Effects Of Types Of Carbon Source On Biological Denitrifying Phosphors And Nitrogen Removal System And Isolation Of DPB

The processes of denitrification and dephosphorization which were independent originally were integrated into Biological Denitrifying Phosphors and Nitrogen removal process. It was widely considered a bright technology of biological phosphorus removal. In this paper, compared with domestic sewage, the influence of different types of carbon sources on biological denitrifying phosphors and nitrogen removal system was researched. And three types of carbon sources, such as glucose, acetic acid and propionic acid were used. It determined how the different carbon sources made contribution to the systems. ERIC-PCR fingerprinting was used to investigate the relationship between variation of microbial community structure and nitrogen and phosphorus removal during the start and the end of the research, and microbial community structure of the reactors. Through denitrification test and phosphate uptake/release test, a new DPB species, which had seldom been reported in journals, was obtained from the acetic-acid system. And it was identified primarily by 16SrDNA method.It was demonstrated that: When the biological denitrifying phosphors and nitrogen removal system performed perfectly, it would possess strong ability to resist the impacts of changing carbon sources in a short time; after three days, phosphate release in anaerobic conditions and fluctuation of phosphorus concentration were appeared; and two weeks later, the stability stabilization were restored in the systems, with acetic acid or propionic acid as carbon source, while with glucose as carbon source, the system lost the ability of denitrifying phosphorus uptake increasingly. Enhanced biological phosphorus removal, acetic acid was used as effective carbon source to enrich denitrifying phosphorus accumulating bacteria (DPB), while propionic acid had no significance on denitrifying phosphorus removal. Because of a great deal of glucose, the dominant bacteria PAOs and DPB were replaced by other bacteria which were unable to accumulate polyphosphate. The sludge yield coefficient of acetic acid was lower than that of propionic acid and glucose, and glucose produced higher sludge yield.Analysis on the microbial community structure of activated sludge in the reactors during the research. The results indicated that microbial community structure in the domestic system and A2N-SBR system distributed a high level of diversity, and the two reactors could stable and effectively removing the nitrogen and phosphorous from wastewater. Because of the stable and complex microbial community, the single carbon reactors could resist the impacts of changing carbon sources in the first three days. As the operating of single carbon reactors, different dominant bacteria were enriched and bacteria which were survival in system were extinct because of the competition of carbon. It proved that carbon source included DO, pH value, were the important factors for controlling ecological niche of bacteria.DPB (denitrifying phosphorus accumulating bacteria) is an important kind of bacteria in the process of biological nitrogen and phosphorus removal. Members of several different bacterial divisions of microorganisms had been proposed as DPB. These include the Enterobacteriaceae colonies, Aerimonas colonies, Pseudomonas colonies and Moraxella colonies. In this study, two different kinds of bacteria were isolated which had the characteristic of anaerobic phosphorus release, aerobic phosphorus absorb and denitrifying. They were named as P1 and P2. P1 has best quality of phosphorous removal, and P-uptake was three times amount of P-release, and P2's P-uptake was twice amount of P-release. And nitrite concentration had no effect on them. Sequence analysis of 16SrDNA identified P1 and P2, P1 belonged to Chryseobacterium sp, and P2 belonged to Microbacterium sp. The bacteria of these genus hadn't been reported as DPB. Data presented here add further supports to the view that may be mediated by different microbial populations under different conditions. The perfect of Biological Denitrifying Phosphors and Nitrogen removal system provide different kinds of DPB ecological environment to survive which exert function of removing phosphorous and nitrogen from wastewater efficiently.This research was sponsored by the National Natural Science Foundation of China (50278101) and Grand science and technology special project in National Water Pollution Control and Management of China(2008ZX07315).