Benzene degradation in a two-phase partitioning bioreactor by Alcaligenes xylosoxidans Y234

An aqueous-organic, two-phase bioreactor system was used for the biodegrada tion of benzene. Through a systematic solvent selection procedure consideri ng biological, physical, operational. environmental and economic factors, h exadecane was chosen as the most promising solvent. The solvent has infinit e solubility for benzene and shows very high phase stability with aqueous m edia. Alcaligenes xylosoxidans Y234 capable of degrading benzene without an y other co-substrate was inoculated into the aqueous phase of the two-phase partitioning bioreactor, which consisted of a 1 1 aqueous phase and 500 mi hexadecane. A feed of 7000 mg of benzene was loaded into the organic phase , which gave an initial equilibrium aqueous phase concentration of 100 mg/l . Over the course of 24 h, 63.8% of the benzene was degraded by the microor ganism, and 36.2% was stripped by aeration. By installing a condenser and u sing a lower gas flow of pure oxygen to reduce stripping. more than 99% of a subsequent 7000 mg benzene addition was degraded by the organisms within 24 h. (C) 2001 Elsevier Science Ltd. All rights reserved.