Abstract: An integrated fixed film activated sludge sequencing batch reactor is provided where both suspended biomass and biomass supported on biofilm carriers are utilized to biologically treat wastewater received by the sequencing batch reactor. The sequencing batch reactor includes two hydraulically connected tanks with suspended biomass being contained in at least one tank and biomass supported on biofilm carriers in the other tank.

Abstract: A method is provided for removing BOD and ammonium from wastewater in a mainstream process that includes deammonification. Wastewater including BOD and ammonium is directed to a first sequence batch reactor (SBBR). The wastewater is treated in the first SBBR and in the process nitrite is accumulated such that the wastewater includes a nitrite-to-ammonium stoichiometric ratio that enables anammox bacteria to effectively remove ammonium and nitrite from the wastewater. Thereafter the wastewater is directed the wastewater from the first SBBR to a second SBBR. The second SBBR is operated under anoxic conditions and employs anammox bacteria to remove ammonium and nitrite from the wastewater. In certain embodiments, a pre-denitrification step or process is employed in the first SBBR to remove BOD.