Leveraging the chemo-physical interaction of halorespiring bacteria with solid surfaces to enhance halogenated organic compounds bioremediation

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PROJECT SUMMARY There is a lack of fundamental understanding on how microbial breakdown of chlorinated organic compounds is influenced by the presence of sorptive surfaces. Several laboratory and field studies have demonstrated a synergy between sorptive materials and microorganisms leading to the development of material aided delivery of bioamendments in both groundwater and sediment applications. However, a mechanistic understanding of the relationship between sorptive surfaces and microbial dechlorination is lacking. To fill this critical knowledge gap, this research team of chemical/environmental engineers and microbiologists will investigate the fundamental mechanism of microbial dechlorination of chlorinated organics on sorptive surfaces and develop quantitative models that allow optimization and engineering scaleup of enhanced bioremediation aided by materials engineering. Improved understanding will allow better prediction of the degradation of sorbed chemicals in the environment and enable optimization of material science aided technologies for the delivery of biodegradation technologies. The project will target chlorinated organics ranging from less hydrophobic compounds like chloroethenes typically associated with groundwater and strongly hydrophobic compounds such as PCBs typically associated with sediments. These pollutants will be investigated individually as well as in mixtures that are commonly encountered at Superfund sites. A set of carbon-based sorbent materials will be produced in the laboratory to provide a range of physical and chemical properties. In addition to the lab synthesized materials, two most commonly used activated carbons (bituminous coal based, and coconut shell based) and graphite will be tested in parallel for comparison. Through systematic laboratory experiments, the physical and chemical properties (such as specific surface area, pore size distribution, electron accepting capacity, and carbon content) will be evaluated for influence on the sorption characteristics and synergy with biodegradation of chloroethenes and PCBs. Final material selection will also be guided by environmental sustainability considerations. Sorption and biokinetics data from the experimental studies with optimized materials will be synthesized into advanced site models to predict material behavior for field-scale remedial applications. Results from the modeling simulations will allow for optimization of the engineering design for pilot and full-scale applications at contaminated groundwater and sediment Superfund sites. This platform of combining tailored materials with biodegradation will be adaptable for targeting other pollutant mixtures.