Nitrogen removal performance using anaerobic ammonium oxidation considering variable conditions

The anaerobic nitrogen removal performance of anammox at 30°C, 25°C, and 16°C were studied by using the UASB (Up flow Anaerobic Sludge Blanket) reactor and the influent concentration of NH(4)(+)-N and NO(2)(−)-N were 16.9 and 20.6 mg L(−1) respectively. Experimental results showed that high-efficiency anammox nitrogen removal could be achieved at 30°C, when hydraulic retention time (HRT) was 0.14 h, the nitrogen removal rate (NRR) was 5.73 kg N m(−3) d(−1). The anammox reactor operated stably for more than 80 days under the condition of 16°C–20°C, and the high NRR of 2.78 kg N m(−3) d(−1) was obtained. In this experiment, DO had little effect on the activity of anammox granular sludge, and the nitrogen removal performance could be quickly recovered in a short period of time after being affected by DO. Moreover, the stoichiometric ratio of NO(2)(−)-N and NH(4)(+)-N consumption (ΔNO(2)(−)-N/ΔNH(4)(+)-N) and the stoichiometric ratio of NO(3)(−)-N production and NH(4)(+)-N conversion (ΔNO(3)(−)-N/ΔNH(4)(+)-N) were 1.21 ± 0.11and 0.25 ± 0.06 respectively at 30°C, which were very close to the theoretical value, it indicated that anammox bacteria were the dominant bacteria at 30°C.