The Effect Of Flow Field In MABR On Its Performance And Distribution Structure Of Biological Flora

Membrane aerated biofilm reactor(MABR)is a new water treatment technology which combined biofilm wastewater treatment technology with membrane separation technology effectively.It has become a new organic wastewater treatment technology with promising application prospects.This technology not only has many advantages such as the small amount of residual sludge,and does not have the problems of sludge expansion and uplift,but also has the advantages of low energy consumption,high treatment efficiency and occupies a limited area.However,the operating conditions have a great influence on the performance of MABR,and the internal flow field which accounts for a large proportion of MABR's operating energy has an important influence on the efficiency of the reactor.First of all,on the basis of MABR flow field simulation optimization of our group's previous research,this study get the optimal internal circulation flow by comparing the nitrogen and carbon removal performance and the thickness of the biofilm under different inner velocity.The study shows that the biofilm thickness is moderate with the biofilm surface flow velocity 0.05m/s,which is beneficial to oxygen and substrate mass transfer,and the reactor has obtained the optimal nitrogen removal and carbon removal performance.The removal rates of COD,NH3-N and TN are reached 94%,95%and 85%,respectively.Secondly,this study applied molecular biology technology PCR and FISH to investigate the distribution of microflora in biofilm under different internal circulation velocity.It is better for biofilm microbial population stratification when the biofilm surface flow velocity is 0.05m/s.The inner layer of the biofilm is mainly AOB but almost no NOB,and most denitrifying bacteria are on the outer layer.So denitrification process can be controlled in the stage of shortcut nitrification and denitrification,and TN removal rate reached 85%.Finally,the appropriate biofilm surface flow velocity can control the thickness of the biofilm effectively and prompting the functional bacteria,nitrifying bacteria and denitrifying bacteria,in the biofilm stratification which is beneficial for MABR to reach simultaneous nitrification denitrification process and improve the denitrification reactor performance.