Solo-Gabriele Helena M, Townsend Timothy G, Messick Brian, Calitu Vandin
Department of Civil, Architectural, and Environmental Engineering, University of Miami, Coral Gables, FL 33146-0630, USA.
J Hazard Mater. 2002 Jan 28;89(2-3):213-32. doi: 10.1016/s0304-3894(01)00311-9.
The combustion of recovered wood from construction and demolition waste as biomass fuel is a common practice. When chromated copper arsenate (CCA)-treated wood is present as part of the wood fuel mix, concentrations of arsenic, chromium, and copper become elevated in the ash. The objectives of this study were to estimate the fraction of CCA-treated wood needed to cause the ash to fail regulatory guidelines and to test a series of solvents for the purpose of extracting the metals from the ash. Ash samples were prepared in an industrial furnace using samples of CCA-treated wood, mixtures of CCA-treated wood and untreated wood, and recycled wood waste collected at construction and demolition recycling facilities. Regulatory guidelines were evaluated by measuring total metals concentrations (using neutron activation analysis) and by conducting standardized leaching tests (toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP)) on the ash. Ten different solvents, ranging from distilled water to strong acids, were also tested for their ability to extract metals. Results of this study indicate that metal concentrations (chromium plus copper plus arsenic) can be as high as 36% of the ash by weight for treated wood samples containing high retention levels (40 kg/m(3)) of CCA. All ash samples from the combustion of 100% CCA-treated wood and mixtures containing 5% CCA-treated wood leached enough arsenic (and sometimes chromium) to be characterized as a hazardous waste under US regulations. Concentrated nitric acid, which was the most effective solvent tested, was capable of removing between 70 and 100% of the copper, between 20 and 60% of the chromium, and 60 and 100% of the arsenic for samples characterized by low retention levels. A particular finding of interest was the efficiency of distilled water and other weak solvents to extract measurable amounts of chromium, especially for ash samples containing low retention levels of CCA. Citric acid was particularly effective at removing arsenic (between 40 and 100%) for ash samples produced from wood containing low CCA retention levels.
将建筑和拆除废物回收的木材作为生物质燃料进行燃烧是一种常见做法。当含铬酸铜砷（CCA）处理过的木材作为木材燃料混合物的一部分时，灰烬中砷、铬和铜的浓度会升高。本研究的目的是估计导致灰烬不符合监管标准所需的CCA处理木材的比例，并测试一系列用于从灰烬中提取金属的溶剂。使用CCA处理木材的样品、CCA处理木材和未处理木材的混合物以及在建筑和拆除回收设施收集的回收木材废料，在工业炉中制备灰烬样品。通过测量总金属浓度（使用中子活化分析）以及对灰烬进行标准化浸出试验（毒性特性浸出程序（TCLP）和合成沉淀浸出程序（SPLP））来评估监管标准。还测试了从蒸馏水到强酸的十种不同溶剂提取金属的能力。本研究结果表明，对于含高保留水平（40 kg/m³）CCA的处理木材样品，金属浓度（铬加铜加砷）可高达灰烬重量的36%。来自100% CCA处理木材燃烧的所有灰烬样品以及含5% CCA处理木材的混合物浸出的砷（有时还有铬）足以被美国法规认定为危险废物。作为测试中最有效的溶剂，浓硝酸能够去除低保留水平样品中70%至100%的铜、20%至60%的铬以及60%至100%的砷。一个特别有趣的发现是蒸馏水和其他弱溶剂提取可测量量铬的效率，特别是对于含低保留水平CCA的灰烬样品。对于含低CCA保留水平木材产生的灰烬样品，柠檬酸在去除砷方面特别有效（40%至100%）。
