Bacteria-supported iron scraps for the removal of nitrate from low carbon-to-nitrogen ratio wastewater

A novel bacteria-supported iron scraps (BSIS) system was developed for nitrate removal from low carbon-to-nitrogen ratio (C/N) wastewater. The system consisted of low-cost iron scraps and the accumulated denitrifying-related bacteria enriched from an Fe-wastewater environment when the system was operating. After operating for 39 d, the nitrate removal rate of the system increased to 73.55% within 24 h. The extraction of bacteria from the system revealed that iron scraps and bacteria had a synergistic effect on nitrate removal and bacteria only took effect when cooperating with iron. Microbial analysis using high-throughput sequencing showed that Hydrogenophaga, which is closely related to hydrogenotrophic denitrification, became the dominant genus in the system. The system provides a promising approach to the treatment of nitrate in low C/N wastewater and it has the potential for large-scale application due to the low cost, simple operation and relatively high removal rate.