Extremum-Seeking Control for Methane Production Optimization in Low-Cost Anaerobic Digesters

Area of Science:

• Biotechnology and Bioengineering
• Chemical Engineering
• Environmental Science

Background:

• Anaerobic digestion is a key process for renewable bioenergy production.
• Small-scale digesters often lack advanced instrumentation and process knowledge.
• Optimizing methane yield in resource-limited settings is crucial for sustainable energy.

Purpose of the Study:

• To develop an extremum-seeking control strategy for optimizing methane production in low-cost anaerobic digesters.
• To address stability issues and process acidification using minimal sensor data.
• To enable efficient bioenergy generation in rural and resource-limited environments.

Main Methods:

• Implemented an extremum-seeking control strategy adjusting the dilution rate.
• Utilized weekly measurements of methane production rate and the FOS/TAC ratio.
• Incorporated a pH control loop and slope generator for stability, based on FOS/TAC ratio.

Main Results:

• Demonstrated robust convergence to optimal methane production.
• Showcased effective disturbance rejection under varying influent conditions.
• Successfully prevented process instability due to acidification, validated via ADM1 simulations.

Conclusions:

• The proposed control strategy achieves near-optimal methane productivity with low-cost implementation.
• It is well-suited for small-scale digesters and resource-limited settings.
• Contributes to sustainable bioenergy generation and efficient renewable resource utilization.