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Disposal of treated wood - Canada
1990 - IRG/WP 3563
It is estimated that treated wood removed from service each year in Canada contains about 16,000 tonnes of creosote, 1000 tonnes of pentachlorophenol and 245 tonnes of CCA or ACA. The amount of CCA treated wood for disposal is expected to increase more than ten-fold by the year 2020. At present, most treated wood is disposed of in landfills, burned (creosote only) or recycled as other products. Other approaches to reduction, reuse, recycling and disposal are discussed.
P A Cooper

Disposal of Pressure Treated Wood in Construction and Demolition Debris Landfill
2005 - IRG/WP 05-50235
Pressure treated wood is often disposed in landfills in the US, very frequently in construction and demolition (C&D) debris landfills. C&D debris disposal facilities in many states are not equipped with liner systems to protect underlying groundwater. In this paper, issues associated with the disposal of metal-containing treated wood in C&D debris landfills are discussed. C&D debris landfills can be biological active systems, dominated by the activity of sulfate reducing bacteria. The leachate is characterized by relatively low biodegradable organic compound concentrations, high salt concentrations, a neutral pH, and a moderately to strongly reducing environment. Simulated landfills containing CCA-treated wood often show relatively high concentrations of As and Cr, but only minimal concentrations of Cu. Cu-based preservatives such as alkaline copper quaternary (ACQ) also show minimal copper leaching, suggesting that disposal of Cu-based wood preservatives posees minimal impact to groundwater from Cu leaching.
T G Townsend, B Dubey, J Jambeck, H M Solo-Gabriele

Disposal of CCA treated waste wood by combustion - An industrial scale trial
1996 - IRG/WP 96-50068
Totally 272 m³ (62.7 t) of CCA treated utility poles were chipped and incinerated at Jalasjärvi Gasification Plant. In average the whole batch of chips contained 57 kg of elementary copper, 95 kg chromium and 76 kg arsenic. During the 56 h combustion trial the measured arsenic emission to the air was 76 g in total. Copper and chromium emission was less than 1 g. The condensing water from the cooling unit and the ash from the gasifier were collected and transported to Outokumpu Harjavalta Metals Oy and finally circulated through a copper refinery line.
A J Nurmi

Bioprocessing preservative-treated waste wood
2000 - IRG/WP 00-50145
Disposal of preservative-treated waste wood is a growing problem worldwide. Bioprocessing the treated wood offers one approach to waste management under certain conditions. One goal is to use wood decay fungi to reduce the volume of waste with an easily managed system in a cost-effective manner. Wood decay fungi were obtained from culture collections in the Mycology Center and Biodeterioration research unit at the USDA-FS Forest Products Laboratory (FPL), Madison, Wisconsin, and from FPL field sites. The 95 isolates had originally been taken from at least 66 sites from around the United States. Isolates were screened in a bioassay (known as the 'choice test') for tolerance to CCA, ACQ, creosote and pentachlorophenol. A tolerant rating was based on fungal growth toward or on treated wood, with 17 tolerant to CCA, 21 to ACQ, 12 to creosote and 5 to pentachlorophenol. Decay capacity of the tolerant isolates was determined as percent weight loss by the ASTM D-1413-76 soil bottle method. We identified 8 isolates for experiments on preservative remediation. Isolates of Meruliporia incrassata and Antrodia radiculosa gave the highest percent degradation of ACQ and CCA-treated wood. Several A. radiculosa isolates and a Neolentinus lepideus isolate grew on creosote-treated wood, but had only a 4-5% weight loss. In this paper we discuss the potential use of decay fungi to degrade or remediate preservative-treated wood.
B Illman, V W Yang, L Ferge

