Electrokinetic Process for Removing Cu, Cr, and As from CCA-Treated Wood

The objective of this research was to evaluate the potential of electrokinetic metal extraction for removing Cu, Cr, and As from CCA-treated wood. Wood chips produced from new, unweathered, CCA-treated lumber were tested in a bench-scale electrokinetic system with two separate electrode compartments and a treatment compartment. Also investigated was the selection of metal extracting reagents for enhancing electrokinetic extraction efficiency. Extraction reagents tested in this study included oxalic acid, citric acid, EDTA, and ascorbic acid. Oxalic acid appeared to be most effective for extracting chromium and arsenic, while EDTA is the most effective reagent for copper extraction. Further testing using acid mixtures showed that EDTA mixed with oxalic acid achieved excellent extraction efficiencies for copper and arsenic. An electrokinetic extraction test, enhanced with the use of EDTA/oxalic acid mixture, removed 74% of Cr, 97% of Cu, and 88% of As from CCA-treated wood chips.