In order to reduce the carbon source for biological short-cut denitrification, Fe(0)-activated carbon was used to enhance nitrogen removal in the absence of organic carbon, and the influences of the Fe/C mass ratio and initial pH value on the nitrogen removal efficiency were explored. The results showed that the nitrite removal efficiency increased from 7.4% to 31.1% when the Fe(0)-activated carbon was used to enhance short-cut denitrification. When the Fe/C mass ratio was reduced from 2:1 to 1:1 and 1:2, both the denitrification rate and nitrite removal efficiency first increased and then decreased. At a Fe/C mass ratio of 1:1, a maximum denitrification rate of 5.58 mg·(g·h)-1 and a maximum nitrite removal efficiency of 41.1% were achieved, respectively, and 0.1 mg of nitrous oxide was emitted. When the pH value was increased from 6.0 to 9.0, the denitrification rate decreased from 7.39 to 5.96 mg·(g·h)-1, and the nitrous oxide emission decreased from 0.19 to 0.12 mg. Therefore, a higher nitrogen removal efficiency could be achieved by Fe(0)-activated at a Fe/C mass ratio of 1:1 and pH value of 6.0. However, more nitrous oxide would be emitted at a low pH value.
Keywords: Fe/C mass ratio; activated carbon; pH; short-cut denitrification; zero valence iron.