Randomly Methylated β-Cyclodextrins (RAMEB) Enhance the Aerobic Biodegradation of Polychlorinated Biphenyl in Aged-Contaminated Soils

The biological removal of polychlorinated biphenyls (PCBs) from contaminatedsoils is adversely affected by the poor bioavailability of these pollutants. Twodifferent aged-contaminated soils containing about 890 and 8500 mg/kg of PCBswere supplemented with biphenyl and treated in slurry- and solid-phase aerobic0.5 litre-microcosms in the presence of RAMEB at 0, 0.5, 1.0, 3.0% (w/w). RAMEB,which was non-toxic and slowly biodegraded by the soil microorganisms, significantlyenhanced the bioavailability (from 30 to 50%) and the biological degradation (from 15to 55%) and dechlorination of PCBs in both soils and treatment conditions. RAMEBeffects were dependent on the concentration at which it was applied, the soil featuresand the treatment conditions. RAMEB enhanced PCB biodegradation by increasingboth the PCB bioavailability and the availability of biodegrading bacteria in themicrocosms. RAMEB appears a promising bioavailability enhancing agent for thetreatment of PCB-contaminated soils, not only for its positive effects on the PCBsbiodegradation, but also for its biodegradability, non-toxicity and relatively low cost.