Ammonia-based aeration control with optimal SRT control: improved performance and lower energy consumption

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies
• Process Control

Background:

• Activated sludge process relies on controlling ammonia nitrogen (NHx-N) and maintaining nitrification.
• Ammonia-based aeration control (ABAC) aims to match aeration to NHx-N loading for efficiency and compliance.
• Existing solids retention time (SRT) control may conflict with ABAC goals, hindering optimal performance.

Purpose of the Study:

• To introduce and evaluate ABAC-SRT control, a strategy aligning ABAC with SRT control.
• To demonstrate the potential for significant energy savings in wastewater treatment.
• To provide practical implementation guidance for full-scale water resource recovery facilities (WRRFs).

Main Methods:

• Developed a supervisory controller to ensure optimal SRT for ABAC.
• Integrated control of SRT, total ammonia nitrogen (NHx-N), and dissolved oxygen (DO).
• Considered practical implementation aspects including set point selection, sludge inventory calculation, and controller tuning.

Main Results:

• ABAC-SRT control strategy demonstrated potential for over 30% reduction in aeration energy consumption compared to traditional DO control.
• Coordinated control of NHx-N, SRT, and DO was achieved.
• Methodology addresses practical implementation challenges for WRRFs.

Conclusions:

• ABAC-SRT control is a promising approach for optimizing activated sludge processes.
• The strategy effectively balances treatment performance with substantial energy savings.
• Successful implementation requires careful consideration of supervisory controller set points and operational parameters.