Effect of Photo-Fenton Operating Conditions on the Performance of Photo-Fenton-SBR Process for Recalcitrant Wastewater Treatment

The study was undertaken to examine the effect of H2O2/Fe2+ molar ratio, one of the important operating conditions of the photo-Fenton process on the performance of combined photo-Fenton-SBR process for treatment of recalcitrant (antibiotic) wastewater. The SBR was fed with photo-Fenton-treated antibiotic wastewater under five H2O2/Fe2+ molar ratios (10, 20, 50, 100 and 150). As H2O2/Fe2+ molar ratio decreased (increase of Fe2+ concentration), BOD5/COD ratio of the photo-Fentontreated effluent increased, and SBR and combined efficiency increased. The SBR efficiency in terms of sCOD removal was observed to be very sensitive to BOD5/COD ratio below 0.40. It decreased from 69±1% at BOD5/COD ratio 0.50 to 44±1% at 0.19. The best H2O2/Fe2+ molar ratio for treatment of the antibiotic wastewater was observed to be 20. At photo-Fenton-SBR operating conditions of H2O2/Fe2+ molar ratio 20, H2O2/COD molar ratio 2.5, pH 3 and 30 min photo-Fenton irradiation time, and 24 hr hydraulic retention time in SBR, the combined photo-Fenton-SBR efficiency was 90% for sCOD removal and final sCOD was 56±2 mg/L, which met the requirements of the Malaysian
Standard (B).