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An introduction to environmental aspects of groundwater arsenic and CCA treated wood poles in Bangladesh
1997 - IRG/WP 97-50081
The environment comprises biosphere, lithosphere, atmosphere and hydrosphere. Therefore, environmental science is a multi-disciplinary study, includes life sciences, physical sciences, chemical sciences, geology, geography, meteorology, forestry, agriculture, soil science, hydrology, ecology, public health, engineering etc. Tremendous industrial and mining activities, deforestation and population explosion are threatening the very existence of life on earth.Groundwater is used for irrigation, drinking and other domestic purposes where other sources of water are not plenty. Groundwater contain different metals resulting from soluble minerals, deposited in ground during its origin. Thus concentration of metals in surface soils and water are increased day by day by lifting of groundwater. Surface soils and water also receive metals from industries and mines and as a result of multipurpose use of products from those. Deforestation is controlled by plantation and preservation of forest products by different wood preservatives. Recently groundwater in some underground rocks of Tertiary and Quarternary age in Bangladesh is very often known to contain arsenic (As) above permissible limits . On the other hand chromated copper arsenate (CCA) impregnated wooden poles has been used for rural electrification in Bangladesh since 1979. It is an attempt to find out through research and review of literatures that whether the groundwater As is contaminatable from As used in wood poles and whether the components of CCA cause environmental problems. Possible way of purification of arsenic containing groundwater for drinking have been suggested.
A K Lahiry
Performance of chromated copper arsenate-treated aspen fence posts installed in Forintek's Eastern test plot from 1951 to 1963
1984 - IRG/WP 3272
Aspen poplar fence posts were pressure treated by the full cell process using three formulations of copper chrome arsenate wood preservative. A total of one hundred and fifty nine of the posts were installed in service in Forintek's Chalk River post plot from 1951 to 1962. During the 1982 general inspection of the post plot all 159 posts were still in service. A groundline inspection was carried out on the material to determine the extent to which decay had progressed during this period. Samples were taken from the surface of tanalith C treated posts and subsequent microscopic examination revealed that soft rot attack was present in the outer portion of posts. The groundline area of posts treated with (K 33), CCA type B and (greensalt) CCA type A were in generally good condition after 22 years and 31 years respectively. Rate of decay was highest for CCA-C tanalith treated posts at 0.3 mm per year with a retention of 3.04 kg/m³ oxides.
C D Ralph
Treatability of Siberian larch and spruce with chromated copper arsenate
1996 - IRG/WP 96-40060
Heartwood of Siberian larch (Larix gmelini) and spruce (Picea jezoensis) was pressure treated with chromated copper arsenate (CCA) Type B using a full cell process. Larch heartwood was somewhat difficult to treat than the spruce, although both species did not meet a minimum requirements of penetration and retention specified by the American Wood Preservers' Association (AWPA) for difficult to treat wood species in ground contact. To improve the preservative treatability of refractory larch and spruce, end matched heartwood lumber had been incised using either a conventional or a double density incising pattern, and then pressure treated with CCA Type B. The use of double density incising is necessary for spruce heartwood in order to acheive adequate treatment with CCA; however, the increase in incision densities and/or the use of high treating pressure may be required for adequate treatment of larch heartwood.
Gyu-Hyeok Kim, Woo-Gue Jee, Jae-Jin Kim
A Soil Bed Test of the Effect of CCA Penetration on the Performance of Hem-fir Plywood
2004 - IRG/WP 04-30332
An accelerated decay test was set up to compare the performance of CCA-treated Western hemlock/amabilis fir plywood treated to meet the preserved wood foundation (PWF) retention standard with various patterns of preservative penetration. Short lengths of treated plywood and comparable untreated material were installed in a soil bed. After eleven years of exposure, the CCA treatments were all sound regardless of penetration, while the untreated material had failed due to decay within three years.
P I Morris, J K Ingram
Fixation of chromated copper arsenate (CCA) wood preservative in Australian hardwoods: A comparison of three Eucalyptus species
1996 - IRG/WP 96-30107
New environmental guidelines for the management of CCA treatment plants were released in Australia in 1995. This has stimulated interest in techniques for controlling or accelerating the fixation of CCA in freshly treated timber products. The ability to understand, then effectively control and/or accelerate fixation of CCA in treated timber products can be an economic, technical and environmental advantage. Data available on fixation of CCA in timber commodities however, is mainly on softwood not hardwood species. In this paper, the rate of fixation of CCA Type C Oxide in poles of three species of Australian Eucalyptus was monitored over a six week period following treatment. These results will assist in the design of adequate drip pad and undercover storage area for pole treaters in South East Queensland.
