Denitrification using a novel Ni-CNF/g-C₃N₄ catalyst and nitrate-enriched wastewater-resourced Achromobacter denitirificans

This study presents a novel hybrid approach combining heterogeneous catalytic chemical reaction with biological intervention to denitrify wastewater. A graphitic carbon nitride (g-C3N4)-supported Ni-carbon nanofiber (CNF) is used as the catalyst, while Achromobacter denitirificans, isolated from an effluent of a sewage treatment plant, is used as the denitrifying bacteria. g-C3N4 acts as an artificial electron elicitor for biological regulation. Ni enhances the activity of key enzymes which are involved in bacterial denitrification, while the CNF surface immobilizes the bacteria. The catalyst and bacterial cells are characterized and identified using spectroscopic techniques and 16S rRNA sequencing, respectively. The data reveal approximately 99% removal of nitrates from water in 24h at the nitrate concentration of 150 mg/L at the catalyst and bacterial dose of 0.025 g/L and 1% (v/ v) with 107 CFU/mL, respectively. Spent water can be recycled and reused. This study provides a new strategy for the denitrification of wastewater.