Control strategy for maximum anaerobic co-digestion performance.

Area of Science:

• Biotechnology
• Environmental Engineering
• Chemical Engineering

Background:

• Optimizing anaerobic co-digestion is crucial for efficient biogas production and waste management.
• Current methods often struggle with dynamic adjustments to substrate variability and process stability.

Purpose of the Study:

• To develop and validate a closed-loop control strategy for optimizing anaerobic co-digestion performance.
• To maximize methane productivity and improve digestate quality while ensuring process stability.

Main Methods:

• A linear programming approach was used to optimize substrate feeding for maximum methane yield.
• Empirical diagnosis functions were developed to quantitatively assess process stability (alkalinity ratio) and methane flow rate.
• A variable-gain control function was implemented to adjust substrate blend set-points based on diagnosis function outputs.

Main Results:

• The control strategy successfully optimized methane productivity and process stability in a hybrid Upflow Anaerobic Sludge Blanket - Anaerobic Filter (UASB-AF) reactor.
• The system operated effectively over 210 days, managing organic loading rates (OLR) from 0.71 to 6.33 gCOD/L d.
• Validation demonstrated the system's ability to maintain stable operation with varying substrate blends (gelatine, glycerine, pig manure supernatant).

Conclusions:

• The proposed control strategy offers a robust method for enhancing anaerobic co-digestion efficiency and stability.
• This approach allows for dynamic optimization of substrate blends, leading to improved biogas yields.
• The validated system demonstrates significant potential for industrial application in waste-to-energy processes.