The Epoxy Resin Wastewater Treated By Catalytic Wet Peroxide Oxidation

The epoxy resin wastewater with high concentrations of organic pollutants and salt cannot be efficiently treated by the conventional methods. A catalytic wet peroxide oxidation (CWPO) process was applied to treat it in this research. The purpose is to degrade the TOC level to less than the limit for diaphragm cells feed, so that the treated epoxy resin wastewater could be reused as a raw material for chlorine and caustic production.First, the influences of pH value, temperature, hydrogen peroxide and ferrous sulfate dosages, and their dosing methods on TOC removal of CWPO process using Fe(Ⅱ) as catalyst were evaluated, and an on-site pilot trial was carried out to confirm the laboratory findings. Second, the combined processes of activated carbon adsorption and CWPO with Fe(Ⅱ) as catalyst were used to treat the wastewater, and then the efficiency and economy of the combined processes were evaluated. Finally, the effect of different catalysts, such as Cu(Ⅱ), Mn(Ⅱ) and complex catalysts, on the CWPO processes were investigated, and the possibility of the catalysts reuse were explored.The experimental results showed that the optimal pH, temperature, catalyst (FeSO4·7H2O2) dosage, oxidant (30%H2O2) dosage of the CWPO process with Fe(Ⅱ) as catalyst were3.0,90℃,6.25g/L and75mL/L, respectively. Besides, multiple additive methods of H2O2and Fe(Ⅱ) significantly enhanced TOC removal than the one step addition as their total dosages were the same. The on-site pilot trial showed that the epoxy resin wastewater (TOC=2500～2700mg/L,[NaCl]=18.2～20.5%) could be degraded to TOC<150mg/L through CWPO process under the optimal conditions. The pilot effleunt TOC level was fit in with the influent TOC limit (200mg/L) for the diaphragm electrolytic cell, and the operating cost of CWPO process was about RMB92.26yuan per cubic meter, which was lower than the acceptable cost of the enterprise.When the combined process of activated carbon adsorption with CWPO were applied to treat the epoxy resin wastewater, the TOC removal efficiencies of "adsorption following oxidation" and "oxidation following adsorption" were compared, and the results found that the former was superior to the latter. If the epoxy resin wastewater was firstly treated with1g/L activated carbon, then it was treated by CWPO further, the effluent TOC value can also meet the requirement of diaphragm cells feed as the H2O2(30%) dose was65mL/L. The TOC removal efficiencies of the CWPO processes with Cu(II) or Mn(II) as catalyst under their optimal condition were inferior to the one with Fe(II) as catalyst, so were the complex catalysts.The spent catalyst separated from the wastewater when the reaction had been finished could be reused after being dissolved by acid. The catalytic effectiveness of resued Cu was better than that of reused Fe, and the TOC removal efficiency almost didn’t decrease even as the spent Cu catalyst was resued for several times, so the catalyst consumption could be saved. Especially, when the spent catalyst needs to be disposed as hazardous solid waste, the CWPO process with Cu(Ⅱ) as catalyst has a great advantage in terms of operating cost.