Biological and integrated chemical–biological treatment of PCB congeners in soil/sediment‐containing systems

Abstract

Abstract A series of experiments was conducted on the integrated chemical–biological treatment of 14 C‐labelled polychlorinated biphenyl congeners in soil/sediment‐containing systems. The hydroxyl radicals, generated by Fenton's reagent (1% (v/v) H 2 O 2 , 1 mmol dm −3 FeSO 4 ), followed by inoculation with Pseudomonas sp., strain LB400, and Alcaligenes eutrophus , strain H850, increased the overall extent of 2‐chlorobiphenyl mineralisation in slurries of contaminated manufactured gas plant soil and sediment by 2·9 and 7·4 times, respectively, compared with biodegradation alone. In uncontaminated topsoil slurries the effect of chemical pretreatment was not observed. In the systems amended with 2,2′,4,4′‐tetrachlorobiophenyl, the application of Fenton's reagent increased the overall extent of mineralisation by 2·4 times, compared with the biological treatment alone, but had no effect in the slurries of contaminated soil and sediment. The increased level of radioactivity in the liquid phase of experimental systems suggests that intermediates produced in the process of chemical oxidation are less hydrophobic than parent polychlorinated biphenyls and therefore more available for further biodegradation.