CCA-treated Wood Waste Research Articles

Sustainable Supercapacitor Electrode Based on Activated Biochar Derived from Preserved Wood Waste

Due to the inherent metals (Cu, As and Cr) in preserved wood waste (CCA-treated wood waste) that pose a risk to both the environment and human health, it is crucial to dispose of CCA-treated wood properly. Carbon materials have received widespread attention for their high porosity, renewability and simplicity of fabrication. This work presents a simple and effective process for producing carbon materials from leftover CCA-treated wood (chromated copper arsenate). Utilizing CCA-treated wood derived carbon (CCA-BC) and activating it with KOH (CCA-AC), electrode materials for supercapacitor applications were created and its electrochemical characteristics were investigated. The resulting material combines the conductivity of the metal in preserved wood with the good porosity provided by carbon materials. Compared with common wood biomass, carbon (W-BC) and common wood activated carbon (W-AC), CCA-BC and CCA-AC have better electrochemical properties. After being pyrolyzed at 600 °C for two hours, CCA-AC performed optimally electrochemically in 1 M Na2SO4 electrolyte, demonstrating a 72% capacity retention rate after 2000 charge and discharge cycles and a specific capacity of 76.7 F/g. This study provides a novel approach for the manufacture of supercapacitor electrodes, which also allows preserved wood waste an environmentally nondestructive form of elimination.

A Comparative Study on Heavy Metal Removal from CCA-Treated Wood Waste by Yarrowia lipolytica: Effects of Metal Stress.

Bioremediation is an effective way to remove heavy metals from pollutants. This study investigated the effects of Yarrowia lipolytica (Y. lipolytica) on the bioremediation of chromated copper arsenate (CCA)-treated wood wastes. Copper ions stressed the yeast strains to improve their bioremediation efficiency. A comparison of changes in morphology, chemical composition, and metal content of CCA wood before and after bioremediation was conducted. The amount of arsenic (As), chromium (Cr), and copper (Cu) was quantified by microwave plasma atomic emission spectrometer. The results showed that yeast strains remained on the surface of CCA-treated wood after bioremediation. The morphologies of the strains changed from net to spherical because of the Cu2+ stress. Fourier-transform infrared spectroscopy showed that carboxylic acid groups of wood were released after removing heavy metals. A large amount of oxalic acid was observed when the optical density (OD600nm) was 0.05 on the 21st day. Meanwhile, the highest removal rate of Cu, As, and Cr was 82.8%, 68.3%, and 43.1%, respectively. Furthermore, the Cu removal from CCA-treated wood increased by about 20% after Cu2+ stress. This study showed that it is feasible to remove heavy metals from CCA-treated wood by Y. lipolytica without destroying the wood structure, especially by copper-induced Y. lipolytica.

Diffusive gradient in thin films (DGT) for profiling leaching of CCA-treated wood waste mulch into the soil environment

Chromated copper arsenate (CCA) is a common wood preservative that has been used worldwide. Studies have shown that there are leaching risks of the preservative components arsenic, chromium and copper. These risks include contamination of soil and water, resulting in toxic effects to humans, animals, plants and ecosystems. This study investigates leaching of the preservative components following exposure of the wood waste as mulch to soil and water. Diffusive gradient in thin films (DGTs) were used to quantify leaching of potentially bioavailable/dissolved forms of the elements along the soil profile. Speciation of chromium was also carried out. All elements were found to leach out of the wood. The containers that included CCA-treated wood waste as a mulch leached higher levels of arsenic, chromium and copper than the controls. The distribution was highest in the top 5 cm of the soil profile and decreased with depth. DGTs proved to be a useful, novel technique for measuring in situ leaching and speciation from waste materials into the environment.

