Response of nitritation performance and microbial community structure in sequencing biofilm batch reactors filled with different zeolite and alkalinity ratio

Ammonium (NH4+-N) adsorption capacity of zeolite varies from place to place, a unique attempt to use different zeolite as adsorbent media in sequencing biofilm batch reactor (SBBR) for maintaining appropriate free ammonia (FA) range to achieve partial nitritation. SBR filled with synthetic zeolite (SSBBR) and natural zeolite (NSBBR) were applied to evaluate the NH4+-N adsorption capacity impacts on nitrogen transformation and microbial characteristics. Significant differences in nitrite production rate (NPR) were both observed in two reactors during 4 different alkalinity ratios. The highest NPR in SSBBR and NSBBR were both obtained when the alkalinity ratio was 5:1 with the values of 1.11 and 0.90 kg N/(m(3).d), respectively. According to Haldane model with inhibition by FA, the kinetics of the reaction were analyzed. High-throughput sequencing analysis results further presented that SSBBR had higher relative abundance average of nitrosobacteria in genus level, which was in favor of better partial nitritation.