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TRANSFORMATION AND MOBILIZATION OF ARSENIC ADSORBED ON GRANULAR FERRIC HYDROXIDE UNDER BIO-REDUCTIVE CONDITIONS
Citation:
AL-ABED, S. R., G. JEGADEESAN, AND P. PINTO. TRANSFORMATION AND MOBILIZATION OF ARSENIC ADSORBED ON GRANULAR FERRIC HYDROXIDE UNDER BIO-REDUCTIVE CONDITIONS. Presented at American Chemical Society National Meeting, Chicago, IL, March 25 - 29, 2007.
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Description:
Biotic and abiotic reduction of arsenic (V) and iron (III) influences the partioning of arsenic (As) between the solid and aqueous phases in soils, sediments and wastes. In this study, laboratory experiments on arsenic adsorbed on granular ferric hydroxide (GFH) was performed to assess its transformation and release. Two types of GFH adsorbents were equilibrated with arsenic having capacities of 1328 mg/kg (TE) and 2000 mg/kg (CHN), respectively. Arsenic release was determined as a function of pH and redox in the abiotic experiments using synthetic leachate (simulating municipal solid waste leachate). In another set of experiments, the two GFH solids were inoculated with methanogenic sludge and known arsenic respiring bacteria, Sulfurospirillum barnesii strain SES-3 and; Sulfurospirillum arsenophilum strain MIT-13 as controls. Batch leaching tests at different pH conditions showed a strong pH dependence on arsenic and iron leaching. In general, abiotic reducing conditions did not play a significant role in arsenic or iron solubilization. It was also observed that microbial Fe (III) reduction invoked by SES-3 and MIT-13 strains were responsible for increased arsenic solubilization. Arsenic mobilization due to its biological reduction from As (V) to As (III) was also observed in the presence of the methanogenic sludge. Solid phase analysis with XAFS (X-ray absorption fine structure) is presented.