Denitrification by Alcaligenes denitrificans in a closed rotating biological contactor

Biological denitrification using a pure culture of Alcaligenes denitrificans was investigated in a closed rotating biological contactor, which operated with a hydraulic retention time of 2 h, a carbon/nitrogen ratio of 2:1, with a dissolved O₂ concentration below 6 mg l^–1 and under three different phosphate concentrations. Alcaligenes denitrificans was not repressed by O₂ limitation and the removal of nitrate was about 30% more efficient at the intermediate phosphate concentration (20 mg P l^–1).