The performance of an anaerobic ammonium oxidation upflow anaerobic sludge blanket reactor during natural periodic temperature variations

An anaerobic ammonium oxidation-upflow anaerobic sludge blanket (anammox-UASB) reactor was operated without temperature control during the four seasons and was therefore subjected to natural periodic temperature variations between 9 and 28 degrees C. The anammox reactor had a high nitrogen removal ability at intermediate and low temperatures. The total nitrogen (TN) concentration of the influent increased from 200 to 1200 mg/L, the nitrogen removal efficiency was maintained at 90%, and the nitrogen removal rate (NRR) increased to 9.15 +/- 0.35 kg N/m(3)/d. The enrichment of anammox bacteria in the UASB granular sludge reached 53.8%, and the dominant bacteria changed from Candidates Brocadia to Candidates Kuenenia after several seasons of cultivation. Dynamics analysis revealed that the maximum reaction rate of the anammox-UASB sludge was 62.5 kg N/m(3)/d, reflecting the high potential nitrogen removal ability of the reactor.