The alternating aerobic-anoxic (AAA) process offers many advantages for wastewater treatment and sludge digestion. Laboratory scale experiments were conducted to investigate the feasibility of using pH as a realtime control parameter for this process. Several well defined control points on the pH curve were identified, e.g., ammonia valley and nitrate apex. These points were directly related to the alternating nitrification and denitrification reactions in the process, and were found to be consistent with those previously identified using ORP. Although both pH and ORP can be used as real-time control parameters, pH provides several additional advantages over ORP. Based on these findings, real-time control strategies (fixed pH setpoints and dynamic pH control) were developed and tested. Results from laboratory scale AAA sludge digestion using fixed pH setpoints (6-8) indicated that 36% MLVSS reduction, 39% TN reduction and almost 48% saving in aeration energy was achieved after 300 hrs of digestion.

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