Chemical oxidation of biologically treated phenolic effluents

Experimental research into the oxidative purification of biologically treated phenolic effluents of the Estonian oil shale chemical industry was undertaken. The main phenolic compounds identified in this wastewater were phenol, cresols, resorcinol and 5-methylresorcinols. For chemical oxidation of phenols different advanced oxidation methods (O3, H2O2, UV, O3/H2O2, O3/UV, H2O2/UV, O3/H2O2/UV) were tested. For tracking of the changes in the concentration of different phenols during the treatment process, HPLC and colorimetry were applied. It was shown that, in principle, phenols can be reduced almost by any oxidation method studied. Oxidation with molecular ozone has the most potential for practical application. Methods not including ozone (H2O2, UV, H2O2/UV) had, in general, lower efficiency for total phenols reduction than the methods combining ozone.