Metal Adsorption onto Bacterial Consortia from Uncontaminated Geologic Settings: Building Predictive

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Metal Adsorption onto Bacterial Consortia from
Uncontaminated Geologic Settings Building
Predictive Models
Terri Huynh David Borrok Dr. Jeremy Fein 5
August 2004 Department of Civil Engineering and
Geological Sciences University of Notre Dame
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Many natural systems are contaminated with heavy
metals. Bacterial adsorption contributes to the
fate and transport of metallic elements.
Modeling of bacterial metal adsorption in real
environments could aid the designs for
remediation.
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Background

• Bacterial plasma membrane is embedded with
  functional groups that deprotonate as a function
  of pH

(Gram staining of Wetland Soil)

• Deprotonated functional groups allow for
  positively charged metals to be adsorbed

(Yee, 2001)
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• Ionic strength effect
• Single bacteria adsorption experiments show
  greater adsorption for lower ionic strengths
• Not known how consortia will behave due to
  presence of many species, gram types, etc.

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• Previous work shows natural consortia exhibit
  similar adsorption behavior in 0.1 M NaClO4 with
  10ppm Cadmium (Borrok, 2004)

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Objectives

• Determine extent of adsorption of lead, nickel,
  and cadmium onto bacterial consortia
• Determine effects of ionic strength on adsorption
  relationship

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Procedure
Wash bacteria in electrolyte differing in ionic
strength
Perform batch adsorption experiment using
bacterial consortia with lead, nickel, and cadmium
Allow consortium to equilibriate for 2 hours with
metal upon pH adjustments
Analyze via ICP OES to determine amount of metal
adsorbed
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Lead Results 1g/L, 10 ppm
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Nickel Results 5 g/L, 5 ppm
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Cadmium Results 10 g/L, 10 ppm
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Implications and Conclusion

• Under these conditions, ionic strength does not
  have a major effect on adsorption of metals by
  bacterial consortia
• Metal adsorption onto bacterial consortia does
  not appear dependent on types and species in
  consortium
• However, nutrient growth media appears to be a
  factor in the amount of each metal adsorbed onto
  bacterial consortia

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Future Work

• Continue batch adsorption experiments using other
  metals as well as exploring growth media effects
• Develop modeling constants for metal adsorption
  of bacterial consortia

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Acknowledgements
David Borrok Dr. Jeremy Fein Dennis
Birdsell Jennifer Forsythe The EMSI Staff With a
special thanks to Jennifer Schaefer
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References
Borrok D., Fein J.B., and Kulpa C.F. , Proton
and Cd Adsorption onto Natural Bacterial
Consortia Testing Universal Adsorption
Behavior, Geochimica et Cosmochimica Acta 68
(2004). Yee N. and Fein J., Cd Adsorption onto
Bacterial Surfaces A Universal Adsorption
Edge? Geochimica et Cosmochimica Acta 65, pp.
2037-2042. (2001). Fein J.B., Daughney C.J., Yee
N., and Davis T.A., A Chemical Equilibrium Model
for Metal Adsorption onto Bacterial Surfaces.
Geochimica et Cosmochimica Acta 61, pp.
3319-3328. (1997).