Wood Preservatives Science Issues: US EPA’s Perspective
2005 - IRG/WP 05-50224-2
The USEPA Office of Pesticide Programs (OPP), Antimicrobials Division (AD), regulates the use of chemicals registered as wood preservatives in the United States. An overview of the registration and re-registration process is presented. The wood preservatives data requirements include toxicological, human exposure, ecological, and environmental fate data. A detailed discussion of wood preservatives data requirements is presented. Currently, the three heavy duty wood preservatives (Pentachlorophenol, Chromated Copper Arsenate, and Creosote) are undergoing the re-registration process. This process is mandated by Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The re-registration process ensures that older pesticides meet contemporary safety standards and data requirements. The challenges of regulating the treated wood will be discussed.
Effects of surfactants and ultrasonic energy on the treatment of wood with chromated copper arsenate
1977 - IRG/WP 3108
Sugar pine stakes 1'' x 1" x 16" were treated by a hot-water bath followed by soaking in cold CCA solution for 10 to 30 minutes. A similar number of stakes were treated by a cold-cold bath. Half of the stakes were subjected to ultrasonic energy during the CCA bath. The mean absorption for stakes given the hot-cold bath was 18.52 pcf (297 kg/m³) and 4.64 pcf (74 kg/m³) for those given the cold-cold bath. The rates of absorption were o.323 pcf (5 kg/m³) per minute and 0.053 pcf (0.85 kg/m³) per minute, respectively. The relationship between absorption in pounds per cubic foot (Y) and soaking time in minutes (X); Y = 12.27+0.323 X, was linear and significant. The linear relationship for the cold-cold treatment was poor (r = 0.305). Neither ultrasonic energy, nor its interaction with soaking time, had a significant effect on solution absorption for either the hot-cold or cold-cold treatments. In a second series, the stakes were treated in the CCA solution with a 3-minute dip, a 48-hour cold soak, and Lowry pressure. Half of the stakes were treated in the solution to which a surfactant had been added. The interacting effect of surfactant and method of treatment was significant. The highest absorption was obtained when the specimens were treated with the solution containing the surfactant by the Lowry method, 35.13 pcf (563 kg/m³). In comparison, the absorption was 22.55 pcf (361 kg/m³), 36 percent lower, when surfactant was not used. The surfactant had a beneficial effect on the results of the 3-minute dip, but not the 48-hour soak.
C S Walters
Equilibrium distribution of toxic elements in the burning of impregnated wood
2001 - IRG/WP 01-50172
The current work focuses on predicting the behavior of arsenic, chromium, and copper in the burning of impregnated wood. A theoretical method is used to study the chemistry of the system, with special interest directed towards the vaporization tendency of the potentially toxic elements. The core of the study is the global equilibrium analysis that simultaneously takes into consideration all chemical reactions. The results of the present study indicate that chromium and copper are unlikely to volatilize at combustion temperatures. Arsenic appears to be more volatile. Nevertheless, the prediction showed that it may be captured by calcium of the wood ash, and small amounts are likely to dissolve in the slag-phase of the ash. It may also form non-volatile compounds with magnesium, copper, and chromium and other elements of the impregnated wood, which efficiently hinders its emissions as gaseous species.
K Sandelin, R Backman
Soft-rot control in hardwoods treated with chromated copper arsenate preservatives. Part 3: Influence of wood substrate and copper loadings
1977 - IRG/WP 2100
The hypothesis is proposed that hardwoods need more chromated copper arsenate (CCA) than softwoods to protect them from soft-rot attack mainly because hardwoods are more readily consumed by soft-rot fungi. Simple model systems, using copper-supplemented agar or groundwood pulp treated with CCA showed that fungi tolerated more toxicant (copper) as more available substrate (malt) was provided. Soft-rot tests with CCA-treated hardwood blocks provided typical dosage-response curves when results were expressed as a ratio of substrate to toxicant (wood to copper). Furthermore, hardwoods needed 10 to 20 times more copper as CCA than softwoods to prevent soft-rot attack. When CCA was substituted by ammoniacal copper arsenate in 5 hardwoods, similar threshold values for soft-rot attack were obtained in terms of a wood-to-copper ratio. Hence, CCA may be behaving poorly against soft-rot fungi in our hardwood specimens mainly because the substrate contained too little copper. The practical implications of these results are discussed.
