Photocatalytic pretreatment of oily wastewater from the restaurant by a vacuum ultraviolet/TiO2 system

The present study aims at investigating the performance of a vacuum ultraviolet (VUV, 185 nm) and TiO2 oxidation system for the pretreatment of oily wastewater from restaurant. The influence of irradiation time, pH, dissolved oxygen (DO), the dosage of TiO2 and the initial chemical oxygen demand (COD) concentration on COD removal efficiency was ascertained and optimum process conditions for stable and effective operation were determined. Under the optimum conditions of irradiation 10 min, initial COD 3981 mg/L, TiO2 150 mg/L, pH 7.0 and flow rate of air 40 L/h, the process of VUV and TiO2/VUV achieved removal efficiencies of COD, BOD5 and oil as 50 +/- 3%, 37 +/- 2%, 86 3%, and 63 +/- 3%, 43 +/- 2%, 70 3%, respectively. The biodegradability factor f(B) of the wastewater was determined as 1.56 which indicated that the VUV/TiO2 process improved the biodegradability of the oily wastewater significantly. Results clearly indicate that VUV/TiO2 photolysis tends to destruct parts of COD. BOD5, and ammonia, as well as enhances the biodegradability of the oily wastewater simultaneously. Thus, this technique could be used as a pretreatment step for conventional biological treatment of oily wastewater. (C) 2010 Elsevier B.V. All rights reserved.