A Self-Sufficient Nitrate Groundwater Remediation System: Geobacter Sulfurreducens Microbial Fuel Cell Fed by Hydrogen from a Water Electrolyzer
Nitrate contamination of groundwater is a major problem, especially in farming areas where nitrogen-based fertilizers are used. Geobacter sulfurreducens electrodes were electrochemically evaluated for their ability to reduce nitrate with implications for groundwater remediation. G. sulfurreducens were optimized for nitrate reduction by modifying growth media during subculture. The Geobacter were then cast on Toray carbon paper electrodes and immobilized with pectin. Cyclic voltammetry demonstrated that the electrodes bioelectrocatalytically reduce nitrate with an onset potential of −0.25 V vs. SCE. Amperometry was used to evaluate nitrate concentrations between 0.5 and 270 mM. The limit of detection is 8 mM with a linear range of 20 mM to 160 mM. Evaluation by a Michaelis Menten kinetic model yields a KM of 110 ± 10 mM. The Geobacter sulfurreducens electrodes were incorporated into a nitrate reducing microbial fuel cell which was fed nitrate contaminated water by a peristaltic pump and hydrogen from a proton exchange membrane (PEM)-based water electrolysis cell and yielded a remediation rate of 6 mg/cm2/day.