Investigation On The FISH Detection Of The Nitrifying Bacteria In Two-sludge Baffled Reactor

In this thesis, Two-sludge Baffled Reactor is used for the study of denitrifying phosphorus removal. And the fluorescence in situ hybridization (FISH) is used to detect nitrifying bacteria in biofilms of the reactor to study the relative abundance of nitrifying bacteria and their change.First, the startup test of aerobic biofilm is cultured in MBBR, the processing performance of the biofilm is studied and nitrifying bacteria is detected by FISH. And then put the cultured denitrifying phosphorus removal bacteria and the cultured aerobic biofilm into different compartments of the Two-sludge Baffled Reactor which is operated under continuous influent. In this paper, the influence of different operation parameters on the impact of denitrifying phosphorus removal is studied and nitrifying bacteria of biofilm in the aerobic compartment is detected by the FISH.The results show that HRT and the percent of nitration reflow will affect the results of denitrifying phosphorus removal. HRT has greater impact on the nitrification of the aerobic compartment comparing with the percent of nitration reflow, which has little effect on it. Detected by FISH analysis, the relative abundance of nitrifying bacteria (including ammonia oxidizing bacteria and nitrite-oxidizing bacteria) on the aerobic biofilms are different in different operation stages of the reactor. HRT has greater impact on the nitrifying bacteria of the aerobic biofilms than the percent of nitration reflow, which has little effect. When HRT is 12.8h, the percent of nitration reflow is 280%, the sludge return ratio is 90%, the reactor performs best. When the concentration of ammonia nitrogen is controlled at 34.91~46.17mg/L, COD is 196.7~276.7mg/L and the concentration of phosphorus is 4.3~5.7mg/L, the reactor can remove about 68% total nitrogen, 71%COD, and 85% phosphorus. The aerobic compartment has good removal of ammonia, the effluent ammonia concentration is almost 0, and ammonia nitrogen removal rate reached 98% or more. At this time, the relative abundance of the ammonia oxidizing bacteria and the nitrite-oxidizing bacteria is about 24% and 15%, respectively. Nitrifying bacteria occupy about 39% of the total eubacteria number. Nitrification system has a good performance.