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Recovery of copper chromium and arsenic from old CCA treated commodities
1998 - IRG/WP 98-50118
Due to the expected increase in spent treated wood over the next several decades, numerous means to reuse and recycle preserved wood have been proposed. Burning this wood for cogeneration or recycling of CCA treated wood into reconstituted composites are possible methods, but they are limited to laboratory scale because of environmental air emission issues and the manufacturing process. In the available literature, laboratory removal of CCA from treated wood has been conducted on 20 mesh size particles or saw dust. This approach requires chipping and grinding of lumber and poles into particles and saw dust. In the current study, about 95 to 100% copper, chromium, and arsenic were removed from 2 by 4's and pole sections without substantial modification of initial sample size. This extraction yield was obtained within 18 hours at temperatures ranging from 80- 100EC using a combination of citric acid and chelating agent at pH 4.
D P Kamdem, Wanli Ma, Jun Zhang, J Zyskowski


Removal of copper, chromium and arsenic from CCA treated wood using boron compounds
2005 - IRG/WP 05-50230
This study evaluates the copper (Cu), chromium (Cr) and arsenic (As) removal from CCA treated wood using boron compounds such as boric acid, borax (sodium tetraborate), and Timbor (DOT, disodium octaborate tetrahydrate) at varying (3 and 5%) concentrations. Remediation processes were taken at 1, 5 and 10 day intervals. Metals in remediated chips or sawdust were then analyzed using ICP and XRF. Results showed that, higher level of Cu was removed followed by As and Cr. The percentage removal of metals was higher in saw dust then chips. Borax at lower concentration (3%) removed 41.4%, 18.3% and 44.9% of Cu, Cr and As, respectively, in 10 days while at higher concentration (5%) 65.8%, 55% and 55.8% of Cu, Cr, As, respectively, were removed for the same period. Boric acid removed 39.7%, 15.5% and 35.6% at lower and 50.7%, 48.9% and 50.9% of Cu, Cr, and As at higher concentration, respectively, while DOT was not an effective extractant. Distilled water extraction removed 27.3%, 23.7% and 22.8% of Cu, Cr and As respectively. In case of chips, borax removed 30.3%, 19.7% and 24.9% of Cu, Cr, and As; boric acid removed 25.5%, 12.2% and 19.5%; DOT removed 22.8%, 10.8%, 14.2% and distilled water 17.7%, 11.1% and 10.2% of Cu, Cr, and As, respectively. Increasing the concentration of solution has greater effect on elements removal. Among the three compounds tested, borax removed higher levels of metals compared to boric acid and DOT.
B Tarakanadha, T Hata, S N Kartal, W J Hwang, Y Imamura


CCA removal from treated wood by chemical, mechanical and microbial processing
1998 - IRG/WP 98-50101-26
Most preservative-treated wood produced and consumed in the U.S. is treated with toxic inorganic compounds containing copper, chromium, and arsenic. Because chromated copper arsenate (CCA) is fixed to the wood, treated wood has not been considered toxic or hazardous and is currently landfilled. Increasing public concern about environmental contamination from treated wood combined with increasing quantities of CCA-treated wood nearing the end of it's service life has presented a recycling challenge for this fiber source. In this study, CCA-treated wood was processed by acid extraction, steam explosion and bacterial fermentation, and evaluated for removal of copper, chromium and arsenic. Copper was the least resistant to removal by these treatments, while chromium was the most resistant to removal. Grinding CCA wood chips into 20-mesh sawdust provided greater access to CCA components and greater removal of CCA metals by acid extraction and bacterial fermentation. Exposing CCA-treated sawdust to Bacillus licheniformis CC01 resulted in 91%, 15% and 45% removal of Cu (as CuO), Cr (as CrO3), and As (as As2O5), respectively. Eighty-one percent CuO, 62% CrO3, and 89% As2O5 was removed from CCA-treated sawdust by oxalic acid extraction alone. Combining acid extraction and bacterial fermentation resulted in similar rates of metal removal from CCA chips and sawdust; 80% reduction in CrO3, 100% removal of As2O5, 90 and 99% removal of CuO from chips and sawdust, respectively. Processing chips by steam explosion did not enhance removal of CCA components alone or in conjunction with acid extraction and bacterial fermentation. Grinding chips following acid extraction and prior to bacterial fermentation did not enhance the ability of the bacterium to remove metals from treated or steam exploded chips. The combination of acid extraction and bacterial fermentation was successful at removing 80-100 percent of the metals from CCA-treated wood sawdust and chips.
C A Clausen, R L Smith


