C/N Ratio Shifted Autotrophic Partial Nitrification to Heterotrophic Nitrification and Aerobic Denitrification in High-Strength Ammonium Wastewater Treatment

Abstract

C/N ratio affected the performance of partial nitrification (PN) process when treating high-strength ammonium wastewater. The PN process could be accomplished at C/N ratios of 0 and 0.5, but its performance decreased significantly when C/N ratio increased to 1 due to the occurrence of simultaneous nitrification and denitrification occurred. Since ammonia-oxidation bacteria (AOB) could not compete with the heterotrophic bacteria, as the C/N ratios increased, the abundance of Nitrosomonas (a genus of autotrophic AOB) decreased, and it was not detected C/N ratios of 2 and 4. Instead, the heterotrophic nitrification and heterotrophic denitrification (HNAD) bacteria were appeared and their relative abundance increased when C/N ratios increase from 1 to 4.

Keywords: Partial Nitrification, High-strength Ammonium Wastewater, C/N, microbial community, Heterotrophic Nitrification and Aerobic Denitrification