The present invention is a method for reducing the nitrate concentration in wastewater within a wastewater treatment apparatus configured to define an aeration zone and a quiescent zone. The method comprises the step of ceasing airflow into the aeration zone for a predetermined time period or until the dissolved oxygen level within the wastewater has reached a predetermined threshold. The method may also comprise the step of mixing the wastewater in the aeration zone to prevent suspended particles within the wastewater in the aeration zone from settling and to avoid substantially disturbing the quiescence of the quiescent zone.