Research On The Influence Of SRT On Microbial Metabolites And Biodiversity

Microbial metabolites can influence the treatment effect and sludge properties of water treatment process. In this research, sequencing batch reactor (SBR) is used as a test object. The influence of SRT on microbial metabolites and biodiversity is studied by two ways. The first one is analyzing the changing mechanism of microbial metabolites under various sludge retention time (SRT), the last one is analyzing the similarities and differences of various SRT condition's microbial metabolites, biodiversity, biological population structure.The results showed that under diffefent SRT conditions microbial metabolites may vary. This difference is also approved by biodiversity and biological population structure. The extracellular polymeric substances'(EPS) concentration and protein proportion achieve maximum when the SRT is 5d, and reach minimum when the SRT is 30d. EPS'polysaccharide proportion achieve maximum when the SRT is 20d. The other components of EPS reach maximum when the SRT is 30d. Under various SRT conditions, EPS concentration and protein proportion varied accordingly, but polysaccharide was the other around.The change of microbial metabolites has little regularity under the changing process of SRT. Generally, the concentration of EPS is in inverse proportion to the change of SRT, but the detailed changing is complicated. When the SRT fluctuation is in the range of 10~30d, the concentration of EPS has short time buffer capacity aganst SRT's decreasing tendency. But the buffer capacity will be destroyed, if the fluctuation range is 5~40d. The variation of EPS component is not obviously. The protein and polysaccharide will be affected by the change of SRT, but the effect on protein is more obviously than polysaccharide. The proportion of protein will decreased in the early change of SRT, however, the final proportion of protein can be increased, if the SRT decrease. In addition, the concentration of soluble microbial product (SMP) showed little regularity in the change process of SRT, and the concentration of SMP change slightly when the range of SRT is 10~30d.Biodiversity and biological population structure have discrepancy under Various SRT condition. The article uses SDI to represent Biodiversity. The research shows that SDI and SRT have no linear relationship and SDI take minimum when the SRT is 10d. The result of PCR-DGGE shows that SDI reach maximum when the SRT is 40d, and the dominant microflora take more activity when the SRT is 30d. Because of the poor homology, the system microorganism of SRT for 40d and the system microorganism of other SRT are different ethnic groups. The SRT has little affected on the homology, provided that the system has short sludge age. In addition, though cloning and sequencing, the research shows that the system of SRT for 40d exists the dominant microbes, which can get energy by degrading sulfate.