[Autotrophic denitrification of groundwater by electrochemical process]

An autotrophic denitrification process and its reactor for removing nitrate from groundwater was investigated in this paper. Using activated carbon fiber(ACF) as electrodes, the electrochemical reactions could produce hydrogen as the donor for autotrophic denitrification. In the process, nitrate was removed effectively and no accumulation of nitrite in the effluent. The results in this study proved that some key factors, such as the applied current density, flow rate of water, oxidation-reduction potential and the nitrate concentration in raw water, influenced the electrochemically denitrifying effect. When the concentration of NO3(-)-N was 28.8 mg/L in inlet water, the optimum applied density was 9 mA, the highest hydraulic load of the reactor was 35 ml/h, and the reactor performed a practical buffering capacity to pH. After applying electricity to the reactor for 1 h, the oxidation-reduction potential decreased to below--200 mA, so an adaptable reductive environment could be provided in the reactor for denitrification.