HR: 0800h
AN: H21C-1038    [Abstracts]
TI: New Sorbents for Removing Arsenic From Water
AU: * McConchie, D M
EM: dmcconch@scu.edu.au
AF: Virotec Research Group, 1884 Denver West Court, Unit 721, Golden, CO 80401-0920 United States
AU: genc-Fuhrman, H
EM: hyg@er.dtu.dk
AF: Technical University of Denmark, Environment and Resources, Bygningstorvet, Bldg. 115,, Lyngby, DK 2800 Denmark
AU: Clark, M W
EM: mclark@scu.edu.au
AF: Virotec Research Group, Environmental Science and Management, Southern Cross University, Military Road, Lismore, NSW 2480 Australia
AU: Caldicott, W
EM: wcaldicott@virotec.com
AF: Virotec International, 54 Hillside Road, Newton Highlands, MA 02461 United States
AU: Davies-McConchie, F G
EM: fionadmc@scu.edu.au
AF: Virotec Research Group, Environmental Science and Management, Southern Cross University, Military Road, Lismore, NSW 2480 Australia
AB: Elevated concentrations of arsenic in the drinking water used in many countries, including some of the poorest developing countries, and recognition that consuming this water can have serious consequences for human health, have led to increased investigations of ways to obtain safe water supplies. Finding new groundwater resources is a possible solution but this is a costly strategy that has no guarantee of success, particularly in areas where water is already a scarce commodity. The alternative is to treat water that is already available, but existing technologies are usually too expensive, too difficult to operate and maintain, or not completely effective when used in less developed countries or remote areas. There is therefore, an urgent need to find a simple and effective but inexpensive sorbent for arsenic that can be used to treat large volumes of water under less than ideal conditions. In this paper we present the results of field and laboratory trials that used a new, highly cost-effective, sorbent to remove arsenic from contaminated water. BauxsolT is the name given to the cocktail of minerals prepared by treating caustic bauxite refinery residues with Mg and Ca to produce a substance with a reaction pH of about 8.5, a high acid neutralizing capacity and an excellent ability to trap trace metals, metalloids and some other ionic species. The trapped ions are tightly bound by processes that include; precipitation of low solubility neoformational minerals, isomorphous substitution, solid-state diffusion, and adsorption; it is also an excellent flocculant. Although ordinary BauxsolT has an excellent ability to bind arsenate, and to a lesser extent arsenite, this ability can be further increased for particular water types by using activated BauxsolT or BauxsolT combined with small amounts of other reagents. Field trials conducted at the Gilt Edge Mine, South Dakota, showed that the addition of BauxsolT to highly sulfidic waste rock reduced the arsenic concentration in leachate water from 35 mg/L to less than 0.005 mg/L; the concentrations of trace metals were also lowered to environmentally acceptable levels and leachate acidity was neutralized. Arsenic concentrations in the leachate water have remained below 0.005 mg/L for the four years since the treatment was carried out and the concentrations of trace metals have remained well below regulatory limits. In another example, the use of BauxsolT blended with a small amount of jarosite successfully reduced the total arsenic concentration in an industrial processing water from 16.4 mg/L to less than 0.001 mg/L; the treatment also reduced the concentrations of Cd, Cr, Ni, Pb and Zn to environmentally acceptable values. In a final example, activated BauxsolT used in simple flow through columns reduced the arsenic concentration in potable water from about 2 mg/L to less than 0.001 mg/L. In all three trials the spent BauxsolT residue released almost no arsenic in a TCLP leaching test and easily met the criteria for classification as an inert solid so that there were no special requirements for the disposal of water treatment residues. In all three studies the BauxsolT-based products compared very favorably with other more costly sorbents that are available.
DE: 1803 Anthropogenic effects
DE: 1831 Groundwater quality
DE: 1045 Low-temperature geochemistry
DE: 1065 Trace elements (3670)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting