Nitrogen removal and aggregation characteristics of Pseudomonas aeruginosa YL and its application capacity for ammonium-rich wastewater treatment

Abstract

Pseudomonas aeruginosa YL, which was isolated and purified from activated sludge, performed a high-efficiency simultaneous nitrification and denitrification ability through the efficient utilization of sole and mixed N-sources. Kinetics analysis carried out by Gompertz model (R2 > 0.99) explicated the optimal condition of N-degradation, and its denitrification pathway was proposed as a sequential heterotrophic nitrification-aerobic denitrification process. Moreover, strain YL had higher flocculating ability, relative hydrophobicity and lower negative charges when NH4+-N used as N-source, which fully proved the stronger aggregation ability of the isolate during heterotrophic nitrification process. The formation mechanism of cell aggregates was explained by discussing the variations of extracellular polymeric substances (EPS) components, and exhibited an obviously relevance of EPS and bioflocculation. Furthermore, the great nutrients removal, stable existence of functional strain and the excellent flocculation-sedimentation performance in a sequencing batch reactor, further confirmed the good potential of strain YL for treating ammonium-rich wastewater.