Biodegradation Of Landfill Leachate By Optimizing SBR Technics And Realizing Shortcut Nitrification-denitrification

In recent years, the treatment to landfill leachate is still a focus and difficult problem in wastewater treatment. Based on the systematic analysis of the research results on the leachate characteristics and its treatment methods at home and abroad ,it is convinced that the leachate treatment process developed from removing the heavy metal and COD ulilateral to removing the COD and TN at the same time, it put forward higher requirement on the selection of the treatment process.Because the single pool SBR technics have the advantage on the removal of the organic matters and its flexible operation, it can be adopted to the nitrogen removal of the system. we adopt SBR technics to seek the optimal method to treat the landfill leachate of Erfeishan refuse landfill in WuHan by acclimating activated sludge and optimizing the SBR technics.The experiment results of activated sludge acclimation demonstrated that the acclimated cultures contained mainly flocculated bacteria and some of protozoa(mainly Opercularia and Rotifers).The microbial degradation resulted in good removal efficiencies of COD(71%～76%) and BOD5(81%～85%) after eight hours'aeration when the sludge loading was in the optimal rage of 1.7～2.0kgCOD/(kgMLSS·d),and the saturation constant(Ks) was 168mg/L and the maximum specific substrate utilization rate(K) was 1.70d-1.At the process of optimizing the SBR technics, we divide up the aeration into two segments for the first time, the first segment can reduce the restraining effect to Nitrosbacteria and Nitrite-oxidizing bacteria because of high organic concentration, and the second segment is mainly to realize shortcut nitrification-denitrification for nitrogen removal. The experiment results demonstrated that the single pool SBR system could well realize shortcut nitrification-denitrification when the dissolved oxygen (DO) was 0.9mg/L at the second segment of aeration. Then we designed a new SBR model——alternately anoxic and oxic in one cycle based on the above experiment, this experiment results demonstrated that it is more ascendant than the single pool SBR in realizing Shortcut Nitrification-denitrification for nitrogen removal, and the maximum removal ratios of NH₄⁺-N are 84.5%,the maximum accumulation rates of NO₂^--N are 31.4mg/L·h, these results all demonstrated that SBR technics was good to remove nitrogen by realizing shortcut nitrification-denitrification, and the alternately anoxic and oxic model is the best.At the last, we not only get some material parameters of the alternately anoxic and oxic model, but also know that the maximum activated sludge loading of NH4+-N was 0.32kg NH₄⁺-N /(kgMLSS·d)and the optimal activated sludge loading of NH4+-N is 0.27kg NH₄⁺-N /(kgMLSS·d)in this system.