水力负荷对生物滞留池处理污水厂尾水的影响

Influence of Hydraulic Load on Treatment of Tail Water from Wastewater Treatment Plant by Bioretention Pond

对已经达到一级A排放标准的污水处理厂尾水进行深度处理是削减入河(湖)污染物总量的重要方式。生物滞留池是易维护、应用灵活的污水生态处理技术,将其用于南京市城南污水处理厂二沉池出水的深度处理,考察了不同进水负荷[0. 2、0. 5、0. 7和1. 0 m^3/(m^2·d)]条件下的处理效果。结果表明,随着水力负荷的提高,生物滞留池对NH_4^+-N的去除率变化较小,对TP、TN和NO_3^--N的去除率呈下降趋势;当进水负荷为0. 5 m^3/(m^2·d)时,生物滞留池对污染物的去除总量最高,对TP、TN、NO_3^--N的去除负荷分别为65、1 450、1 435 mg/(m^2·d)。因此,推荐采用0. 2～0. 7 m^3/(m^2·d)作为生物滞留池处理污水厂尾水的水力负荷设计值。

The advanced treatment of tail water from wastewater treatment plants (WWTP)that has reached the first level A discharge standard,is an important way to reduce the total amount of pollutants entering into rivers or lakes.The bioretention pond,known as an easy-to-maintain and flexible applied sewage ecological treatment techn01ogy,was applied to advanced treatment of the tail water from the secondary sedimentation tank of Chengnan WWTP in Nanjing,and the removal effect of pollutants under four influent loads of 0.2,0.5,0.7and 1.0m3/(m2·d)was investigated.The results showed that the removal rate of NH4^+ -N in the bioretention pond changed little and overall profiles of the removal rate of TP,TN and NO3^- -N were decreasing with the increase of the hydraulic load.When the influent load was 0.5m3/(m2·d),the total amount of pollutant removed by the bioretention pond was the highest, and the removal loads of TP,TN and NO3^- -N were 65,1450and 1435mg/(m2·d)respectively. Therefore,it is recommended to use 0.2-0.7m3/(m2·d)as the hydraulic load design value of the bioretention pond for the treatment of tail water from WWTP.