Relationship of phosphorus removal, extracellular polymeric substances characteristics, and microbial community diversity in an aerobic moving bed biofilm reactor: Effect of carbon sources

Abstract

The aerobic moving bed biofilm reactor (AMBBR) was established to explore the effect of carbon source types (sodium acetate, sodium propionate and starch) on phosphorus removal, extracellular polymeric substances (EPS) composition, variation of Polyhydroxyalkanoate (PHA) and glycogen, and microbial community structure. The results showed that carbon source of sodium propionate improved the pollutant removal efficiency in the AMBBR system. The removal efficiency of COD, NH4+-N, total phosphorus (TP) and PO43- reached to 91.72 ± 2.85 %, 86.76 ± 2.02 %, 72.14 ± 1.70 % and 71.66 ± 2.60 % respectively. Sodium propionate tends to favor the stability and growth of the carrier attached biofilm. TP concentration of the tightly bound EPS (TB-EPS) showed a significant positive correlation (R = 0.929 **, p = 0.01) with TB-EPS protein (PN) concentration in the carrier attached biofilm. Under sodium propionate condition, PHA and Glycogen accumulating concentration as well as the phosphorus accumulating and release amount exhibited the highest during one cycle of the AMBBR. Sodium propionate improved the growth of nitrite oxidizing bacteria (NOB), denitrifying bacteria (DNB), phosphorus accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs). However, Pseudpmonas as a well-known denitrifying phosphorus accumulating bacteria (DNPAOs) was greatly increased under sodium acetate condition. Principal component analysis (PCA) results revealed that the abundance of Candidatus_Accumulibacter (PAOs) and Dechloromonas (DNPAOs) were strongly correlated with TB-EPS PN concentration. These results indicated that suitable carbon source type could enhance phosphorus removal by improving the growth of EPS and metabolism of microbial community.