Scale-up of a chemical process for copper-based preservative-treated wood wastes recycling
2012 - IRG/WP 12-50286
In recent years, the development of appropriate wood waste disposal options has been encouraged by severe regulations and expensive fees associated with wastes landfilling or burning. An efficient and economically attractive leaching process was developed at laboratory scale (200 mL) for CCA-, ACQ- and CA-treated wood wastes recycling. This leaching process consisted of three leaching steps of 2 hours each, at 75°C with a sulfuric acid concentration at 9.8 g/L followed by three water-rinsing steps. The objective of this study was to investigate a possible application of this process to various mixtures of copper-based preservatives-treated wood wastes at pilot scale (80 L). The mixture of copper-based preservative-treated wood wastes was defined in order to represent wood waste stream evolution in the next decades. At the end of the leaching process, more than 98% of arsenic, 89% of chromium and 99% of copper were removed from a mixture of treated wood. Metal concentrations of the effluents produced during leaching steps were higher than regulations for effluents discharge in urban sewer. Leachate treatment by precipitation-coagulation was highly efficient and achieved more than 98% metal removal. The remaining arsenic, chromium and copper concentrations of the final effluents satisfied Quebec City municipal effluent discharge regulations. Chemicals consumption (sulfuric acid, ferric chloride, sodium hydroxide) depends of the mixture composition of treated wood. Remediation costs (total direct, indirect and general costs) ranged from $140 to $180 per metric ton of treated wood (ttw) depending on percentage of CCA-treated wood in the mixture. The use of wood residue for energy production represents an operating income estimated at $155/ttw (considering an energetic value of $13 per GJ).
L Coudert, L Gastonguay, J F Blais, G Mercier, P Cooper, P Morris, A Janin, N Reynier


Removal of nano- and micronized-copper from treated wood by chelating agents
2013 - IRG/WP 13-50294
Micronized and nano-copper (Cu)-based and arsenic and chromium-free systems have received much attention for wood protection in recent years. Because they have different fixation, and micro-distribution properties, such copper systems may be more or less subject to release using known remediation methods than soluble forms of Cu. This study evaluated Cu recovery from wood treated with micronized- or nano-Cu via chemical extraction, and determined optimum release rates of Cu from micronized- and nano-Cu-treated wood compared with the release rates from soluble Cu-based wood preservatives. Chemical remediation in the study included chelating agents EDTA, oxalic acid, bioxalate, and D-gluconic acid at different durations, pH, and concentration levels to remove Cu from treated wood along with distilled water as controls. Cu removal rates increased from around 60% to over 95% when bioxalate was employed in the extraction process for all extraction durations. In extractions of nano CuO-treated wood for 24h, oxalic acid was able to remove 95% of Cu; however, bioxalate was able to remove somewhat less Cu. Bioxalate was, on the other hand, more effective than oxalic acid in removing Cu from ACQ-D, MCQ, MCA, CA-C and Cu-Et-treated wood. D-gluconic acid extractions resulted in the lowest Cu removal rate for nano-CuO. As the pH of D-gluconic acid was reduced from 10 to 2, the percentage Cu removal considerably was improved except for nano CuO. Results suggested that there is no distinctive difference in Cu removal rates among ACQ-D/MCQ, CA-C/MCA and Cu-Et wood preservatives. Nano-CuO was found to be resistant against EDTA extractions. Since it is a weak, noncorrosive, nonvolatile, nontoxic, biodegradable and inexpensive organic acid, D-gluconic acid can be used as an alternative to commercial EDTA and bioxalate in chemical remediation of Cu-treated waste wood.
S N Kartal, E Terzi, B Woodward, C A Clausen, S T Lebow


