| The characteristics of landfill leachat are high contents of organic compounds, heavy metal and ammonia nitrogen, and the the compostion of landfill leachate is very complex. The removal rate of pollutants is low by conventional biological wastewater treatment, One of the problems is that the microorganism in bioreactor which generally originated from the tamed sewage sludge of municipal sewage treatment plant can not adapt to water properties of leachate, so optimization of microbial community structure of leachate treatment system may be a new effect method to solve this problem.There are plentiful biofacies in mineralized refuse. The microorganism in mineralized refuse has experienced the whole stabilizing process of landfill, and to be influenced by the internal environment of long-term "natural domestication, selection and induction" of landfill internal environment.This makes the microorganism of mineralized refuse with strong microbial degradation of pollutants and high toleration of toxic substances in leachate. Through the test, high efficiency bacterial strains with strong microbial degradation of leachate pollutants and high tolerance of ammonia nitrogen were screened, and then compared the degradation capability of activated sludge inoculated with high efficiency bacterial strains to activated sludge uninoculated, based on this to explore the use of activated sludge inoculated with high efficiency bacterial strains to strengthen degradation capability of routine biosystem. The main conclusions made in the research are as follows.â‘ Through using the common enrichment medium and self-designed domesticated medium and isolation medium, three high efficiency bacterial strains have been selected from the mineralized refuse. Experimental results revealed that the leachate CODcr degradation rate of each of the bacterial strains was more than 20 %. And the leachate CODcr degradation rate of the bacterial strain mixed with three bacterial strains is higher than a single bacterial strain. It probably suggests synergistic effect exists in these strains, and it is beneficial to removal of organic matter in leachate.â‘¡In sludge domesticated stage, when the influent is the raw leachate, compared activated sludge (reactorâ… ) inoculated by high efficiency bacterial strains from the mineralized refuse with the noninoculated conventional activated sludge (reactorâ…¡), reactorâ… showed strong anti-shock loading capability of leachate and strong resistance ability against the raw leachate.When the sludge was domesticated, with keeping sludge load in the system at about 0.5 kgCOD/(kgMLSS?d), the COD removal rate of the reactorâ… and the reactorâ…¡were stable at 0.51 and 0.37,and the removal rate of ammonia nitrogen were stable at 0.81 and 0.75. The degradation ability of activated sludge inoculated by high efficiency bacterial strains has been markedly strengthened.â‘¢By comparison of activated sludge ERIC-PCR fingerprint in SBR reactor, before or after inoculation the band of ERIC-PCR fingerprint changed, and it can be found that the inoculation of activated sludge with high efficiency bacterial strains changed the microbial community structure, for example some dominant microorganism disintegrated, and some inferior microorganism was changed into dominant microorganism after inoculation. By comparison of the zone changes between before or after domestication with leachat, it can be found that some dominant microorganism can not adapt to the leachate characteristics and disappeared, and the high efficiency bacterial strains from the mineralized refuse got changed to dominant microorganism, It also shows that the microorganism from the mineralized refuse has stronger microbial degradation of pollutants and higher toleration of toxic substances in leachate than the microorganism from ordinary sludge.â‘£The high efficiency bacterial strain from mineralized refuse to inoculate slug for leachate treatment, through selective and competitive propagation with the intrinsic microbial population of treatment system, to implement recombinant relations of microbial population and enhance dominant microorganism in the leachate treatmetn system, and improve the behaviour of activated sludge and metabolism level as well. According to ecological theory, the interaction between new-added microbial population and intrinsic microbial population causes community succession under the selection of environment, and forms optimization of species components which adapt to leachate environment, and thus enhances degradation capability of routine biosystem.
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