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Landfill leachate treatment has become a hot research topic. Because water quality of leachate is complex, now there has no perfect process, to Seek economic efficiency of the leachate treatment process is important.Second stage biological contact oxidation is a new technics of Landfill leachate treatment. The core technologies is intensified pretreatment.This paper do a depth discussions and analysis to pretreatment unit’s operating parameters,influencing factors and the problems. At the same time,it research the theory for Removaling of pollutants in this unit by Experimental data. From the pilot study was conducted in the following:1)The Operation of intensified pretreatment unit. Comparison of ,in normal temperature and low temperature,the differences in the effectiveness of unit operations.2)From experiment and study ,it get the enhanced pool of acid hydrolysis’s parameters, Better determine the operating conditions.3)it analyse the pretreatment unit’s operating parameters,influencing factors.4) Study it in the course of the actual operation Problems and Solutions.Through the study above it find that:①In normal temperature, COD, NH3-N, TP, BOD5 removal rate reached 70%,80%, 53%,66%..In low temperature, Removal rate has decreased,but it still meet the design requirements. BOD5/COD Can achieve a level of 0.35. The pH value between 7.6-8.4, The pH value of Effluent water is above 7.0. Landfill leachate’s chroma is between 250-300 times. The Effluent water’s chroma is 200 times. pretreatment unit has a certain heavy metals removal capacity,but But relatively low.②In low DO environment, the high efficient Stage of degradation of nutrients was shorter, and the higher the DO, the longer the high efficient Stage.The DO’s range is 0.4mg/L-0.8mg/L.The best HRT is 22h-26h. In normal temperature, when DO is 0.75 mg/L,HRT is 22-26h, back flow is 10%-15%, System running best. In low temperature, when DO is 1.5 mg/L,HRT is 22-26h, back flow is 15%, System running best.③Effect of temperature on the impact of treatment is Mainly in the 12℃-8℃. Under these conditions the unit operating performance is decrease. The main factors Impact of the treatment effect is temperature, pH, sludge load, the C / N, C / P, the carbon and so on. There is a certain amount of loss N and COD in system. COD burthen and NH3-N burthen are main factors to the unit’s operation.④Pre-aeration to hydrolysis-acidification has the good performance in winter.⑤The intensified pretreatment has Problems, such as Bubble,sludge expansion, Nutrition ratio is unreasonable, Indicators decline in winter.But it can be Improved through adjust back flow and aeration aeration volume.
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