| Rainwater is a important part of the water circulation system in nature.The comprehensive utilization of area rainwater is an important composition to improve the urban ecological environment,and is one of major approaches to achieve the water resource sustained growth.This article carrys out an investigation and study for the rainwater quality for certain area,then on the basis of quality characteristics,suitable methods and processes fit for rainwater are proposed,and study the new and practicable technology of rainwater comprehensive utilization.First,this article monitors the rainwater quality for certain area,and obtains the rainwater quality material of this area.The emphasis of this article are the study on the fluidized pellet bed solid-liquid separation technology to treat rainwater and rainwater ecological greenbelt to treat rainwater.Based on the above research,the major conclusions of this paper are stated as follow:(1)The pollutant load of road rainwater is far greater than the pollutant load of roof rainwater,and he pollutant load of roof rainwater is about 30%-50%of the pollutant load of road rainwater.The COD difference is particularly evident:the COD of roof rainwater is all below 50mg/L,and the COD of roof rainwater is between 100 and 250mg/L.(2)The pollutant load of road rainwater following rainfall duration has a strong regularity:with the extension of rainfall duration,the pollutant concentration will gradually decrease,but also will increase with the increase of rainfall intensity and has peak.(3)Through the pilot test and full scale test,the effects of the fluidized pellet bed solid-liquid separation technology to treat rainwater is remarkable,especially,the removal of turbidity and Chromaticity.The removal efficiency of Chromaticity is above 90%and the water quality indexes of the treated water could meet the standard of City Miscellaneous Water Quality Control Indicators(GB/T18920)for city greening.(4)The optimal conditions of the fiuidized pellet bed solid-liquid separation technology to treat rainwater:the optimal dosage of PAC is 40mg/L,the optimal dosage of PAM is 2mg/L,the seemly stirring speed is between 2 r/min and 10 r/min,flow rate is between 6m~3/h and 18m~3/h.(5)The effects of the rainwater ecological greenbelt to treat rainwater is remarkable.Especially,the removal of SS is 95%.Simultaneously,thetechnologycan remove nutrient salt effectually and has regularity.The TP and TN removal efficiency is 70%and 55%respectively.(6)The rainwater ecological greenbelt can remove contamination effectually,and increase the water resource supply,so the technology can apply to rain harvesting for developing country.
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