UV-O3, UV-H2O2, UV-TIO2 AND THE PHOTO-FENTON REACTION - COMPARISON OF ADVANCED OXIDATION PROCESSES FOR WASTE-WATER TREATMENT

Results of the photochemical mineralization of 4-chlorophenol (4-CP) and of a wastewater from dyehouse industry by the methods UV/O3, UV/H2O2, UV/TiO2 and UV/H2O2/Fe2+ (photo-Fenton reaction) are reported and compared. Under illumination with a 150 W high pressure mercury lamp, TOC-degradation efficiency for 4-CP had the following order: UV/H2O2/Fe2+ > UV/O3 > UV/H2O2 = UV/TiO2. Complete decolourization of the dye waste occurred within 20 minutes with ozone. A mineralization grade of approximately 75% was reached after 90 minutes with the photo-Fenton reaction and after 150 minutes with UV/ozone. The combinations UV/TiO2 and UV/H2O2 were found to be less efficient for bleaching and degradation of the dye waste. Furthermore, a novel combination for wastewater treatment, UV/Fe2+/O3, was investigated. Addition of Fe2+ to the UV/ozone process increased the mineralization rate of 4-CP while no significant effect on dye waste degradation could be observed.