Leaching characteristics of CCA-treated wood waste: A UK study

CCA-treated wood is expected to increase in the UK waste stream over the next 20–50years. The potential pollution from this waste has been evaluated through two leaching studies, one based upon batch leaching tests and another based upon a series of lysimeter tests. The aim of the studies was to characterise the behaviour of arsenic (As), chromium (Cr) and copper (Cu) from this wood when applied to soil as a mulch. Results demonstrate that all three elements leach from CCA waste wood, occasionally in concentrations exceeding regulatory thresholds by two to three orders of magnitude. In the lysimeter study, wood mulch monofills and wood mulch in combination with soil were used to monitor the leaching of As, Cr and Cu. Peak concentrations for As, Cr and Cu were 1885μg/l, 1243μg/l and 1261μg/l, respectively. Freshly treated wood leached 11, 23 and 33 times more Cu, Cr and As, respectively than weathered wood. The toxic and mobile species of arsenic (As III, As V) were detected. Leaching in the CCA wood monofill was influenced by rainfall, with higher concentrations of metal(loid)s produced in lower intensity events. As and Cu were mobilised preferentially, with all metals exhibiting similar temporal trends. Retention of leached metal(loid)s was observed in lysimeters containing soil. Leaching processes appear to be favoured by the chipping process, diffusion and weathering. This study has shown that weathered waste wood mulch can cause significant pollution in soil water with potential impacts on both the environment and human health.

CCA-Treated Wood Waste Remediation Process Optimization with Successive Recirculation Loops Study

This study aims to improve a decontamination process developed for chromated copper arsenate (CCA)-treated wood waste. This process included metal extraction from the wood by a sulphuric acid-leaching step, and the treatment of metal-loaded leachate by precipitation with ferric chloride and sodium hydroxide. This study showed that sodium hydroxide can be advantageously replaced by calcium hydroxide to enhance performance (>99% metal precipitation above pH 6.5 with Ca(OH)2 and above pH 7 with NaOH) and lower chemical costs [US$30.8/ton of treated wood (TTW) with Ca(OH)2 instead of US$50.83TTW with NaOH]; however sludge production and sludge disposal cost were higher when using Ca(OH)2 for precipitation. Moreover, this study investigated the possibility of recycling the final process effluent obtained after metallic sludge separation. This effluent was successively reused in the process for the leaching step. Five recycling loops comprised of one leaching step, one precipitation step of the leachate with Ca...

An innovative membrane method for the separation of chromium ions from solutions containing obstructive copper ions

Chromium is one of the major pollutants of water and wastewater; this ion can be seen in different industrial effluents along with other metal ions such as Cu, As [E. Velizarova, A.B. Ribeiro, and L.M. Ottosen, A comparative study on Cu, Cr and As removal from CCA-treated wood waste by dialytic, Journal of Hazardous Material 94 (2) (2002)147–160]. In the current paper, experimental investigations have been done on the removal of the chromium ions from aqueous solutions which contain Cu 2+ as obstructive ion. Electrodialysis is coupled with complexing to recommend a new technique for the elimination of chromium (III) ions. Ethylendiaminetetraacetate acid (EDTA) was used as the complexing agent. The effect of different operating conditions (feed flow rate, voltage or current density, the ratio of the chromium (III) concentration to the copper concentration, EDTA molar ratio to Cr (III) and pH of the feed) on the removal of chromium ions was investigated. The Taguchi method was implied to design the experiments. The optimum operating conditions were determined using the analysis of variance (ANOVA) method. The proposed method resulted in relatively high chromium removal (95% Cr (VI) and 87% Cr (III)) at the optimum operating conditions.

Application of a CCA-treated wood waste decontamination process to other copper-based preservative-treated wood after disposal

Chromated copper arsenate (CCA)-treated wood was widely used until 2004 for residential and industrial applications. Since 2004, CCA was replaced by alternative copper preservatives such as alkaline copper quaternary (ACQ), copper azole (CA) and micronized copper quaternary (MCQ), for residential applications due to health concerns. Treated wood waste disposal is becoming an issue. Previous studies identified a chemical process for decontaminating CCA-treated wood waste based on sulfuric acid leaching. The potential application of this process to wood treated with the copper-based preservatives (alkaline copper quaternary (ACQ), copper azole (CA) and micronized copper quaternary (MCQ)) is investigated here. Three consecutive leaching steps with 0.1M sulfuric acid at 75°C for 2h were successful for all the types of treated wood and achieved more than 98% copper solubilisation. The different acidic leachates produced were successively treated by coagulation using ferric chloride and precipitation (pH=7) using sodium hydroxide. Between 94 and 99% of copper in leachates could be recovered by electrodeposition after 90min using 2A electrical current. Thus, the process previously developed for CCA-treated wood waste decontamination could be efficiently applied for CA-, ACQ- or MCQ-treated wood.

