Removal of organic matter from a variety of water matrices by UV photolysis and UV/H₂O₂ method

A re-circulated flow-through photoreactor was used to evaluate the ultraviolet (UV) photolysis and UV/H₂O₂ oxidation process in the purification of three different water matrices. Chemically coagulated and electrocoagulated surface water, groundwater contaminated with creosote wood preservative and 1,2-dichloroethane (DCE) containing washing water from the plant manufacturing tailor-made ion-exchange resins were used as sample waters. The organic constituents of creosote consist mainly of harmful polycyclic aromatic hydrocarbons (PAH) whereas 1,2-DCE is a toxic volatile organic compound (VOC). Besides analyzing the specific target compounds, total organic carbon (TOC) analysis and measurement of change in UV absorbance at 254nm (UV₂₅₄) were performed. Initial TOC, UV₂₅₄ and pH varied significantly among treated waters. Initial H₂O₂ concentrations 0-200mg/l were used. The UV/H₂O₂ treatment was efficient in removing the hazardous target pollutants (PAHs and 1,2-DCE) and natural organic matter (NOM). In addition, high removal efficiency for TOC was achieved for coagulated waters and groundwater. Also, the efficiency of direct photolysis in UV₂₅₄ removal was significant except in the treatment of 1,2-DCE containing washing water. Overall, UV₂₅₄ and TOC removal rates were high, except in case of washing water, and the target pollutants were efficiently decomposed with the UV/H₂O₂ method.