Removal of Organic Pollutants from Soil: The Ozonation of Clofibric Acid in Aqueous Slurries

Ozonation is particularly suited for the treatment of recalcitrant soil contaminants. Clofibric acid, an active metabolite of some blood lipid regulators, was used as a model organic contaminant, and quartzite as a model soil. The measurements performed at different pHs, both in slurries of contaminated soil and in clofibric acid aqueous solutions, indicate that a markedly higher TOC removal can be obtained in the slurry mode. It has been demonstrated that clofibric acid can be effectively removed from contaminated soils by a direct treatment with ozone in a slurry system. In terms of TOC removal degree, this treatment appears to be more effective than a two-stage process, which consists of washing the contaminated solid with water and subsequently ozonating the liquid solution obtained. The enhanced reactivity of the contaminated slurry was also evident when measuring the time evolution of the CA-quartzite sandwater system. A simplified model of the slurry system was developed and interesting results were obtained by using at the same time the data collected in three runs at a fixed pH. Work is in progress to improve the results obtained in this investigation by separately studying the release of CA from contaminated quartzite sand to the liquid phase and the ozonation of aqueous CA solutions.