Clean up of contaminated soils by bio-electrochemical techniques

Research abstract

In-situ aerobic bioremediation processes are attractive, efficient and cost-effective methods that can be used widely for the clean up of contaminated groundwater systems. Successful implementation of in situ bioremediation is dependent upon the effective supply of electron donors/acceptors and nutrients into the porous medium. Microbial processes require an electron donor, macronutrients (e.g., nitrogen and phosphates), micronutrients, trace nutrients, and an electron acceptor. The availability of dissolved oxygen as electron acceptor, however, is considered one of the essential variables governing intrinsic aerobic biodegradation rate in soil and groundwater. Long-term addition of oxygen to subsurface systems presents an engineering problem because of the limited solubility of oxygen in water, the heterogeneity of soil, the preferential flow paths, and the limited hydraulic conductivity of fine-grained soils (e.g. less than 10-4 cm/sec). A possible method for increasing dissolved oxygen levels at contaminated sites is by electrolysis.

This research investigates the potential applications of direct current in enhancing in-situ aerobic biodegradation of contaminants. Direct current of few Amp/m2 is used to generate and inject dissolved oxygen into a low permeability soil by electro-osmosis. Once oxygen is generated at the anode, its progress throughout soil will be monitored. The microbial activity in the soil will be assessed and correlated to the travel rate of oxygen through the soil.

Research activities/experience

This study will involve using different measurement techniques, including Gas Chromatography (GC), Ion Chromatography (IC), Total Organic Carbon (TOC) analysis, Chemical Oxygen Demand (COD) analysis, and others. Biological activity assessment will involve bacterial culturing and maintenance techniques, microcosm studies and growth rate determination.

The participant is expected to work jointly with graduate students in the laboratory. He/she will need to ultimately develop an understanding in electrochemistry and microbial activities. The participant is expected to develop the skills of preparing environmental samples for analyses.

Special skills or interests that would help an RET/YSP participant with this assignment (i.e., an interest in physics, experience with specific laboratory equipment, etc.)

An interest in the environment, chemistry and biology.

Lab safety/issues unique to this laboratory

A general Lab Safety Overview will be presented by Environment Health and Safety to participants prior to the beginning of lab assignments. The participants should attend the training in order to handle chemicals in the lab.

Suggested literature to be reviewed by RET/YSP prior to beginning this research assignment

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