Abstract: Dual purpose apparatus and process for increasing the efficiency of absorption of oxygen by a biodegradable waste in a continuous operation in a waste collection station and for removing the oxygen enriched waste from the collection station by separately introducing waste and oxygen, which may be air, into a collector under a highly agitated state, and agitating the air and waste under pressure in a collector by a partially recessed vortex type impeller as back pressure is provided to the collector either by a nozzle means or an outlet means. The collector is mis-matched relative to the impeller to increase the retention and mixing time of the air and waste in the collector.