义乌市城镇污水提标处理的环境与经济效益分析

自2014年以来，浙江省义乌市全面推进城镇污水治理工作，在城镇污水提标处理方面开展了诸多实践。以义乌市2015年和2017年施行的污水排放标准为情境要素，结合该市9座污水处理厂实际运行数据及能耗、化学药剂和污染物排放的生命周期环境影响清单数据，模拟分析了义乌市城镇污水提标处理的环境和经济效益。结果表明，义乌市污水提标处理虽然有益于水体污染物减排，但由于既有污水处理厂普遍进水碳源不足，污水二级处理工艺需仰赖增加化学药剂投放来进行强化，使得投入了大量资金的污水提标处理并未能真正有效地解决水体污染问题，而且还会在气候变暖、土壤酸化、土壤生态毒性等方面产生负面影响。进一步地，围绕污水提标处理的强效思路、污水过度处理负面效应的缓解对策、及污水处理经济效益的增收策略进行了展望，以期为义乌市乃至我国构建经济高效、绿色低碳的污水治理模式提供参考。

Environmental and economic impacts of implementing tighter effluent standards at municipal wastewater treatment plants in Yiwu City,China

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.