A Green and Novel Technology for Recovering Copper and Wood from Treated Waste - Part I
2015 - IRG/WP 15-50309
Preservative treatment of wood extends its service life. The US consumes about 70 million pounds of copper and produces about 7 billion board feet of treated wood annually. Burning and reusing CCA and copper treated wood wastes are disallowed by US EPA due to health and environmental concerns. Millions of pounds of copper and wood are disposed by landfill annually. The objective of this study was to develop a green technology that can remove copper from the treated wood wastes so that copper and wood can be reused. In this study, seven different aqueous solutions were evaluated for copper removal from treated wood sawdust and chips. Citric acid demonstrated the highest efficiency by recovering 100% copper followed by ammonium citrate and ammonium carbonate/bicarbonate solutions. Formation of copper complexes with the ligands such as citrate and ammonium ions attributed to the key chemical mechanisms for efficient copper removal. The changes of extraction solution color progressively from yellowish orange to dark blue corresponded to the changes in the ratio of citrate ions to ammonia in the solutions. Citric acid has been used extensively as a food and cosmetic additive. The safety, high efficiency and low cost of citric acid compared to the chemicals previously reported for treated wood remediation can overcome the obstacles for commercial consideration. The performance demonstrated in the extraction study by the ammonium salts provides a novel extraction system with further cost reduction options. The finding of excellent copper removal using treated wood chips is very significant since it saves a great amount of energy required to produce sawdust. After removal of copper, the chips offer more opportunities than sawdust for reuse in landscaping, pulping, energy production and many other applications. With the development of such a green and novel technology, we can reuse millions of tons of wood and copper to protect the environment, save natural resources and benefit generations to come.
S Chen


Preliminary study of the fungicidal and structural variability in copper naphthenates and naphthenic acids
1996 - IRG/WP 96-30114
Copper naphthenates, an oil-borne wood preservative listed by the American Wood-Preservers' Association (AWPA), is manufactured by complexing copper(II) with naphthenic acids. Prior to AWPA listing as a wood preservative, field experiments showed that copper naphthenates generally had good stability and were active against wood-destroying organisms. Recently, however, there have been reports of some copper naphthenate-treated poles rapidly failing. One possible explanation for the varying effectiveness could be that the structure, and resulting biological activity, of the naphthenic acids used to make copper naphthenate may vary. To test this hypothesis several naphthenic acids and copper naphenates were obtained and their fungicidal activity against three wood-destroying fungi measured. In addition, the chemical structure of the naphthenic acids were examined by proton- and carbon- NMR. Different activities were observed, especially against a copper-tolerant fungus. Some apparent correlations were seen between the fungicidal activity and chemical structures for the few samples studied.
T Schultz, D D Nicholas, L L Ingram Jr, T H Fisher


Sequestration of copper ions by the extracellular mucilaginous material (ECMM) of two wood rotting basidiomycetes
2004 - IRG/WP 04-10533
The radial growth rate of colonies originating from either whole or ECMM-free inocula of Coriolus versicolor was investigated. The presence of ECMM allowed colonies to maintain higher growth rates than those form ECMM-free inocula up to 2 mM CuSO4 in the medium. The ECMM of C. versicolor and G. trabeum was able to reduce the diffusion of copper ions in solution. The ‘raw’ ECMM of both fungi had a greater ability to reduce the diffusion of copper ions than ECMM which had been subject to dialysis to remove soluble, low molecular weight components. The ‘insoluble’ fraction of ECMM for both species was more effective than the ‘soluble’ fraction at reducing the diffusion of copper ions. It is concluded that ECMM confers some protection to hyphae against the toxic effects of copper ions on growth in vivo and that this due to the binding of copper ions to both the polysaccharide and to low molecular weight components of the ECMM
D Vesentini, D J Dickinson, R J Murphy


Influence of different fixation and ageing procedures on the leaching behaviour of copper from selected wood preservatives in laboratory trials
2003 - IRG/WP 03-20264
The paper focuses on the role of different parameters, such as fixation, sample size, wood species, and leaching in internationally standardized ageing procedures for wood preservatives from Europe, Japan and the United States. The leaching protocols used were EN 84, JIS K 1571 and AWPA E11 protocols. The wood species were Scots pine, Sugi and Southern Yellow Pine respectively. Three types of commercially important copper-based wood preservatives were used as model formulations, namely copper/copper-HDO, ammoniacal copper/quat and CCA. The most important factors determining the extent of copper leaching in the different lab trials were the sample size (volume/surface ratio) and the fixation conditions prior to leaching. On the other hand, the wood species and the leaching protocol itself were found to have only minor influence on the copper leaching rate in the test methods included in this study.
J Habicht, D Häntzschel, J Wittenzellner


