Concurrent vanadate and ammonium abatement in a membrane biofilm reactor.

[Display omitted] • Simultaneous V(V) and NH 4 +-N removals are achieved in a MBfR. • V(V) is reduced to insoluble V(IV) confirmed by SEM and XRD characterization. • Nitrification/denitrification bioprocesses achieve NH 4 +-N removal. • Pseudomonas cooperates with others for V(V) and NH 4 +-N removals. • The gene abundances increase with improved enzyme activities for nitrogen cycling. Ammonium (NH 4 +) is commonly used as either a precipitant or extractant in metallurgy of non-ferrous metal and rare earth ore (e.g., vanadium). This results in the coexistence of toxic metal and NH 4 +-N in the effluent. Despite its toxicity, there remains little in the way of biological treatments to synchronously eliminate vanadate [V(V)] and NH 4 +-N in vanadium smelting wastewater. In this study, simultaneous V(V) and NH 4 +-N removal was achieved using a membrane biofilm reactor (MBfR). The removal efficiencies for V(V) and NH 4 +-N reached 96.8 ± 0.8% and 75.4 ± 1.2%, respectively, with initial concentrations for both beginning at 10 mg/L along with a hydraulic retention time at 36 h. V(V) was mainly reduced to V(IV) precipitates. Complete nitrogen removal was achieved with negligible NO 3 –-N/NO 2 –-N accumulation. Pseudomonas was identified as the main contributor to V(V) reduction, nitrification, and denitrification. The identified V(V) reducers and nitrifying/denitrifying bacteria were positively related to the V(V) and NH 4 +-N removal capacity of MBfR. The increased gene abundance and improved enzymic activity for nitrogen cycling collectively evidenced that V(V) reduction was catalyzed by denitrification enzymes and NH 4 +-N was removed through nitrification/denitrification. Collectively, the results from this study offer a novel strategy for the treatment of vanadium-bearing smelting wastewater by eliminating V(V) and NH 4 +-N in a one-step bioprocess. [ABSTRACT FROM AUTHOR]