Report on the burning of wood treated with wood preservatives containing copper, chromium and arsenic
A J Dobbs, C Grant
Mixtures of copper, chromium and arsenic salts are used extensively in the UK to preserve timber. This report is concerned with the fate of these metals when timber treated with these salts is burned. A large percentage of the arsenic present in the timber is shown to be volatilised during combustion and the potential environmental implications of this are assessed by comparison with the release of arsenic during coal burning. From this assessment it is concluded that burning of treated wood is unlikely to add significantly to the quantity of arsenic present in the atmosphere, although the concentration of arsenic in the discharged flue gases could give rise to local problems. Much of the arsenic and the chromium that remains in the ash is in the water soluble form and the possible implications of this are discussed. Recommendations based on findings reported here have been made to the Directorate General Water Engineering for consideration by the Arsenic Wastes Working Party which will be producing guidelines for the disposal of treated wood under the Control of Pollution Act 1974.