Study On Eutrophic Water Purification Using A Biofilm Reacter Including Novel Material And Functional Flora In The Treatment System

Large quantities of nitrogen and phosphorus have been released into the aquatic system. It results in the active eutrophication, which brings serious damages for life and productive activities of man. The remediation and treatment of eutrophication has been one of research subjects calling attention to international and domestic academics. Nowdays, absorbing materials and microorganism attract more attention. But the function of absorbing materials is easilly influenced by temperature, pH, phosphorus concentration and so on; bacteria in the practical application accounted for only a small fraction of all; especially there is less detailed study on the treating eutrophic water, whose water quality vary with the season.In this study, we utilized one novel material to build an aerobic bioreactor for treating eutrophic water. On one hand, the concentrations of main water quality indexes (total phosphorus:TP, total nitrogen:TN, chlorophyll a:Chl-a) were monitored to verify the ecological purification ability; on the other hand, the MPN culture system and the supernatant including Rpf were used to investigate the composition of and existence condition of VBNC bacteria by isolating strains in different stages from the bioreactor. PCR-DGGE was used to analyze the effect of Rpf on microorganism in the bioreactor; genomic DNA extraction, PCR,16S rRNA gene sequencing, blast, neighbour-joining tree and function exploring were all conducted. The important achievements on the research were followed:1. The biofilm reactor had remarkable ability to purify the eutrophic water. It can remove TP, TN and Chl-a. The mean removal rates of TP, TN and Chl-a achieved 95.9, 92.4 and 95.8%, respectively. Some frequently mentioned factors, such as temperature, pH, phosphorus concentration impacted slightly on TP removal.2. The results of MPN culture system showed the amount of culturable bacteria of treatment group (2.9×109-2.1×1010 cell/g) was higher than the control group’s (5.3×107-2.4×109 cell/g), The effect values (VR) of Rpf were 8.7-54.7. These illustrated that the novel material played the important role in enriching microbes and there were VBNC superior floras that were sensitive to Rpf in the eutrophic water bioreactor.16S rRNA gene blast of isolated bacteria and phylogenetic relationship analysis showed the major VBNC bacteria belonged to the following genera:Bacillus, Burkholderia, Enterobacter, Pseudomonas and Brevibacillus; the isolated bacteria were with the similarities of 97.6-100.0% to the known standard strains.3. MPN culture system including samples coming from the bioreactor was as templates to extract genomic DNA, conduct PCR and DGGE, sequence target genes, blast. DGGE profile illuminated that genetic diversity of treatment group was higher than the control group and there were VBNC bacteira that were sensitive to Rpf in the bioreactor.4. The bacterial change study revealed there are differences among microbial community structures in the sewage treatment system. Bacteria belonged to Burkholderia cepacia and Bacillus cereus appeared at every stage, which had the potential functions of degrading refractory organics, removing nitrogen and phosphorus, respectively; algicidal strains in every stage came from different genera: Bacillus, Brevibacillus, Ochrobactrum and Enterobacter; bacteria belonging to genus of Bacillus, Bacillus, Enterobacter and Pseudomonas had nitrogen removal ability.The biofilm reactor nearly worked 2 years, which could repair eutrophic water remarkably. Adjusting grille and primary setting tank, the bioreactor can be served as an ideal way in sewage treatment. In addition, the novel material was the excellent carrier of bacteria because of its strong absorption ability, it was worth using widely. Based on the fact of exsiting VBNC bacteria in the treatment system of eutrophic water and our previous studies on the environment functions of VBNC bacteria, it can be speculated that there were also VBNC bacteria in kinds of sweage treatment system, and if we focus on the practical application of culturable VBNC bacteria, it will provide new research ideas and methods for technology, equipments and promoting biological treatment effect of sewage treatment system.