Study On Treatment Of High-concentration Phenolic Wastewater From Chemical Factory By Photochemical Technology

A large chemical company produces large amount of wastewater containing higher concentration phenolic organics from production process. The wastewater mixed with complex constitutes, higher COD concentration and large amount of inorganic salt ions (PO43-and Na+) has to be treated to meet effluent limits. Because this wastewater contains a lot of phenolic organic compounds, it is bio-toxic to microorganisms resulting poor biodegradation capacity. In present study, the process of UV/H2O2, UV/TiO2/H2O2and UV/Fe2+/H2O2photocatalytic process were studied and effects were compared. Combine with the method of chemical sedimentation after above units to meet the requirement of effluent standards.UV/H2O2method was studied to degrade phenolic wastewater. Results indicated that the intensity of UV light source is conclusive to the reaction time of the system while the influence of reaction temperature on the system is not significant. The optimization operating condition is as follows:H2O2dose of353.OmM, initial pH of5.00, and reaction time of10hours with COD removal efficiency97%. Furthermore, the reaction patheway of UV/H2O2was discussed.To further increase reaction rate, the catalysts were added into the system. UV/TiO2/H2O2and UV/Fe2+/H2O2process were chosen to treat phenolic wastewater. Through single factor experiment and response surface methodology, The optimal conditions for UV/TiO2/H2O2process is as follows:pH of4.40, TiO2dosage of2.64g/L and [H2O2] feeding of399.8mM, while for UV/Fe2+/H2O2process they are as follows:initial pHof4.86,[H2O2] of557.4mM and [Fe2+]/[H2O2] of1/33. Then, of the chemical sedimentation was used to remove residul TP afterward to meet the referred effluent standard.The operation parameters and effluent quality of UV/TiO2/H2O2and UV/Fe2+/H2O2process were compared, and it can be concluded that UV/Fe2+/H2O2process has more potential for industrial application because it has lower residence time and better removal efficiency. A further study for the apparent kinetic for COD degradation by UV/Fe2+/H2O2system was alao taken in this research. The results showed the functional relation between oxidation rate and H2O2, Fe2+and COD concentration, and activation energy (Ea) of the oxidation reaction was got to be0.53kJ/mol. Kinetic study implied that the initial concentrations of H2O2, Fe2+and COD have obvious effects on the initial reaction rate, while reaction temperature has no significant effect on it.