CONSTRUCTION OF A BACTERIAL CONSORTIUM FOR THE BIOFILTRATION OF BENZENE, TOLUENE AND XYLENE EMISSIONS

On equal parts of benzene, toluene and p-xylene (BTX), a stable bacter ial consortium was enriched for removal of BTX vapours from air. As de monstrated by gas chromatographic monitoring, this consortium removed all three BTX components but was able to grow only on benzene and/or t oluene. A Pseudomonas strain, PPO1, isolated putida from this consorti um behaved in an identical manner. When immobilized on a porous peat/p erlite column, both the consortium and the PPO1 isolated removed all t hree BTX components from metered air streams. However, due to the accu mulation of products from the incompletely metabolized p-xylene, the r emoval rates were unsatisfactory and declined further with time. P. pu tida ATCC 33015 bearing the TOL plasmid was capable of growing on tolu ene, on para-and on meta-xylene isomers, but not on benzene. When the PPO1 and ATCC 33015 strains were immobilized, in equal parts, on peat/ perlite columns a much improved and sustainable removal of all three B TX components was observed at the rate of 40-50 g/h. m(3) filter bed. Due to the dominance of the ring-hydroxylating pathways over the TOL p athway, the classical enrichment approach did not result in a consorti um capable of the sustained removal of all BTX components. However, a rationally formulated consortium consisting of members with complement ary metabolic abilities was capable of this task and should be of use both in industrial emission control and in soil venting operations.