Two-particle model of anaerobic solid state fermentation

Area of Science:

• Biochemical Engineering
• Environmental Biotechnology
• Mathematical Modeling

Background:

• Anaerobic solid-state fermentation (ASSF) stability is crucial for efficient waste treatment.
• Stable ASSF requires methanogenic seed sludge and is influenced by mass-transfer limitations.
• Existing studies highlight the complexity of microbial interactions and substrate degradation in ASSF.

Purpose of the Study:

• To develop a structured mathematical model for anaerobic solid-state fermentation (ASSF).
• To investigate the influence of particle characteristics and mass transfer on ASSF stability.
• To propose strategies for preventing volatile fatty acid accumulation in ASSF.

Main Methods:

• Development of a structured mathematical model incorporating multiple-reaction stoichiometry, microbial growth kinetics, and material balances.
• Postulation of two particle types: 'seed' (low biodegradability, high methanogenic activity) and 'waste' (high biodegradability, low methanogenic activity).
• Simulation of particle diffusion and liquid-gas interactions within the fermenting solid mass.

Main Results:

• The theoretical model qualitatively aligns with existing experimental ASSF studies.
• Computer simulations demonstrate the impact of biodegradability and mass transfer intensity on ASSF stability.
• Identification of key factors influencing volatile fatty acid accumulation within seed particles.

Conclusions:

• The developed model provides a framework for understanding ASSF dynamics.
• Biodegradability and mass transfer are critical parameters for maintaining ASSF stability.
• Strategies derived from the model can help optimize ASSF processes and prevent operational issues like VFA accumulation.