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.
Yangtze River Conservationurban water environment improvementeffectiveness assessmentpipeline networkwastewater treatment
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