A novel in situ technology for the treatment of nitrate contaminated groundwater

A novel in situ membrane technology was developed to remove nitrate (NO3−) from groundwater. Membrane-fed hydrogen gas (H2) was used as an electron donor to stimulate denitrification. A flow-through reactor fit with six hollow-fiber membranes (surface AREA=93 cm2) was designed to simulate groundwater flowing through an aquifer with a velocity of 0.3 m/day. This membrane technology supported excellent NO3− and nitrite (NO2−) removal once H2 and carbon limitations were corrected. The membrane module achieved a maximum H2 flux of 1.79×10−2 mg H2/m2 s, which was sufficient to completely remove 16.4 mg/L NO3−-N from a synthetic groundwater with no NO2− accumulation. In addition, this model in situ treatment process produced a high quality water containing <0.5 mg/L total organic carbon.