Development of a sustainable method for the disposal ofchromated copper arsenate (CCA) treated wood
Year: 2010
Type: dissertation
Abstract: Preserved wood is commonly found in solid waste. Among the different types of \npreserved wood, CCA wood has received much attention due to the scale of usage and its \nsignificant role in soil and water contamination after disposal. As the ash of CCA wood is \nhazardous, it cannot be burned, and the best available disposal method is thus landfilling. \nLeaching of the metals from disposed CCA wood in landfills pollutes the environment. \nTo reduce the contamination of CCA, treatment before landfilling is required. \nNowadays, ethanol is seen as a promising source of energy. Lignocellulosic materials \nsuch as wood are resources for ethanol production. This research focuses on the \npossibility of producing ethanol from CCA wood. It suggests that production of ethanol \nwill not only be a solution to the disposal but will also generate a clean fuel. \nThe results showed the existence of copper, chromium and arsenic did not have a \nnegative effect on the fermentation, and producing ethanol from CCA wood is feasible. \nThe copper removed by sulfuric acid completely precipitated during the hydrolysis and \niv \nneutralization. In addition about 50% of the chromium (VI) and also 60% of the arsenic \n(V) were removed from the leachate by yeast during fermentation. \nTCLP tests of the hydrolyzed wood leached less than 4 ppm of arsenic while minimal \namounts of chromium and copper remained in the hydrolyzed wood which makes \nlandfilling of hydrolyzed wood acceptable. \nBaker's yeast behaves selectively by uptaking arsenic (V) and chromium (VI) but not \narsenic (III) and chromium (III). There is competition between copper and chromium \nsorption by yeast. The kinetic model for removal of copper and chromium is a zero order \nmodel while the appropriate model for uptaking arsenic by yeast is a first order model. \nThe kinetic models confirm that there are different mechanisms of uptaking metals by \nyeast, a diffusion mechanism for removal arsenic and a surface adsorption mechanism for \ncopper and chromium. \nAs an overall conclusion of this study, using discarded CCA wood as the feed for ethanol \nproduction is a sustainable method for disposal of CCA treated wood.
Author: Azita Hajizadeh Moghaddam
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Funder: Concordia University
OpenAlex ID: W97490992