A wastewater treatment system includes a wastewater collection system, at least one aeration subsystem aerating the aerobic portion, and at least one filtration subsystem. The wastewater collection system has an anoxic portion, an aerobic portion downstream of the anoxic portion, an anaerobic portion downstream of the aerobic portion. The filtration subsystem includes at least one bioreacting filter receiving fluid from the aerobic portion, being operable to filter wastewater received from the aerobic portion, and discharging filtered fluid into the anoxic portion, an oxygen contactor fluidically connected between the aerobic portion and the at least one bioreacting filter and operable to diffuse oxygen into the fluid being supplied from the aerobic portion, and an oxygen supply operable to supply oxygen to the oxygen contactor.