Isolation, Identification And Characteristic Of An Aerobic Denitrifying Bacteria With High Nitrogen Removal Efficiency

In recent years,water eutrophication caused by nitrogen has become a worldwide environmental problem.Chinese water resources is seriously affected by nitrates,nitrites,ammonia nitrogen and other substances,which have seriously affected the balance of ecological environment and threatened the health of human beings.Therefore,the removal of nitrogen pollutants in water has an increasing attention to the researchers.Currently,the hotspot and main direction of biological nitrogen removal technology are using aerobic denitrifying bacteria with short growth period,extensive substrate utilization and strong adaptability to the environment.The main results are as follows:(1)In our research,two aerobic denitrifying strains with good denitrification were obtained by enrichment,primary screening and secondary screening from soil that sampled from urban sewage outfall.After morphological observation and molecular identification,strain FX-2 belong to Paracoccus sp.,strain FX-11 belong to Pseudomonas sp..(2)Our research focused on strains of FX-2 and FX-11with higher nitrogen removal capacity.To optimize strains denitrification conditions design different single factor,such as carbon sources,temperature,inoculum size,initial pH,C/N,speed and so on.Response surface method is further used to determine the best conditions for denitrification.The results show that the optimum conditions for the strain FX-2 were pH=7.5?30??C/N6.5.Under this condition,the TN degradation rate of strain FX-2 was 73.15±1.8%.As well,the optimum conditions for the strain FX-11 were pH=7.5?31??C/N6.5.Under this condition,the TN degradation rate of strain FX-11 was 81.34±1.1%.(3)The compound bacteria agent was constructed which was composed of strains FX-2?FX-1and Y1-3-1 in a 2:1:2 ratio.Compared with the single strain,the compound bacteria agent reduced the accumulation of nitrite nitrogen.The compound bacteria agent is further strengthened as follows:1 Immobilization technologyThe immobilized carriers could improve the adaptability of strains to the harsh environment which was immobilized by Mycelium balls,SA+PVA+GO,SA+Polyurethane foam.2 Spray drying technologyThe optimum spray drying conditions were:protective agent ratio(talcum powder:?-cyclodextrin)3:1,inlet air temperature 160?,feed flow 14 mL/min,in this case the number of viable cells reached 8.47×10~7 cfu/g.The total nitrogen removal rate was increased by approximately 6%,9%and 8%,which was achieved through 3 different carriers.Bacterial powder in the removal of total nitrogen has no significant increase.Due to the weaker mechanical strength of SA+Polyurethane and longer immobilization cycle of Mycelium balls,the best method of preparing the compound bacteria agent is using SA+PVA+GO.(4)Study on the effect of compound bacteria agent on water quality of Koi Fish.It was found that the ammonia nitrogen,nitrite nitrogen,total nitrogen,and COD in the water of the experimental group were reduced compared to the control group by addition of immobilized cell.It shows that the compound bacteria agent can improve the water quality of aquaculture water through the synergy between different strains.