International collaborative laboratory comparison of two wood preservatives against subterranean termites: Third update and first report
1996 - IRG/WP 96-10174
At the 24th annual meeting of IRG in Orlando, USA, in May 1993 an international subterranean termite laboratory bioassay to compare the various preferred termite protocols used by IRG termitologists was initiated. The author was nominated to co-ordinate this comparative laboratory evaluation of two wood preservatives, copper-chrome-arsenic (CCA) and copper naphthenate (Cu-Na) against the subterranean termites used as test termites in Australia, France, Japan, Thailand, United Kingdom and the Unites States of America. Solutions of these two wood preservatives were prepared and impregnated into Pinus radiata wood blocks to obtain loading of 0.0, 0.5, 1.0, 2.0 and 4.0 kg/m³ respectively. All preservative treatments were carried out at the Division of Forestry and Forest Products in Melbourne. The treated specimens were dispatched to the participating researchers who subjected these specimens to attack by their test termite species, and have now returned the specimens to Melbourne. This paper reports the amount of wood consumed and the mean mass loss (%) on both treated and untreated wood blocks by the termites in the various laboratory bioassays.
J R J French


Types of decay observed in CCA-treated pine posts in horticultural situations in New Zealand
1984 - IRG/WP 1226
The few reported failures of 11-12-year-old horticultural posts in New Zealand in 1982 were caused by brown-rot. A subsequent survey of CCA-treated posts in all the major horticultural areas has revealed decay of many posts. A microscopic examination of these posts has shown decay by brown-rot, white-rot, soft-rot and bacteria. Several types of bacterial decay have been observed.
J A Drysdale, M E Hedley


An investigation of the effects of pre-steaming on the treatment of sawn spruce timber with Celcure A, a copper-chrome-arsenic preservative
1981 - IRG/WP 3150
Difficulties in the treatment of spruce using standard vacuum/pressure techniques with both water-borne and organic solvent preservatives are well known. We have evaluated the influence of steaming on treatability with a waterborne CCA preservative.
C R Coggins


Electrodialytic remediation of creosote and CCA treated timber wastes
2002 - IRG/WP 02-50190
There is a growing concern about the environmental issue of impregnated timber waste management, since an increase in the amount of waste of treated wood is expected over the next decades. Presently, no well-documented treatment technique is yet available for this type of waste. Alternative options concerning the disposal of treated wood are becoming more attractive to study, especially the ones that may promote its re-use. Inside this approach, the electrodialytic process (ED) seems a promising technique for removal of preservative chemicals from treated wood waste. The method uses a direct electric current and its effects in the matrix as the “cleaning agent”, combining the electrokinetic movement (mainly due to electromigration, but also electro-osmosis and electrophoresis), with the principle of electrodialysis. This work reports results from the application of the electrodialytic process to an out-of-service Portuguese creosote and CCA-treated Pinus pinaster Ait. railway sleeper and pole. The behaviour of the process is described and the main results discussed. The average removal rate, estimated in accordance with prEN 12490, for creosote from treated timber waste was around 40 %.. For CCA treated timber waste, experimental conditions that could optimise the process efficiency (e.g. current density, time) were studied. The highest removal rates obtained until now, in our studies, were 93 % of Cu, 95 % of Cr and 99 % of As for sawdust using 2.5 % oxalic acid (w/w) as the assisting agent. For CCA treated wood waste in the form of chips, the best removal rates obtained until now were 84 % of Cu, 91 % of Cr and 97 % of As.
E P Mateus, A B Ribeiro, L Ottosen