M A Hulme, J A Butcher
Performance of Paraserianthus falcataria treated with ACZA, ACQ, CC or CCA and exposed in Krishnapatnam harbour, India
2005 - IRG/WP 05-30382
Paraserianthus falcataria (=Albizia falcataria) treated to two retentions with ammoniacal copper zinc arsenate (ACZA), ammoniacal copper quaternary (ACQ), ammoniacal copper citrate (CC) and chromated copper arsenate (CCA) was assessed over 34 months in a tropical marine waters at Krishnapatnam harbour on the east coast of India. ACZA treatment showed comparatively better resistance than CCA, ACQ and CC, while CC provided the least resistance to marine borer attack. Eight species of borers i.e. Martesia striata, M. nairi, Teredo furcifera,T. parksi, Lyrodus pedicellatus, Nausitora hedleyi, Bankia campanellata and B. rochi were recorded on test panels. Of these, M. striata, L. pedicellatus, T. furcifera and B. campanellata were the dominant species, while other species settled sporadically. The results suggest that copper based preservatives are less likely to perform well under extreme tropical exposures without arsenic.
B Tarakanadha, K S Rao, J J Morrell
Laboratory studies of CCA-C-leaching: influence of wood and soil properties on extent of arsenic and copper depletion
2002 - IRG/WP 02-50186
The extent which a wood preservative leaches is important for efficacy studies and environmental concerns. However, little information exists on the effect soil properties have on leaching. This study investigated leaching of stakelets which had been cut from five different southern yellow pine (SYP) sapwood boards then treated with CCA-C to a target retention of 6.4 kgm-3 (0.4 pcf). All stakelets were leached for 12 weeks by a common laboratory method in five different soils or water, with five replicate stakelets per board/soil. The physical and chemical properties of the five different soils were determined and the average leaching of the individual components of CCA was correlated with the various soil properties. Unfortunately, migration of a soil component (likely iron) into the stakelets from at least one of the five soils interfered with Cr determination by X-ray fluorescence; consequently, Cr depletion was not studied. Stakelets cut from one board tended to have lower Cu and As losses than the average of the other four boards for all five soils and water, and stakelets from another board tended to have higher Cu losses. Stakelets from all five boards had similar initial Cu and As levels, suggesting that the board effect was not due to differences in initial retentions. Cu loss was approximately equal to or greater than As loss for stakelets exposed to all five soils, but for wood leached in water the As loss was about twice the Cu loss. The soil property which was most statistically correlated to Cu loss was % Base Saturation (r2 of 77%), with Soil Acidity (pH) also important as a single predictor, and the Cr and Cu Soil Contents important as secondary predictors. The relationship between % Base Saturation (or Soil Acidity) and % Cu leached was not linear, however. A negative correlation was observed between Soil Cu Content and the metal leached from wood. The best factor to predict As loss was the Soil Cu Content, with Exchangeable K and % Silt also contributing to give an overall r2 of 72.3%. The % Organic Matter and the Soil As Content were also important as secondary predictors. We conclude that depletion of CCA is extremely complex and that Cu and As depletion appears to be influenced differently by the soil properties. Furthermore, extent of leaching can vary between different wood samples of the same species and even samples cut from the same board; thus, leaching data are not precise. Recommendations are given for a standard laboratory method for ground-contact leaching.
D Crawford, R F Fox, D P Kamden, S T Lebow, D D Nicholas, D Pettry, T Schultz, L Sites, R J Ziobro
Water repellency of wood treated with alkylammonium compounds and chromated copper arsenate
2000 - IRG/WP 00-30231
The comparative water sorption properties of southern pine treated with CCA and several alkylammonium compounds was evaluated for freshly treated wood and for wood after exposure in a fungus cellar. It was found that CCA imparts considerable water repellency to wood which is reduced somewhat after exposure to wet soil. With the exception of a long chain (C20 -C22) compound, the alkylammonium compound treated wood exhibited an increased water sorption rate and also exhibited increased total swelling.
