2-21　Release Behavior of Harmful Elements During Heat Treatments of CCA-treated Wood

Abstract

Chromated copper arsenate–treated wood produced by injecting a solution containing sub–percent of chromium, copper, and arsenic (hereinafter referred to as CCA–treated wood) is one of the construction wastes. As fundamental research on the development of clean gasification process for biomass, pyrolysis (400–800°C) which is the initial stage of gasification and CO₂ gasification (1000°C, 0–60min) characteristics of CCA–treated wood were investigated. The release behavior of high volatile arsenic during pyrolysis and gasification of CCA–treated wood was followed. When the CCA–treated wood was pyrolyzed, the release of arsenic proceeded with increasing temperature and the release extent was 41% at 800°C. In the case of gasification, the release extent of arsenic increased with gasification time and 90% of the arsenic was released into gas phase within 60min. Furthermore, it was possible to suppress the release of arsenic by 800°C during pyrolysis by mixing organic sludge rich in iron and calcium with CCA–treated wood.