Hydrogen-dependent denitrification in a two-reactor bio-electrochemical system

An autotrophic biological process was developed for the treatment of nitrat e-contaminated drinking water. Thr system comprised of two steps: the water to be treated was first enriched with hydrogen (energy source) in the cath odic chamber of an electrochemical cell. and then denitrified in the biorea ctor. The bioreactor was a packed bed of granulated activated carbon, and t he water flow was directed in an upward continuous mode. The system was ope rated for one year, at various water velocities and current intensities. De nitrification rates up to 0.25 kg N m(-3) d(-1) were obtained at the hydrau lic residence time of 1 h. The system was stable. When detected in the effl uent; the concentration of nitrite was low, even under conditions that resu lted in the elution of very high concentrations of nitrate. (C) 2001 Elsevi er Science Ltd. All rights reserved.