[Effect of Substrate Ratio on Removal of Nitrogen and Carbon Using Anaerobic Ammonium Oxidation and Denitrification]

Real domestic sewage was treated in a sequencing batch reactor (SBR). When the partial nitrification of SBR was achieved, the effluent was fed with quantitative NaNO₂, which served as the influent of the anaerobic ammonium oxidation (ANAMMOX) process of the anaerobic SBR (ASBR). The effect of different substrate ratios on the removal of nitrogen and carbon using anaerobic ammonium oxidation and denitrification was investigated under conditions with a temperature of 24℃ and pH of 7.2±0.2. The results showed that ① the nitrogen removal efficiency was optimum when the influent NO₂^--N/NH₄⁺-N was 1.4-1.6. The average effluent concentrations of NH₄⁺-N, NO₂^--N, and chemical oxygen demand (COD) were 2.14, 1.07, and 30.50 mg·L^-1, and their removal rates were 93.62%, 97.79%, and 74.75%, respectively. The △NO₂^--N/△NH₄⁺-N and △NO₃^--N/△NH₄⁺-N ratios were 1.60 and 0.17, respectively. Total nitrogen was removed by the joint action of denitrifying and ANAMMOX bacteria. ② When the influent ratio of NO₂^--N/NH₄⁺-N increased, the contribution of ANAMMOX to nitrogen removal decreased, but the contribution of heterotrophic denitrification to nitrogen removal increased gradually. ③ The NH₄⁺-N and NO₂^--N degradation processes corresponded with zero-order reactions and fitted the linear relationship in the typical cycle. Their specific degradation rates were 0.404 and 0.599 mg·(g·h)^-1, respectively. Their ratio was 1.48, and the specific degradation rate of COD gradually increased.