义乌市城镇污水提标处理的环境与经济效益分析

Water utilities in Yiwu City, Zhejiang Province, China, has devoted substantial efforts to satisfy ever-tightening effluent discharge regulations and standards since 2014. Based on the operational data and life-cycle inventory data (including pollutant emission, energy and chemicals consumption) at 9 wastewater treatment plants (WWTPs) in Yiwu, this study simulates and analyzes the change in the overall environmental and economic impacts of implementing stricter standards in 2017 than a baseline in 2015. Results show that tightening discharge levels indeed help reduce waterborne pollutants. However, an excessive amount of chemicals are consumed for the enhanced treatment processes, especially owing to insufficient influent carbon sources in most existing WWTPs. In addition, these intensive practices are also found to cause detrimental effects in terms of climate warming, terrestrial acidification and ecotoxicity. Finally, this work puts forward prospects of future efforts for establishing cost-effective, green and low carbon wastewater treatment paradigm in Yiwu and even China, which can meet tightening effluent standards, reduce unintended negative effects, and increase economic revenue of wastewater treatment services.