By Courtney Swyden
Texas A&M University graduate student Itza Mendoza-Sanchez and advising professors Robin Autenrieth and Jeff Cunningham are researching bioremediation of groundwater, a technology that employs microorganisms to transform toxic chemicals into non-toxic chemicals.
Twenty-six groundwater sites in Texas are contaminated, according to the U.S. Environmental Protection Agency Web site. Most of these sites include chlorinated volatile organic compounds like trichloroethene (TCE) and perchloroethene (PCE), which are widely used solvents. These chemicals are resistant to degradation which leads to toxicity of groundwater.
“Contamination of water is making it more expensive to provide this vital liquid to all people on earth. Therefore we have to care for water, preserve it, clean it and prevent it from contamination,” said Mendoza-Sanchez, a recipient of a $5,000 2004-05 U. S. Geological Survey research grant.
One aspect of biodegradation that Mendoza-Sanchez and her professors are focusing on is the flow velocity of groundwater. Mendoza-Sanchez is developing an experimental model for the biodegradation of PCE in groundwater to evaluate the effect that different flow velocities have on biodegradation.
“We are trying to better understand the processes affecting biodegradation in groundwater to develop an efficient technology to remediate contaminated sites in an inexpensive and efficient way,” said Mendoza-Sanchez.
PCE can be biodegraded under anaerobic conditions by bacterially mediated sequential reductive dechlorination. Basically, PCE is converted sequentially to TCE, dichloroethene, then to vinyl chloride and finally to the benign end product, ethene, with the help of bacteria.
Mendoza-Sanchez is creating glass beads columns that will be used as lab-scale models of a contaminated aquifer. The columns will be kept under anaerobic conditions, filled with a pre-contaminated water (with known amounts of TCE and/or PCE), and then inoculated with a bacterial culture. Water will be pumped through at different rates.
If the groundwater flow velocity affects the dechlorination rate, then contaminated sites can be evaluated to see if bioremediation technologies could be used, she said.
“I hope that the results of my research can be useful to develop low-cost water treatment and remediation technologies,” said Mendoza-Sanchez.
Mendoza-Sanchez’s research is funded by TWRI as part of the National Institutes for Water Research annual research program. TWRI is the designated institute for water resources research for Texas.
For more information on Mendoza-Sanchez’s research, visit the “USGS Research Grants” page.
