US Patent 7294260 Aerobic wastewater treatment plant having 3-compartment vessel

An aerobic wastewater treatment plant having a peripheral wall, at least three compartments being formed within the peripheral wall in conjunction with bottom wall, the peripheral wall having first and second end walls which are radiused and having at least portions thereof which have the same radius and the first and second side wall, the side wall and end walls being shaped and adjoined to each other so as to form a smooth contour on the outer surface of the peripheral wall, the peripheral wall preferably having an oval-like configuration when viewed in top plan view.