Rainfall Runoff Pollution Reduction By Bank Side Infiltration System In Baoji City

Urban rainfall runoff is one of major factors which cause the pollution of urban manmade water body.This paper presents a way of using bank side infiltration system to dispose the pollution of urban rainfall runoff.The characters of urban rainfall runoff and CSO_s are analyzed,and the design of bank side infiltration system is expounded.It is also discussed the removal characteristic of urban rainfall Runoff.Through the operation of bank side infiltration system and the analysis of the experimental data,we can conclude:(1) Urban rainfall runoff and CSO_s in Baoji city contain high suspended solids and high organic content.The concentration of SS in rainfall runoff ranged from 126mg/L to 989mg/L and COD from 100mg/L to 854mg/L;The concentration of SS in CSO_s ranged from 154.5mg/L to 1352mg/L and COD from 210mg/L to 1930mg/L.The rainfall runoff and CSO_s have obvious First Flush effect,and the high concentration of SS is the main factor which caused serious rainfall runoff pollution.(2) The bank side infiltration system was designed to remove SS in the rainfall runoff of Baoji city.The main parameters are as follows:flow rate being 365m³/h; filtering material being river sand;filtering velocity being 29.2m/d;depth being 0.8m the net size of infiltration tank being 30m long,10m wide.(3) Bank side infiltration system performed well for both SS and COD removal. The concentration of SS in effluent ranged from 12 mg/L to 43mg/L and COD from 20.3 mg/L to 45.1mg/L.The removal rates of COD,SS,TP and TN reached to83.5～91.2%,81.8～91.9%,46.8～60.2%and 14.7～33.6%.The average removal rates of COD,SS,TP and NH₃-N reached to 88.3%,87.8%,53.7%,and 26.1%.The bank side infiltration system combined with the storm water pumping station can be used for controlling urban runoff pollution.