Mechanistic insights into enhanced carbon and phosphorus capture and low-carbon nitrification-autotrophic...

A pilot-scale two-stage A/B process was operated, integrating chemically enhanced primary treatment for high-rate carbon capture (A-stage) with nitrification-sulfur autotrophic denitrification (SAD) for downstream nutrient removal (B-stage). The configuration enhanced carbon and phosphorus capture while limiting carbon footprint. Sludge recirculation enabled high organic carbon and phosphorus recovery under low iron dosages (15-20 mg Fe/L). Stable operation was maintained as influent temperature decreased from 24 °C to 13 °C. In the B-stage, complete nitrification and effective nitrate reduction were achieved via SAD, without the need for external organic carbon. Average energy consumption was 0.32 kWh/m³, corresponding to 0.29 kg CO₂-eq/m³. These findings highlight the potential of the integrated A/B configuration to achieve simultaneous resource recovery and low-carbon nitrogen removal in municipal wastewater.