Microbial decomposition of salt treated wood
1993 - IRG/WP 93-50001-22
Specialized microorganisms which are able to convert fixed inorganic preservatives from treated wood into water soluble components are investigated. A number of brown rot fungi like Antrodia vaillantii have been isolated from cases of damage and examined under unsterile conditions with CCA-, CCB-, CCF- and CC-treated wood at retention levels of at least 50% higher than recommended for wood in ground contact. Depending on the kind of fungus, preservative retention, wood particle size, culture conditions and duration Cr and As can be almost completely leached from the treated wood. Cu reacts with oxalic acid to a compound of limited water solubility.
R-D Peek, I Stephan, H Leithoff

Biological detoxification of wood treated with salt preservatives
1992 - IRG/WP 92-3717
The use of microorganisms that are capable to convert chemically fixed inorganic preservative complexes from impregnated wood waste into watersoluble components is investigated. A number of fungi were isolated from deteriorated and initially well-treated wood. They revealed an exceptionally high production of organic acids (pH 2). The fungi were identified and used together with others of the same genus for experiments under non-sterile conditions on a laboratory scale with CCA-, CCB and CC-treated wood at retention levels of at least 50% higher than recommended for wood in ground contact. As a result Cr and As were leached to more than 90% depending on culture conditions, whereas Cu reacts with oxalic acid to a complex with limited water solubility.
I Stephan, R-D Peek

Why did Japan replace CCA by alternatives?
2004 - IRG/WP 04-50215
Since chromated copper arsenate (CCA) was technically introduced into Japan in 1963, CCA was used for extending service life of various wood commodities, especially sill plates (dodai) in Japanese houses. However, the problem on the disposal of CCA-treated wood waste became public and related industry concern, and questionnaire survey conducted by Japan Wood Preservers’ Industry Association indicated that Japanese treatment plants could not meet the new strict criterion (tolerance limit) of arsenic (<0.1 mg/) in the discharged water in the revise regulation, Water Pollution Prevention Act in 1995. In addition, on the basis f the fact that alternatives to CCA were domestically standardized in 1995 (JUS K 1570, 1995), Japanese wood preserving industry came to a self-imposed decision to restrict the use of CCA. Alternatives actually appeared in the marketplace in 1991, and a drastic increase in their use has been prominent since 1996. They account for over 85% of total amount of wood produced by pressure-impregnation with preservatives.
H Ishida, T Ito, M Yamai, H Matsusaka, K Tsunoda

Metal Leaching from Pressure Treated Wood in Sanitary Landfill Leachate
2004 - IRG/WP 04-50220
Pressure treated wood products contain heavy metals to prevent biological decay. Scrap treated wood from construction activities and demolished structures containing treated wood are typically disposed in landfills. To examine the potential mobility of metals from pressure-treated wood disposed in landfills, wood samples were leached using leachate from lined landfills and the concentrations of arsenic, chromium and copper were measured. Samples evaluated included unweathered and weathered chromated copper arsenate (CCA) treated wood samples and arsenic- and chromium-free pressured-treated wood products. Results showed that in general the arsenic and chromium concentrations leached using the landfill leachate samples varied somewhat among the sites, but tended to be similar or somewhat lower than the TCLP and SPLP concentrations. Copper leaching was greatest when extracted with the landfill leachate for CCA-treated wood. Among the alternatives to CCA-treated wood, copper leaching was more in the TCLP for some of the alternatives while landfill leachate extracts had higher copper concentrations in others.
B Dubey, T G Townsend, H M Solo-Gabriele

Future Directions Regarding Research on the Environmental Impacts of Preservative-Treated Wood: Environmental Impacts of Preservative-Treated Wood. February 8-11, 2004, FL, USA Workshop – Research Needs
2004 - IRG/WP 04-50222
This paper presents a series of documents that focus on research needs for potential future work focusing on the environmental impacts of preservative-treated wood. These documents were developed through a conference sponsored by the Florida Center for Environmental Solutions (FCES), located in Gainesville, Florida. The conference was held in Orlando, Florida, February 8 – 11, 2004 and the title of the conference was, “Environmental Impacts of Preservative-Treated Wood.” Approximately 150 people from 15 countries attended the conference. The “research needs” documents developed to date were summarized from: 1) feedback received from conference participants prior to the conference and 2) a two hour workshop held at the conclusion of the conference. A draft voting ballot has been prepared from these documents. This ballot is currently being reviewed by the FCES conference Technical Advisory Committee and a final ballot will be released in mid-April for a vote among the conference participants. A copy of the draft voting ballot is included at the end of this document. Results of the vote will be released at the 35th Annual IRG Meeting in Slovenia.
H M Solo-Gabriele, J D Schert, T G Townsend

