ASH FROM THE COMBUSTION OF WOOD TREATED WITH INORGANIC WOOD PRESERVATIVES - ELEMENT COMPOSITION AND LEACHING

Wood samples impregnated with inorganic wood preservatives containing the elements arsenic, boron, chromium, copper, fluorine, and/or zinc were burned in a furnace. Three different kinds of ash were collected: furnace, boiler, and so-called fly ash. Analyses showed that the ash contained large amounts of elements originating from the inorganic wood preservatives. Further interest was focused on the leachability of the above-mentioned elements. For this purpose a laboratory batch leaching test according to the German Standard DIN 38 414 part 4 was chosen. The results indicate that the leachability is in a range where the release of these elements to the environment from deposited ash can be considered as detrimental.