What Is Stormwater Drainage?

Rainwater treatment is the purification process of surface runoff water (rainwater, snowmelt water, watering water) in urban areas.

Rainwater treatment

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Rainwater treatment is the purification process of surface runoff water (rainwater, snowmelt water, watering water) in urban areas.

According to different drainage systems of the pipeline system (diversion system or combined system), rainwater treatment can be treated separately or combined with domestic sewage and industrial wastewater. The amount of water for rainwater treatment is calculated according to the rainwater channel (calculated by the dilution factor or the water volume of the rainwater pumping station), but a rainwater conditioning tank should be set before entering the structure. Rainwater quality can be: BOD20-80mg / L, SS150-300mg / L, oil 8-18mg / L. When rainwater is treated separately, a permanent rainwater collection sedimentation pond (pool) is set up with a grille in front of the pond and sometimes a filter in the back of the pond. The flow velocity of the water in the pond should be less than 0.01m / s, the residence time should not be less than 1-2h (up to 2-5 day and night water flow), and the BOD after treatment can be reduced by 50-70%. When combined with domestic sewage and industrial wastewater, the water volume of the grille and grit chamber should be calculated based on the total water volume. The residence time in the sedimentation tank should not be less than 1h. The aeration tank may not process rainwater or treat part of the rainwater as calculated, and the volume of the sludge deposition and treated part shall be calculated as the total amount of mud. If the rainwater treatment will be used for industrial circulating water, the treatment requirements are calculated according to the water quality of the circulating water. The drainage outlet after the rainwater treatment can be set on the shore of the water body according to the situation.