Removal of phenol at high concentrations using UV/Persulfate from saline wastewater

This study investigated the degradation of phenol at high concentrations from saline wastewater using UV/Persulfate (UV/PS) in a bench scale reactor. The effect of operational variables such as PS concentration (50, 80, 100, 150, and 200 mM), solution pH (3, 7, and 10), initial phenol concentration (200, 450, 1,000, 1,500, and 2,000 mg/L), and NaCl concentration (30,000, 50,000, and 70,000 mg/L) were surveyed. The results revealed that maximum removal of phenol (91%) was obtained after 60 min of reaction at PS molar concentration of 150 mM. Also, changes in pH values had no significant effect on removal efficiency and had slightly greater removal at acidic pH, so pH 3 was selected as optimum. Phenol removal efficiency was increased from 91 to 93% with an increase in the NaCl concentration from 30,000 to 70,000 mg/L, respectively. In addition, phenol removal percentages decrease with an increase in the initial phenol concentration. Efficiency of PS and UV photolysis were 30 and 21%, respectively. The results showed that UV/PS process could be optimally used to remove phenol from saline wastewater and could be effective, economically and environmentally.