Nitrification performance and microbial community analysis in carbon membrane-aerated biofilm reactor

Abstract

A carbon membrane-aerated biofilm reactor was developed to treat nitrogenous inorganic wastewater. Influent NH4+-N concentrations and HRT were changed to investigate nitrification performance of reactor, oxygen utilization and NH4+-N's removal loading. Biofilm's surface characteristics and dominant bacteria of nitrifier were analyzed. The results show that under the conditions of intra-membrane pressure of 0.017 MPa, influent NH4+-N of 50 mg/L and HRT of 8 h NH4+-N removal efficiency reaches 96% and effluent average nitrite is 17 mg/L, which benefits short-cut nitrification to a certain extent. The bacteria within biofilm consume all oxygen supplied through carbon membrane. The maximum specific removal rate of NH4+-N is 9.7 g/(m2·d), which is limited by the amount of bacteria grown onto carbon membrane' s surface. Fluorescent in situ hybridization analysis indicates that within the biofilm Nitrosomonas and Nitrosospira are main ammonia-oxidizing bacteria and occupy about 19% and 21% of the total bacteria number, respectively. The Nitrobacter are not observed and Nitrospira are dominant nitrite-oxidizing bacteria, the fraction of which is 20% of total bacteria.