Full-scale simultaneous partial nitrification, anammox, and denitrification for the efficient treatment of carbon and nitrogen in low-C/N wastewater
Xi Cao, Tianqi Liu, Xiang Li, Yong Huang, Qin Nie, Ming Li
Abstract
• Full-scale SNAD system successfully treated real low C/N wastewater • NRR was 0.9 kg/(m 3 ·d) with anammox contributing 61% • Rapid initiation of partial nitration with low DO and high FA • Organic matter was maximally resourced by heterotrophic bacteria A full-scale simultaneous partial nitrification, anaerobic ammonia oxidation (anammox), and denitrification (SNAD) reactor was initiated to address the problem of high energy consumption for the treatment of low C/N wastewater. The SNAD system achieved a nitrogen removal rate of 0.9 kg/(m 3 ·d) at an influent NH₄ + –N concentration of 500 mg/L after 450 days of stable operation. Partial nitrification was achieved by maintaining free ammonia levels at 0.8±0.3 mg/L and dissolved oxygen concentrations between 0.3 mg/L and 1.2 mg/L, which resulted in synergistic nitrogen removal, with anammox contributing 61% and denitrification contributing 39%. Microbiological analyses indicated that the dominant microorganisms were Candidatus Brocadia, Thauera, Denitratisoma , and Nitrosomonas . In conclusion, study provides a solid foundation for the broader implementation of the SNAD process in wastewater treatment systems.