Charcoals Evaluation Regarding the Effect of Preservative–Treated Woods Leached Metal Loss on Water–Based Environment

This study used the adsorption of charcoals (bamboo charcoal and Bey–Charng charcoal) to evaluate the effect of the metal components leached from CCA– and ACQ–treated woods on water–based environment, especial for water quality and fish (Oreochromis hybrids) body in a 48–week long period. The retention contents of CrO3, As2O5, and CuO in the CCA–treated wood were 1.15, 0.44, and 0.12 kg/cm3, respectively, after 48 weeks; the retention content of CuO in the ACQ–treated wood was 0.13 kg/cm3. The iodine value of bamboo charcoal and Bey–Charng charcoal was 146.99 mg/g and 109.85 mg/g, respectively, before testing, and the methylene blue adsorption value was 712.13 mg/g and 642.36 mg/g, which decreased with time after 48 weeks. According to the water quality analysis results, the electrical conductivity of water with charcoals was higher than that without charcoals at the initial stage, and the pH value of that with charcoals was kept above 7. After the test, the contents of heavy metals Cr, As, and Cu ions in the water without charcoals were 0.038, 0.697, and 0.709 ppm; the contents in the water with charcoals were 0.020–0.022, 0.472–0.469, and 0.001–0.139 ppm, respectively, the As content was higher than the drinking water standard (0.01 ppm) of the Environmental Protection Administration, Executive Yuan, and the Cr and Cu contents were lower than the standard 0.05 and 1.0 ppm. Therefore, the adsorption of charcoals has a certain effect of preservative– treated woods leached metal loss on the water quality in water–based environment