What Is Rain-Sewage Separation?

Rainwater can be discharged directly into rivers through the rainwater pipe network, while sewage must be collected through the sewage pipe network and sent to a sewage treatment plant for treatment. After the water quality meets the corresponding national or local standards, it is discharged into rivers, which prevents river pollution. Because the pollutant concentration of initial rainwater is high, where conditions permit, facilities are set up to collect the initial rainwater and discharge it into the sewage pipe network for treatment.

In the past, due to backward urban infrastructure construction, drainage pipes were not separated according to the source of water; instead, a combined drainage system was adopted in which rainwater and sewage shared one drainage pipe. With economic development and increasing environmental awareness, and given that water resources are becoming increasingly precious, in order to make better use of various water resources, a drainage method in which rainwater and sewage each use a separate drainage pipe has been implemented, which is called rain-sewage separation.

Because rainwater is lightly polluted, after separation it can be discharged directly into urban inner rivers, and after natural sedimentation it can serve as natural landscape water as well as urban municipal water for spraying roads. Therefore, rainwater flowing into rivers after purification and buffering can improve the utilization efficiency of surface water. At the same time, sewage is discharged into the sewage pipe network and treated by sewage treatment plants to achieve reuse of reclaimed sewage. After rain-sewage separation, the sewage collection rate is accelerated and the sewage treatment rate is improved, avoiding pollution of rivers and groundwater by sewage, significantly improving the urban water environment, and also reducing sewage treatment costs - which is a major benefit of rain-sewage separation.

Rain-sewage separation facilitates the collection, utilization, and centralized management of rainwater, reduces the impact of water volume on sewage treatment plants, and ensures the treatment efficiency of sewage treatment plants. It will greatly enhance the city's environmental quality, urban grade, and management level, and effectively improve the living environment and quality of life of the general public.