Screening And Characterization Of Low Temperature And High Efficiency Aerobic Denitrifying Bacteria

With the development of national industrialization and the improvement of people's living standards,the increasing water consumption and pollutant discharge make the problem of water pollution more and more serious.In the water pollution,the problem of nitrogen source pollution is a key issue that needs to be solved urgently.At present,how to effectively remove the nitrogen pollution in water has aroused widespread concern of the society.Because of the low temperature climate in northern winter,the growth of microorganisms and the expression of reductase will be greatly inhibited by low temperature conditions.Denitrification decreases dramatically.Temperature has become the most significant limiting factor for denitrification in winter.Therefore,through biological enrichment,Therefore,screening and isolation of strains with good growth rate and denitrification ability under low temperature conditions,so as to increase the number of indigenous low-temperature-resistant denitrifying bacteria in wastewater treatment structures of wastewater treatment plants in winter.It has important research significance to solve the problem of poor biological denitrification effect in winter sewage treatment plant.In this experiment,40 strains with aerobic denitrification function were successfully isolated from three different reaction pools in A~2O treatment process section of a municipal wastewater treatment plant in Shijiazhuang City.Among them,96%of the strains are Pseudomonas.sp,and Pseudomonas bacteria are the dominant strains among these strains.A further aerobic denitrifying bacteria was screened by further low temperature experiments and named as strain 41.The strain was identified as Pseudomonas sp.,a Granz-negative bacterium.The napA gene was successfully amplified.The 16S rRNA sequence of strain 41 was uploaded to Genbank database and its login number was MN197797.Through the single factor environmental factor experiment,we know that the optimum carbon source of strain 41 is sodium citrate,the optimum C/N is 10,and the optimum denitrification temperature is 30?.When sodium citrate was used as carbon source,pH was 7-9,temperature was 15-30,C/N was higher than 10,all nitrate nitrogen could be removed by the strain.The strain can remove all nitrate nitrogen,and finally there is no accumulation of nitrite nitrogen.The removal rate of total nitrogen in water is above 90.73%.In order to further explore the influence of multi-factors on the aerobic denitrification ability of strain 41,we carried out a response analysis method.According to the experiment,the best conditions of multi factor denitrification of strain 41 are as follows:initial pH 8.21,C/N 12.81,shaking rate 115.37 rpm,temperature 28.57?.In the condition of appeal cultivation,the removal rate of nitrate nitrogen of the strain can reach 97.67%at36 h.The feasibility of the inference is verified by experiments.The strain 41 screened in this study exhibited excellent denitrification characteristics even in low temperature environment.It is suitable for the denitrification treatment of weak alkaline domestic sewage.It can be used as a good candidate strain for denitrification at low temperature in winter sewage treatment plant.The experimental research has accumulated original data and scientific basis,and laid a solid foundation for the future application in actual sewage treatment.