An organic waste material treatment process comprising subjecting the organic waste material to conditions under which anaerobic digestion occurs followed by conditions under which aerobic composting occurs. Preferably, the organic waste material is pre-conditioned before anaerobic digestion by subjecting the organic waste material to aerobic composting conditions to facilitate a rise in temperature of the organic waste material. The treatment process is conducted in a single vessel, wherein air and water are evenly distributed to the contents of the vessel. A plurality of vessels may be interconnected, such that water may be extracted from one vessel, whose contents have undergone anaerobic digestion, then recirculated to an interconnected vessel to facilitate conditions for anaerobic digestion of the contents of the interconnected vessel.