The occurrence of fixation reactions in Copper Chromium Arsenate (CCA) treatment solutions is increased where the treatment of unseasoned and partially seasoned timbers in hot climates occurs. The by-products of the fixation reactions are predominantly insoluble chromium arsenate compounds, commonly referred to as CCA sludge. Historically, this material has been disposed of into toxic waste landfills with little or no treatment at the timber treatment site. Attempts to use immobilisation techniques that would meet landfill leachate requirements have been difficult to achieve at economic rates. This paper describes the development of a chemical treatment process which separates the CCA sludge from the work solution and resolubilises the chemicals into a form suitable for reintroduction back into the CCA treatment solution. This process has successfully treated in excess of 100 tonnes of CCA sludge since 1990.

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