排水系统提质增效的外水定量分析及剥离措施研究

Research on quantitative analysis and reduction strategies of external water for improving quality and quantity of drainage system

污水处理厂进水COD低是制约活性污泥工艺降解污染物效果提升的瓶颈。针对污水处理厂进水COD低的问题,建立了一种联用基于污水管网简化的水质水量模型逆向分析和正向摸查的外水入侵评估方法。通过污水管网简化的水质水量模型的逆向分析,确定了各级管网外水入渗量,并准确找出外水入侵的重点区域为主城区东北和西南侧。通过正向摸查发现,地下水入渗、雨水错接混入和河水倒灌为外水入侵主要原因,且外水侵入重灾区与定量分析结果一致。针对外水入侵的重点区域和外水入侵主要途径,实施了外水剥离措施,释放了管道内外水、增加污水收集量、提高旱天污水处理厂的进水COD浓度和保证旱天无溢流,最终达到污水处理厂进水COD浓度显著提升的目标。

Low-influent COD of wastewater treatment plants is the bottleneck that affects the operation effect and hinders the long-term improvement of the urban water environment.According to the national requirements of improving the quality and efficiency of urban sewage systems,an external water invasion assessment method that combined water quality and water quantity model based on a simplified wastewater pipe network and a forward survey method was established to solve the problem of low influent COD concentration of wastewater treatment plant.The reverse analysis by a water quality and quantity model based on a simplified wastewater pipe network determine the amount of external water infiltration in the pipe network,and accurately locates the key areas of external water intrusion in the northeast and southwest of the main urban area.The forward survey identifies the main ways of external water invasion as groundwater infiltration,rainwater misconnection,and river backfilling.And the main external water invasion areas are consistent with the quantitative analysis results.External water stripping measures targeted at the main invasion areas and the main invasion ways are implemented,to reduce external water,increase sewage collection amount,improve the influent COD concentration of wastewater treatment plant,and ensure no overflow in dry days,to achieve the goal of significantly improving the influent COD concentration of wastewater treatment plant.