Application of Partially Miscible Solvent System for an Efficient Extraction of Organic Pollutants from Contaminated Sludge

A systematic study of extraction of various organic pollutants from highly contaminated solid media (e.g., sludge) by applying a phase transition of a benign partially miscible solvent system composed of water/ethyl acetate/ethanol was conducted. This solvent system possesses an upper critical solution temperature of about 55 °C. The efficiency of the phase transition extraction (PTE) process is found to be higher and much faster compared to those obtained without phase transition (at ambient temperature). The influence of various operating conditions on the process efficiency was investigated. The performance of the phase transition extraction when applied on contaminated sludge is much better than the extraction with ethyl acetate only, although the latter is shown to be a very efficient solvent for extracting various organic contaminants (e.g., pharmaceuticals, persistent organic pollutants) from aqueous solutions. The efficiency of phase transition extraction from the aqueous solution was somewhat lower than that achieved with ethyl acetate, but it shows a clear advantage in the presence of detergents, as emulsion formation is prevented.