[Start-up Performance of Low-substrate Anaerobic Ammonium Oxidation Under Different COD Concentrations]

An anaerobic sequencing batch reactor(ASBR)was used to treat low-substrate simulated wastewater with NH₄⁺-N and NO₂^--N concentrations of (25.00±0.40) mg·L^-1 and (33.00±0.60) mg·L^-1, respectively. The COD concentrations were controlled at 5.00, 15.00, 30.00, and 50.00 mg·L^-1 by adding sodium acetate, and its effects on start-up of anaerobic ammonia oxidation (ANAMMOX) were investigated under the temperature of 30℃. The results showed that ① The start-up of ANAMMOX could be achieved successfully after 74, 94, 106, and 129 days. The nitrogen removal efficiency was optimum when the COD concentration was between 15.00 and 30.00 mg·L^-1. In the steady phase, the average effluent concentrations of NH₄⁺-N were 1.98 and 1.89 mg·L^-1, the average effluent concentrations of NO₂^--N were below 0.62 mg·L^-1, and the average effluent concentrations of TN were 2.37 and 2.28 mg·L^-1. ② The average contribution of heterotrophic denitrification to nitrogen removal decreased to 4.78%, 9.59%, 10.21%, and 36.50%, respectively, during start-up process. The average contribution of ANAMMOX to nitrogen removal gradually increased to 95.22%, 90.41%, 89.79%, and 63.50%, respectively. ③ The activities of ANAMMOX exceeded denitrification activities at 44, 76, 86, and 114 days, respectively, which finally reached 0.700, 0.690, 0.670, and 0.510 mg·(g·h)^-1, and the denitrification activities were 0.110, 0.130, 0.240 and 0.410 mg·(g·h)^-1, respectively. Thus, the research results have provided references for the application of ANAMMOX to engineering.