Fate and Transport of Pollutants in the Environment

-Extracellular electron transport mechanisms for metal oxide reduction (Supported by Department of Energy): We are developing better approaches to biologically reduce and immobilize uranium and other metal contaminants in groundwater, with a focus on the role of extracellular electron shuttling.  Specifically, we are evaluating how microbial nano wires and soluble electron shuttles allow microbes to access metal oxides trapped in soil and sediment nano pores.

The fate of PAHs associated with coal tar sealcoat in urban areas (Supported by USGS): We are quantifying the fate and toxicity of polycyclic aromatic hydrocarbon (PAH) pollutants in an urban watershed, and are especially concerned with the fate of PAHs originating from coal tar sealcoat.   The loss and redistribution of PAHs deposited with coal tar to other carbonaceous materials (e.g., soot, charcoal, asphalt) is being quantified in lake cores, with the goal of determining whether these PAHs are being lost from lake sediments over time, and/or becoming more or less bioavailable.

Stress enabled microbial adaptation and evolution (Supported by NASA): We are exploring the ability of microorganisms to adapt and grow in a microfluidic cell along a concentration gradient of the antibiotic ciprofloxacin.  An underlying premise of our work is that stress promotes genetic mutation, and that adaptation to the antibiotic will be reflected the microbial genome.

 Biogeochemical processes that control natural attenuation of trichloroethylene (TCE) in low permeability zones (Supported by DOE SERDP): We are exploring the biotic and abiotic pathways of TCE transformation in groundwater sediments, with a focus on how mass transfer, nutrients, and reactive mineral components affect pathways for TCE transformation.  Anaerobic and nutrient rich conditions are expected to promote biological dechlorination of TCE, whereas nutrient poor and iron rich conditions are expected to promote reductive dichloro-elimination.      

Development of Innovative Catalytic Technologies for Water Treatment

Development of a trickle bed reactor for nitrate reduction (Supported by Texas Hazardous Waste Research Center): We are developing new catalytic trickle bed reactor for both direct drinking water treatment of nitrate, and for the treatment of brines from ion exchange resins used to remove nitrate from drinking water.  The primary goal is to enhance mass transfer of hydrogen from the gas to liquid phase, which is limiting overall reactor activity because of its very low water solubility. 

Synthesis of new bimetallic alloys for oxyanion reduction (Supported by Texas Hazardous Waste Research Center): We are developing new catalysts tailored at the nanoscale to enhance reactivity for nitrate and perchlorate.  The catalysts combine Pd and either Au or Ag in an alloy state, which strains the Pd lattice and enhances reactivity above that for Pd alone.  Different bimetal ratios are being evaluated for nitrate reduction activity, as well as for stability under water treatment conditions.

Mitigating the Environmental  Impacts of Energy Production and Generation

Geological carbon sequestration (Supported by DOE EFRC): We are evaluating the role of CO2 and brine exposure to reservoir minerals on reservoir wettability, mineral roughness, and associated microseismic events during geological carbon sequestration.  An underlying premise is that mineral reactions during CO2 injection enhance mineral surface roughness and water wettability.