D D Nicholas, A Kabir, A D Williams, A F Preston
Rapid fixation of Chromated Copper Arsenate (CCA) wood preservatives by microwave treatment
2000 - IRG/WP 00-40184
Rapid microwave heating of freshly chromated copper arsenate (CCA) treated timber indicates that rapid preservative fixation is possible within approximately 40 seconds. The leaching of CCA was evaluated using simulated rainfall. Cost analyses indicates that microwave fixation using an on-line conveyor belt fixation process with an output of 4m3/hour using a microwave power supply of 230 kW costs approximately AU$ 16/m3 for electricity costs of AU$ 0.077/kW-h. When electricity cost are AUS$ 0.017/kW-h the treatment costs are reduced to AU$ 10/m3.
G Torgovnikov, P Vinden, E Mapanda, P R S Cobham
Chromated copper arsenate preservative treatment of hardwoods. Part 2: leaching performance of seven North American hardwoods
1997 - IRG/WP 97-30132
Seven North American hardwood species were treated with 2% CCA-C solution and fixed at temperatures of 21°C and 50°C and conditions of high relative humidity (95%) as described in Part 1 of this presentation. Red pine (Pinus resinosa) was included as a softwood for comparison. Adequately fixed wood blocks (99.9% chromium fixation) were exposed to leaching tests according to AWPA E11-87 test. Particularly high leaching losses were determined for red oak, red maple and beech.. In the case of red oak all three elements were leached in high quantities, while from red maple and beech higher arsenic leaching occurred. Higher leaching of arsenic was observed in those red maple blocks that fixed the fastest. Leaching losses from aspen, basswood and yellow poplar were low and comparable for both fixation temperatures. Very low leaching of arsenic from aspen and yellow poplar was observed in all series of experiments. Leaching results obtained confirmed the validity of the division of the examined hardwoods into three groups according to the CCA fixation and leaching results: fast fixing/high leaching group (beech, red oak and red maple), intermediate fixation rate and leaching amount (white birch and red pine) and slow fixing and low leaching group (aspen, yellow poplar and basswood).
T Stevanovic-Janezic, P A Cooper, Y T Ung
Properties of particleboard made from recycled CCA-treated wood
2000 - IRG/WP 00-50146
Recovery of chromated copper arsenate (CCA)-treated wood for reuse ha s been the focus of several international research groups due to the imminent disposal problem created when large quantities of CCA-treated wood ultimately come out of service. Bioleaching with Bacillus licheniformis CC01 and oxalic acid extraction are two methods known to remove significant quantities of metals from CCA-treated wood. Remediated particulate CCA-treated southern pine was reassembled into particleboard (PB) using 10% urea-formaldehyde resin. Particleboard panels were evaluated for internal bond (IB), modulus of elasticity (MOE), modulus of rupture (MOR), thickness swell (TS) and water absorption compared to particleboard manufactured from virgin southern pine and CCA-treated southern pine. Particleboard panels prepared from the remediated chips showed an average 28% reduction in IB and a 13% reduction in MOR compared to values for PB prepared with virgin chips under the pressing parameters used in this study, though individual IB values for all specimens were above the ANSI standard for medium density particleboard. An 8% increase in MOE in the remediated chip PB compared to the virgin chip PB may indicate densification of the fiber surface as a result of the acid extraction step of the remediation process. Thickness swell and water absorption after 24-hour submersion also increased in PB prepared from remediated chips (15% and 14%, respectively). We conclude that pressing parameter optimization could alleviate decreases in MOR and IB seen in PB made from remediated chips, and that the effects of acid extraction on MOR and IB properties should be further evaluated.
