Grade Control Solution for Combined Sewer Overflow Pollution Quantity and Quality

Twelve rain-runoff events from an urban catchment with combined sewer system in Hanyang district of Wuhan City were monitored through a three-year period.According to the temporal variation of runoff quantity and quality,a grade control solution of building detention pond,wetland and so on based on taking the advantage of WWTP is proposed to mitigate the impact of the combined sewer overflows.It is suggested that the intercepting ratio set as 2 is most cost-effective.In addition,storage of the initial runoff of 10 to 15 mm for later treatment can reduce 70% to 80% of rainfall runoff pollution.