Research And Development Of An Integrated Device For Collecting And Treating Green Rainwater

With the process of urbanization,the shortage of urban water resources becomes more and more acute,and open source is particularly important.Compared with other underlying rainwater,green rainwater is less polluted and more feasible for recycling.It is of great significance to study the collection and treatment technology of green rainwater.Green rainwater in campus rainfall was collected,and six water quality indexes(pH,SS,turbidity,CODCr,BOD5 and NH3-N)were tested to reveal the water quality characteristics of green rainwater runoff,and linear regression analysis was conducted for water quality indexes with similar change rules.The water quality of green rainwater was evaluated,and the reasonable initial abandonment rate was given.According to the characteristics of runoff water quality,a new type of incipient rainwater abandonment system with identifiable rain frequency was developed.According to green rain water quality evaluation and pollutant distribution,determine the reasonable rainwater treatment process,design and produce a green rainwater collection processing integration device,and device placed inside the campus green hollows,using quartz sand,activated carbon filter cotton two different types of filtering material rain parallel processing experiment was carried out,and the test results to make analysis,is even more important than to select the suitable filtering material.Finally,the water quality of recycled rainwater was tested to study the changes of the water quality with the storage time.The main conclusions are as follows:(1)The concentration of SS,turbidity,CODCr and BOD5 in greenbelt runoff rainwater is related to the rainfall interval.The longer the rainfall interval is,the more pollution load is accumulated on the greenbelt and the higher the concentration value is.The concentrations of SS,turbidity,CODCr,BOD5 and NH3-N change with runoff time and show a decreasing trend.The decreasing speed is first fast and then slow,and the concentration finally tends to be stable,and the concentration after stabilization is far lower than the maximum concentration.(2)SS has a good linear correlation with turbidity,CODCr and BOD5,but a poor linear correlation with NH3-N,indicating that most of the organic pollution load exists in green rainwater in the form of insoluble particles,while NH3-N is dissolved in green rainwater(3)Within 0-15 min of runoff,the greenbelt rainwater is highly polluted by particulate matter,and SS and turbidity are the main control targets to reduce the pollution load of greenbelt rainwater,and the rainwater that lasts for 0-20 min of runoff is determined as the initial abandoned flow.(4)Sand filtration has good removal effect on SS,turbidity,CODCr and BODs in green rainwater,the average removal rate is up to 68.1%,83.9%,51.1%and 53.4%,respectively,and the effluent quality can meet all the water requirements in "Urban Hybrid water Quality Standard".Activated carbon filter cotton was used as filter material to remove CODCr,BOD5 and NH3-N in green rainwater,with an average removal rate of 58.6%,69.1%and 42.7%,respectively.However,the removal efficiency of SS and turbidity is not as good as sand filtration.If the use of recycled rainwater does not have high requirements for SS and turbidity,considering the project economy and daily maintenance and cleaning of the filter material,active carbon filter cotton is preferred as the filter material.(5)The collected rainwater was tracked and detected,and it was found that the water quality index did not increase with the change of storage time,indicating that PP material was used to make the reservoir,which could ensure the long-term preservation of rainwater.