C A Clausen, S N Kartal, J H Muehl
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
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
Effect of soil chemistry and physical properties on wood preservative leaching
1998 - IRG/WP 98-50111
When treated wood is placed in contact with soil, complicated mass transfer and chemical reactions occur which causes the preservative components to leach from the wood. There are several factors that are known to affect the amount of chemical leached from wood. These are properties of the preservative and carrier, preservative retention, degree of fixation, exposure time, grain orientation, surface area of the product, wood species, and site factors. With regard to site factors, the chemical and physical properties of soil play an important role in the depletion of biocides from treated wood. The effect of soil properties on the leaching of wood preservatives has only been studied to a limited degree but appears to be a major factor in the performance of treated wood. In this study the effect of five soils with widely different physical and chemical properties on the leaching of chromated copper arsenate (CCA-C), pentachlorophenol (Penta) and didecyldimethylammonium chloride (DDAC) from southern pine was evaluated.
Joan-Hao Wang, D D Nicholas, L S Sites, D E Pettry
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
Chromated copper arsenate preservative treatment of hardwoods. Part 1: CCA fixation performance of seven North american hardwoods
1997 - IRG/WP 97-30131
There has been an increased interest in utilisation of hardwoods from eastern North America for exterior applications which require protection with preservatives such as CCA. We have examined CCA fixation at two selected temperatures of seven common North American species: red maple (Acer rubrum L.,), white birch (Betula papyrifera ), yellow poplar (Liriodendron tulipifera L.), trembling aspen (Populus tremuloides ), red oak (Quercus rubra L.), basswood (Tilia Americana ) and beech (Fagus grandifolia Ehrh.). The softwood red pine (Pinus resinosa) was included in all studies for comparison. Chromium fixation was followed by the expressate method at both ambient temperature (21°C) and at 50°C under high humidity (95%) conditions. Cr, Cu and As contents of the expressate were determined by X-ray fluorescence method and chromium (VI) was determined by diphenyl carbazide method at different times during fixation. Based on CCA fixation results it was possible to divide the examined hardwoods into a fast fixing group (beech, red oak and red maple), intermediate group (white birch and red pine) and slow fixing group (aspen, yellow poplar and basswood). Variable fixation rates for the different species are discussed in relation to different densities and different cell wall components and their contents in the different hardwoods.
T Stevanovic-Janezic, P A Cooper, Y T Ung
Thermochemical Remediation of Preservative-Treated Wood
2008 - IRG/WP 08-50254
Remediation methods continue to be developed and refined for CCA-treated wood in order to divert this material from landfills and create secondary products from the wood fiber. A two-step thermochemical remediation method was developed to assess the efficiency of metal removal from CCA-treated spruce flakes. Nearly all the metals (As, Cr, and Cu) were thermochemically extracted from chromated copper arsenate (CCA) treated Spruce using solutions of oxalic acid and sodium hydroxide. Oxalic acid was found to be highly effective for removing As and Cr, whereas mixtures of oxalic acid and sodium hydroxide were more effective for removing copper. Up to 100 % As and 97 % Cr were removed from treated flakes after one hour using a 1 % oxalic acid solution (pH 1.4) at 80 °C, but less half of the Cu was removed at pH 1.4 even after six hours. Nearly all the As, Cr, and Cu were extracted from the treated flakes after six hours using a 1 % oxalic acid solution adjusted to pH 3 with sodium hydroxide. However, the removal of As and Cr was slower with oxalic acid solutions that contained sodium hydroxide. A two-stage process in which the flakes were first extracted for one hour with oxalic acid (pH 1.4) then extracted for another hour after adjusting the solution to pH 3 with sodium hydroxide removed 99 % As, 96 % Cr, and 92 % Cu. The effects of temperature, pH, time, mixing, rinsing, and liquid to solid ratio on the removal of metals from CCA-treated Spruce flakes and particles is discussed.
R Sabo, C A Clausen, J E Winandy
Comparison of laboratory and natural exposure leaching of copper from wood treated with three wood preservatives
2008 - IRG/WP 08-50258
Standard and non-standard laboratory and field leaching tests were used to compare copper leaching from wood treated to above ground and ground contact specified retentions for three wood preservative systems, CCA-C, ACQ-D and a micronized copper formulation with quat DDAC as co-biocide. Copper leaching was highest for the ACQ formulation. Percent leaching was lowest for the micronized copper system (MCQ) but amount of copper leached (mg/m2) was higher for MCQ than for CCA because of the higher copper content in the former formulation. The amounts of copper leaching varied considerably from test to test, but in most cases, the relative amounts of copper leaching from wood treated with the three formulations were consistent. One exception was the AWPA E20 soil leaching test which provided variable results, that showed that leaching of copper from CCA and MCQ samples was more similar to that from ACQ samples than observed for the other test methods. Also, the natural exposure tests (horizontal and vertical exposure) has less dramatic differences among the preservative systems.