Effects of liquefaction time and temperature on heavy metal removal and distribution in liquefied CCA-treated wood sludge

Wood liquefaction was studied as a recycling method for chromated copper arsenate (CCA)-treated wood waste. The effects of liquefaction temperature and time on the removal of the heavy metals and their distribution in liquefied CCA-treated wood sludge were investigated. The residue content decreased as the temperature increased from 120 to 180 °C regardless of the reaction time. It decreased gradually with the increase of reaction time under liquefaction temperatures 120 and 150 °C. But it decreased as the reaction time increased from 30 to 60 min then increased when the reaction time increased to 90 min under liquefaction temperature 180 °C due to the re-condensation of decomposed wood components. The total concentrations of arsenic, chromium, and copper in the sludge samples increased, while the percentage of the removed metals decreased, with increasing liquefaction temperature, which could be related to the changes of wood residue content and the fate of the heavy metals under different liquefaction conditions. The exchangeable/acid extractable fraction of all three heavy metals decreased as the liquefaction temperature increased. At the same time, Cr and As increased in both oxidizable and reducible fractions. The amount of Cr in the oxidizable fraction increased 40% as the liquefaction temperature increased from 120 to 180 °C. The major change of Cu distribution was the increase in reducible fraction with the increase of liquefaction time. The results of this study suggested that high liquefaction temperature tends to inhibit the heavy metal recovery when liquefaction is used as a recycling method for CCA-treated wood waste.

Optimization of a chemical leaching process for decontamination of CCA-treated wood

Increasing volumes of discarded Chromated Copper Arsenate (CCA)-treated wood require the development of new treatment and recycling options to avoid the accumulation of wood wastes in landfill sites, resulting in dispersion of contaminants in the environment. The aim of this study is to design an economic chemical leaching process for the extraction of arsenic, chromium and copper from CCA-treated wood. Choice of chemical reagent, reagent concentration, solid-to-liquid ratio, temperature, reaction time and wood particle size are parameters which have been optimized. Sulphuric acid was found to be the cheapest and most effective reagent. Optimum operation conditions are 75 °C with 0.2N H 2SO 4 and 150 g wood L −1. Under these conditions, three leaching steps lasting 2 h each allowed for 99% extraction of arsenic and copper, and 91% extraction of chromium. Furthermore, arsenic concentration in TCLP leachate is reduced by 86% so the environmental hazard is reduced. Decontamination process cost is estimated to 115 US$ per ton of treated wood. These results demonstrate the feasibility of chemical remediation and that sulphuric acid leaching is a promising option for CCA-treated wood waste management.

Assessing the Current and Future Impacts of the Disposal of Chromated Copper Arsenate-Treated Wood in Unlined Landfills

Several states have recently considered altering disposal requirements for chromated copper arsenate (CCA)-treated wood waste, particularly Florida, where CCA-treated wood waste is disposed in unlined construction and demolition (C&D) debris and Class III municipal solid waste (MSW) landfills. The primary concern is the potential for CCA-treated wood waste to elevate arsenic levels in groundwater downgradient of the disposal sites. To address this concern, we evaluated the impact of past disposal practices of these wastes in unlined Florida C&D and Class III landfills by conducting a statistical analysis of two sets of groundwater data compiled by the Florida Department of Environmental Protection (FDEP). The databases contain water quality data from C&D and Class III landfills in Florida covering 15 yr of record from February 1992 through February 2007 and together provide the most complete datasets to evaluate this issue. Comparative statistics of the different population groups in the databases showed that the arithmetic mean concentrations of total arsenic were in most cases higher in background wells than in wells downgradient of the landfills. The statistical analysis indicates that past disposal of CCA-treated wood in C&D and Class III landfills in Florida has not increased arsenic levels downgradient of the landfills. Policy decisions regarding the continued disposal of CCA-treated wood waste as a nonhazardous waste in unlined landfills must therefore be based on a scientifically sound assessment of potential future impacts. Quantitative predictions of future impacts are difficult and pose several scientific challenges. Therefore, future management decisions should be based on a more accurate and comprehensive risk analysis that assesses the risks and benefits of different alternatives and takes into account the natural attenuation capacity of soils and aquifer solids for arsenic and the practical limitations of managing this waste stream as a hazardous waste.

