The BS addition enhanced PCBs removal by both chemical and
biological treatment of soil; however, the highest removal was
achieved by an integrated chemical–biological approach. The joint
application of MO, oxidizing chemicals in moderate dosages and
the BS resulted in increased soil microbial respiration and DHA,
compared to that obtained by the application of the microbial consortium
alone – this testifies to the stimulatory effect of the
amendments on microflora. The slight variations if any in soil pH
support the application of moderate dosages of the chemicals in
the combined treatment. The removal of PCBs by a 42-d combinedchemical–biological treatment was independent of the carrier of
the H2O2 when BS was utilized resulting in approx. 47–50% PCBs
removal. EDTA addition in the experiments with CaO2 did not
affect the treatment efficacy even after the prolongation of the
treatment time from 1 to 42 d. In general, the addition of microorganisms
and CaO2 has proven less effective at stimulating
enzymatic activity than that achieved by joint addition of microorganisms
and H2O2 (except the case of MO + CaO2 + BS). The joint
application of both the BS and EDTA and the combined chemical–
biological treatment did not result in higher degradation of
PCBs compared to that for the treatment supplemented by EDTA
or the BS only.