Fungicidal activity of some organic solvents, copper carboxylates and their complexes with 2-aminoethanol
1997 - IRG/WP 97-30136
We evaluated the activity of eight organic solvents against wood - rotting fungus Trametes versicolor in order to choose the most appropriate one for rapid screening tests of some copper(II) carboxylates and their adducts with 2-aminoethanol. Their activity against the selected fungus was classified in the following order: chloroform > N,N-dimethylformamide > acetonitrile > methanol > dimethyl sulfoxide > ethanol > acetone. The non-polar white spirit did not dissolve in the growth medium and the results could not be directly compared with the results for other solvents. As an appropriate solvent for screening of the tested copper(II) carboxylates, dimethyl sulfoxide (DMSO) was chosen. Minimal inhibitory concentration against Trametes versicolor of the screened carboxylates was in the concentration range of 1x10-4 to 1x10-3 mol/l. Coordinated amine ligands slightly, and not significantly, decreased fungicidal properties of the tested carboxylates.
M Petric, F Pohleven


Termite resistance of pine wood treated with chromated copper arsenates
1997 - IRG/WP 97-30128
Two four-week, no-choice laboratory tests were performed with CCA-treated southern yellow pine and radiata pine against Formosan subterranean termites, Coptotermes formosanus. CCA retentions as low as 0.05 kg/m3 (0.03 pcf) provided protection from all but light termite attack (rating of 9 on a 10-point visual scale). Similar and consistent light attack on wafers containing retentions as high as 6.4 kg/m3 (0.4 pcf), coupled with complete termite mortality, demonstrates that the mode of action of CCA treatments relies upon toxicity rather than having any repellent effects against termites.
J K Grace


Problems of fixation of CCA-preservatives in palm-wood
1985 - IRG/WP 3338
Palm-wood may be used for posts and poles where it needs proper treatment for long time use. Based on observations by W. Killmann on low CCA-fixation in palm-wood, samples of Jubaea-palm grown in a Greenhouse at Hamburg, have been treated in two different series with a 4% solution of CCA-type B. After 1-16 weeks of storage the blocks were split into sticks of 1-2 mm² and leached. In all series 50% of the chromium and copper content of the individual blocks was leached independent of the time of storage, whereas simultaneously treated pinewood samples showed complete fixation after 4 weeks of storage.
H Willeitner, K Brandt


Field Testing of Copper Carboxylate Preservatives
2003 - IRG/WP 03-30322
This paper details our ongoing experience with field testing of copper naphthenate and other copper carboxylate preservative systems. Results from field stake tests at an AWPA Hazard Zone 4 test site are presented. In general, copper carboxylates made with ‘synthetics’ yielded results equivalent to or only slightly lower than systems with straight nap acids or nap acids amended with synthetic neo acid bottoms.
H M Barnes, M G Sanders, T L Amburgey


The leaching of copper, chrome and arsenate from CCA-impregnated poles stored for ten years in running water
1978 - IRG/WP 3122
There is no evidence to indicate that the chromium and copper components are leached from the outermost 5 mm of sapwood in poles impregnated with Boliden K33 and Tanalith C and stored in running water for ten years. The arsenic component, however, seems to be leached out during the first few months to an extent of about 20% of the initial amount. The leaching time is dependent on the preservative used.
F G Evans


Recent soft-rot research in softwoods and hardwoods
1980 - IRG/WP 1108
The purpose of this paper is to describe briefly the current status of our research on soft-rot fungi. The work to be discussed is still in progress and any results described must be regarded as provisional.
J A Butcher


A new concept of oxalic acid biosynthesis in physiology of copper-tolerant brown-rot fungi
2001 - IRG/WP 01-10394
Recently, a wide variety of roles of oxalic acid (oxalate) in wood decay systems have been receiving much attention. Copper tolerance of wood-rotting basidiomycetes has been believed to be due to the detoxification of copper wood preservatives by oxalate produced by these fungi. However, biochemical mechanism of oxalate biosynthesis in relation to physiology of wood-rotting fungi has not been elucidated although two oxalate-forming enzymes, oxaloacetase and glyoxylate dehydrogenase, have been studied in our laboratory. Recently, a new role of glyoxylate cycle in oxalate biosynthesis in wood- rotting fungi has been presented, and the cycle commonly occurred to varying extents among the fungi although they were grown on glucose. Enzymatic analyses showed that isocitrate was cleaved by isocitrate lyase in the glyoxylate cycle rather than oxidized by isocitrate dehydrogenase in tricarboxylic acid (TCA) cycle, and the fungi were found to lack a normal TCA cycle due to the absence of - ketoglutarate dehydrogenase. It is noteworthy that glucose was efficiently converted to oxalate in a theoretical yield of about 80%, accumulating in the culture media of F. palustris. The results further indicate that acetyl-CoA derived from glucose was not completely oxidized to CO2 in TCA cycle but was mainly converted to oxalate with help of the other coupling metabolic cycles, including glyoxylate cycle. Formation of oxalate from several intermediary metabolites using cell-free extracts of F. palustris confirmed that oxalate is also the final product of the metabolic pathway in the in vitro system. Thus, it is proposed as a new concept that most of copper-tolerant brown-rot fungi may acquire the energy by oxidizing glucose to oxalate, i.e. oxalate fermentation expressed in the following equation; Glucose + 5O2 --> 2 Oxalate + 2CO2 + 4H2O.
E Munir, T Hattori, M Shimada


