Treatment of Recalcitrant Organic Compounds in Oil Reclaiming Wastewater by Ozone/Hydrogen Peroxide and UV/Titanium Dioxide

Refractory organic compounds in samples of a biologically treated oil reclaiming wastewater with a COD of about 300 mg/l were removed by ozonation with or without hydrogen peroxide or by irradiation with UV light in the presence of titanium dioxide in laboratory scale batch experiments. A 5 hrs UV/TiO2 treatment at pH 3 (energy consumption: about 0.9 kWh/l) resulted in a COD elimination of 70% and an enhanced biodegradability of the organic wastewater constituents. Ozonation was hardly affected by hydrogen peroxide, and a treatment for 47 min (energy consumption about 0.005 kWh/l) led to a COD reduction of about 17% and also to an improved biodegradability. Both processes are suitable for further treatment of biologically oxidized oil reclaiming wastewaters.