The Fenton method was applied to the removal of chemical oxygen demand using chromate (CODcr) and color from high-strength livestock wastewater in which the initial CODcr was 5000-5700 mg/L. The optimum ratio of H2O2 (mg/L) to the initial CODcr was 1.05 and the optimum molar ratio of H2O2/Fe2+ was 2. The optimum initial pH and the optimum reaction time were 3.5-4 and 30 min, respectively. Under optimal conditions, the removal ratios of CODcr and color of the supernatant after static precipitation of the produced sludge were 88 and 95.4%, respectively. Addition of Fenton's reagents in several aliquots did not affect the efficiencies of CODcr and color removal. (c) 2007 Elsevier B.V. All rights reserved.