Research Area:
Many biologically active environments are not exposed to elemental oxygen such as certain zones in the groundwater, sediments, wastewaters and sludge. In the absence of oxygen, the anaerobic microbial conversion of priority pollutants is unique from that under aerobic conditions. Certain priority pollutants which require a reduction step to initiate biotransformation are more susceptible to biodegradation if oxygen is absent. Examples include polyhalogenated contaminants such as chlorinated solvents (e.g. perchlorothylene), polynitrated aromatics (trinitrotoluene) or oxidized inorganic pollutants (e.g. nitrate, hexavalent uranium, perchlorate, etc). Even hydrocarbon pollutants that are normally degraded under aerobic conditions; may also be subject to different routes of biodegradation in the absence of oxygen when coupled to alternative electron accepting processes, such as denitrification, dissimilatory iron reduction, sulfate reduction and methanogenesis. Heavy metals can be converted from toxic soluble aqueous ions to benign insoluble minerals by sulfate reduction, in which simple organic substrates are utilized to promote sulfate reduction. The resulting biogenic sulfides form insoluble sulfide minerals with the heavy metals. The research is focused on developing low cost bioremediation technology applied in bioreactors, permeable reactive barriers and in situ. The processes are monitored with molecular microbial ecology tools to gain insights on the microbial populations involved in the bioconversion as well as advanced surface spectroscopy methods to elucidate biogenic minerals formed.
Current Activities in Research Area
- Anoxic oxidation of arsenite with nitrate and chlorate for bioremediation of arsenic
- Use of zero valent iron for sulfate reduction in permeable reactive barriers for acid mine drainage
- Bioremediation of landfill leachate plumes
- Bioremediation of uranium utilizing inorganic electron donating compounds
- Anaerobic oxidation of ammonium (Anammox) for the treatment of sludge liquors
- Autotrophic denitrification
- Impact of fluoride on anaerobic wastewater treatment processes
- Reductive dehalogenation of perfluorooctanesulfonate (PFOS)
- Packed bed bioreactors for perchlorate reduction utilizing elemental sulfur as electron donor