Study On Optimal Purification Process Of Dual Water Supply In Residential District

For a long time, tap water is the main source of the civil drinking water .With the industrialization and development of economic, the sources of drinking water plants deteriorated seriously. The kinds and quantity of the contaminants increased rapidly. Conventional processing units, such as coagulation-flocculation, sedimentation, filtration etc., are employed to get rid of the suspending and colloid in the water. They are incapable of removing the organic micropollutants from water effectively. Especially the chlorination-disinfection unit brings on the formation of potentially carcinogenic disinfection by-products, which is bad to health. For the long using time of the water pipes in the cities and poor supervise of the water tanks and pools which are used for second supply ,the second pollution is more and more serious . So to improve the quality of tap water is what we should do to insure people's health. Due to the limitation of economic status, it is impossible to rebuild the existing water supply facilities and water pipes completely. It's also difficult to change the conventional water treatment technology of all water work in a short period. What's more, the water used for drinking is little proportion in the whole urban water supply. Therefore, a small scale centralized drinking water treatment system which produces a kind of high quality drinking water will be needed. It is also a short cut to solve the pollution of water source and improve the human living condition.At present in some economically developed areas in China, dual water supply system which supplys water separably for different purposes advents in some new residential buildings. The system deals with drinking water with advanced treatment technologies to meet the high quality standard so that people can drink water directly. The treated water is carried by other cycle pipes to the domestic.As part of a practical scientific research item from science administration of Guangzhou, this study aims to discuss water treatment process in residential water supply in Guangzhou. Based on a detailed analysis and comparation of present advanced treatment technologies, a more optimal purification process, which consists of sand filtration, GAC(Granular Active Carbon) adsorption, and NF membrane has been suggested by pilot research. The tests indicated this process effective in removing CODMn, ammonia, volatile organic and so on. In addition, some tests on the function parameters such as the filtering velocity of the GAC filter, the function pressure of the NF membrane and the using rate of the discharged water, have been done to determine the optimal values. It is found that the whole purification process performs safely and steadily in product water quality when the values of mentioned parameters are 6m/h, 0.5MPa and 40% respectively.Based on the study, the above-mentioned treatment process has been adopted in the design of dedicated drinking water system in Zhujingdijing residential district. Through more than half of year's operation, the system shows its good treatment ability .Theproduced water meets the requirement of "the Water Quality Standard for fine drinking water (CJ94-1999)". By the estimation, the cost of the treated water is about 20 RMB per cubic meter.This study supplies strong trial reference and foundation for practice and can direct the operation of dedicated drinking water system.