Recycling of CCA/CCB treated wood waste through bioremediation - A review

Impregnated-preserved wood has been widely used for more than a century. Some of the most extensive uses of treated timber are for posts and logs. Copper based formulations such as CCA (copper, chromium, arsenic) or CCB (copper, chromium, boron) are among the most important and widely used commercial wood preservatives. The life cycle of CCA/CCB treated wood is estimated to be about 20-50 years, depending on the method of treatment and conditions of service after which the wood is discarded as waste. Popular waste disposal options such as land filling and burning of the spent treated timber are not acceptable these days due to environmental, health and economical reasons. There is therefore a worldwide need to develop alternative methods for disposal of CCA/CCB treated wood wastes. One of the options being investigated in recent years is the use of copper tolerant organisms (fungi) for bio-recycling of CCA/CCB treated wood through bioremediation and biodeterioration (bulk reduction). This paper discusses copper toxicity and the mechanisms of copper tolerance by brown rot fungi. Bioremediation of CCA/CCB treated wood wastes using brown rot wood decay fungi and potential uses for the clean wood fibres are also discussed.