Review of disposal technologies for chromated copper arsenate (CCA) treated wood waste, with detailed analyses of thermochemical conversion processes

Department of Mechanical Engineering, University of Leuven, Louvain, Flemish, Belgium
Environmental Pollution (Impact Factor: 4.14). 04/2005; 134(2):301-14. DOI: 10.1016/j.envpol.2004.07.025
Source: PubMed


Several alternative methods for the disposal of chromated copper arsenate (CCA) treated wood waste have been studied in the literature, and these methods are reviewed and compared in this paper. Alternative disposal methods include: recycling and recovery, chemical extraction, bioremediation, electrodialytic remediation and thermal destruction. Thermochemical conversion processes are evaluated in detail based on experiments with model compounds as well as experimental and modelling work with CCA treated wood. The latter category includes: determination of the percentage of arsenic volatilised during thermal conversion of CCA treated wood, identification of the mechanisms responsible for arsenic release, modelling of high temperature equilibrium chemistry involved when CCA treated wood is burned, overview of options available for arsenic capture, characterisation of ash resulting from (co-)combustion of CCA treated wood, concerns about polychlorinated dibenzo-p-dioxins/furans (PCDD/F) formation. Finally, the most appropriate thermochemical disposal technology is identified on short term (co-incineration) and on long term (low-temperature pyrolysis or high-temperature gasification).

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Available from: L. Helsen, Aug 07, 2014
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    • "mg Cr g −1 , 2.6–9.8 mg Cu g −1 [14] [15] [16] "
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    ABSTRACT: Pyrolysis or combustion of waste wood can provide a renewable source of energy and produce byproducts which can be recycled back to land. To be sustainable requires that these byproducts pose minimal threat to the environment or human health. Frequently, reclaimed waste wood is contaminated by preservative-treated timber containing high levels of heavy metals. We investigated the effect of feedstock contamination from copper-preservative treated wood on the behaviour of pyrolysis-derived biochar and combustion-derived ash in plant-soil systems. Biochar and wood ash were applied to soil at typical agronomic rates. The presence of preservative treated timber in the feedstock increased available soil Cu; however, critical Cu guidance limits were only exceeded at high rates of feedstock contamination. Negative effects on plant growth and soil quality were only seen at high levels of biochar contamination (>50% derived from preservative-treated wood). Negative effects of wood ash contamination were apparent at lower levels of contamination (>10% derived from preservative treated wood). Complete removal of preservative treated timber from wood recycling facilities is notoriously difficult and low levels of contamination are commonplace. We conclude that low levels of contamination from Cu-treated wood should pose minimal environmental risk to biochar and ash destined for land application.
    Journal of Hazardous Materials 06/2014; 276. DOI:10.1016/j.jhazmat.2014.05.053 · 4.53 Impact Factor
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    • "The recovery of As, Cr, and Cu from treated wood allows wood waste conversion into value added-products. Over the last decades, metal extraction from treated wood wastes using biological [12] [13] [14] [15] [16], physical [16] [17] [18] [19], chemical [20] [21] [22] [23] [24] or combined methods [25] [26] has been widely studied. The thermal remediation processes developed for the management of copper-based treated wood reduce the economic viability of biological or chemical remediation processes in Europe. "

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    • "This practice, in addition to reducing unnecessary landfill, can replenish soil organic matter reserves , provide plant nutrients, and help close the nutrient cycling loop between rural producers and urban consumers (Jones et al. 2013). Pyrolysis or incineration of organic waste wood is an effective strategy to generate energy (Helsen and Van den Bulck 2005). These processes result in the production of biochar and ash, respectively, which can be applied to agricultural soils as either an organic amendment or liming agent (Campbell 1990; Lehmann 2007; Demeyer et al. 2001; Atkinson et al. 2010). "
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    ABSTRACT: Recycled waste wood is being increasingly used for energy production; however, organic and metal contaminants in by-products produced from the combustion/pyrolysis residue may pose a significant environmental risk if they are disposed of to land. Here we conducted a study to evaluate if highly polluted biochar (from pyrolysis) and ash (from incineration) derived from Cu-based preservative-treated wood led to different metal (e.g., Cu, As, Ni, Cd, Pb, and Zn) bioavailability and accumulation in sunflower (Helianthus annuus L.). In a pot experiment, biochar at a common rate of 2 % w/w, corresponding to ∼50 t ha(-1), and an equivalent pre-combustion dose of wood ash (0.2 % w/w) were added to a Eutric Cambisol (pH 6.02) and a Haplic Podzol (pH 4.95), respectively. Both amendments initially raised soil pH, although this effect was relatively short-term, with pH returning close to the unamended control within about 7 weeks. The addition of both amendments resulted in an exceedance of soil Cu statutory limit, together with a significant increase of Cu and plant nutrient (e.g., K) bioavailability. The metal-sorbing capacity of the biochar, and the temporary increase in soil pH caused by adding the ash and biochar were insufficient to offset the amount of free metal released into solution. Sunflower plants were negatively affected by the addition of metal-treated wood-derived biochar and led to elevated concentration of metals in plant tissue, and reduced above- and below-ground biomass, while sunflower did not grow at all in the Haplic Podzol. Biochar and ash derived from wood treated with Cu-based preservatives can lead to extremely high Cu concentrations in soil and negatively affect plant growth. Identifying sources of contaminated wood in waste stream feedstocks is crucial before large-scale application of biochar or wood ash to soil is considered.
    Environmental Science and Pollution Research 11/2013; 21(5). DOI:10.1007/s11356-013-2272-y · 2.83 Impact Factor
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