Copper naphthenate performance: A new way to look at old data
2000 - IRG/WP 00-30215
Although copper naphthenate has over a 50-year test history, it is still considered as a "new" preservative in the United States when it is used for utility poles. It has also been extensively used in remedial treatments for poles and has considerable retail or over-the-counter sales. The test history includes a number of different tests and a rationale for evaluating this data and comparing the performance of copper naphthenate to other common pole preservatives is presented. Thus, the efficacy of copper naphthenate can be easily summarized.
C R McIntyre


The biostatic effect of copper on decay of fire retardant-treated mining timber
1991 - IRG/WP 1507
Blocks of Eucalyptus grandis were treated with 20kg/m³ ammonium sulphate as fire retardant and challenged with Coriolus versicolor. Replicates were soil buried. A second set of blocks was treated with retardant and copper at 6.6 kg/m³ (ie 1% w/w), and challenged similarly. After 8 weeks weight losses produced by Coriolus versicolor in untreated, retardant treated and copper supplemented blocks were 45, 25, and 0% respectively, and corresponding weight losses in soil were 27, 25 and 10%. These results, and electronmicroscopical observations, showed conclusively that Eucalyptus grandis treated with fire retardant was rapidly decayed, and that copper inhibited such decay.
G D Shelver, E A Shelver, A A W Baecker


Depletion of boron and copper from CCB treated test specimens using different leaching protocols
2004 - IRG/WP 04-50208
The objective of this study was to measure the depletion of inorganic wood preservative components regarding the proposed OECD guideline "Estimation of emissions from preservative-treated wood to the environment: laboratory method for wooden commodities exposed in the use class 4 and 5" as part of the project "Investigations concerning the influence of test parameters on the release of biocidal actives from treated timber in leaching tests". Pine sapwood specimens (50x10x150) were pressure impregnated with CCB according to European Use Class 4. Before leaching all samples were stores 4 weeks for fixation. In addition leaching tests were performed according to the European Standard EN 84 by means of EN 113 blocks. Parallel investigations were carried out between two laboratories to assess the repeatability and comparability of the methods. The results of chemical analysis of leachates taken at different time intervals show that similar depletion rates were determined for copper and boron independent on the leaching protocol used. However, the loss of copper as well as chromium in short term dipping experiments was often lower than the detection limit. Furthermore it can be stated that the difference between parallels was higher for the results which were obtained for the OECD guideline that EN 84. A comparison of both laboratory results indicate that a quite good repeatability is given in case of the CCB treated material.
E Melcher, R-D Peek, U Schoknecht, R Wegner


Light organic solvent preservative treatment of glue-laminated radiata pine
1986 - IRG/WP 3380
The high permeability of radiata pine (Pinus radiata D. Don) is associated with ray-tissue and in particular the cross-field pits linking ray-tissue to tracheids. This pathway is absent in the tangential grain direction, leading to poor preservative penetration when treatment is restricted to the radial face - for example, timber fabricated into glue-laminated beams.
P Vinden


Effectiveness and synergistic effects between copper and polymer betaine
1996 - IRG/WP 96-30097
Different formulations of "Copper Amine" and Polymer Betaine were studied. During laboratory tests a synergism between both active ingredients against soft rot and dry rot has been found. The efficacy against soft rot according to the "BAM method" and the European Standard ENV 807 depends only on the amount of copper. Long term tests in a fungus cellar for determining the relative protective effectiveness in ground contact show similar results as CCA-treated wood.
H Härtner, V Barth


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