Analysis Of Microbial Community Structure In Domestic Wastewater Activated Sludge And Separation Of Functional Microorganism

Activated sludge was the main body of wastewater biological treatment system, the microbial community structure and biodiversity, and the structural stability and functional stability of activated sludge played an important role in the effectiveness of wastewater treatment system. In this paper, the PCR-DGGE and16S rDNA clone library techniques were applied to study the microbial diversity and community succession in the activated sludge of the laboratory domestic wastewater treatment system(anoxic-oxic process, A/O), through this to examine the relationship between the dominant microorganisms and the change of water quality, and provide theoretical direction for practical engineering application; on the other hand, the traditional cultivation method was used for isolating functional strains from the stable activated sludge, which laid the fundament for development of domestic wastewater treatment functional microorganism agent.In this dissertation, the microorganisms of domestic wastewater activated sludge had been studied systematically, including the cultivation and acclimation of domestic wastewater activated sludge, the microbial diversity and succession law during activated sludge acclimation within domestic wastewater treatment system, the isolation and preliminary identification of microbial strains degrading domestic wastewater. The main results were as follows:(1) The removal efficiencies of A/O process on CODcr was high,90%, and of TP、TN were low,35%and25%, respectively, and NH4+-N removal rate declined along with the sludge acclimation.(2) Five methods of extracting total microbial DNA from activated sludge were compared. The result showed that high temperature lysis method could be more suitable for bacterial PCR-DGGE analysis of activated sludge, while SDS lysis method could be more suitable for fungal PCR-DGGE analysis.(3) Using PCR-DGGE technique, the microbial community structure and biodiversity of different acclimation periods sludge samples was investigated. The result of PCR-DGGE showed: there were abundant species of microorganism existing in the system, bacterial diversity was higher than that of fungi, and obvious changes of microbial community structure happened during the sludge acclimation. The sequence was determined through comparison with GenBank(NCBI):16S rDNA sequences corresponding to7excised bands from activated sludge samples were analyzed and classified into three lineages of the bacteria, including Proteobacteria groups, Pedobacter sp., Sphingobacterium sp..The sequencing results of dominant bands in the DGGE combined with water treatment effect showed that Proteobacteria groups, Pedobacter sp.and Sphingobacterium sp. played a key role in removing CODcr.(4) Using16S rDNA clone library sequence analysis method, the bacterial community composition of the stable sludge was studied. The clone library sequence analysis indicated that the bacterial diversity of the activated sludge was broad, mainly included Proteobacterium groups, Bacteroides groups, Firmicutes groups, Zoogloea sp., Pseudomonas sp., Bradyrhizobium sp., Sphingobacterium sp., Clostridium sp., Sludge bacterium, Xanthomonas sp., Acidovorax sp., Dechloromonas sp., Rhodobacter sp., Sphaerotilus sp., Pedobacter sp., Polaromonas sp., Phenylobacterium sp., Planctomyces sp., Herbaspirillum sp..(5) Using traditional cultivation method,68pure strains were gained from stable sludge of A/O process, Through organic hydrolysis test and simulated domestic wastewater degradation test,5strains were considered as functional strains, by PCR, sequencing and homology analysis,5strains had high similarity with Alcaligenes sp., Bacillus sp., Naxibacter sp..