Experimental Study On Screening And Degradation Characteristics Of Highly Efficient Mixed Bacteria For Bioaugmentation Treatment Of Domestic Sewage

This paper takes the biochemical pond of a waste water treatment plant(WWTP)in Lanzhou as the research object.Aiming at the water quality fluctuation problem caused by the unstable operation of the biochemical pond,the research of bioaugmentation technology by adding bacteria is carried out.According to the control factors derived from the water quality test results of the influent and effluent water,the corresponding degrading bacteria were selected,the mixed degrading bacteria were constructed,the degradation performance and strengthening effect of the mixed degrading bacteria were studied.It provides a reference method to solve the problem that the WWTP is difficult to meet the standard due to the fluctuation of the influent water quality.According to the control factors derived from the water quality test results to guide the selection of corresponding degrading strains: oil degrading strain YZ-1,denitrifying strain FX-4 and phosphorus removal strain CP-7 were obtained.They were identified as Pseudomonas aeruginosa,Pseudomonas stutzeri and Klebsiella oxytoca,respectively.The degradation rates of oil,nitrate nitrogen and total phosphorus within 72 hours were 54.91%,40.02% and 58.52%,respectively.The optimum inoculation amount,pH,temperature and sodium chloride concentration of the above three pure strains were obtained.The mixed degradation bacteria were constructed and degradation performance experiments were carried out.Proportions and degradation properties comparison were carried out,the mixed bacteria YFC were obtained with the volume ratio of YZ-1:FX-4:CP-7 was 1:2:2.The results showed that the best environmental parameters for YFC were 1g/L of rapeseed oil concentration,8 of pH,30?,sodium acetate of co-substrate,and 12:1 of C/N.The degradation performance of mixed bacteria YFC were studied by using SBR.Compared with the control group R1,the average degradation rates of oil,COD,total nitrogen,ammonia nitrogen,nitrate nitrogen and total phosphorus in the bioaugmented group R2 with adding mixed bacteria YFC increased by 6.2%,7.38%,15.91%,11.78%,3.04% and 9.83%,respectively.The bioaugmented group was easier to operate during the reaction process,and could respond on water quality variation.With the help of high-throughput sequencing to analyze microbial diversity,it was found that the mixed bacteria YFC addition improved the microbial community structure and was more conducive to the pollutants degradation.In this study,Mixed bacteria were constructed and applied in the sewage treatment system by screening bacteria with specific degradation function,which laid a theoretical foundation for the use of bioaugmentation technology to cope with the increasingly severe water quality impact of WWTP and the later practical application.