Chromated Copper Arsenate-Treated Wood in Recovered Wood

Abstract

Wood represents approximately 25% of the C&D waste stream, and a possible limitation to wood recycling is the presence of CCA-treated wood. Research was performed to measure the percentage of chromated copper arsenate (CCA)-treated wood present in recovered wood stockpiles at construction and demolition (C&D) waste recycling facilities in Florida. Because of the elevated levels of chromium, copper, and arsenic in CCA-treated wood the presence of this material in C&D-recovered wood waste limits possible management options. Quantifying the fraction of C&D wood waste comprised of CCA-treated wood is a necessary first step in addressing this issue. Shredded wood samples were collected from the 12 C&D recycling facilities in Florida in an effort to quantify the fraction of recovered wood that was treated with the waterborne preservative CCA. The samples were further size reduced and mixed, and ultimately ashed at 550°C in a laboratory furnace. Copper and chromium concentrations in the ash were measured using a flame atomic absorption spectrophotometer. These concentrations were used to calculate the amount of CCA-treated wood present in the original wood samples. The average percentage of 0.25-pcf standard retention, Type C, CCA-treated wood was estimated to be 6.5% based on copper and 5.9% based on chromium. In addition to providing needed measurements of CCA wood presence in C&D-recovered wood, this paper presents a methodology for estimating CCA wood amounts at other locations. Key words: Construction and demolition waste; CCA; chromium; copper; waste wood; recycling; treated wood; wood; solid waste