The Disposal of CCA-Treated Wood in Simulated Landfills: Potential Impacts
2003 - IRG/WP 03-50198
Landfills are typically where CCA-treated wood is currently disposed, and will likely continue to be the primary form of management in the future. It has been shown that arsenic, copper and chromium leach from CCA-treated wood in certain situations; however, the impact of the disposal of CCA-treated wood on landfill leachate is currently unknown. The objective of this research is to examine the potential effect of the disposal of CCA-treated wood on landfill leachate characteristics. Disposal in C&D debris landfills, the facilities where CCA-treated wood is typically managed in Florida, United States (U.S.), was examined. In other states, CCA-treated wood may go to municipal solid waste (MSW) landfills, which are required to have liners and leachate collection systems under U.S. law. Thus, the MSW landfill disposal scenario was examined as well. Finally, the disposal scenario of CCA-treated wood in a monofill, or a landfill where only CCA-treated wood is disposed, was explored. The effect of CCA-treated wood on leachate in each of these three scenarios was examined by creating simulated landfill environments each containing CCA-treated wood. Six lysimeters (simulated landfill columns), two for each disposal scenario, were constructed and operated; both control lysimeters (no CCA-treated wood) and experimental lysimeters containing CCA-treated wood were constructed for the three scenarios. Natural and simulated rainwater was allowed to infiltrate and percolate through the waste in the lysimeters creating leachate. Leachate was generated by the lysimeters and analyzed for arsenic, copper and chromium concentrations and general water quality parameters.
J Jambeck, T G Townsend, H M Solo-Gabriele

Management strategies for the disposal of CCA-treated wood
2000 - IRG/WP 00-50155
A two-fold management strategy is presented for the disposal of wood treated with chromated copper arsenate (CCA). The first part focuses on the use of alternative wood treatment preservatives. The second part of the management strategy addresses short-term disposal issues (less than 25 years) by developing new methods to handle the waste. A set of seven alternative wood preservatives were evaluated through this study. Issues evaluated included efficacy, depletion, corrosion, and costs. Results indicate that viable alternatives are available for CCA-treated wood for the lower retention levels (4 to 6.4 kg/m3). The development of disposal-end management strategies for CCA-treated wood began by tracking the discarded wood within the disposal sector of the State of Florida, USA. It was found that existing disposal methods, which included disposal within unlined landfills and recycling either as mulch or wood fuel, were not acceptable. New disposal-end management strategies evaluated included treatment methods for CCA-treated wood ash and two sorting technologies for separating CCA-treated wood from other wood types within the disposal stream. Results indicate that citric acid is effective at removing arsenic from CCA-treated wood ash. Chemical stain and x-ray based methods were found suitable for sorting treated from untreated wood.
H M Solo-Gabriele, T G Townsend

