Microbial communities of an anammox reactor inoculated with indigenous sludge for treatment of high-salinity and mesophilic underground brine

Anaerobic ammonium oxidation (Anammox) has been implemented as a cost-effective nitrogen removal process in wastewater treatment. In order to apply the process to saline wastewater treatment at temperatures below 30?C, the effectiveness of marine anammox bacteria has been manifested in a pilot-scale reactor. Nevertheless, mesophilic conditions, often found in underground brine containing high NH4+ concentration, have not been implemented for an anammox process. This study aim at enriching anammox bacteria capable of removing nitrogen from underground brine possessing a salinity of 3% and a temperature over 30C For the selection of a promising inoculum, biomasses from a settling brine tank in a natural gas plant are subjected to quantifying transcripts of anammox 16S rRNA and hydrazine oxidoreductase (hzo) genes by quantitative reverse transcription PCR. Amplicon sequencing based on 16S rRNA gene reveal that anammox bacteria are successfully enriched in the reactor.