Abstract
ABSTRACT
Non-aqueous phase liquid (NAPL) containing many chlorinated solvents and polychlorinated biphenyls (PCBs) was separated from ground water. Because the NAPL contained a significant volume of usable chlorinated solvents, separation of these solvents was investigated both at a lab and in the field. Criterion was established that, prior to reuse, a PCB concentration in recovered solvent must be less than 2ppm which is a regulatory quantifiable level (40CFR761). A laboratory study found that at least 80% of reusable solvents could be recovered by a simple batch distillation to meet this concentration limit. The recovery reached 90% when the NAPL was distilled with five theoretical plates. The field work was conducted via a mobile distillation unit which has been approved by the EPA for use in the clean-up of PCB wastes. The unit had neither rectifying plates nor reflux. PCB concentration was reduced to less than 2ppm in distillate at 78% recovery of solvent, which was similar to the lab result.
Cost comparison was performed between two options: (1) solvent recovery and incineration of still bottom and (2) incineration of NAPL. Solvent recovery was identified to be a more cost-effective and environmentally sound approach, and was attractive in terms of resources recovery and waste minimization.
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