ELECTROLYTIC AERATION OF ANOXIC GROUNDWATER

An electrochemical cell was designed to aerate anoxic groundwater with the ultimate goal of enhancing intrinsic bioremediation at a former manufactured gas plant site. Nickel, titanium, and palladium-coated titanium (Pd-Ti) were tested as electrode materials. Among these three materials, the Pd-Ti electrodes had the best oxygen generation capability. Fouling of the Pd-Ti electrodes due to the deposition of precipitates during a test in a field site necessitated an operational strategy in which the polarity of the electrodes was reversed periodically to clean the deposits. However, the Pd-Ti electrodes had a lifetime limited to a few weeks when the electrode polarity was reversed.A modified electrochemical cell was developed using a mixed metal oxide coated titanium anode and a stainless steel cathode. The design minimized the accumulation of the deposited material between the cathode and the anode. Laboratory studies performed in a batch system showed that oxygen generation was not impeded by the presence of precipitates on the cathode. Long-term tests at a field site showed that the voltage during operation and oxygen levels in the delivery well were stable. Tests in a simulated sand tank aquifer in the laboratory demonstrated that oxygen diffuses out of the delivery well and into the aquifer. A simple cost analysis showed that the technology may be cost-competitive with current remediation technologies