Dewatering of activated sludge by Fenton's reagent

The specific resistance, moisture and element analysis were used to evaluate the increase in filtration and dewatering efficiency when applying the Fenton system, Fe2+/HO, and Fe3+/H2O2, to treat excess sludge. Addition of Fe2+, Fell and H2O2 were also selected as treatment processes for comparison. The excess sludge used in this study was obtained from the wastewater treatment plant of An-Ping Industrial Park in Thinan, Taiwan. Results show that ferrous and ferric ions can catalyze hydrogen peroxide to promote the filterability of sludge. Four ratios of Fe2+/H2O2 were used to investigate the effect of Fe2+ concentration on the reduction of specific resistance. When 6000 mg/l of Fe2+ and 3000 mg/l of H2O2 were added into the sludge, the specific resistance of the treated sludge had only 10% of that of the original sludge. Ferric ions also have high catalyzing ability similar to ferrous ions. However, Fenton's reagent, Fe2+/H2O2, has a higher dewatering efficiency than other processes. The moisture of the cake sludge generated by treatment with Fenton's reagent was 75.2%, and those conditioned by other processes were approximately 85%. The mechanism by which Fenton's reagent increased the sludge dewaterability could be the destruction of cells leading to the release of the intercellular material. (C) 2002 Elsevier Science Ltd. All rights reserved.