Comparison of Ammonium-oxidizing Bacterial Community Changes in Sludges from a Sewage and a Marine Fish Market Wastewater Treatment Plant During Enrichment Cultivation Under High Saline Conditions

Abstract

Objectives:It is important to enrich and cultivate ammonia oxidation bacteria (AOB) in order to successfully treat nitrogen in high saline wastewater using a deammonification process. Two different inocula, a sewage sludge and a fish-market wastewater sludge, were cultivated to enrich AOB and compared the changes of microbial community.<br/>Methods:A sequential batch reactor (SBR) inoculated with the sewage sludge (PN1) enriched AOB under high-strength ammonium condition (500-3,000 mg NH4⁺-N/L) and then the salt concentration in the medium was gradually increased up to 20 g-NaCl/L. The other SBR seeded with the fish market wastewater sludge (PN2) was operated to enrich AOB directly under 20 g NaCl/L without any acclimation step.<br/>Results and Discussion:Both PN1 and PN2 successfully showed more than 60% of the nitrite accumulation efficiency at a high saline concentration of 20 g NaCl/L. At the level of the phylum, Proteobacteria containing nitrifying microorganisms became dominant in both PN1 and PN2. However, the most dominant bacterial species in PN1 and PN2 were Nitrosomonas eutropha (60.7%) and N. halophila (20.2%), respectively.<br/>Conclusions:Although different results of the most abundant AOB were shown in both sewage sludge and fish-market wastewater sludge conditions, nitritation was successfully developed even with wastewater containing high salinity. Therefore, in this study, both sludges can be applied for inoculation to the PN process for efficiently treating wastewater with high concentration of ammonium and saline.