A marine sewage treatment system having a digestor unit including a first tank receiving the sewage effluent, a secondary treatment unit including a second tank receiving the fluid discharged from the first tank and a final filter receiving the fluid discharged from the second tank, the first and the second tanks including baffles controlling the flow of fluid within the tanks and the first and the second tanks each being supported via a guide and anchor assembly for automatically leveling and agitating the fluid within the first and the second tanks.