摘要
Nitrogen removal performance and nitrifyingpopulation dynamics were investigated in a redox stratifiedmembrane biofilm reactor(RSMBR)under oxygen limitedcondition to treat ammonium-rich wastewater.When theNH_(4)^(+)-N loading rate increased from 11.1±1.0 to 37:2±3:2 gNH_(4)^(+)-N·m^(-2)·d^(-1),the nitrogen removal inthe RSMBR system increased from 18.0±9.6 mgN·d^(-1)to 128.9±61.7 mgN·d^(-1).Shortcut nitrogen removal wasachieved with nitrite accumulation of about22:3±5:3 mgNO_(2)^(-)-N·L-1.Confocal micrographsshowed the stratified distributions of nitrifiers anddenitrifiers in the membrane aerated biofilms(MABs)atday 120,i.e.,ammonia and nitrite oxidizing bacteria(AOBand NOB)were dominant in the region adjacent to themembrane,while heterotrophic bacteria propagated at thetop of the biofilm.Real-time qPCR results showed that theabundance of amoA gene was two orders of magnitudehigher than the abundance of nxrA gene in the MABs.However,the nxrA gene was always detected during theoperation time,which indicates the difficulty of completewashout of NOB in MABs.The growth of heterotrophicbacteria compromised the dominance of nitrifiers inbiofilm communities,but it enhanced the denitrificationperformance of the RSMBR system.Applying a highammonia loading together with oxygen limitation wasfound to be an effective way to start nitrite accumulation inMABs,but other approaches were needed to sustain orimprove the extent of nitritation in nitrogen conversion inMABs.
基金
This research was supported by the National Natural Science Foundation of China(Grant No.50908164)
the 7th European Community Framework Program(PIIF-GA-2008-220665)。
