Shortcut nitrification–denitrification by real-time control strategies

The study aimed at solving the instability of shortcut nitrification–denitrification through real-time control strategies. The results showed that excess aeration (aeration was still on after nitrosation) had an adverse impact on the stabilization of shortcut nitrification–denitrification, with nitrosation ratio ( NO 2 - –N/ NO x - –N) decreasing from 96% to 29% after excess aeration for 13 cycles, indicating that excess aeration was prone to change nitrification modes from shortcut nitrification to full nitrification. By using real-time control, shortcut nitrification and full nitrification were clearly detected by characteristic points on ORP and pH curves. Thus, aeration was stopped once nitrosation was completed, and shortcut nitrification–denitrification was maintained with nitrosation ratio ( NO 2 - –N/ NO x - –N) higher than 96%. The study showed that real-time control strategy could prevent excess aeration and achieve stable shortcut nitrification–denitrification.