Pyrite and sulfur-coupled autotrophic denitrification system for efficient nitrate and phosphate removal

The inefficiency of nitrogen removal in pyrite autotrophic denitrification (PAD) and the low efficiency of PO43−-P removal in sulfur autotrophic denitrification (SAD) limit their potential for engineering applications. This study examined the use of pyrite and sulfur coupled autotrophic denitrification (PSAD) in batch and column experiments to remove NO3−-N and PO43−-P from sewage. The effluent concentration of NO3−-N was 0.32 ± 0.11 mg/L, with an average Total nitrogen (TN) removal efficiency of 99.14%. The highest PO43−-P removal efficiency was 100% on day 18. There was a significant correlation between pH and the efficiency of PO43−-P removal. Thiobacillus, Thiomonas and Thermomonas were found to be dominant at the bacterial genus level in PSAD. Additionally, the abundance of Thermomonas in the PSAD was greater than that observed in the SAD reactor. This result indirectly indicates that the PSAD system has more advantages in reducing N2O.