Isolation And Identification Of Low Temperature Functional Bacteria And Study On Nitrogen Removal Performance Of Wastewater

In order to reduce the problem of water eutrophication,the production and domestic sewage need to be treated with nitrogen removal before discharge.Biological method is the mainstream technology of sewage nitrogen removal at present.In the low temperature environment in winter in north China,the efficiency of biological nitrogen removal is low,which affects the effluent.In order to reduce the impact of low temperature on biological denitrification of sewage,measures such as equipment insulation and increasing hydraulic retention time are often used,but there are problems such as increased investment and floor space.The biological enhancement technology of sewage denitrification process has the characteristics of low cost,high efficiency and green environmental protection,and has become one of the promising technologies to improve the biological denitrification effect of low temperature sewage.In this paper,aiming at the problem of poor denitrification efficiency of low temperature sewage in northern China,based on the isolation of low temperature denitrification functional strains,the effects of carbon source,inoculation amount,carbon/nitrogen ratio(COD/N)and p H on ammonia nitrogen removal performance of strains were studied.This paper can provide experimental data and technical basis for the construction of microbial agents to enhance ammonia nitrogen removal from low temperature sewage.The main findings are as follows.First,10 strains of denitrifying bacteria were isolated and purified from the primary screening bacteria extracted from sewage sludge.After 16 S r DNA identification,No.1,2,3,and 10 are Acinetobacter,No.4,5,6,8,and 9 are Pseudomonas,and the strain No.7 is presumed to be Pseudomonas puffin.Ten strains of functional bacteria were added to the medium with different initial ammonia nitrogen concentrations and the changes of ammonia nitrogen,nitrite nitrogen and nitrate nitrogen concentrations were measured.It was found that 7 functional bacteria could degrade ammonia nitrogen under heterotrophic conditions,and the ammonia nitrogen removal rate of all strains was above 90%.The degradation of ammonia nitrogen will not result in a large amount of nitrite and nitrate accumulation.Through further ammonia nitrogen removal experiments,it was determined that the ammonia nitrogen removal efficiency of strain 1 in Acinetobacter and strain 6 in Pseudomonas was the best.Strains 1 and 6 were named Acinetobacter Albensis X1 and Pseudomonas sp.X6,respectively.According to the study on the low-temperature ammonia nitrogen degradation characteristics of Acinetobacter albensis X1 and Pseudomonas sp.X6,it can be seen that the ammonia nitrogen removal performance of the two functional strains is the best when sodium citrate is the sole carbon source.The ammonia nitrogen degradation rates of strain X1 and strain X6 were 95.28% and 98.11%,respectively.It is determined that the suitable carbon source is sodium citrate.In the range of 1-5%(V/V)inoculation amount,combined with ammonia nitrogen degradation rate and economic cost,it is determined that the appropriate inoculation amount is 3%(V/V)which the ammonia nitrogen degradation rates of the two functional strains were 95.49% and 98.07%,respectively.In the range of COD/N of 5-17.5,the ammonia nitrogen degradation rates of strain X1 and strain X6 were better when COD/N was greater than 12.5,according to the ammonia nitrogen degradation rate and considering economic factors,it is determined that the suitable COD/N is 12.5,and the ammonia nitrogen degradation rates of the two functional bacteria were 93.44% and 97% respectively.In the p H 6-8,considering the quality of domestic sewage and economic factors,the appropriate p H was selected as 7,and the ammonia nitrogen degradation rates of the two functional strains were above 90%.