P A Cooper, Y T Ung
Rapid Microwave-Assisted Acid Extraction of Metals from Chromated Copper Arsenate (CCA)-Treated Southern Pine Wood
2009 - IRG/WP 09-50262
The effects of acid concentration, reaction time, and temperature in a microwave reactor on recovery of CCA-treated wood were evaluated. Extraction of copper, chromium, and arsenic metals from chromated copper arsenate (CCA)-treated southern pine wood samples with three different acids (i.e., acetic acid, oxalic acid, and phosphoric acid) was investigated using in microwave reactor. Oxalic acid was effective in removing 100% of the chromium and arsenic at 160°C and 30 min., and acetic acid could remove 98% of the copper and arsenic at the same conditions. Oxalic acid greatly improved the extraction efficiency of arsenic and chromium when time was prolonged from 10 min. to 30 min. Acetic acid also showed improved ability to remove arsenic and copper when the reaction temperature was increased from 90°C to 160°C.
Bin Yu, Chung Y Hse, T F Shupe
Seasonal shifts of fungal community structure at the interface of treated or untreated wood and soil
2010 - IRG/WP 10-10721
Many wood species are degraded rapidly in soil by the fungal community. In order to preserve wood and structures in which it is used, chemical preservatives are used. Little is known about the interaction of treated wood and the surrounding soil fungal community. For this work, presented at IRG 41, wooden specimens (Pinus sylvestris sapwood, sizes 25 mm x 50 mm x 500 mm (longitudinal)) were treated with a formulation of chromium-copper-arsenic-(CCA) at two concentrations. Untreated wood of the same dimensions was used as controls. After drying and an appropriate fixation period, the specimens were buried in soi1 up to half of their length at the BAM test site in North East Germany. The interface of the wooden specimens and soil were sampled in spring, summer and autumn 2008 and the nucleic acids were extracted. The structure of fungal community was assessed by T-RFLP analyses (terminal-restriction fragment-length polymorphism) of the fungal ITS (internal transcribed spacer) region. In addition, samples were sequenced to identify fungal community members. Significant differences in the fungal community composition were detected in response to the presence (and concentration) of wood preservatives and to the season. The species identified were predominated by ascomycete fungi, and only at the actual interface of the non-preserved wood and the soil were basidiomyecte fungi detected. The interface to CCA preserved wood was composed of sequences affiliated to the genera Phoma, Peziza and Cladosporium. Patterns of the fungal communities were highly reproducible and the spatial sampling at the test site had only a minor effect on their composition.
M Noll, I Stephan
Hydroponic Phytoremediation of Chromated Copper Arsenate (CCA) and Copper Contaminated Water
2014 - IRG/WP 14-50304
The removal of selected metals by duckweed (Lemna minor) and parrotfeather (Myriophyllum aquaticum) from a simulated aqueous environment contaminated with Chromated Copper Arsenate (CCA) and copper sulfate was studied in a controlled laboratory experiment. The duckweed and parrotfeather’s tissues were analyzed to evaluate the removal of copper (Cu), chromium (Cr), and arsenic (As) from CCA contaminated water (125 mg/L Cu, 220 mg/L Cr, and 205 mg/L As) and from copper sulfate contaminated water (60 mg/L Cu) over a 7 day period. The vigor of the plants was also recorded during this period. The results showed that the duckweed and parrotfeather both removed the metals from the water in each experiment. For the CCA contaminated water study, duckweed removed approximately 60% of each metal from solution while parrotfeather removed approximately 45% of each metal. For the copper contaminated water study, duckweed removed approximately 85% of the copper concentration from solution while parrotfeather removed approximately 77% copper from solution. As for the vigor of the plants in the CCA study, duckweed remained rather healthy throughout most of this study. Parrotfeather sharply declined in vigor after two days into experiment. In the copper study, both plants remained fairly healthy through the duration of the experiment.
C Keith, H Borazjani, S Diehl, Y Su, Fengxian Han, B Baldwin