Comparison of O3, H2o2 and O3/H2o2 Processes for Decolorisation and Cod Removal of Instant Coffee Wastewater

Abstract

Application of advanced oxidation processes including O3, H2O2 and O3/H2O2 for decolorisation and COD concentration removal of instant coffee wastewater treatment after anaerobic treatment. This wastewater mainly contains inert COD that is hard treated by the biological process. The efficiency of decolorisation and COD removal is investigated by changing of pH, concentrations of O3 and H2O2, O3:H2O2 molar ratio, and concentrations of Cl–, SO4 2–, HCO3 –. The advanced oxidation process applied O3/H2O2 is the highest efficiency of decolorisation and COD removal to compare with that of O3 and H2O2 separately. A pH optimum range is between 7 and 9 of O3, H2O2 và O3/H2O2 and the best molar ratio of O3:H2O2 is 3 for the highest efficiency. In the optimal conditions, decolorisation and COD removal efficiencies of O3, H2O2 and O3/H2O2 are 71 % and 62 %, 70 % and 47 %, 95 % and 73 %, respectively. Additionally, a presence of Cl–, HCO3 –, SO4 2– ions will moderately decrease the decolorisation and COD removal efficiencies. Advanced oxidation process using O3/H2O2 is applied as a possible method for instant coffee wastewater removal after treated by the biological processes.