Location model for CCA-treated wood waste remediation units using GIS and clustering methods

In the next decades, a significant increase is expected in the amounts of CCA-treated wood waste that annually need to be properly disposed. This waste should be recycled only after its remediation, so planning and optimisation of the remediation units location is of major importance. A location model for CCA-treated wood waste was implemented using Geographic Information Systems (ArcGIS 8.2), with geographic information, namely land use information and the results of a questionnaire sent to Portuguese wood preservation industries. Two different clustering methods (Self-Organizing Maps and K-means) were tested in different conditions to solve the multisource Weber problem using SOMToolbox for MATLAB. The solutions obtained with the data and with both clustering methods could be used to decide on the location of these plants. SOM provided more robust and reproducible results than K-means, with the disadvantage of longer computing times. The main advantage of K-means, compared to SOM, is the reduced computing time (considering an average of all the runs, the K-means computing time is half the SOM computing time) together with the fact that it allows to obtain the best solutions in the majority of the cases, in spite of bigger variances and more geographical dispersion.

Effect of different extracting solutions on the electrodialytic remediation of CCA-treated wood waste Part I.: Behaviour of Cu and Cr

Removal of Cu and Cr from chromated copper arsenate (CCA)-treated wood waste under batch electrodialytic conditions was studied. The effect of different types of extracting solutions, such as deionised water or aqueous solutions of NaCl, formic acid, oxalic acid, and EDTA, on the magnitude and direction of the fluxes of Cu- and Cr-containing species in the electrodialytic cell was investigated. Oxalic acid was found to have the best performance if simultaneous removal of the two elements is required (removal efficiencies of 80.5% for Cu and 87.4% for Cr, respectively). A mixture of oxalic acid and formic acid also led to similar removal efficiencies. In these experiments, the target elements were accumulated in both the anode and cathode compartments of the electrodialytic cell due to the formation of negatively charged complexes with the organic acids used besides the free cationic forms. The latter were not present if EDTA was the extracting solution resulting in directing the Cu and Cr fluxes to the anode compartment. Contrary, these fluxes were exclusively to the cathode compartment if deionised water or an aqueous solution of NaCl were used. These extracting solutions proved suitable for solubilising (re-mobilisation) of Cu but were less efficient for Cr removal (less than 20% removal). Overall, the results obtained show the important role of the proper selection of the type and composition of the extracting solution for the success of subsequent electrodialytic removal of Cu and Cr from CCA-treated wood waste.

Evaluation of XRF and LIBS technologies for on-line sorting of CCA-treated wood waste

Contamination of wood waste with chromated copper arsenate greatly limits recycling opportunities for the wood waste as a whole. Separation of CCA-treated wood from other wood types is one means by which such contamination can be removed. The purpose of the current study was to evaluate two detector technologies for sorting CCA-treated wood from other wood types. The detector technologies evaluated included X-ray fluorescence spectroscopy (XRF) and laser induced breakdown spectroscopy (LIBS). The XRF detector system utilized in this study was capable of rapidly detecting the presence of CCA in painted wood, wet wood, heartwood, sapwood, and at portions of the wood containing knots. Furthermore, the XRF system was capable of distinguishing between CCA-treated wood and wood treated with alternative wood treatment preservatives, but was limited by the fact that it was not designed for on-line operation so tests were conducted in a batch mode on a conveyor. The analysis time used in this study (3 s) can be decreased significantly for an XRF system designed specifically for on-line operation. The LIBS system developed for this study was found to effectively identify CCA-treated wood for pieces ranging in thickness from 1 to 8 cm. High sorting efficiencies were noted when 10 laser shots were taken on a piece of wood. Furthermore, the LIBS system was found to be effective for identifying wood that has been coated with stains and paints in addition to identifying wood that has been CCA treated. The major drawback with the LIBS system developed in this study was the limited laser pulse energy. With an increase in laser pulse energy it is anticipated that the working focal length of the LIBS system can be increased to enable the monitoring of wood samples of more variable thicknesses. Limitations associated with analysis of very rotted pieces of wood and wet wood can also be overcome by using a higher pulse energy laser. Overall, both technologies show incredible promise for sorting CCA-treated wood from other wood types. The next recommended step would be to run an improved full-scale operation at one facility to document sorting efficiencies and fine-tune the improvements proposed in the current study. Such a study could potentially open-the-door for more widespread sorting of wood waste.

