CAREER: Microbial Reductive Dechlorination Coupled with Iron Corrosion

University Of Delaware, Newark DE

Investigators

Abstract

9984669 Chiu This research is designed to understand the interactions between anaerobic microorganisms and elemental iron in groundwater systems containing chlorinated solvents. Preliminary work with elemental iron and a hydrogenotrophic, dechlorinating microbial culture suggests important implications for two groundwater remediation technologies, permeable reactive barriers (PRBs) and accelerated bioremediation. While complex biogeochemical processes in iron PRBs can critically affect their long term performance, leading to premature failure, data also suggest that iron may selectively support microbial dechlorination while suppressing competing microorganisms and thus may be used to enhance the efficiency of anaerobic bioremediation. Batch and long-term column experiments will be conducted using a Dover mixed culture and its non-methanogenic sub-culture to study (1) the effects of microbial colonization and dechlorination on the fate of chlorinated ethenes in iron PRBs and (2) the potential of using iron to enhance biological dechlorination for site remediation. Head space and aqueous samples will be taken continually at different depths to monitor chlorinated ethenes and their daughter products, hydrogen, acetate, methane and pH over time. Iron and aqueous samples from batch and column experiments will also be examined by confocal and electron microscopes and denaturing gradient gel electrophoresis to characterize surface colonization and microbial community structures. In addition, samples of iron and groundwater will be obtained from PRBs in the field and similarly examined. The education plan focuses on the application of problem-based learning in undergraduate courses to enhance learning effectiveness through the use of realistic problems and by encouraging student-centered learning and teamwork. Academically prepared students, especially those from underrepresented groups, will be recruited in this and future research projects. Research experience will be replicated in the classroom by developing discovery-based teaching modules so that the experience can be shared by all students. Problem-based learning, undergraduate research and research-based education will help students develop critical thinking, problem-solving, teamwork and communication skills. ***