Computer simulation of control strategies for optimal anaerobic digestion

Area of Science:

• Biotechnology
• Environmental Engineering
• Process Control

Background:

• Anaerobic digestion (AD) is crucial for biogas production and waste management.
• Effective process control is essential for optimizing AD efficiency and stability.
• Existing control strategies require rigorous evaluation under various operational conditions.

Purpose of the Study:

• To implement and compare three established control strategies for anaerobic digestion using ADM1.
• To evaluate controller performance under diverse scenarios, including start-up, steady-state, and disturbances.
• To identify the most effective control strategy for optimizing AD processes.

Main Methods:

• Simulation of anaerobic digestion using the Anaerobic Digestion Model No. 1 (ADM1) in Simulink/Matlab.
• Implementation and testing of three distinct control strategies: extremum-seeking variable gain and proportional feedback controllers.
• Evaluation of controller performance across five scenarios: start-up, steady-state, and disturbances in influent concentration, pH, and ammonia.

Main Results:

• The extremum-seeking variable gain controller demonstrated strong overall performance.
• A proportional feedback controller targeting pH achieved comparable results to the advanced controller.
• The proportional pH controller resulted in less mechanical wear on system components, specifically the pump.

Conclusions:

• Fast proportional control of reactor pH is a critical factor for optimal performance in low-buffering anaerobic digestion.
• Simpler control strategies, like proportional pH control, can be as effective as complex methods.
• Optimized pH control enhances the stability and efficiency of anaerobic digestion processes.