Influence of C/S ratios on nitrogen removal and microbial community on mixotrophic DEAMOX process

The effect of glucose in an inorganic and organic denitrifying ammonium oxidation (DEAMOX) reactor was assessed during short-term performance. The simultaneous effect of carbon (C) and sulfide (S) ratios on nitrogen removal and microbial community will improve our understanding of mixotrophic synergetic process. The nitrogen removal efficiencies were investigated under six different C/S ratios during DEAMOX process. Increasing C/S ratios promoted the TN removal efficiency which fluctuated widely from 53.28% to 87.39%. The most suitable C/S ratio was 1.6, which achieved a TN removal efficiency of 87.86% and provided a good coupling system. Denitrification was encouraged and accelerated nitrite accumulation with glucose addition, and anammox still played a dominant role in nitrogen removal performance. Denitrification microorganisms (Thiobacillus and Thauera) cooperated with anammox microorganism (Candidatus Kuenenia) during the DEAMOX process, and maintained a synergic relationship with nitrogen removal. Moreover, adding glucose improved the growth of the heterotrophic denitrification microorganism, and decreased the concentration of anammox bacteria. Overall, this research provides a theoretical basic for the practical application of a mixotrophic DEAMOX process.