REMOVAL OF U AND MO FROM WATER BY IMMOBILIZED DESULFOVIBRIO-DESULFURICANS IN COLUMN REACTORS

Intact cells of Desulfovibrio desulfuricans were immobilized in polyac rylamide gel and used to remove soluble U and Mo from water by enzymat ically mediated reduction reactions in column reactors. Formate or lac tate served as the electron donor and oxidized U(VI) and Mo(VI) specie s served as electron accepters. Greater than 99% removal efficiencies were achieved for both metals with initial concentrations of 5 mg/L U and 10 mg/L Mo. Hydraulic residence times in the columns were between 24 and 36 h. Sulfate concentrations as high as 2000 mg/L did not inhib it reduction of U or Mo in the columns. However, nitrate inhibited ura nium reduction at concentrations near 50 mg/L and inhibited molybdenum reduction at concentrations near 150 mg/L. The results indicate that enzymatic reduction of U and Mo by immobilized cells of D. desulfurica ns may be a practical method for removing these contaminants from solu tion in continuous-flow reactors. (C) 1998 John Wiley & Sons, Inc.