Screening,Identification And Characterization Of Phosphorus-accumulating Bacteria In Domestic Sewage Under Different Temperature Conditions

In order to further improve the application range and treatment intensity of biological phosphorus removal,effectively control the problems of water eutrophication caused by sewage discharge,and obtain more strains with outstanding phosphorus accumulation ability and strong resistance,in order to further study polyphosphate The metabolic mechanism of the bacteria lays the foundation.In this study,two sets of SBR reactors were started and operated in the laboratory under anaerobic/aerobic/anoxic?A/O/A?operation under normal temperature and low temperature conditions,respectively.The purpose of enrichment of phosphorus-concentrating bacteria includes monitoring the water quality indicators of various influent and effluent.Next,the polyphosphate strains in the two reactors were separated and screened and identified by using an obligatory medium.Finally,a preliminary study on the phosphorus accumulation characteristics of Phosphorus-accumulating Organisms under two temperature conditions was carried out.The experimental results are as follows:The start-up of the two SBR reactors and the analysis of their operational efficiency results were obtained.The COD removal effect was better during the start-up operation of the two reactors,and the microorganisms in the two groups maintained high biological activity.The effluent COD concentration was stable below 50 mg/L,and the removal rate was above 90%.The removal effect of NH₄⁺-N and PO₄^3--P during the operation of the normal temperature reactor was very good.The effluent concentration of the two indexes was lower than the detection limit,and the removal rate was stable above 95%.During the operation of the low temperature reactor,the removal rates of NH₄⁺-N and PO₄^3--P reached 60%and 70%,respectively.There was almost no accumulation of NO₃^--N and NO₂^--N in the effluent during the operation of the two reactors.In summary,the two groups of reactors were successfully started,and the targeted selection of microbial communities in the reactor and the enrichment of phosphatidyl flora were achieved.The bacterial community structure in the high-throughput analytical reactor found that the tested bacteria were divided into 1boundary,24 gates,54 families,105 orders,180 families,294 genera,434 species,and633 OTU sequences.Proteobacteria,Actinobacteria,Bacteroidetes and Chloroflexi were the dominant bacteria in the initial mud source,accounting for 33.15%,25.96%,11.45%and 10.95%of the total experimental bacteria,respectively.Subsequently,the differences in bacterial community structure at each level were compared and analyzed.It was found that the bacterial community had the dominant flora corresponding to the upper level in each level,accompanied by the operation of the reactor,and the relative of the different flora.The abundance changes,and the dominant flora also has a significant replacement effect.When the two reactors reached the end of the operation,it was found that the Acinetobacter was the absolute dominant bacteria in the final reactor under room temperature conditions.Under the low temperature conditions,the bacteria Arcobacter and Acinetobacter were enriched in the reactor and became the dominant bacteria group.The isolation and screening of polyphosphate strains,the identification of strains and the research on the growth and polyphosphate characteristics of some strains showed that 17 strains of normal-temperature polyphosphate strain and 20 strains of low-temperature polyphosphate strain were obtained in the strain separation and screening work.The strains were screened by aerobic phosphorus uptake experiment,and 5 strains of room temperature phosphorus-accumulating organisms and 3 strains of low temperature phosphorus-accumulating organisms were selected for subsequent growth and phosphorus accumulation.The strain identification mainly carried out physiological and biochemical experiment identification and 16S rDNA sequence analysis,andfinallydeterminedthattheselectedstrainsofthe phosphorus-accumulating organisms belonged to Pseudomonas,Acinetobacter,Rhodococcus,Gordonia and Pimelobacter.The growth curve of the strain was determined by measuring the growth curve of the strain and the aerobic phosphorus uptake experiment.The results showed that the growth curves of all the phosphorus-accumulating organisms were typical,and the growth cycle of the room temperature strains were significantly shorter than that of the low temperature strains.The amount of polyphosphate in the room temperature strains were higher,and the amount of polyphosphate in all the experimental strains exceeded 8 mg/L.The experiment proves that the polyphosphorus process of the strains is related to their growth activity,and is accompanied by the whole process of the initial end of the phosphorus accumulation activity in the exponential period of the most vigorous growth.