| Three gorges reservoir area is located in the upper-middle of Yangtze river which is the key development zone of Yangtze river basin economic development from the east to the west. Its development has important strategic significance to carrying out the strategy for western development and promoting the development of the Yangtze River economic belt. But the economic development, population increase and the urbanization bring enormous pressure to the water environmentThe three gorges dam successfully storage water to 175meters by experimental in 2010 October 24th to 26th.Compared with before, hydraulics conditions is changing, self-purification declining, Reservoir flow field changes resulting in slick shortened, and increasing of the width; in this case, in the same exclusively conditions water pollutant concentration increases, water environmental pollution heavier.After years of management, three gorges reservoir area has established many wastewater treatment plants and has made some achievements. But due to the environmental protection foundation was weak, environmental protection investment limited, reservoir still faced with severe pollution problem. Together with part small towns are numerous, small towns close to water, its pollution more is not taken lightly. Therefore, the three gorges reservoir area small towns'water pollution treatment is imminent.According to the research achievements of water supply and drainage facilities and residents used water features by typical small towns; on the investigation statistical analysis basis of wastewater treatment process operation status, this paper put forward that in three gorges reservoir area use ditches ecosystem towns sewage treatment in technology and economy is feasible. This article mainly following conclusions:(1) Features of water supplied and drained in small towns in three gorges reservoir areaIn the small towns of three gorges reservoir water infrastructure is relatively completed, drainage infrastructure remains to be perfect; sewage collection rate of sewage pipe network is lower. Currently Two way sewage into the reservoir mainly by two ways, which are indoor drainage pipelines - septic tank - dark canal - open channel or Indoor drainage pipelines - septic tank - sewerage pipeline - wastewater treatment plant. Water for domestic use has a large proportion in total in urban life-water quantity of water. Small town's per capita life-water quantity is only 65.8 L/d, which is just 0.47~0.66 of townsman life-water quantity standards (GB/T 50331-2002) and 0.39 ~ 0.66 of the outdoor water design rules" (GBS0013-2006).Drainage sanitation and shower facilities of water reservoir model in door are the most common mode of water using in small towns.(2) The ecological processes in small towns sewage treatment is feasible in technology and economyFrom a theoretical perspective analysis of ecological technology, it has good sewage treatment ability and the treatment effect by multiple factors. Through example this paper demonstrates the selected ecological process in three gorges reservoir area all can satisfy the requirements of local sewage treatment. Sewage discharge of wastewater In the ammonia nitrogen, total nitrogen and floaters, chemical oxygen demand (COD), BOD, total phosphorus or other monitoring indexes accord with the urban sewage treatment plants standards for pollutants discharge "(GB18918-2002) level 1 class B standard requirement. The ecological processes in small towns sewage treatment is feasible in technology and economy(3)Use ditches ecosystem for small towns'sewage treatmentThe removal of CODcr, TN, TP were 47.6%, 30.0% and 18.9%, respectively. Through the analysis about the existence of pollutants in the inlet and outlet wastewater we can obtain that the main way of pollutants removal in the upland ditch is particulate-intercept and adsorption. The removal rates of PN, PP were 60.6% and 49.6%, respectively. The writer trying to make a technology that combines the ditch optimization and pond-wetlands in series based on the study, which can be used to treat the urban domestic wastewater and lessen the pollution.Enhanced ditch system has strong ability to remove organic and SS, and nitrogen and phosphorus removal efficiency of pretty good also. SS ,CODcr and TN in effluent has respectively achieves first-level A standard and the first-level B standard and TP and NH4+-N achieve the secondary standard of《Discharge standard of pollutants for municipal wastewater treatment plant》(GB18918-2002).Conclusion: this paper put forward a kind of wastewater treatment process combined with the three gorges mountain terrain. This kind of ecological sewage system treatment effect is good and stable, and is not affected by external dynamic conditions of constraint, greatly saves energy, save operating costs. On the other hand, this technology combined with the local ditch pond system, in the treatment of wastewater can also have a certain landscape effect. Therefore, ditches ecosystem for small towns'sewage treatment has promoting significance.
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