Studying On The Water Quality Characteristic And Resource Utilization Of Runoff Rainwater For The Urban Residential Communitys In Kunming City

Kunming city as a research object to be used to study the characteristics of the rainwater in urban residential district as well as its collection, disposition and utilization. The capacity and quality of the first5times rainfall were monitored since2012. The pH, SSD,COD, NH3-N,TP TN, turbidity and the heavy metal content in rain water, which had be collected from the runoff of building roof, roadside, green space, was characterized for studying its distribution and EMC values. The main factors influencing the quality of runoff in residential area are:the rainfall conditions (rainfall, rainfall intensity, rainfall duration), underlying surface conditions, the time interval of two consecutive rainfall, regional climate, meteorological conditions and regional atmospheric precipitation which were analyzed combining the relevant monitoring data;Based on the correlation analysis of COD, TP and SS and the calculation results of the initial rainwater abandon flow in the early years of, a series of further experiments were carried out to study the efficiency of the PAC and TF as coagulants to purify initial rainwater and also the quality differences between initial stage and later stage rainwater in storage cellar made with different materials. Based on the above study, a design suitable to rainwater recycle use for urban residential district of Kunming was given in the paper, and a comprehensive benefits was valuated also, the paper also has carried on the applicable to residential area of Kunming city rainwater utilization way and the use of technology research and design, and a comprehensive utilization benefit analysis was carried out.Based on the study above, the results show that the quality of rain water no touching the ground is far better, COD value is very low, with SS (4mg/L), which is lower than the1st level of water quality standard of GB3838-2008.The pollutant concentration in first rainfall water is relatively higher with a SS for572.9mg/L, COD for384mg/L separately in runoff of district roadside, and according to the initial pollutant concentration in runoff in3different underlying surfaces, rendered as road> roof> green. The tendency of pollutants’concentration decreased gradually to balance as the duration of runoff was extended throughout3underlying surfaces, except the pH with a tendency from weakly acid to neutral acid level, and the water quality of runoff became better as the increase of rainfall.Regardless of underlying surface, the residential area runoff of rainwater in water quality in addition to the pH value from weak acid to neutral slowly rising trend, the rest of the pollutants are first rapidly decreased with the extension of rainfall, runoff lasted, after certain runoff time will slowly reduce or leveled off. With the increase of number of monsoon rainfall, rainfall runoff water quality is getting better and better.Studying on the runoff quality of5rainfalls at the Chuanfang community in Kunming, result indicated that:pollutants density in rainwater rendered as road> roof.> green;The pH of rainwater from the roof:7.70, SS:99.2mg/L, the COD:58mg/L, NH3-N:1.65mg/L, turbidity:77.0NTU, TP:0.39mg/L, TN:2.72mg/L, Cu:0.011mg/L, Pb:0.034mg/L,and Zn:0.204mg/L; Road pH:6.62, SS:263.5mg/L, the COD:175mg/L, NH3-N:2.36mg/L, turbidity:128.6NTU, TP:0.59mg/L, TN:3.21mg/L, Cu:0.040mg/L, Pb:0.061mg/L, and Zn:0.236mg/L; Green:pH:6.51, SS:72.8mg/L, the COD:55mg/L, NH3-N:2.73mg/L, turbidity:68.7NTU, TP:0.38mg/L, TN:2.80mg/L, Cu:0.010mg/L, Pb:0.026 mg/L, and Zn:0.106mg/L.Rainfall, rainfall intensity and rainfall duration have significant effects on rainwater quality of runoff, rainfall, rainfall intensity, the greater the rain runoff water quality, the better, rainfall, the longer diameter rain water quality, the better;Two consecutive rainfall the longer interval, the runoff of rain water quality is poor;The variation of types and concentration of pollution which was affected by the air temperature have a remarkable influence on the quality of ground-untouched rainfall; and the stability of atmosphere is negative effect to the kind of rainfall.The study shows that:for the three different underlying surface, the correlation of COD, TP and SS is high with the whole R2, more than85%; the relevance of COD and SS is slightly higher than that of TP and SS; the average value of COD:SS in road runoff is584.67mg/g; the concentration distribution of COD, TP and SS in3different conditions were ranked as:the relevance of the road> greenbelt> roofing.By initial rainwater coagulation experiments, we found that only the dosage of the polyaluminium chloride125g/m3, the COD and SS can be reduced to28mg/L and4.48mg/L respectively, with a removal rate were over88and a ideal removal rate for NH3-N and turbidity.The results of storage experiment indicated that a better solution is using solidified soil cellar and Concrete water cellar storing rainwater respectively;There are a relatively obvious change for pollutants concentration in early stage of waterfall compared with the later stage of it.Through the study of initial stage rainwater at Chuanfang community, the initial abandoned flow of the residential district of Kunming in dry reason is9.6mm for roof,12mm for roadside and green space recorded since the runoff is formed. The abandoned flow can be adjusted according to the frequency of the rainfall. Finally, by studying the using approach of rainwater recycle of urban residential district, the process design and its comprehensive use effect, we conclude that:the rainwater resources utilization in residential district has the good economic benefit, environmental benefit and social benefit.