Autotrophic denitrification with anaerobic Fe(2+) oxidation by a novel Pseudomonas sp. W1

In the present study, a novel Pseudomonas sp. W1 was characterized in terms of its ability to perform nitrate removal coupled with anaerobic Fe⁻¹ oxidation under autotrophic growth condition. The effects of operating parameters with respect to the initial solution pH, temperature and initial Fe⁻¹ concentration on nitrate removal were investigated by central composite design. Based on the results of response surface methodology, the maximal nitrate removal efficiency was achieved under the following conditions: pH 7.0, temperature 30 °C and initial Fe⁻¹ concentration 1,100 mg L⁻¹. Under this optimal condition and with an initial NO(3)(-)-N concentration of 55 mg L⁻¹, this strain could remove NO(3)(-)-N with 90% reduction of NO(3)(-)-N, corresponding to oxidizing Fe⁻¹ with 71% oxidation of Fe⁻¹ after 7 days of incubation. The result of kinetic evaluation indicated that this bacterium showed significant substrate affinity to both NO(3)(-)-N and Fe⁻¹.