Comparison of Treatment Efficiencies of Fenton's Oxidation for Untreated and Biologically Treated Wastewaters

This article first presented direct applicability of Fenton's oxidation to high-strength wastewater, especially when efficiency of biological treatment for high-strength wastewater is insufficient. Fenton's oxidation was applied both to biologically pretreated molasses wastewater (BMW) and untreated molasses wastewater (MW), and the removal of color and chemical oxygen demand using chromate (CODcr) were compared between the two wastewaters. The optimum reaction time was 20 min for both BMW and MW. Neither the different dosages of Fenton's reagents nor the initial pH affected the removal ratios of CODcr and color from either BMW or MW. The maximum removal ratios of CODcr and color were approximately 90 and 97% for BMW and 88 and 98% for MW, respectively. Although these ratios are similar, the optimum H2O2 dose (g L-1)/initial CODcr (g L-1) ratio and the optimum H2O2/Fe2+ molar ratio for BMW treatment were larger than those for MW treatment. This indicates that direct Fenton treatment of MW uses less H2O2 and is thus preferable compared to Fenton treatment of BMW.