| With the fast development of livestock farming, more and more livestock cultivation farms emerged. And livestock wastewater had already become chief pollution resource in today's countryside. Livestock wastewater has disgusting odor, high contents of organic matters, suspend sludge, nitrogen and phosphorus. In order to make certain the optimal experiment parameters, treatment efficiency of integrated membrane bioreactor was studied at different dissolve oxygen concentration and hydraulic detention times; and bacterium diversity was analyzed by molecular biology method to find colony structure and predominant strain in certain condition. The results indicated that:(1) Dissolve oxygen concentration was controlled between 0.5 mg/L and 4.5mg/L. As Dissolve oxygen concentration increased from 0.5 mg/L to 1.5 mg/L, the removal rate of NH3-N,TN,TP,COD all corresponding increased. While dissolve oxygen concentration increased form 1.5mg/L to 4.5mg/L, the remove rate of NH3-N,TN,TP all decreased except COD, and the remove rate of DO reach to maximum when DO was 2.5mg/L. when DO was 1.5mg/L,the remove rate of NH3-N,TN,TP,COD was 93.03%,94.87%,67.62%,91.16% respectively.(2) HRT was controlled between 2 and 8 hours. when HRT increased from 2 hours to 8 hours ,the remove rate of NH3-N,TN,TP,COD gradually increased; when HRT increased from 8 hours to 12 hours, the remove rate of TN,TP steadied at a higher level and the remove rate of TP presented decrease trend while the remove rate of COD still kept on increasing. when HRT was 8 hours, the remove rate of NH3-N,TN,TP,COD was 96.33%,94.12%,63.12%,92.18% respectively.(3)When DO was 1.5mg/L, HRT was 8 hours, membrane bioreactor existed aerobic-oxygen deficiency- anaerobic environment which had good effect of nitrogen and phosphorus removal,meanwhile the remove rate of COD maintained at a higher level.(4) Researched the diversity of bacteria in MBR reactor at DO 1.5 mg/L, and theHRT was 8 hours. The 16S rDNA cloning lib was constructed, which had the content of 75.9%. Then using 4 kinds of restriction endonucleases, such as: HinfI, HaeIII, AluI and MspI, to cut the clones (29 were succeed to inserting the 16S rDNA fragment). The results showed that there were 12 different patterns of cleavage maps when combination two restriction endonucleases arbitrarily. The Shannon-Wiener index of the lib was 2.1811 and the Simpson was 0.8585. The uniformity and richness were 0.8777 and 3.2667, respectively.(5) According to analyzing the 16S rDNA PCR-RFLP patterns, 8 samples were sent to bio-company to have sequencing. Then determined their genera by hunting for the similar sequences and comparing their similarities with internet tools: NCBI and Blast program. All clones were found a high-similar standard strain. 4 sequences of them belonged toγ-proteobacteria subclass, and 3 sequences belonged toβ-proteobacteria subclass. The chones NO.14 and NO.26 were judged as the Nitrosomonas communis and Nitrosomonas europaea respectively, both of whose similarities were 99% .NO.4 was the Flavobacteria and NO.14 was the Nitrospira. Meanwhile, 3 clones had the similarities between 91%-97% with the uncultured bacteria. So the conclusion was theγ-proteobacteria and theβ- proteobacteria were the superior bacteria in this MBR reactor.
|
PDF Full Text Request