Release behavior of arsenic, chromium, and copper during heat treatments of CCA-treated wood

Biomass has been attracting attention as an environmentally friendly energy resource due to concerns about global environmental problems. 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 degrees C) which is the initial stage of gasification and CO2 gasification (1000 degrees C, 0-60 min) 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 degrees 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 60 min. Furthermore, it was possible to suppress the release of arsenic by 800 degrees C during pyrolysis by mixing organic sludge rich in iron and calcium with CCA-treated wood.