A comparative study on Cu, Cr and As removal from CCA-treated wood waste by dialytic and electrodialytic processes

In this study, electrodialytic and dialytic techniques were used for Cu, Cr and As removal from 20-years out-of-service CCA-treated Pinus pinaster Ait. pole. The effect of applying direct current, as “cleaning agent”, of up to 120 mA was investigated. Focus was given to a parallel comparison with the performance of a pure dialytic experiment (without an external power supply) in order to reveal transport of charged particles induced solely by internal electrochemical potential differences in the system. Oxalic acid proved to be a more suitable pre-treatment solution than deionised water for wood chips incubation. Evaluation of the IARs of Cu, Cr and As showed that the rates of their appearance in the electrolytes were not linearly related to the current (except for Cr in the catholyte), mainly because of membrane retention. The maximum removal efficiencies obtained in a batch electrodialytic cell operated for 14 days were as follows: Cu, 84%; Cr, 87%; and As, 95%.

Special Treatment: Disposing of CCA-Treated Wood

Research ArticleOpen AccessSpecial treatment: disposing of CCA-treated wood. W C Holton W C Holton Search for more papers by this author Published:1 June 2001https://doi.org/10.1289/ehp.109-a274Cited by:3AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit FiguresReferencesRelatedDetailsCited by Fukuyama T, Ueda H, Hayashi K, Tajima Y, Shuto Y, Kosaka T and Harada T (2008) Sensitizing Potential of Chromated Copper Arsenate in Local Lymph Node Assays Differs with the Solvent Used, Journal of Immunotoxicology, 10.1080/15476910802085715, 5:2, (99-106), Online publication date: 1-Jan-2008. Solo-Gabriele H, Townsend T, Hahn D, Moskal T, Hosein N, Jambeck J and Jacobi G (2004) Evaluation of XRF and LIBS technologies for on-line sorting of CCA-treated wood waste, Waste Management, 10.1016/j.wasman.2003.09.006, 24:4, (413-424), Online publication date: 1-Jan-2004. Moskal T and Hahn D (2016) On-Line Sorting of Wood Treated with Chromated Copper Arsenate Using Laser-Induced Breakdown Spectroscopy, Applied Spectroscopy, 10.1366/000370202760355316, 56:10, (1337-1344), Online publication date: 1-Oct-2002. Vol. 109, No. 6 June 2001Metrics About Article Metrics Publication History Originally published1 June 2001Published in print1 June 2001 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.

Special treatment: disposing of CCA-treated wood.

Research ArticleOpen AccessSpecial treatment: disposing of CCA-treated wood. W C Holton W C Holton Search for more papers by this author Published:1 June 2001https://doi.org/10.1289/ehp.109-a274Cited by:3AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit FiguresReferencesRelatedDetailsCited by Fukuyama T, Ueda H, Hayashi K, Tajima Y, Shuto Y, Kosaka T and Harada T (2008) Sensitizing Potential of Chromated Copper Arsenate in Local Lymph Node Assays Differs with the Solvent Used, Journal of Immunotoxicology, 10.1080/15476910802085715, 5:2, (99-106), Online publication date: 1-Jan-2008. Solo-Gabriele H, Townsend T, Hahn D, Moskal T, Hosein N, Jambeck J and Jacobi G (2004) Evaluation of XRF and LIBS technologies for on-line sorting of CCA-treated wood waste, Waste Management, 10.1016/j.wasman.2003.09.006, 24:4, (413-424), Online publication date: 1-Jan-2004. Moskal T and Hahn D (2016) On-Line Sorting of Wood Treated with Chromated Copper Arsenate Using Laser-Induced Breakdown Spectroscopy, Applied Spectroscopy, 10.1366/000370202760355316, 56:10, (1337-1344), Online publication date: 1-Oct-2002. Vol. 109, No. 6 June 2001Metrics About Article Metrics Publication History Originally published1 June 2001Published in print1 June 2001 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.

