Analysis Of Microbial Population Of Denitrifying Phosphorus Removal From Domestic Sewage In ABR-MBR Process

ABR-MBR,as a combined process,was developed mainly based on the synergy mechanism of microbial phase separation and circulation.In order to reveal the relationship between the operating conditions of ABR-MBR process and microbial community,and provides theoretical and technical guidance for practical application.Species abundance,along with diversity of microbial communities and dominant biomass population were investigated by Miseq High-throughput Sequencing.Based on the ABR-MBR process of the short-cut nitrification denitrifying phosphorus removal for treating domestic sewage,the effect of the operation parameters on the microbial population was investigated,and the following conclusions were obtained:?1?The ABR-MBR process has good stability during operation,when ammonia nitrogen loading in ABR is 0.77?1.0?1.5 kg·?m³·d?^-1,the effective and stable removal of COD and NH₄⁺-N can be achieved by the combination of ABR-MBR;Microbial population diversity is more stable,functional microorganisms being stable in the system as well.It is shown that the stable operation of the system and the better treatment effect depends on the microbial diversity and its function structure stability in the ABR-MBR process.?2?Short-cut nitrification can be efficiently achieved in MBR in the operation process of ABR-MBR combined process,the numbers of ammonium oxidizing bacteria?AOB?can be significantly increased and inhibited?at a temperature of 30±2?,pH of 7.1⁷.4 and DO of 0.5¹ mg·L^-1,by gradually increasing the ammonia nitrogen loading of influent in the MBR,so that the short nitrification will be achieved efficiently and stably.It is indicated that the nitrite accumulation ratios was closely related to the bio-activities and the abundance of AOB in the ABR-MBR process.When the influent ammonia nitrogen loading reaches 0.21 kg·?m³·d?^-1 to 0.94 kg·?m³·d?^-1,the relative abundance of Nitrosomonas increases from 4.97%to 22.56%,whereas the average nitrite accumulation ratio raises from 10%to 60%or above.However the relative abundance of Nitrospira kept at a low level,with the results of only 0.06%to 2.12%during the operation.It is showed that shortcut nitrification can be efficiently achieved by a large number of AOB growth.Still,a slight increase of NOB abundance would have low effect on the realization of shortcut nitrification.?3?Denitrifying phosphorus removal can be efficiently achieved of ABR in the operation process of ABR-MBR combined process.The effect of the research on phosphorus abundance was tested at a temperature of 30±2?,pH of 7.1⁷.4 and DO of0.5¹ mg·L^-1 by controlling the HRT of 6 h in the ABR,and the HRT of 3 h in the MBR,with a reflux ratio change of 100%,200%and 300%respectively.When raising the level from 100%to 300%,the relative abundance of Rhodocyclales on Betaproteobacteria was60.54%?51.17%and finally 51.14%,The removal effect of phosphorus being also better.It is shown that Rhodocyclales as a dominant biomass,could easily assist the removal on phosphorus.When the reflux ratio reached 200%,the relative abundance of Aeromonas?Pseudomonas?classified_fEnterobacteriacea and norank_fMoraxellaceae on Gamma-proteobacteria reached 55.12%,they able to denitrify phosphorus removal simultaneously.Sphingobacterial and Dechloromonas are denitrification dephosphorization bacteria.As a similar case,removal rate of phosphorus reached 92.3%which indicated that phosphorus removal efficiency is closely related to the species and relative abundance of denitrification dephosphorization.