Assessment of runoff treatment operations with combined rainwater treatment system in the old city zone

Abstract Considering the diversity of pollution degree in different underlying surfaces, and the great difficulty in construction and high economic cost for an existing built community in an older city zone, in order to rationally distribute the load carrying capacity of each treatment facility, a design concept of combined rainwater treatment system was put forward to treat vehicle lane rainwater, square rainwater, and roof rainwater. In this study, one older city zone in Guangming new district, north-western Shenzhen, China was selected to meet the combined treatment of vehicle lane rainwater and roof rainwater, and four typical rainfall events were selected to analyze the water quantity and water quality control effect of this combined rainwater treatment system under different rainfall intensity and rainfall duration. Results showed that under the treatment of initial treatment facility and biological filtration facility, the runoff volume of vehicle lane and roof were all controlled effectively, and the discharge amount of different pollutants was also reduced effectively although initial treatment facility and biological filtration facility could not effectively decrease pollutant concentration. Therefore, this combined treatment of vehicle lane rainwater and roof rainwater can provide reference for the popularization and application of different kinds of combined rainwater treatment systems.