00/03489 Total recycling of CCA-treated wood waste by low-temperature pyrolysis

00/03489 Total recycling of CCA-treated wood waste by low-temperature pyrolysis

Disposal practices and management alternatives for CCA-treated wood waste

Limited information is available about the ultimate fate of chromated copper arsenate (CCA)-treated wood waste upon disposal. This lack of information, coupled with concerns over potential environmental impacts, has prompted the current investigation, which focuses on establishing an inventory for this waste stream and identifying alternatives to current disposal practices. The state of Florida (USA) was utilized as a case study for this investigation. The results indicate that approximately 300 metric tonnes of the chemical were disposed of in Florida during 1996. By the year 2006 this figure will quadruple and by 2016 it will reach a value of 2700 metric tonnes. The majority of CCA-treated wood waste is processed through construction and demolition recycling facilities, resulting in a wood waste composition containing on average 6% CCA-treated wood. The primary market for wood waste in Florida is energy recovery and, as a consequence, the majority of CCA-treated wood waste is inadvertently burned for energy recovery purposes. Recommendations for handling this waste stream are discussed. Recommendations include options for waste minimization, reuse, recycling, and ultimate disposal.

Disposal practices and management alternatives for CCA-treated wood waste

Limited information is available about the ultimate fate of chromated copper arsenate (CCA)-treated wood waste upon disposal. This lack of information, coupled with concerns over potential environmental impacts, has prompted the current investigation, which focuses on establishing an inventory for this waste stream and identifying alternatives to current disposal practices. The state of Florida (USA) was utilized as a case study for this investigation. The results indicate that approximately 300 metric tonnes of the chemical were disposed of in Florida during 1996. By the year 2006 this figure will quadruple and by 2016 it will reach a value of 2700 metric tonnes. The majority of CCA-treated wood waste is processed through construction and demolition recycling facilities, resulting in a wood waste composition containing on average 6% CCA-treated wood. The primary market for wood waste in Florida is energy recovery and, as a consequence, the majority of CCA-treated wood waste is inadvertently burned for energy recovery purposes. Recommendations for handling this waste stream are discussed. Recommendations include options for waste minimization, reuse, recycling, and ultimate disposal.

Low-temperature pyrolysis of CCA-treated wood: thermogravimetric analysis

A thermo-analytical study of untreated and chromated copper arsenate (CCA) treated wood samples is performed in order to obtain a better understanding of the low-temperature pyrolysis of CCA-treated wood waste in an inert atmosphere. The type of wood used in this study is Pinus sylvestris sapwood. The influence of the presence of CCA and the heating rate on the pyrolytic behaviour of wood samples is studied, as well as the release of volatile compounds and metals (Cr, Cu, As) during the pyrolysis process. This paper shows that CCA has a significant influence on the thermal behaviour of wood samples, which is more pronounced the higher the CCA concentration of the sample is. The temperature at the onset of pyrolysis, as well as the temperature where the maximum rate of decomposition occurs, are lowered by the CCA treatment. The final char yield (including the metals) is higher and the rate of weight loss is much more peaked for CCA-treated wood. It could be postulated that the CCA compounds act as promotors of the pyrolysis reactions favouring the formation of char. For higher heating rates, there is a shift of the DTG peak to higher temperatures for both untreated and CCA-treated wood samples. Within the accuracy of the evolved gas analysis (EGA) method applied, it is observed that the presence of CCA does not significantly influence the type and relative amount of measured volatiles. The volatilisation of metal compounds is shown to be strongly dependent on temperature and residence time of the wood sample at a given temperature. A critical point (10 min at 400°C) exists, below which the release of Cr and Cu is negligible and the release of As is below 10%. Above this critical point (longer times at 400°C), there is a dramatic increase in metal release for all three metals. The CCA concentration itself also has an influence in the sense that higher concentrations in the original sample give higher relative concentrations of metals in the resulting pyrolysis residue.