Microbial population dynamics in a partial nitrification reactor treating high ammonia strength supernatant from anaerobically digested sludge: Role of the feed water characteristics.

Abstract Partial nitrification was developed in this study for the sidestream treatment of high ammonium strength digested sludge supernatant in an integrated fixed film activated sludge (IFAS) reactor operating under sequencing batch mode. This paper elucidated the impacts of feed water characteristics on microbial population dynamics and kinetics in a partial nitrification reactor treating ammonium rich digested sludge thickening lagoon supernatant. It was observed that increased ammonium concentration (100–800 mg-N/L) in the reactor feed led to the enhanced specific ammonium conversion (4.6–12.6 mg-N/g biomass) and nitrite accumulation (0–11.6 mg-N/g biomass) rates, but a reduced microbial community diversity. The increased raw supernatant percentage reduced specific ammonium conversion (6.6 mg-N/g biomass) and nitrite accumulation rates (5.2 mg-N/g biomass) and led to an increased microbial community diversity. Different genera have different tolerances towards the NH 4 +-N concentration and raw supernatant percentage. Microbial community structures varied significantly in suspended flocs and in the attached biofilm. The kinetics analysis revealed that flocs in the IFAS system played a major role in carrying out the partial nitrification processes. Graphical abstract Image 1 Highlights • Nitritation was achieved when the NH 4 +-N concentration in the feed was ≥ 400 mg/L. • High NH 4 +-N concentration in the feed decreased the microbial community diversity. • High raw supernatant % in the feed increased the microbial community diversity. • The NH 4 +-N conversion rate was positively related to the abundance of NH 3 oxidizer. • The suspended flocs played a major role in partial nitrification. [ABSTRACT FROM AUTHOR]