Nitrate reduction by iron supported bimetallic catalyst in low and high nitrogen regimes

In this study, the effect of initial nitrate loading on nitrate removal and byproduct selectivity was evaluated in a continuous system. Nitrate removal decreased from 100% to 25% with the increase in nitrate loading from 10 to 300 mg/L NO3-N. Ammonium selectivity decreased and nitrite selectivity increased, while nitrogen selectivity showed a peak shape in the same range of nitrate loading. The nitrate removal was enhanced at low catalyst to nitrate ratios and 100% nitrate removal was achieved at catalyst to nitrate ratio of ≥ 33 mg catalyst / mg NO3-N. Maximum nitrogen selectivity (47%) was observed at 66 mg catalyst / mg NO3-N, showing that continuous Cu-Pd-NZVI system has a maximum removal capacity of 37 mg NO3 -N/gcatalyst /h. The results from this study emphasize that nitrate reduction in a bimetallic catalytic system could be sensitive to changes in optimized regimes.