Enhancement of recalcitrant compounds biodegradation by Fenton's oxidation treatment

As an alternative to the traditional anaerobic digestion systems an advanced treatment of toxic and recalcitrant compounds has been investigated by combining chemical and biological oxidation process. The chemical treatment has been carried out by Fenton oxidation system which generates hydroxyl radicals by the reactions of hydrogen peroxide and ferrous iron, at acid pH values. In optimising the Fenton’s pre-treatment the iron and hydrogen peroxide concentration ratio was found to be crucial. After the chemical treatment the samples were flocculated, decanted and the supernatant was fed to a post-activated sludge treatment. The data obtained, in applying the proposed treatment system to the tannery and pulp mill wastewater, confirm that the hydroxyl radicals provide an effective enhancement of the recalcitrant compounds.