CCA removal from treated wood using a dual remediation process

Novel approaches to remediate chromated-copper-arsenate (CCA)-treated waste wood are needed to divert this material from landfills. In this study, CCA-treated wood wafers were treated with a two-step remediation process to remove copper, chromium and arsenic. Process conditions, involving an acid extraction and bacterial culture with a metal-tolerant bacterium, were optimized. It was determined that 18 h of exposure to 1.0% oxalic acid was an optimal exposure time for the size of wood used in this study. Oxalic acid concentration was then varied to determine optimal concentration for metal removal. Increasing concentrations of oxalic acid removed increasing quantities of copper, chromium and arsenic. Acid extraction at 0.80% and bacterium exposure resulted in a total reduction of 78% copper, 91% chromium and 93% arsenic. An 0.8% of oxalic acid followed by bacterial culture with Bacillus licheniformis CC01 afforded the best conditions for maximum removal of copper, chromium, and arsenic from treated wood with minimal exposure of the wood fiber to acid conditions.