Applied Research Of Reformative Combined Sewage System In Small Towns

The urban drainage system refers to a mode of wastewater collecting and transporting within a designated area. There are two basic systems for it: the separated sewage system and the combined sewage system. The choice between the two systems must be based on considerations on both the swage disposing method and the environmental quality request, and meanwhile it is also constrained by the actual situation of the swage system. The validity of the system itself and the operating status can directly affect the investment result of the whole catchments engineering, i.e., the aspired social and environmental benefits. A review of the development of city sewage systems of the whole nation since the Reform and Opening-up shows that, although the urban sewage system has been developing for many years, its overall level is still lagging behind that of developed countries due to problems accumulated historically. Now there are serious problems concerning the sewage projects across the country, many of which just follow the stereotype by indiscriminately adopting the separated sewage system, regardless of the actual economic and environmental conditions.Yet outside China the situation is that they have already covered the first and second stages, stage one being collecting, transporting and drainage in ductwork without wastewater treatment, and stage two being point source pollution, and have entered the third stage, which is treatment of non-point source pollution.It's obvious from Hesperian experience that, among the alternative plans to improve the Na-receiving water quality, the plan to adopt a separated method instead of a combined method is both expensive and less effective, while adding controlling establishment to combined sewage system is more economical and useful than rebuilding combined sewage system to separated sewage system.In order to demonstrate weakened efficacy of reformative combined sewage system to run off pollution, 1 made three experiments about Tianfu Street surface runoff. Through experimental analysis , data collection and rules sum-up, the constitutions and concerntrations of COD and SS the correlations of these constitutions have been given. The draft plan submitted by the Huayang pane) of Shuangliu county, Chengdu, by using the model of surface buildings and streets, provides the annual quantity of accumulated pollutants in rivers, with the conclusion that the reformative combined sewage system is able to reduce annual river pollutants approximately from earth...