THE EFFECT OF CHEMICAL PRETREATMENT ON THE AEROBIC MICROBIAL-DEGRADATION OF PCB CONGENERS IN AQUEOUS SYSTEMS

A series of experiments was conducted to examine the effects of chemic al pretreatment on biodegradation of C-14-labeled PCB congeners in aqu eous systems. Fenton's reagent was used to generate hydroxyl radicals (OH.) which were successful in partially oxidizing/transforming otherw ise recalcitrant molecules of tetrachlorinated PCB, but had little or no impact on the biodegradation of a monochlorinated congener, Applica tion of Fenton's reagent (1% H2O2, 1 mM FeSO4) followed by inoculation with pure cultures Pseudomonas sp, strain LB 400 and Alcaligenes eutr ophus, strain H850 resulted in the removal of approximately 38% of 2-c hlorobiphenyl and 51% of 2,2',4,4'-tetrachlorobiphenyl in the form of (CO2)-C-14. Comparison of the rate and extent of biodegradation of 2,2 ',4,4'-tetrachlorobiphenyl after the application of Fenton's reagent w ith the dynamic and final level of radioactivity in the aqueous phase of experimental system suggests two possible means of microbial utiliz ation of tetrachlorinated PCB congener altered by chemical oxidation: (a) consumption of the partially oxidized chemical dissolved in the aq ueous phase, and (b) direct microbial attack on the transformed compou nd, which may still be adhered to the solid surface.