen cycle, and their implications for the climatic system are still lacking. This paper reviews how the nitrogen cycle has been disturbed and altered by anthropogenic activities, with a central focus on potential pathways of N2O generation. The authors also estimate the N2O-N emission mainly due to anthropogenic activities will be around 8.316 Tg N2O-N yr-1 in 2050. In order to minimize and tackle the N2O emissions and its consequences on the global ecosystem and climate change, holistic mitigation strategies and diverse adaptations, policy reforms, and public awareness are suggested as vital considerations. This study concludes that rapidly increasing anthropogenic perturbations, the identification of new microbial communities, and their role in mediating biogeochemical processes now shape the modern nitrogen cycle.
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Affiliation(s)
- Babita Aryal
- Naaya Aayam Multidisciplinary Institute, NAMI, University of Northampton, Jorpati, Kathmandu, Nepal
| | - Roshni Gurung
- Naaya Aayam Multidisciplinary Institute, NAMI, University of Northampton, Jorpati, Kathmandu, Nepal
| | - Aline F Camargo
- Federal University of Santa Catarina, Post-graduation Program in Biotechnology and Biosciences, Florianopólis, Brazil; Laboratory of Microbiology and Bioprocesses, Federal University of Fronteira Sul, Erechim, Brazil
| | - Gislaine Fongaro
- Laboratory of Applied Virology, Department of Microbiology, Immunology and Parasitology, Federal University of Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Helen Treichel
- Laboratory of Microbiology and Bioprocesses, Federal University of Fronteira Sul, Erechim, Brazil
| | - Bandita Mainali
- School of Engineering and Mathematical Sciences, La Trobe University, Bendigo, VIC, 3550, Australia; School of Engineering, Macquarie University, Sydney, Australia
| | - Michael J Angove
- Department of Pharmacy and Biomedical Science, La Trobe Institute for Molecular Science (LIMS), La Trobe University, Bendigo, VIC-3550, Australia
| | - Huu Hao Ngo
- Faculty of Engineering, University of Technology Sydney (UTS), PO Box 123, Broadway, NSW, 2007, Australia
| | - Wenshan Guo
- Faculty of Engineering, University of Technology Sydney (UTS), PO Box 123, Broadway, NSW, 2007, Australia
| | - Shukra Raj Puadel
- Department of Civil Engineering, Pulchowk Campus, Institute of Engineering, Tribhuwan University, Pulchowk, Lalitpur, 44700, Nepal; Department of Environmental Engineering, College of Science and Technology, Korea University, Sejong, Republic of Korea.
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