Wood products are treated with preservatives to prohibit degradation by a multitude of organisms and to prolong the products' life in adverse environments. Historically, nearly 80% of all treated wood products in North America are treated with chromated copper arsenate (CCA). However, by the end of 2003 CCA-treated wood was restricted to industrial applications, resulting in a substantial increase in the volume of CCA-treated wood slated for disposal. Until recently, landfilling was an acceptable means of discarding wood products impregnated with CCA, generating approximately 24 million tons of CCA waste. Concerns over metals leaching from the landfills and the impact on surrounding soil and groundwater have generated the need for a safe and efficient method of disposing of the CCA-treated wood.

Fast pyrolysis, the heating of biomass at temperatures between 400°C and 650°C in the absence of oxygen, is a promising technology for treating CCA-impregnated wood waste. Pyrolysis of lignocellulosic material produces char, liquid condensate (bio-oil), and non-condensing gases. Current research is focused on removing CCA from wood while utilizing the energy content of the wood. This is accomplished by concentrating the CCA metals in the bio-oil, for possible re-use in wood preservatives, during pyrolysis. A lab-scale pyrolysis system, capable of operating in the desired temperature range under atmospheric and vacuum conditions, has been designed. The system is also designed to enable the collection of each pyrolysis product so that complete mass balances on the metals can be performed, tracking the fate of the CCA components. This paper discusses the characterization of CCA-treated wood waste, the lab-scale pyrolysis system, and preliminary mass balances on the CCA metals.