Insights into microbial community variability and functional genes of various Candidatus Scalindua-based anammox processes treating nitrogen-rich saline wastewater.

Marine anammox bacteria (MAB) has been enriched in four sequencing batch reactors to treat nitrogen-rich saline wastewater. The community variability and cell activity of MAB were studied under different operating conditions. Besides, a novel hydrazine oxidoreductase (Hzo) primer set was designed and used for fast detection of MAB. The results indicated that, independent of operating conditions, Candidatus Scalindua wagneri was the dominant species in nitrogen-rich saline wastewater treatment. Low inoculation pretreatment temperature was a useful operational method to enhance the MAB abundance. Both the enzyme synthesis and cell penetrativity were promoted by Fe(III) addition, which benefited to improve the nitrogen removal performance. High influent NH-N and NO-N could decrease the synthesis of enzyme and protein which related with nitrogen removal from saline wastewater through MAB. The Hzo gene was an effective functional gene for specific and fast detection of MAB in engineered systems.