Biosurfactant-based washing of an aged PCB-polluted soil and photocatalytic treatment of the resulting effluents

A two phases process consisting of a soya lecithin (SL)-based soil washing process followed by the photocatalytic treatment of resulting effluents was developed and applied in the remediation of an actual-site soil historically contaminated by polychlorinated biphenyls (PCBs)1. Triton X-100 (TX) was employed in the same process as a control surfactant. SL and TX displayed a comparable ability to remove PCBs from the soil; however, SL displayed a lower ecotoxicity, a lower ability to mobilize soil constituents and a higher soil detoxification capacity. The photocatalytic treatment resulted in marked depletions (from 50% to 70%) of total organic carbon (TOC) and PCBs initially occurring in the SL and TX contaminated effluents. Despite the ability of SL to adversely affect the rate of TOC and PCB photodegradation, higher PCB depletion and dechlorination yields along with lower increases of ecotoxicity were observed in SL-containing effluents with respect to the TX ones. The process seems to have the required features to become a challenging procedure for the sustainable remediation of actual site, poorly biotreatable PCB-contaminated soils. 1. Occulti, F.; Camera Roda, G.; Berselli, S.; Fava, F. Biotechnology and Bioengineering 2008, 99, 1525-1534.