Technologies for the Management of Wood Waste Containing Metals-Based Preservatives
2005 - IRG/WP 05-50224-16
Disposal of the metals from preservative treated wood can occur through two general strategies: “removal and confinement” or “dilution”. The acceptability of each of these two choices is typically dictated through the disposal regulations of a particular region. A considerable amount of research has been conducted to develop new and innovative “removal and confinement” technologies for treated wood waste. These technologies include disposal through bioremediation processes (including use of bacteria and fungi), chemical extraction processes, electro-dialytic treatment, and alternative thermo-chemical processes. “Removal and confinement” strategies will likely require adequate sorting and separation of the waste prior to disposal for mixed waste streams. “Dilution” strategies, which are typically less costly than “removal and confinement” technologies, include the management of treated wood through the regular solid waste stream. In some cases recycling of the wood waste may be allowed for certain re-use and recycling applications. In most regions, management of treated wood as regular solid waste will likely occur through either landfill disposal or through incineration at solid-waste processing facilities. Disposal through incineration will require air pollution control devices to minimize volatile releases and as a result the majority of the metals will accumulate within the ash. If the treated wood waste is co-disposed with other wastes there may be sufficient dilution to provide for a non-hazardous ash, which can be landfilled. Over time disposal of metal-treated wood in landfills (as either unburned wood or as ash) will likely result in the release of the metals from the wood resulting in higher metals concentrations in leachates from landfills. Whether or not this leachate is treated will depend upon whether or not there is sufficient dilution to maintain metals concentrations below certain regulatory thresholds. Thus the choice of suitable disposal options for wood treated with metal-based preservatives is dictated highly by the regulations of a particular region. These regulations are a reflection of the community’s “dilution capacity” and the balance between economics and allowable levels of environmental contamination.
H M Solo-Gabriele, T G Townsend

CCA-treated Wood Disposed in Landfills and Life-cycle Trade-Offs With Waste-to-Energy and MSW Landfill Disposal
2005 - IRG/WP 05-50231
CCA-treated wood as a solid waste is managed in various ways throughout the world. Although some wood is combusted for the production of energy in the U.S., more often than not, CCA-treated wood is disposed in landfills. In other countries, wood, often including CCA-treated wood, is combusted for the production of energy. This paper is presented in two parts. Part I evaluates the impact of CCA-treated wood in three landfill settings: a wood monofill, a C&D debris landfill and a municipal sold waste (MSW) landfill. Part II utilizes the data found in the first part, along with data found in the literature to examine the trade-offs between landfilling and waste-to-energy (WTE) combustion of CCA-treated wood through a life-cycle assessment and decision support tool (MSW DST). The disposal of CCA-treated wood affected all three landfill disposal scenarios increasing concentrations of arsenic and chromium especially. Although the acid-forming phase of the MSW landfill aggressively leached metals, the methanogenic phase was not as aggressive and the impact to the leachate from the CCA-treated wood was less than for C&D debris landfills. Additionally, the decreased impact is a result of the CCA-treated wood comprising a smaller portion of the MSW waste stream by mass. For this reason, and because MSW landfills are lined, MSW landfills were concluded to represent a preferred disposal option over unlined C&D debris landfills. If leachate is collected, leachate treatment in both situations may become more difficult and expensive if concentrations exhibited in this research are observed. Between landfilling and WTE for the same mass of CCA-treated wood, WTE is more expensive (nearly twice the cost), but when operated in accordance with U.S. EPA regulations, it produces energy and does not emit fossil carbon emissions. If the wood is managed via WTE, less landfill area is required, which could be an influential trade-off in some countries. Although metals are concentrated in the ash, the MSW landfill scenario releases a greater amount of arsenic from leachate on an annual basis, but it is more dilute. The ash disposal scenario releases less arsenic from leachate on an annual basis, but concentrates it. The ash disposal releases more chromium on an annual basis. The WTE facility and subsequent ash disposal greatly concentrates the chromium, often oxidizing it to the more toxic and mobile Cr(VI) form. Elevated arsenic and chromium concentrations in the ash leachate may increase disposal costs.
J Jambeck, K Weitz, T G Townsend, H M Solo-Gabriele

Recycling of CCA treated wood in the US
1998 - IRG/WP 98-50101-08
The production of CCA treated wood has increased dramatically in recent years. Previous estimates of the volume of treated wood to be removed were based on the assumed service life of the material, generally 20 to 25 years. This study based on a survey of contractors installing treated decks, determined that the actual service life of these decks is much shorter than their assumed functional service life. Home owners replace decks for various reasons beyond the soundness of the wood, including many reasons related to the look, appearance, and style of the deck. These new estimates of CCA treated wood likely to be removed in the near future greatly increases the volume destined for disposal primarily in landfills. This increases the pressure on these sites and may make competing disposal methods more attractive.
J McQueen, J Stevens, D P Kamdem

