Abstract
Recently, the anammox （anaerobic ammonium oxidation） process is attracting attention as a novel microbiological nitrogen removal process. It makes possible to reduce the operational costs of aeration and carbon sources （e.g. methanol） compared with the conventional nitrification/denitrification process. This study focuses on the feasibility of nitrogen removal from an anaerobic digestion supernatant using a fixed-bed anammox reactor. In a demonstration test for the treatment of wastewater containing high concentration ammonium, the maximum nitrogen removal rate of 2.90 kgN･m－3･d－1 was obtained after about 80 days of operation. The ratio of ammonium and nitrite consumption and nitrate production was 1:1.26:0.20. In case the nitrite concentration at the inlet of anammox reactor increased, the nitrogen removal rate gradually decreased. The inhibition of anammox activities was obvious by nitrite concentration higher than about 100mg･L－1. The effects of fluctuation in the influent nitrogen load were also evaluated by intentionally increasing the influent ammonium concentration. When the anammox reactor was operated with the influent load ranging from 2.76 kgN･m－3･d－1 to 3.61 kgN･m－3･d－1, the performance was little changed from steady operation, attaining the average nitrogen removal efficiency of 81％.
