Abstract: An apparatus for the treatment of liquid sewage, the sewage to be treated being aerated and mixed prior to being directed sequentially through primary and secondary settling circuits wherein primarily settleable solids and secondarily settleable solids are removed respectively. Such removed solids are then directed to a digester compartment, the secondarily nonsettleable sewage being discharged from the sewage treatment apparatus. In a preferred embodiment, a portion of the primarily and secondarily settleable solids are recirculated to the aerating and mixing area thus allowing for the floculation of the liquid sewage. In a further preferred embodiment an overflow weir is provided upstream of the sewage treatment apparatus outlet thereby providing a surge capacity for the sewage treatment apparatus.The apparatus uses a hollow propeller having a plurality of holes therein on the backface thereof; the propeller is mounted on a hollow shaft.