Microbially-Enhanced Chemisorption of Heavy Metals:  A Method for the Bioremediation of Solutions Containing Long-Lived Isotopes of Neptunium and Plutonium

Abstract

Immobilized cells of a Citrobacter sp. removed neptunium and plutonium negligibly from solution using an established technique that used biologically-produced phosphate ligand (Pi) for metal phosphate bioprecipitation. Removal of these transuranic radionuclides was enhanced by prior exposure of the biomass to lanthanum in the presence of organophosphate substrate to form cell-bound LaPO4. Polyacrylamide gel-immobilized cells removed little Np and Pu per se, but preloaded LaPO4 promoted the removal of Np and Pu upon subsequent challenge in a flow-through column. Approximately 2 μg of Np was loaded per 1 mL, column, when the experiments were stopped after 10 mL, with maintenance of approximately 90% removal of the input metal. Transuranic element removal by this technique, generically described as microbially-enhanced chemisorption of heavy metals (MECHM), is via a hybrid of bioaccumulative and chemisorptive mechanisms.

LLNL SFA FY11 Program Management and Performance Report: Environmental Transport of Plutonium

“…Most Pu microbiology to date has been performed on a handful of laboratory strains (Macaskie and Basnakova, 1998;John, 2001;Rusin et al, 1994;Francis, 2007;Panak and Nitsche, 2001) and at relatively high Pu concentrations (micromolar to millimolar). The general lack of knowledge concerning the diversity, biodensity, exopolymer production potential, and direct Pu-reduction capacity of microorganisms at Pu-contaminated DOE sites is a knowledge gap that needs to be filled in order to assure that DOE's longterm stewardship goals are met.…”

Proton and Cd adsorption onto natural bacterial consortia: Testing universal adsorption behavior

“…Accurate and quantitative models that describe bacteria-metal adsorption are critical to understanding the availability and cycling of metals (Tornabene and Edwards, 1972;Tortell et al, 1999), for predicting the behavior of heavy metal contaminants (Volesky, 2001) and in the development of a number of contaminant remediation strategies (Macaskie and Basnakova et al, 1998;Espisito et al, 2001). Surface complexation models (SCMs), originally developed to describe the adsorption of metal ions onto mineral surfaces, have recently been applied to describe the adsorption of metals onto bacterial surfaces (Xue et al, 1988;Plette et al, 1995;Plette et al, 1996;Fein et al, 1997;He and Tebo, 1998;Fein, 2000).…”

Environmental Transport of Plutonium: Biogeochemical Processes at Femtomolar Concentrations and Nanometer Scales

“…Most Pu microbiology to date has been performed on a handful of laboratory strains (MACASKIE and BASNAKOVA, 1998;JOHN, 2001;RUSIN et al, 1994;FRANCIS, 2007;PANAK and NITSCHE, 2001) and at relatively high Pu concentrations (micromolar to millimolar). The general lack of knowledge concerning the diversity, biodensity, exopolymer production potential, and direct Pu-reduction capacity of microorganisms at Pucontaminated DOE sites is a knowledge gap that needs to be filled in order to assure that DOE's long-term stewardship goals are met.…”