Model calibration and validation for OFMSW and sewage sludge co-digestion reactors

Area of Science:

• Biochemical Engineering
• Environmental Science
• Waste Management

Background:

• Co-digestion of sewage sludge and municipal solid waste is a key process for waste treatment and energy recovery.
• Existing models often struggle with the variability of organic waste particle size distribution (PSD).

Purpose of the Study:

• To present a novel mathematical model for co-digestion processes based on the Anaerobic Digestion Model no. 1.
• To develop a calibration method for the model that is independent of waste particle size distribution.

Main Methods:

• The model extends the Anaerobic Digestion Model no. 1 using surface-based kinetics for organic waste disintegration.
• Biomethane potential experiments were conducted on organic waste samples with varying particle sizes.
• The model was calibrated and validated using experimental data.

Main Results:

• The disintegration process was identified as the rate-limiting step when organic waste solids are present.
• The kinetic constant for disintegration was found to be independent of waste particle size distribution.
• The calibrated model showed good agreement between simulated and observed biomethane production across different particle sizes.

Conclusions:

• The proposed mathematical model and calibration procedure are robust and effective for co-digestion processes.
• This approach simplifies the assessment of treatment efficiency and methane production prediction in full-scale digesters.
• The model's independence from PSD enhances its applicability to diverse organic waste streams.