长江大保护试点城市水环境治理模式及成效

长江流域城市水环境治理取得阶段成果，全面评估其治理成效，总结城市水环境治理经验至关重要。以长江大保护4个试点城市水环境提质增效工程PPP项目为研究对象，评估城市水环境治理成效。结果表明：管网工程中，各试点城市生活污水集中收集率达标，污水厂进厂生活污水化学需氧量 (COD) 达标率75%，九江和岳阳老旧小区改造后污水收集率为100%，改造后出口管网污水COD明显提升；污水处理工程中，试点城市污水厂处理率均达标，平均水力负荷达标率46.2%，平均COD负荷达标率30.8%，出水达标排放，九江白水湖、芳兰污水厂处理单位污水电耗较高；污泥处理处置工程中，各厂污泥含水率满足合同要求，处理吨水及单位污水COD去除的污泥产生量均较高；生态环境改善方面，试点城市水环境治理工程大幅削减污染物负荷，但工程影响范围内地表水质均未达标，超标因子为氨氮、总氮、总磷和COD；工程范围内黑臭水体治理达到合同要求，宜昌生态化岸线比例提高38.9%；社会文化贡献方面，试点城市水环境治理工程建设取得较好的社会贡献。评估结果对完善水环境治理项目，促进长江流域经济社会可持续发展有着重要意义。

Practice model and effectiveness of water environment improvement in pilot cities for Yangtze River Conservation

The urban water environment improvement in the Yangtze River basin have achieved milestones results, and it is crucial to comprehensively assess its effectiveness and summarize the experience. The public-private partnership (PPP) projects in four pilot cities were used as cases to assess the effectiveness of urban water environment improvement in the Yangtze River basin. The results showed that, for the sewage pipeline projects, the centralized collection rate of domestic wastewater in all pilot cities met the standards; the rate of chemical oxygen demand (COD) of flows into the treatment plants meeting the guidelines were above 75%; the wastewater collection rates of old residential communities were 100% after the project implementation in Jiujiang and Yueyang cities, and the COD of the effluent from the pipeline system significantly increased accordingly. For the sewage treatment projects, the treatment rates of sewage plants met the standards in four pilot cities; the rates of average hydraulic loads and average COD loads meeting the standards were 46.2% and 30.8% respectively; the effluent concentrations from the treatment facilities met the discharge standards, but the electricity consumptions per cubic meter of treated water were high at the Baishui Lake and Fanglan plants in Jiujiang city. For the sludge treatment and disposal projects, the water contents of sludge in all plants met the requirements but the sludge productions per cubic meter of treated water and per kilogram of COD removal are relatively high. For the ecological environment improvement, the loads were significantly reduced by the projects in the pilot cities. However, the surface water concentrations of ammonia nitrogen, total nitrogen, total phosphorus and COD were still above the compliance standards in the areas affected by the projects. The treatment of black smelly water bodies in the project-affected area met the contract requirements, and the proportion of ecological shoreline in Yichang city increased by 38.9%. In terms of social and cultural contribution, the water environment improvement projects achieved significant results in the pilot cities. The evaluation results have important implications for improving the effectiveness of water environment management projects and promoting sustainable economic and social development in the Yangtze River basin.