Environmental Impacts of CCA-Treated Wood: A Summary from Seven Years of Study Focusing on the U.S. Florida Environment
2003 - IRG/WP 03-50205
Wood treated with chromated copper arsenate (CCA) was identified in 1995 as the cause of elevated arsenic concentrations within wood fuel used for cogeneration within Florida. Since this time a research team from the University of Miami and University of Florida has evaluated the environmental impacts of CCA-treated wood within the State. Research has focused on two distinct areas: in-service leaching of the CCA chemical and disposal pathways for the discarded product. In-service leaching was evaluated by sampling soils located below 9 pre-existing decks (8 CCA treated and 1 not CCA treated) and 2 decks (one CCA treated and one untreated) constructed over a leachate collection system. Results showed that CCA-treated decks leach chemicals in quantities that will impact soil quality. For the pre-existing decks, the average background soil arsenic concentrations were 1.5 mg/kg. Immediately below the pre-existing decks the average soil arsenic concentration was 28.5 mg/kg. Runoff for the decks constructed over a leachate collection system contained over 1 mg/L arsenic and chromium. Arsenic in the runoff was predominately in the +5 valence; however, some As(III) has been measured. A considerable effort by this research team has been placed on evaluating the fate of CCA-treated wood upon disposal. The research has shown that the quantities of discarded CCA-treated wood will increase significantly in the future. Current disposal pathways for CCA-treated wood include construction and demolition (C&D) debris landfills (which are generally unlined in Florida) or inadvertent mixing within mulch and wood fuel that is produced from recycled C&D wood. Samples collected from C&D debris facilities located in Florida indicate that CCA-treated wood can represent up to 30% of the recycled wood by weight. Research has shown that the CCA chemical is capable of leaching from CCA-treated wood (both in the unburned form and as ash) in quantities that exceed regulatory thresholds established by the U.S. Environmental Protection Agency, thereby suggesting that discarded CCA-treated wood should in many cases be managed as a hazardous waste. When CCA-treated wood represents 5% or more of a recycled wood mixture, the ash from its combustion will typically be characterized as a toxicity characteristic (TC) hazardous waste. Both new and weathered CCA-treated wood has been found in a majority of cases to leach arsenic at concentrations greater than the TC regulatory limit. Results from chemical speciation analysis indicate that unburned wood leaches arsenic primarily in the +5 valence and chromium in the +3 valence. Chemical speciation of the ash however was much more variable with some samples showing significant amounts of As(III) and Cr(VI). Commercial mulch purchased at retail establishments in Florida also was shown to leach arsenic at levels that exceeded the State’s risk-based Groundwater Cleanup Target Levels. The presence of leachable arsenic within the mulch was attributed to the presence of CCA-treated wood. Potential solutions to the CCA-disposal problem have been explored including options for waste minimization and disposal-end management of the treated wood. Waste minimization focuses on the use of alternative wood treatment preservatives that do not contain arsenic. Non-arsenical chemicals evaluated include ACQ, CBA, CC, and CDDC. These alternatives were shown to leach less arsenic but more copper than CCA-treated wood. Options for disposal-end management explored through this study include sorting technologies to separate CCA-treated wood from other wood types. Sorting technologies explored included the use of a chemical stain and two systems based upon the use of lasers or x-rays. Chemical stains were found to be effective for sorting small quantities of CCA-treated wood. Both the laser and x-ray systems were shown to be a very promising technologies for sorting large quantities of wood in a more automated fashion.
H M Solo-Gabriele, T G Townsend, J D Schert

