镇江市某城镇污水处理系统外水分析

Analysis of Extraneous Water in an Urban Sewage Treatment System in Zhenjiang

污水系统内存在的低浓度外水是导致污水处理厂进水BOD_(5)偏低的主要原因,为了定量分析不同外水的水量,基于镇江市某城镇污水处理厂提质增效工作,跟踪监测该污水处理厂及其所属泵站在晴天和雨天时的水质水量变化,并与降雨量、排水户排水浓度建立联系。以服务区界内水系平均BOD_(5)浓度代表外水平均浓度,评估各节点泵站受河(湖)水等持久性外水和降雨等瞬时性外水的影响程度,结果发现,不同泵站的外水来源比例以及受外水入侵程度不同。根据泵站评估结果指导污水收集系统进行排查,定位了缺陷部位并提出相应工程整改措施和总体的长效化管理措施。通过分析工程案例确定了措施的可行性,并根据预期削减水量对整改效果进行了预评估,表明了整改措施的有效,可为其他城镇污水处理厂定量分析和削减排水系统的低浓度外水提供参考。

The extraneous water in the urban sewage treatment system is considered as the main cause for the low concentration of BOD_(5)in the influent of urban sewage treatment plants.An urban sewage treatment plant in Zhenjiang has made efforts to improve quality and efficiency.In order to quantitatively analyze the quantity of various extraneous water,in sunny and rainy days,we track and monitor the changes of water quality and quantity in the sewage treatment plant and its pump stations.The changes were linked to the rainfall and the concentration of BOD_(5)from drainage entities.The average concentration of BOD_(5)for water systems within the service areas is applied as the average concentration of extraneous water,and the influences of stable extraneous water such as rivers and lake water and other transient extraneous water such as rainfall were evaluated on each pump station.The results show the proportion of extraneous water of different pump stations is different,and the degree of extraneous water intrusion is different.According to the evaluation results from the pump stations,we guided the investigation of the sewage collection system,and located the defective parts.Furthermore,corresponding engineering rectification measures and overall long-term management measures were proposed.Through the analysis of this engineering case,the feasibility of the measures is determined.Moreover,according to the plan on extraneous water reduction,the rectification effect is pre-evaluated.Our work has proved the effectiveness of the rectification measures.This work can provide a reference for the quantitative analysis of water quality in other urban sewage treatment plants,and the protocols on the extraneous water reduction with low BOD_(5)concentration.