A ballasted sequencing batch reactor system for treating wastewater comprising: one or more sequencing batch reactors (SBR 12, 12', 12") fluidly connected to a source of wastewater, the one or more sequencing batch reactors (SBR 12, 12', 12") comprising a treated effluent (50, 50', 50") outlet and a waste activated sludge outlet (76, 90, 92); a weighting agent impregnation subsystem (26, 26') fluidly connected to a biological flocs outlet of the one or more sequencing batch reactors (SBR 12, 12', 12") and comprising an inlet for weighting agent (33, 38) and a weighted biological flocs outlet fluidly connected to the one or more sequencing batch reactors, the weighting agent impregnation subsystem (26, 26') configured to mix biological flocs and weighting agent (33, 38) to form weighted biological flocs; a weighting agent recovery subsystem (74, 74') fluidly connected to the waste activated sludge outlet (76, 90, 92) of the one or more sequencing batch reactors (SBR 12, 12', 12") and an inlet of the weighting agent impregnation subsystem, the weighting agent recovery subsystem (74, 74') configured to recover weighting agent from the weighted biological flocs of a waste activated sludge and reintroduce the recovered weighting agent to the weighting agent impregnation subsystem (26, 26'); and the system further comprising a sludge storage tank (88, 88') configured to receive settled sludge comprising settled weighted biological flocs from the waste activated sludge outlet (76, 90, 92) of the one or more sequencing batch reactors (SBR 12, 12', 12"), store the settled sludge therein, and regulate the flow of the settled sludge to the weighting agent recovery subsystem (74, 74'). one or more sequencing batch reactors (SBR 12, 12', 12") fluidly connected to a source of wastewater, the one or more sequencing batch reactors (SBR 12, 12', 12") comprising a treated effluent (50, 50', 50") outlet and a waste activated sludge outlet (76, 90, 92); a weighting agent impregnation subsystem (26, 26') fluidly connected to a biological flocs outlet of the one or more sequencing batch reactors (SBR 12, 12', 12") and comprising an inlet for weighting agent (33, 38) and a weighted biological flocs outlet fluidly connected to the one or more sequencing batch reactors, the weighting agent impregnation subsystem (26, 26') configured to mix biological flocs and weighting agent (33, 38) to form weighted biological flocs; a weighting agent recovery subsystem (74, 74') fluidly connected to the waste activated sludge outlet (76, 90, 92) of the one or more sequencing batch reactors (SBR 12, 12', 12") and an inlet of the weighting agent impregnation subsystem, the weighting agent recovery subsystem (74, 74') configured to recover weighting agent from the weighted biological flocs of a waste activated sludge and reintroduce the recovered weighting agent to the weighting agent impregnation subsystem (26, 26'); and the system further comprising a sludge storage tank (88, 88') configured to receive settled sludge comprising settled weighted biological flocs from the waste activated sludge outlet (76, 90, 92) of the one or more sequencing batch reactors (SBR 12, 12', 12"), store the settled sludge therein, and regulate the flow of the settled sludge to the weighting agent recovery subsystem (74, 74').