Fungal degradation of wood treated with metal-based preservatives. Part 1: Fungal tolerance
1996 - IRG/WP 96-10163
In recent years, concerns have arisen about the leaching of heavy metals from wood treated with chromated copper arsenate (CCA), particularly because of the large amount of CCA treated wood that will be discarded in the coming years. The long term objectives of this work are to determine the fate of copper, chromium and arsenic with the aging and potential decay of CCA-treated wood, and to develop strategies for recycling and remediation of disposed wood. In this study, we determined the ability of various decay fungi to decompose southern yellow pine wood treated with CCA or other metal-based preservatives. Isolates of Meruliporia incrassata and an isolate of Antrodia radiculosa caused the highest weight losses in CCA-treated southern yellow pine. One isolate of Meruliporia incrassata produced similar weight losses in CCA-treated and untreated southern pine after 10 weeks. Pine samples treated with very high levels of copper sulphate were decayed by Meruliporia incrassata, but the fungus was unable to decay wood treated with copper napthenate or copper-8-quinolinolate.
B Illman, T L Highley

The results of detection on CCA components of the soils contacted with CCA-treated woods - A trial study for the availability of the burial Method as a disposal CCA treated wood waste
1993 - IRG/WP 93-50005
The objecteve of this experiment is to get a knowledge that, when CCA treated wood wastes were buried in a soil as a disposal, the soil would be or not be contaminated by the components of CCA preservatives in wood wastes. The specimens used were cutting logs and chips made of the CCA treated electric pole waste. The soil was buried to the 15 cm depth and the log specimens were set in the soil for parallel direction to the ground line. The chips specimens were placed in the bottomless boxes which were set on the ground floor at 20 cm depth under the ground line. The soil samples were taken from where were directly contacted with the specimens and from where were the nearest places apart from the specimens and were analyzed for CCA components after 6 months and after 6 years since these installation. The results were summerlized as follows. The levels of CCA components in the soil where were directly contacted with the specimens were slightly increased. However that in the soil where were collected over 5 cm far from the specimens were not increased. Therefore, the CCA components in the woods were not contaminated to the soil where were over 5 cm far from the specimens. According to our results, we can consider that the burial method for the disposal of CCA treated wood wastes was an avalable method and also practical possiblity to prevent from environmental contamination.
K Suzuki, H Sonobe

Thermal decomposition behavior of CCA-treated wood for safe disposal and the safe recovery of heavy metals through pyrolysis
2006 - IRG/WP 06-50238
If we could estimate the chemical changes in heavy metals by temperature in chromated copper arsenate (CCA)-treated wood during pyrolysis, it is expected that we could solve the environmental problems of heavy metals, which may occur during pyrolysis, and therefore, the thermal decomposition behavior of effective elements of CCA-treated wood was examined to find a safe disposal method. First, CCA-treated wood was combusted at a temperature that prevents volatilization of arsenic compounds, and the arsenic compounds were extracted from carbonized wood. Then, it was considered how to recover heavy metals from chromium compounds and copper compounds. The Thermo Gravimetric Analysis (TGA) result of CCA-treated wood showed that arsenic (III) oxide was volatilized into the atmosphere at 300? and arsenic (V) oxide was volatilized at 800?. When heavy metals were recovered from the carbonized-treated wood after thermal decomposition of CCA-treated wood at 300?, which could suppress the volatilization of arsenic compounds, it was relatively easy to recover copper and arsenic while it was difficult to recover chromium from the carbonized-treated wood.
Dong Won Son, Dong-heub Lee, Sun-hae Cheon, Myung Jae Lee

