Bioremediation and decay of wood treated with ACQ, micronized ACQ, nano-CuO and CCA wood preservatives

Abstract Copper (Cu) removal from wood treated with micronized, nano- or soluble forms of Cu was evaluated relative to exploration of systems that could detoxify chemicals in wood for recycling and a broader interest in bioremediation by fungi. Decay of treated wood blocks by the fungi was also studied relative to the amount of copper metal initially present, and also removed. In the fungal bioremediation tests, liquid fungal cultures were first employed to remove Cu from treated wood, and also to evaluate mechanisms that fungi use to overcome Cu-based preservatives. In most cases, when treated ground wood samples were exposed to the fungi used, Cu removal rates were over 90%; however, nano-CuO-treated wood was resistant to removal by most fungi tested. No distinct differences were seen between ACQ and micronized ACQ-treated wood in terms of Cu removal. Moderate to high mass loss associated with decay of the treated wood blocks occurred by the brown rot fungi. Mass loss was associated with moderate levels of Cu removal from the blocks, but in some blocks the removal of Cu was not correlated with mass loss. Several strains of Serpula lacrymans were found to remove 80–98% of the Cu from ground wood samples. Bioremediation of Cu-treated wood by fungi may offer advantages even though longer fungal remediation process durations may be needed for higher Cu releases. It might be important to develop specific remediation processes for new generation nano-Cu-based wood preservatives.