Abstract: The organic pollutants in a waste water stream can be reduced 90-95% by providing oxygen to sludge organisms for biological oxygenation of the pollutants. The raw waste water and activated organisms (sludge containing little or no pollutants) are mixed in a vessel for less than 30 minutes. In this vessel, the organisms absorb and adsorb 90-95% of the organic pollutants present in the influent raw waste water. Any means for gentle agitation can be used in this vessel. The waste-enriched organisms are separated from the supernatant liquid in a clarifier and sent to an oxygenation vessel where the organisms metabolize the waste by treatment with an oxygen-containing gas having at least 30% by volume oxygen. The thus-activated organisms are returned to the mixed liquor vessel to complete the cycle.