A Prediction of Arsenic Groundwater Concentrations Influenced by Construction and Demolition Debris Landfills in Florida Containing CCA-Treated Wood
2006 - IRG/WP 06-50242
Groundwater fate and transport models can provide an indication of the potential impacts of arsenic from the infiltration of leachate from unlined C&D debris landfills containing CCA-treated wood. A solute transport model, Migration of Organic/Inorganic Chemicals (MYGRT), was chosen to predict groundwater contaminant concentrations at specified locations from a hypothetical source (C&D landfill) that contains CCA-treated wood. MYGRT simulates a single contaminant, generated from a surface source, migrating downward through the unsaturated soil layer, mixing with the underlying groundwater, and then migrating horizontally downgradient through the aquifer. The software incorporates the processes of advection, dispersion and retardation. Because of the slow and complex transport mechanisms involved, groundwater impacts may not be observed for many years. A small fraction of the arsenic from the CCA-treated wood disposed in C&D debris landfills was simulated as leached (17.1%). Although hundreds of years later, exceedances of current and potential groundwater cleanup target levels were predicted.
J Jambeck, T Townsend, H Solo-Gabriele

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

Possible regulatory status of treated wood waste and implications
1998 - IRG/WP 98-50101-07
In relation to the European Community or the French regulations, treated wood waste can get two different regulatory status: <<recycled product or fuel>> or <<waste>>. Then, into the waste status, two categories are possible for these residues: <<domestic waste and assimilated>> or <<hazardous waste>>. These different status and categories are important for the environmental issue of treated wood waste management. But they also can have strong economical implications, linked to the waste management cost on one hand and on the materials image on the other hand. On the basis of the EC regulations, up to now, no treated wood waste is namely quoted as <<hazardous waste>>. However, through the classification criteria defined by different EC directives, creosote or heavy metals treated wood waste could be to considered that way. The technical arguments for such a classification and the practical implications are discussed.
G Deroubaix

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

Application of radio frequency heating to accelerate fixation of CCA in treated round-wood
1999 - IRG/WP 99-40133
The potential of radio frequency heating to accelerate the fixation of chromated copper arsenate (CCA) in treated round-wood was assessed. Pre-dried Douglas-fir and western red cedar round-wood sections were pressure treated with CCA in a pilot plant retort, after which they were placed individually in a pilot radio frequency (RF) chamber. Based upon the color reaction of chromotropic acid with hexavalent chromium and the quantitative assessment using diphenyl carbazide, fixation was achieved in less than 6 hours. During heating, the temperature at various locations inside the pole sections was monitored by fiber-optic thermocouples. The moisture profiles before, and after fixation, were also recorded. Further studies will examine other benefit of RF heating, including a) sterilization, and b) rapid drying of round-wood with minimum check formation.
Fang Fang, J N R Ruddick

Effect of water repellents on leaching from CCA treated wood
1995 - IRG/WP 95-50044
CCA treated fence boards brushed with a water repellent finish had consistently lower leaching losses of all CCA components compared to the rate for matched samples without the water repellent. These results are after 12 cycles of simulated rainfall in the laboratory (1800 mm rainfall total) and four months of natural rain exposure in Toronto.
P A Cooper, R MacVicar

Rates of emission from CCA-treated wood in the marine environment: measurement, modelling and requirements for further research
2001 - IRG/WP 01-50166-12
Accurate estimates of rates of emission of leachate from preservative treated wood are crucial for realistic predictions of the environmental impact of its use in maritime construction. Estimates are available for some commonly used preservatives, but these vary widely. Though variable, these measurements suggest that emission generally decreases exponentially with time. Part of the variation is due to differences in methodology employed. Physical and chemical characteristics of the seawater used (e.g. temperature, salinity, pH and oxygen content) affect emission rate. So too do the specifics of the treatment process especially the preservative formulation used, and pre- and post-treatment handling of the wood. The nature of the treated wood samples is also important, with misleadingly high estimates being obtained from samples with unrepresentatively high proportions of cross-cut surfaces. A suggested strategy for developing an informative and standardised methodology is discussed. To form useful models of impacts of leaching, emission rates need to be considered in conjunction with site-specific information regarding a) water exchange rates between the area where leaching occurs and the sea, and b) the extent of partitioning of leachate between the water column, biota and sediment. The risk of environmental impact may be reduced by modification to treatment procedures and by careful planning of installation.
S M Cragg, C J Brown, R A Albuquerque, R A Eaton

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