The Discussion On The Comprehensive Techniques Of Prevention And Treatment Of Water Environment Pollution In Small Towns

Since the past ten years, the small towns in China have been rapidly developing and have become one of the important powers, which pushes the development of the Chinese-characteristic towns.However, with the rapid development of economy, the small towns have been discharging a large mount of wastewater, which has polluted the water environment badly. But, according to many aspects such as sewage quality and quantity, principal source and infrastructure, the small towns of China are different not only from the foreign small towns but also from the large-medium cities of China. Thus, it is very urgent that one technical route with Chinese small towns-characteristics should be found to prevent and treat the water environment.The pollution sources of water environment in small towns include sewage discharged from small towns, polluted water from poultry farms, pollution resulted from pesticide and chemical fertilizer.At first, the thesis analyzed the characteristics of small towns such as economy, society and environment. Then, the pollution sources, sewage quality and quantity, sewage discharge and so on have been discussed. The pattern of ecological agriculture, i.e. ' livestock to firedamp to fruit tree' or ' livestock to firedamp to field,' has been put forward to treat the pollution resulted from livestock dejection and polluted water. Because the agricultural pollution made by pesticide and chemical fertilizer has large quantity and distributed widely, it is very difficulty to control this kind of pollution. So, the method of comprehensive prevention and scientific management is brought up.Secondly, the theoretical contrast analysis has been used in the current wastewater treatment techniques of towns and selected three techniques which are suitable to small towns. They are SBR, oxidation ditch and artificial-wetland. Finally, according to the above threetechniques, the optimum decision-making has been made by the method of analytic hierarchy process in the most typical flow of 1 X 104m3/d found artificial wetland is the optimum choice for small towns' wastewater treatment. At the same time, a practical case has been used to demonstrate the conclusion.The thesis has found one technical route with Chinese small towns' characteristics to prevent and treat the water pollution, which can protect the water environment and delay the water pollution of small towns of China. Thus, the thesis has some reference value.