HR: 1400h
AN: B13B-06    [Abstracts]
TI: Defluoridation by Bacteriogenic Iron Oxides: Sorption Studies
AU: * Evans, K
EM: kerry.tokaryk@utoronto.ca
AF: Geology Department, University of Toronto, Earth Sciences Centre, 22 Russell Street, Toronto, ON M5S 3B1, Canada
AU: Ferris, F
EM: grant.ferris@utoronto.ca
AF: Geology Department, University of Toronto, Earth Sciences Centre, 22 Russell Street, Toronto, ON M5S 3B1, Canada
AB: At concentrations above 1 mg/L, fluoride in drinking water can lead to dental and skeletal fluorosis, a disease that causes mottling of the teeth, calcification of ligaments, crippling bone deformities and many other physiological disorders that can, ultimately, lead to death. Conservative estimates are that fluorosis afflicts tens of millions of people worldwide. As there is no treatment for fluorosis, prevention is the only means of controlling the disease. While numerous defluoridation techniques have been explored, no single method has been found to be both effective and inexpensive enough to implement widely. Our research began in India, with a large-scale geochemical study of the groundwater in a fluoride-contaminated region of Orissa. Having developed a better understanding of the geochemical relationships that exist between fluoride and other parameters present in an affected area, as well as the complex relationships that arise among those parameters that can impact the presence of fluoride, we began investigating certain remediation scenarios involving iron oxides. A common approach to remediation involves the partitioning of fluoride from groundwater by sorption onto a variety of materials, one of the most effective of which is iron oxide whose surface area acts as a scavenger for fluoride. In the presence of iron oxidizing bacteria, the oxidation rate of iron has been shown to be ∼6 times greater than in their absence; fluoride should, therefore, be removed from an aqueous environment by bacteriogenic iron oxides (BIOS) much more quickly than by abiotic iron oxides. Most recently, sorption studies have been conducted using both BIOS and synthetic hydrous ferric oxides in order to compare the behavior between biotic and abiotic sorbents. These studies have provided sorption isotherms that allow comparison of fluoride removed by sorption to BIOS versus synthetic iron oxides. Sorption affinity constants have also been determined, which allow for the prediction of fluoride removal in a wide variety of groundwater systems. Sorption isotherms and affinity constants show the use of BIOS to be a promising technique for the remediation of fluoride in groundwater.
DE: 0418 Bioremediation
DE: 0448 Geomicrobiology
DE: 0496 Water quality
SC: Biogeosciences [B]
MN: 2009 Joint Assembly