| Because of the rapid development of small towns surrounding Three Gorges Reservoir Region, water consumption and wastewater also increases rapidly along with it.But the most small towns' ecological environment is frail, and the draining system is not perfect, the majority of discharged sewage without any processing directly into the Yangtze river,increased Yangtze River's pollution load, and will eventually affect the quality of the three gorges reservoir. In this paper, based on a full research, monitoring and statistical analysis to water supply and drainage facilities in the, the residents of water features and characteristics of domestic wastewater quality and quantity of shibao small town, it study on using the height difference of upland small town' drainage ditches for drop-aeration, combined with bio-contact oxidation, constructed wetlands and stabilization pond technology for the drainage ditches to carry out the transformation,to design domestic sewage purification treatment facility has the characteristic of artificial strengthened technology and the natural ecology purification technology organic synthesis with characteristic of upland small townand and carries on the productbility experiment. Through the experimental study of 8 months, it draws the following main conclusion.(1)Shi Bao town has complete water supply facilities and popular rate of running water close 100%. It exists four kind of sewage collections and emissions way, but the lack of coverage of the drainage network of the town. Residents' per capita consumption of water is small, only 56.5L / d. The most common mode of water consumption is the one with water supply and drainage sanitation and shower equipments inside the house. The proportion of residents' every water consumption varies greatly in winter and summer. Domestic sewage discharged Shi Bao town has the characteristics of high nitrogen, medium phosphorus and low organic matter concentration with the low carbon nitrogen ratio.(2)Enhanced ditch is a purification trentment facility using drainage ditch to treat sawage. It is a natural way to start reactor, 47 days later completes.System has a good and stable removal effect to CODcr in nitiating phase, the average removal rate reached 74.1%. System's removal effect to TP and NH4+-N has a big fluctuation, to tend to be stable in start later period , but the removal rate is not high. In routine run phase, enhanced ditch showed a stronger CODcr and SS removal effect and the ability to have a good nitrogen and phosphorus removal effect. CODcr, SS and TN in effluent has respectively achieves first-level A standard and the first-level B standard of《Discharge standard of pollutants for municipal wastewater treatment plant》(GB18918-2002). TP and NH4+-N achieve the secondary standard.(3)HRT, volume loading, temperature and so on can affect removal effect of enhanced ditch. It can all obtain the good removal effect when HRT=21.4～25.0h and CODc , NH4+-N, TN, TP volume loadings in influent less than 0.6kgCODcr/m3·d, 0.05kgNH4+-N/m3·d, 0.05kgTN/m3·d, 0.004kgTP/m3·d. There are closely relation in system's nitrification and the water temperature. Under the different temperature's experimental study indicated: NH4+-N in influent increased 10mg/L and the removal rate drop approximately 20% when the average temperature drops 6.7℃, simultaneously , the low temperature will cause the nitrite accumulation.(4)This experiment using the enhanced ditch internal treatment stage water outlet and water inlet's height difference carries on drop-aeration.It has 6 depreciation areas in the system and the depreciation heights are between 0.50.7m. In routine run phase, the average oxygen-rich values are bigger than 2.8mg/L, thus effectively guarantee the stable and efficient operation of the system. Because of the difference of oxygen translational speed, drops height, saturated concentration of dissolved oxygen in water, dissolved oxygen initial density in water, difference of drop-aeration effect are greatly not only in 6 depreciation areas but also in the different run phase of every depreciation area.(5)Through to enhanced ditch's 5 kind of plants to carry on the synthesis quite to discover: Nitrogen content difference of 5 kind of plants is not big, between the 24.97-30.94mg/g dry weight. The phosphorus content difference is big. The water hyacinth's phosphorus content is highest, achieves 10.59 mg/g dry weights. In the biomass comparison, the Canna and the water hyacinth have the very obvious superiority. Because the Canna and the water hyacinth have very strong nitrogen and phosphorus's absorption and removal ability in the unit area, simultaneously have the very strong anti-high temperature and plant disease ability, but also has the good ornamental value, therefore are most suitable stransplant plants in 5 kind of plants for constructed wetlands stage and stabilization pond stage.(6)Enhanced ditch to process the small towns domestic sewage has the remarkable superiority in the technology, the economy and the environment benefit aspect. Combining the technical economy strength, characteristic and current situation of sewage disposal of small towns surrounding Three Gorges Reservoir Region, enhanced ditch have the good promoted value.The long-term and productbility experiment has certain reference significance to the actual project of other parts.
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