Heat treatment of incinerator retired sorbents containing heavy metals

Previous studies have indicated that an effective control technique for hea vy metal emissions from incinerators is to use solid sorbents to capture me tals by physical deposition and chemical adsorption. However, the adsorbed heavy metals on the retired sorbents could possibly cause secondary polluti on if they are inadequately treated. The main objective of this study is to increase the stability of four heavy metals (Cu, Pb, Cr and Cd) on retired sorbents by heat treatment. The stability was based on the toxicity charac teristic leaching procedure (TCLP) tests. The parameters evaluated included : (1) different temperatures (900, 1100 and 1300 degreesC); and (2) various heating times (20, 40 and 60 min). The results indicated that most of the leaching rates decreased with increasing temperature for the four toxic hea vy metals. The heat treatment time did not regularly influence the stabilit y of heavy metals, and affected it slightly when the temperature was contro lled at 1300 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.