(565b) Investigation of the Extraction and Recycle Potential of CCA Treated Wood Waste

Since the early 1970’s, the most widely used preservative in the wood preservation industry has been chromated copper arsenate (CCA) treatment.  Current estimations suggest that there may be as much as 240 million tons of CCA wood waste available for Disposal by the year 2020.  

Until recently, landfilling the out of service materials was a generally accepted method of disposal.  Recently, problems with soil and groundwater contamination have arisen, and the role of CCA impregnated wood waste in the matter has been confirmed. As a result, the need for an efficient and effective method of heavy metal separation form wood waste has become eminent. 

The focus of this research is to recover the energy value from the wood while offering a recycling opportunity for the CCA components of the wood.  In this research, the removal of the copper, chromium and arsenic from the CCA treat wood was examined using pyrolysis.   Mass balances were conducted to determine if the metals were found in the pyrolysis char or in the pyrolysis liquid fraction.  In addition, the metal contaminated char was subjected to electrokinetic treatment (EK) and the post treated char was examined.  Result show that pyrolysis is an effective method for removing the Arsenic and some of the chrome from the char.  By treating the char with EK the removal of almost all of the metals contaminates could be extracted from the char.   The ultimate goal of this research was to evaluate pyrolysis and EK as a combine treatment process for recycle.  The full scale potential of this process will also be discussed.