Isolation Of Aerobic Denitrifier And Its Application In Landfill Leachate Treatment

Landfill leachate is a kind of high concentration organic wastewater with high concentration of NH₄⁺-N and CODCr and complex components,nitrogen removal problem has always been the bottleneck of its processing technology.As a new technology of biological denitrification,aerobic denitrification shows promising application in the field of wasterwater treatment.This paper has carried on the research with aerobic denitrifier systematically,including the isolation and identification of aerobic denitrifier,the nitrogen removal characteristics of aerobic denitrifier and bacteria consortium,a preliminary study on treating landfill leachate of aerobic denitrifier and bacteria consortium,the acclimation and cultivation of aerobic denitrifying activated sludge.The main results were as follows:1.Two aerobic denitrifiers were isolated from the activated sludge of landfill leachate through traditional microbiological methods.Based on their morphological feature,physiological and biochemical properties,and 16S rDNA sequence analysis,they were identified as Bacillus sp.and Pseudomonas sp.,named as GL2 and GL19 respectively.2.Aerobic denitrification characteristics and nitrification function were studied to show that the factors including carbon source,C/N,pH and cultivation temperature were important for denitrification of strain GL19 and bacteria consortium.The optimized condition for aerobic denitrification was as follows:sodium citrate as the carbon resource,C/N no less than 15,pH of 6-10,DO of 4.8?7.7 mg/L,culture temperature of 15?34? and the initial nitrate nitrogen of 140.0 mg/L.Combining these conditions,the removal rate of nitrate nitrogen reached 100%,and the average removal rate of TN reached 96.5%and 97.3%respectively,without the accumulation of nitrite nitrogen.The strain GL19 and bacteria consortium had the capability to utilize nitrite nitrogen or ammonia nitrogen to accomplish high nitrogen removal efficiency.These results suggested that strain GL19 and bacteria consortium with the function of cold resistance and highly effective aerobic denitrification could achieve simultaneous nitrification and denitrification.3.In practical application of landfill leachate,when the concentration of NH4+-N,TN and CODCr was 400.0?1000.0 mg/L,406.0?1015.0 mg/L and 3019?12076 mg/L,respectively.Both GL19 and bacteria consortium enhancement group show good enhancement of nitrogen removal,and the former was better than the latter.After 10 days'treatment,the TN removal rate of GL19 group was 75.6%?79.8%?77.9%and 67.8%,respectively.that removal rate could reach above 1.7%?2.5%?10.6%and 7.0%higher than bacteria consortium group,11.6%?30.0%?25.4%and 15.5%higher than the control group.the CODCr removal rate of GL19 group was 83.3%?67.0%?47.7%and 52.7%,that removal rate could reach above 16.4%?12.0%?2.7%and 9.4%higher than bacteria consortium group,55.9%?29.2%?26.2%and 29.2%higher than the control group.4.The results of the acclimation and cultivation of aerobic denitrifying activated sludge showed that strain GL19 could obviously promote the growth of activated sludge and significantly enhance the resistance to low temperature.Through batch-flow and continuous-flow,experimental group cultivated aerobic denitrifying activated sludge successfully in single-stage reactor,and achieved simultaneous nitrification and denitrification to some extent in low temperature.when the concentration of NH4+-N,TN and CODCr was 227.0?377.9 mg/L,366.4?439.5 mg/L and 4240?4700 mg/L,The average removal rate of those indicators reached 98.4%?77.1%?92.9%respectively.There were about 12 days' with temperature below 15? in the whole process,among which 10.5? is the lowest temperature.The aerobic denitrifying activated sludge with the function of cold resistance and highly effective aerobic denitrification could be cultured with an extended scale and then used directly in practical engineering application,meanwhile,it can provide references for the acclimation and cultivation of aerobic denitrifying activated sludge of simultaneous nitrification and denitrification practical engineering application in winter of south area.