Thermal desorption treatment of contaminated soils in a novel batch thermal reactor

Low-temperature thermal desorption, in which thermal energy is used to vapo rize and physically separate volatile and semivolatile organic contaminants from soil, is among the most promising and economic ex situ soil remediati on alternatives. Experiments were performed using a bench-scale thermal des orber, the batch thermal reactor, which was developed as a prototype to com mercial desorbers. A treatability study using four representative samples o f industrial contaminated soil was followed by a fundamental study of the t hermal desorption process using three controlled samples prepared by mixing a soil with binary mixtures of selected polynuclear aromatic hydrocarbons. For the industrial samples the effect of desorber residence time, temperat ure, and several pretreatments on contaminant removal was investigated. Thr ee of the five samples were successfully treated to the legislated soil rem ediation limits. Using the prepared samples, the effects of sample porosity , contaminant molar mass, desorber residence time, and temperature on therm al desorption were investigated. The experimental results were fitted to an exponential desorption equation, and the desorption rate curves were gener ated to provide a basis for scale-up.