This report documents a study of the effectiveness of an auto-oxidation technique for treating potentially toxic pollutants from a manufacturing source. The particular waste used for evaluation was a tannery unhairing effluent. Tannery unhairing waste was treated in a pilot plant scale auto-oxidation unit designed and built by Technical Associates for Industry, Inc., Red Bank, New Jersey 07701. This waste is highly alkaline with a pH generally higher than 11 and has a COD greater than 50,000 mg/liter, consisting largely of protein and sulfide. The auto-oxidation pilot plant in static tests effectively and rapidly removed sulfide from the waste. Removal of COD, nitrogen, and suspended solids was considerably less effective. Combining the auto-oxidation with ultraviolet light and a hydrogen peroxide addition improved the COD removals very little.