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Use of xad - 4 resins for remediation of pcb contaminated soils
Polychlorinated biphenyls (PCBs) are common contaminants of concern became of their low water solubility, persistence in the environment, and carcinogenicity and thus require remediation. Resin technology has been proposed for the remediation of the PCBs from soils and sediments. The process as envisioned would involve mixing the resins with the contaminated media and then separating them to extract PCBs. Extraction of PCBs from contaminated media requires PCB desorption and thus an understanding of the variables that affect PCB desorption are important. In this study, desorption of PCBs from contaminated media was evaluated in laboratory studies as a function of three variables. These process variables are organic content of the media, the resin to soil ratio, and the mixing regime. XAD-4 resins, which have been found to be strong adsorbents of PCBs. were used as the study resin. Based on the data collected, it was observed that desorption of PCBs decreases with an increase of the organic content (measured as total extractable organics, TEO), increases with increases in resin: soil ratio, and decreases as mixing decreases. From data collected, time estimates for remediating a heavily PCB contaminated soil similar to the one studied as a part of this project were calculated. From this analysis, it appears that the best application for resin technology may be for soils and sediments that contain PCBs at concentrations slightly higher than the 50 ppm threshold that requires disposal in a TSCA permitted landfill. Recommendations to further explore the feasibility of the resin technology for this application are given.