Nitrate Removal from Groundwater by Nanoscale Zero-Valent Iron (NZVI) Coupling Autohydrogenotrophic Denitrification

In this work, the denitrification performance of a bio-reactor based on nanoscale zero-valent iron (NZVI) coupling autohydrogenotrophic denitrification was investigated. A series of bio-reactors were configured by inoculating and acclimating pure culture capable capable of denitrification. Effects of various parameters including nitrate (NO3-_N) loading, NZVI to nitrogen ratio (Fe/N), pH and atmosphere on denitrification were evaluated by batch tests. The results showed that the optimum Fe/N and NO3-N loading were 2.8 and 105 mg/L, respectively. Dentrification process remained unaffected by pH ranging from 6.0 to 9.0, while sharp accumulation of nitrite (NO2-_N) occurred at pH 9.0. Complete NO3-_N removal was obtained by providing both nitrogen (N2) and hydrogen gas (H2). In general, excellent nitrogen removal efficiency was always achieved in the chemical-biological coupling system, indicating that the system had strong stability and adaptability for practical application, which offered both theoretic and technical supports to a new efficient and costeffective method to eliminate NO3-_ N from water.