Continuous ozonation of polycyclic aromatic hydrocarbons in oil/water-emulsions and biodegradation of oxidation products

The continuous ozonation of polycyclic aromatic hydrocarbons (PAH) was stud ied in a two stage ozonation system followed by aerobic biological degradat ion. The highly condensed PAH benzo(e)pyrene and benzo(k)fluoranthene were oxidized selectively in synthetic oil/water-emulsions. The influence of the ozone mass transfer gas-liquid on the reaction rate of benzo(k)fluoranthen e was studied for process optimization. The dissolved ozone concentration i s influenced by temperature to a higher degree than the reaction rate of PA H. In dependence on pH, PAH oxidation occurs by a direct reaction with ozon e inside the oil droplets. Two main ozonation products of benzo(e)pyrene we re quantified at different retention times during ozonation and their trans formation could be shown in the biological treatment step. (C) 1999 IAWQ Pu blished by Elsevier Science Ltd. All rights reserved.