Simultaneous Removal of Heavy Metals and Organic Pollutants from Contaminated Sediments and Sludges by a Novel Technology, Sediments Remediation Phase Transition Extraction

A novel process for the simultaneous removal of heavy metal ions and organic pollutants from contaminated soils/sediments/sludges was developed and its feasibility has been demonstrated. This process entitled sediments remediation phase transition extraction (SR-PTE), is based on using partially miscible solvent mixtures in which specific organic soluble chelating agents are dissolved. Extraction efficiency is improved by a phase transition cycle induced by temperature variation. The SR-PTE technology was tested on authentically polluted river sediments, and on heavily contaminated sludge from waste-water treatment plant, using the extraction of cadmium as a model metal. With this technology, up to 90% of cadmium ions were removed within approximately 15 min, as well as practically all the organic matter, including polycyclic aromatic hydrocarbons (PAHs). Although the removal efficiencies are similar to those achievable with conventional washing (with water plus chelant solutions) process, the advantage of the proposed technology is its ability to extract in a single process both heavy metals and organic contaminants and concentrates them in the organic phase.