Bessie Woodward

Using copper-tolerant fungi to biodegrade wood treated with copper-based preservatives

Within the United States, the volume of wood products that was treated with copper-based preservatives grew exponentially during the 1970 s and 1980 s and remains at a high level today. Ultimately, these materials will have to be reused, recycled, or disposed in an environmentally acceptable manner. We are exploring whether copper-tolerant fungi might have utility in bioprocessing spent, treated wood after it is withdrawn from service. In laboratory experiments, Southern Pine sapwood was treated with copper-based wood preservatives, then challenged with wood decay fungi known to be tolerant of copper. For each preservative, fungal isolates were assessed for their potential to reduce the bulk of the treated product, as observed by weight loss. Low retention levels of some preservatives stimulated decay by Wolfiporia cocos, but not Postia placenta. Isolates of the copper-tolerant fungus Wolfiporia cocos (Schw syn. Poria cocos) varied significantly in their ability to degrade wood treated with copper-bearing preservatives and to concentrate copper in the mycelium. Copper was bioaccumulated (w/w basis) in mycelium of some isolates harvested from decayed wood, but the concentration of copper in the decayed wood residue was generally similar or only slightly different from that in the wood before decay.

Chemical remediation of wood treated with micronised, nano or soluble copper preservatives

Abstract The potential for extraction of copper from wood treated with micronised, nano or soluble forms of copper has been evaluated in view of chemical remediation. In focus were EDTA, oxalic acid, bioxalate, and d-gluconic acid for extraction of Cu from treated wood. Bioxalate extractions for 24 h resulted in Cu removal over 95% for all tested materials, and the effectiveness of oxalic acid extraction was very similar to that of nano-CuO-treated wood. Bioxalate was more effective than oxalic acid in removing Cu from ACQ-D, MCQ, MCA, CA-C and Cu-ethanolamine treated wood. d-gluconic acid extractions resulted in the lowest Cu removal for nano-CuO even though d-gluconic acid was effective for all other materials. As the pH of d-gluconic acid decreased, Cu removal was improved except for nano-CuO. There is no distinctive difference in Cu removal from wood treated with ACQ-D, MCQ, CA-C, MCA and Cu-ethanolamine.

Fifty-Year Durability Evaluation of Posts Treated with Industrial Wood Preservatives

Abstract Long-term durability data are needed to improve service life estimates for treated wood products used as critical structural supports in industrial applications. This article reports the durability of longleaf pine (Pinus palustris) posts pressure treated with ammoniacal copper arsenate (ACA), chromated copper arsenate (CCA), creosote, or pentachlorophenol and exposed for 50 years in southern Mississippi. During inspections, posts were subjected to a pass/fail evaluation by applying a load to the top of the post. No failures occurred in any of the 125 posts treated with CCA or in any of the 75 posts treated with pentachlorophenol. Three of 25 ACA-treated posts and 5 of 25 creosote-treated posts failed. Estimated times to 50 percent failure in the ACA- and creosote-treated posts were calculated as 96 and 78 years, respectively. The estimated years to failure for the CCA- and pentachlorophenol-treated posts could not be calculated because of the lack of failures but presumably would be greater than...