Abstract
Simultaneous nitrification-denitrification under fixed constant dissolved oxygen (DO) condition in a single reactor was examined by using two different carriers, polyacrylamide-gel carrier and cellulose carrier immobilizing nitrifiers and denitrifiers, respectively. The DO condition enabling the highest simultaneous nitrification-denitrification rate was found between 0.5 and 0.75 mg/l. When DO concentration of culture broth was maintained at 0.5 mg/l, the simultaneous nitrification-denitrification was successfully realized in a single reactor as designed, resulting in the apparent nitrogen removal rate corresponding to 83% of the theoretical value.
