Research On The Influence Of Aeration Strategy And Ammonia Nitrogen On Microbial Community Construture

Aeration strategy and ammonia nitrogen were used as the control factors to explore the running effect of the SBR reactor and the change law of microbial community structure in this experiment. Three aeration strategies were studied in this test, the aeration time:anoxic time was 8h:4h, 4h:2h and 4h:8h respectively. There were 45-63 mg/L and 101-134mg/L two levels of ammonia nitrogen density under each strategy. Therefore the test was divided into six reaction stages as A1, A2, B1, B2,C1 and C2 to explore the sludge characteristics, pollutants removal and microbial community structure changes.The result illustrated that the sludge characteristics were controlled by oxygen time. The MLSS significantly decreased with the C strategy, and the SVI continued to decline as the result of excessive aeration in the first four reaction stage, which led to sludge aging phenomenon. COD removal effect was stabled when ammonia nitrogen concentration was low, but the sudden increase of ammonia nitrogen resulted in a transient decrease of effluent COD. Ammonia nitrogen removal was mainly affected by the inflow ammonia nitrogen concentration, when the concentration of ammonia nitrogen increased, the removal rate was declined from the original 80% to about 40%,and with the proliferation of the ammonia oxidizing bacteria, ammonia nitrogen removal efficiency increased in the last four stages. Nitrate nitrogen in outflow accumulated in A stage, the final concentration was 8.87 mg/L, nitrate nitrogen accumulated less in B stage with the final concentration of 3.76-5.93mg/L, which indicated that the long-term aeration inhibits the activity of denitrifying bacteria and nitrate nitrogen removal. Ammonia nitrogen continued to decline in the single cycle,and the nitrate nitrogen accumulated to the maximum at the end of the aeration, then declined significantly at the anoxic phase, the nitrite nitrogen content was always less than 0.2 mg/L. Different aeration strategy lead to different change laws of the nitrogen pollutants in a single cycle.Diversity analysis results indicated that the total bacteria community structure was affected by aeration strategy. The most abundant diversity was observed under Stage B of intermittent aeration. Similarity analysis results illustrated that the community similarity of C stage was low compared with Stage A, and aerationstrategy affected community division of the total bacteria. By rubber cutting sequencing we found that the belts in spectrum of total bacteria all belong to uncultured bacterium, which played an important role in the process of sewage treatment. Ammonia oxidizing bacteria was mainly affected by the concentration of ammonia nitrogen, better adaptability to changes in aeration strategy, the community diversity index kept a higher level. While nitromonas was significantly affected by aeration strategy, the community structure was complicated under Stage B and became simple under Stage C, which showed that the strategy of aeration/anoxic alternate was conducive to the survival of nitromonas. Denitrifying bacteria was sensitive to the dissolved oxygen. The diversity index remained low during the test and recovered under Stage B and C. The community division was in conformity with the aeration strategy.