Highly efficient ammonium removal through nitrogen assimilation by a hydrogen-oxidizing bacterium, Ideonella sp. TH17.

Ideonella sp. TH17, an autotrophic hydrogen-oxidizing bacterium (HOB), was successfully enriched and isolated from activated sludge in a domestic wastewater treatment plant (WWTP). Batch experiments were conducted to identify the cell growth and ammonium (NH-N) removal, and to verify the pathways of nitrogen utilization under different conditions. At a representative NH-N concentration of 100 mg/L in domestic wastewater, it was the first time that a HOB strain achieved a nearly 100% ammonium removal. More than 90% of NH-N was assimilated to biomass nitrogen by strain TH17. Only a little of N (<10% of initial NH-N) was detected without NO emission in aerobic denitrification process. Autotrophic NH-N assimilation contributed predominantly to biomass nitrogen production, supplemented by assimilatory nitrate (NO-N) reduction under aerobic conditions. A total of 17 amino acids, accounting for 54.25 ± 1.98% of the dry biomass, were detected in the bacterial biomass harvested at 72 h. These results demonstrated that the newly isolated strain TH17 was capable of removing NH-N and recovering nutrients from wastewater efficiently. A new solution was thus provided by this HOB strain for ammonium treatment in sustainable WWTPs of future.