Benzene/toluene/p-xylene degradation. Part I. Solvent selection and toluene degradation in a two-phase partitioning bioreactor

A two-phase organic/aqueous reactor configuration was developed for use in the biodegradation of benzene, toluene and p-xylene, and tested with toluen e. An immiscible organic phase was systematically selected on the basis of predicted and experimentally determined properties, such as high boiling po ints, low solubilities in the aqueous phase, good phase stability, biocompa tibility, and good predicted partition coefficients for benzene, toluene an d p-xylene. An industrial grade of oleyl alcohol was ultimately selected fo r use in the two-phase partitioning bioreactor. In order to examine the beh avior of the system, a single-component fermentation of toluene was conduct ed with Pseudomonas sp. ATCC 55595. A 0.5-l sample of Adol 85 NF was loaded with 10.4 g toluene, which partitioned into the cell containing 1 l aqueou s medium at a concentration of approximately 50 mg/l. In consuming the tolu ene to completion the organisms were able to achieve a volumetric degradati on rate of 0.115 g l(-1) h(-1). This system is self-regulating with respect to toluene delivery to the aqueous phase, and requires only feedback contr ol of temperature and pH.