Study On The Application Of Ecological Filter In Urban Rainwater Purification

In recent years,with the shortage of water resources and the enhancement of national environmental awareness,urban rainwater processing and utilization technology have been paid more and more attention.Rainwater,as a kind of available non-traditional water source,has the characteristics of non-exhaustion,renewable,abundant water and relatively stable water quality compared with other water resources,and it has the advantages of convenient collection,sustainable,less impurity and low cost.It can be widely used in production and life with a simple disposal,so it have a greater utilization potential.In this paper,according to the characteristics of rainwater quality in Chongqing,we use the ecological filter ditch to achieve the decentralized treatment of rainwater,which can effectively reduce the rain and sewage confluence and reduce the pressure of urban sewage treatment.Carried out relevant research,including:(1)The initial rainwater of different functional areas in Chongqing was collected and analyzed the concentration and changes of CODCr,NH3-N,TP and SS.(2)According to the above-mentioned distribution of rainwater quality,the simulated rainwater configuration is carried out and used for the start of the ecological filter ditch system.(3)The effects of different filter and their filling methods,plant and their ratio,running time and C / N ratio on the removal rate of CODCr,NH3-N,TP and SS in simulated rainwater were investigated by single factor test.(4)The orthogonal test are performed on the basis of the single factor test,the most suitable operating parameters of the ecological filter ditch system was carried out.The study concluded as follows:(1)The indicators of rainwater pollutants in summer are better than those in winter,and the indicators of rainwater pollutants are better than those of pedestrian street and bus station.At the beginning of rainfall,the concentration of pollutants in each area was peaked,the rate of descent was the highest in the first 30 minutes.(2)The start phase of ecological filter ditch rainwater treatment system is about 2 months,in the later stage,the growth of plants was good,the biofilm was mature and the microbial content was abundant.The removal rate of CODCr,NH3-N,TP and SS was stable.(3)The single factor test have shown that: The pollutants’ removal rate of mixed filling filter is better than that of horizontal filling,and the effect of plant cross planting on the removal of pollutants is better than that of single planting.The removal rate of CODCr,NH3-N and TP was the highest when the running time was 240 min,and when C / N ratio was 10,the removal rate of CODCr,NH3-N and SS was the highest.(4)Orthogonal test have shown that:The most effect on CODCr and TP removal rate wae the species of plant and its ratio.C/N ratio had the greatest influences on NH3-N removal rate,filter and its filling method had the greatest effect on SS removal rate.The optimum conditions for the removal of the ecological filter ditch rainwater treatment system are: the filter and its filling method was quartz sand + slag(mixed filling),the plant and its ratio was Siberian Iris + Drought Crab(cross planting),running time for 180 min,and C / N ratio of 9.