Int. J. Environmental Technology and Management, Vol. 9, No. 1, 2008 47 Copyright © 2008 Inderscience Enterprises Ltd. Biofiltration of hydrophobic VOCs pretreated with UV photolysis and photocatalysis Madjid Mohseni* and Lizbeth Prieto Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC, Canada V6T 1Z3 Fax: +604-822-6003 E-mail: mmohseni@chml.ubc.ca E-mail: lprieto@ccmc.unam.mx *Corresponding author Abstract: The effects of pretreatments on the biofiltration of gas phase α-pinene, a poorly water soluble Volatile Organic Compound (VOC), was evaluated in a controlled and long-term experimental investigation. Ultraviolet (UV) photolysis and photocatalysis were used and compared as pretreatment techniques. A control experiment involving biofiltration alone allowed for the direct evaluation of the coupled UV-biofiltration. α-Pinene contaminated streams with flow rates of 5–6.5 l/min and concentrations of up to 130 ppmv were passed through the systems. UV pretreatment on average converted between 20 and 50% of α-pinene into water soluble intermediates. When comparing the effectiveness of each pretreatment process, UV photocatalysis provided greater α-pinene conversion, especially at low retention times and high contaminant loading. The untreated α-pinene along with the by-products of UV photooxidation was then removed effectively in the biofiltration stage. The UV-biofiltration process offered 50–80% more α-pinene removal compared to the control biofilter. Regardless of their effectiveness at removing the contaminant, photolysis and photocatalysis pretreatments had similar synergistic impact on the performance of the downstream biofilter. Keywords: air pollution; volatile organic compounds; VOC; hydrophobic compounds; biofiltration; ultraviolet; UV; photooxidation; photolysis; photocatalysis. Reference to this paper should be made as follows: Mohseni, M. and Prieto, L. (2008) ‘Biofiltration of hydrophobic VOCs pretreated with UV photolysis and photocatalysis’, Int. J. Environmental Technology and Management, Vol. 9, No. 1, pp.47–58. Biographical notes: Madjid Mohseni is an Associate Professor of Chemical and Biological Engineering at the University of British Columbia, Vancouver, Canada. His research activities focus on UV-based advanced oxidation and biological processes for the treatment of contaminated air and water. Lizbeth Prieto was an Undergraduate visiting Student of Chemical Engineering from Mexico. She spent about one year at the University of British Columbia where she worked on this project under the direction of Dr. Mohseni.