Advanced Magnetic Biofilm Carriers for Stable Partial Nitrification Through Targeted Enrichment of Ammonia-Oxidizing Bacteria

Abstract

Biofilm carriers can effectively support the retention of functional microorganisms augmenting the partial nitrification (PN) process. However, conventional biofilm carriers are ineffective in selectively enriching key ammonia-oxidizing bacteria (AOB) hindering the sustained nitrite (NO2--N) accumulation. This study introduces magnetic modified polyurethane (MF) carrier facilitates the selective enrichment of AOB and suppression of NO2--N oxidizing bacteria. The results demonstrate that the MF system achieves over 90% NO2--N accumulation. The magnetic field fosters continuous biomass accumulation, while the regulated secretion of extracellular polymeric substances ensures the stability of AOB under fluctuating conditions. Microbial community analysis revealed that MF significantly enhanced biofilm formation potential and the resilience of system. Furthermore, compared to the control, the relative abundance of Nitrosomonas increased by 10% in MF. These findings suggest that magnetic carriers represent an efficient strategy for enhancing AOB and offering a robust approach for the rapid initiation the PN process.

Keywords: Magnetic effect, Partial nitritation, Nitrite accumulation, Biofilm carrier