Organic carbon released from tire chips enhances pyrite particle-based autotrophic denitrification of water.

The incorporation of organic matter may enhance the efficacy of mixed-nutrient denitrification. In this study, we explored the effects of waste tire chips on the autotrophic denitrification of pyrite. The synergy between organic carbon and sulfur in mixed-nutrient denitrification resulted in exceptional efficiency. A high tire chip ratio increases the carbon supply to the mixed nutrient denitrification filter, enhances the relative contribution of heterotrophic denitrification, and improves the overall denitrification performance. After an empty bed reaction time (EBRT) of 5 h, the nitrate removal efficiencies of FeS:Tire filler ratios of 1:0, 2:1, 1:1, and 1:2 were 29.20 %, 54.83 %, 71.13 %, and 76.44 %, respectively. A tire-derived organic carbon source increases the abundance of microbial communities and stimulates the activity of key enzymes involved in nitrogen and sulfur metabolism.