Study On Low Impact Development Technology Of Rainwater Utilization In Green Building And Community

Rainwater is an important part in the urban water circulation system, for it plays akey role in adjusting and supplementing urban water resources and improving theecological environment. Built-up areas, which occupy nearly70%of the urban area, arethe starting point of the urban rainwater drainage system. Therefore, the rainwaterutilization in built-up areas is a significant element in the whole urban rainwaterutilization system, and it decides whether the whole system is good or not. Thus, inorder to improve the urban water environment, the current problems existed in built-upareas must be firstly solved properly. The low-impact development technology reducesthe density of pollutants by controlling the pollution in the source, and the runoff flowby retaining the source water. By applying the low-impact development technology tothe green building areas, we can imitate and recover the nature to the maximum extent.For example, we can protect the water quality, reduce the runoff flow, extend the runoffconcentration, weaken the peak, replenish the groundwater and decrease the soil erosion.The sustainable developments of environment and society are achieved as well in theprocess. The low-impact development technology is a scientific and reasonable way tosolve the rainwater problems in built-up areas of our nation. The main content andconclusions of the thesis are as follows:①Based on the studies and comprehensive evaluation of the low-impactdevelopment rainwater utilization technology, such as the green roofs, grass swales, raingardens, penetration pavement, multi-functional storage tanks of landscape water and soon in green building areas. the rainwater low-impact development technology in greenbuilding areas is an innovative idea, and is better than other rainwater utilization systemon aspects such as the recover of the eco-environment and key technology application.It minimizes the impacts of land development on the water and ecological environments,weakens the peak, purifies the water as well as keep the value of the landscape in thebuilt-up areas. It has a true sustainable management on rainwater.②The experiment study of the low-impact development ecological channelsystem with the control of the flow of rainwater runoff. The flow control of ecologicalchannel is not necessarily related with the start time, but has a close relation with soilpermeability. It is better to adopt the soil with a big osmotic coefficient for it isadvantageous to the control and retaining of rainwater. ③The experiment study of the low-impact development ecological channelsystem with the control of the flow of rainwater runoff. In the early stage of theecological channel experiment, backfill medium nutrients separate out and there is aclear phenomenon of leaching. After the start stage, the ecological channel remove80%~95%of SS,70%~80%of COD,50%~60%of TN, and TP with an unstableremoval rate. There are nitrification and denitrification phenomena in the verticaldenitrification purifying process of the ecological channel. In the depth of20-40cm, thenitrification is clear while in the depth of60-100cm, denitrification is obvious. In orderto promote the denitirfication, we can provide the carbon source in the bottom ofdenitrification zone, but should look of the control of effluent COD.④The study on water balance design and the ecological purification technologyof low-impact development multi-functional storage tanks in green building areas. themulti-functional landscape water storage tank can well combine the flood control,rainwater storage utilization with the landscape and eco-environment. Thenon-traditional water balance design is the basis of non-traditional water utilizationdesign of green building areas. By calculating the water balance with a time span of onemonth, it improves the matching between the calculation method and the water amountchange tendency and the utilization rate of rainwater in green building areas. The waterquality can be guaranteed by methods such as aeration, physical purification, chemicalpurification, water ecological study, mirco-pollution biological treatment and addingPSB.