(144e) Laboratory-Scale Pyrolysis of CCA-Treated Wood Waste for Metals Recycle

For over 30 years chromated copper arsenate (CCA) has been the most widely used wood preservative. However, concerns over possible exposure to the toxic metals has lead to the restriction of CCA-treated wood to industrial applications since 2003. The restricted use policy has lead to an increased volume of CCA-treated wood slated for disposal, with some estimates as high as 24 million tons of CCA available for disposal by 2020. Although landfilling the out of service material has been the acceptable means of disposal, concern over soil and groundwater contamination, linked to the leaching of CCA-metals from landfills, has created the need for an alternative disposal method for CCA-treated wood waste.

This research focuses on employing fast pyrolysis as a means of recycling CCA-treated wood waste. A primary goal is to concentrate the metal components in the bio-oil, for re-use in wood preservatives, while recovering the energy value of the wood. Pyrolysis experiments were performed in a laboratory-scale pyrolysis system at temperatures ranging from 400°C to 550°C, at varying carrier gas flow rates, under atmospheric conditions, and each pyrolysis product was analyzed for CCA-metal content. Subsequent analysis of the bio-oil product included the determination of viscosity, water content, and pH. The char fraction additionally underwent electrokinetic (EK) treatment to extract the remaining CCA-metals. The results of this study and details of on-going research will be presented in this paper.