Experimental Study On The Treatment Of Urban Green Space On The Rainwater Runoff

In recent years, with the development of economy and improvement of people’s lives, thedemand for water in increasing. It has become an urgent problem which limits China’seconomic development and people’s living standards improvement. Urban rainfall runoffpollution makes this situation becomes worse. Urban green space is an important part of theurban ecosystem. Urban green space, as a special land treatment system, due to the bettereffect of removing the pollution of rainwater runoff, bettering the environment and theadvantage of low cost and maintenance, is widely used to remove the material of therainwater runoff pollution in major cities. This thesis focuses on the actual situation of theNorthwest Territories, through experimental studies to determine the technical parameters ofthe deal with rainwater runoff green space system theory and data, which supports for theapplication and promotion of the technology in the Northwest.Through accessing to the Northwest Rainwater runoff water quality data and analysing theactual rainwater runoff pollution characteristics of the Northwest, we can provide a theoreticalbasis for the configuration of the experimental water. After the test water has beenconfigurated well, we determine the best experimental percolation medium through analysingthe improvement of the soil of the Northwest Territories green percolation layer removal ofrainwater runoff. On this basis, we simulate the Greenland experimental device which isgrowing different grass, and analyse the experimental results that simulate green space deviceremoval the urban rainwater runoff, and determine the optimal parameters of the Northwestgreenbelt system and study green space system mechanism to handle rainwater runoffpollutants. The experimental results show that:（1） Though studying the penetration rate of the original soil, quartz sand improvedartificial percolation media, coal ash improved artificial media, and the removel rate of theturbidity, total phosphorus, ammonia, COD_cr, we find that the penetration rate of the quartzsand improved soil is the best and it can make original soil penetration rate increase by from3.5×10^-6m/s to4.2×10^-5m/s; All of three percolation medium for the removal effect ofthe turbidity and total phosphorus go good; For the COD_cr, the removal of the original soil isstronger than the quartz sand, coal ash removal less effective; For the ammonia,the coal ashremoval effect is better than the quartz sand, and the effect of undisturbed soil remove is theworst. Considering the penetration rate and improved soil removal of rainwater runoff effects,the study selects quartz sand as urban green space system the percolation layer of fill media.（2） We find that ryegrass relative to bluegrass grass grows faster and the landscapeeffects of the ryegrass are stronger than bluegrass through the conducting simulated greenexperimental apparatus grass cultivation process. We also find that ryegrass is stronger than the other two experimental groups in the removal effect of the turbidity, TP, ammonia, COD_crby the subsequent experiments.（3） The simulation of urban green space system goes well in the influent speed291.7L/h m², the influent concentration for turbidity=160NTU; COD_cr=140mg/L;ammonia=5mg/L; TP=1.8mg/L.The pollutant removal efficiency of water indicatorswhich is treated by the ryegrass is better:86.3%for turbidity removal efficiency can beachieved; TP removal rate can reach96.4%; ammonia nitrogen removal rate can be achieved63.5%; COD_crremoval efficiency of71.8%.（4） The two types of vegetation play a certain role in the removal of rainwater runoffpollutants. For the turbidity,the vegetation can make the average removal rate increase by8.25%;For the ammonia, the vegetation can make the average removal rate increase by18.5%;For the TP, the vegetation can make the average removal rate increase by39.3%; For theCOD_cr, the vegetation can make the average removal rate increase by18.7%.（5） Through studying the green space system mechanism to dealing with rainwaterrunoff pollutants, we find: the number of the organic matter which is in the soil is increasingwith the time going on, and then gradually declining, the number of the organic matterbasically resumes after9days rainfall. Due to soil moisture, soil respiration has been adownward just when the rain stops. However, with the extension of the time after the rainfall,soil moisture gradually reduces and the soil respiration formation gradually is enhanced, whenit reaches5.4mg/g, the soil respiration formation gradually reduces, the number of the soilrespiration formation basically resumes after9days rainfall. Soil microbial is increasing withthe time going on, and then gradually declining trend. Five days after rainfall, the number ofthe microbial reaches4.2×10⁸/ml, which is the maximum. The number of the Soil microbialbasically resumes at11days after rainfall.（6） The degradation of the soil for rainwater runoff pollutants occurs mainly in the7days after the rain, basically restoring to the level in9days after rain. So in the experimentthat we choose soil regeneration cycle for10days is reasonable and feasible.