Comprehensive study on pilot Nitrification-Sludge Fermentation coupled Denitrification system with extended sludge retention time

This study showcases a pilot-scale NSFD system's efficient denitrification and sludge reduction over 150 days without external carbon, thanks to long SRT. It optimized microbial metabolism, enhancing hydrolysis and denitrification while inhibiting methanogenesis. Longer SRT also increased predatory micro-animals, boosting cell lysis and energy dissipation for better sludge management. The MBBR environment favored hydrolytic acidifying bacteria, leading to niche differentiation. Biofilm sludge primarily contributes to anaerobic fermentation, while suspended sludge plays a key role in denitrification. Extended SRT enhances the synergy between these two functions, generating a biological driving force for system operation.