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This study investigated perchlorate reduction by autotrophic elemental sulfur oxidizingbacteria. A perchlorate reducing microbial consortium was enriched from a denitrifyingwastewater inoculum in medium containing elemental sulfur (Ssup0/sup), crushed oyster shell,nutrients and 5 mg/L perchlorate. Perchlorate could be reduced to 0.5 mg/L inapproximately 15 days. The enrichment culture was subsequently inoculated into acontinuous upflow packed-bed bioreactor containing Ssup0/sup and crushed oyster shell medium.High-level perchlorate concentrations (5-8 mg/L) were reduced to 0.5 mg/L with anempty bed contact time (EBCT) of 13 hours. Low levels of perchlorate (80-120 g/L)were treated varying two parameters, recirculation ratio and empty bed contact time(EBCT). Little or no recirculation was required to efficiently reduce perchlorate to lessthan 4 g/L. The system also proved somewhat independent of EBCT. Using molecularidentification techniques a -proteobacterium with 99% 16S rRNA sequence similarity tothe known perchlorate reducing bacteria, Dechloromonas sp., was isolated from furtherbatch enrichments. Experiments are ongoing to determine if members of this genus arethe sole perchlorate reducers or part of a consortium present in the sulfur containingbioreactors. Includes 17 references, tables, figures.

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Edition: Vol. - No. Published: 11/01/2006 Number of Pages: 13File Size: 1 file , 390 KB