Multiscale Modelling of De Novo Anaerobic Granulation

Area of Science:

• Bioprocess Engineering
• Mathematical Modeling
• Microbial Ecology

Background:

• Granular biofilms are crucial in wastewater treatment and other bioprocesses.
• Understanding de novo granulation and multispecies biofilm evolution is key for optimizing bioreactor performance.
• Existing models often lack the multiscale and multispecies complexity required for accurate prediction.

Purpose of the Study:

• To develop and validate a multiscale mathematical model for de novo granulation and multispecies granular biofilm evolution.
• To explore the ecological dynamics, biomass distribution, and dimensional changes within anaerobic granules.
• To investigate the influence of various operational parameters on the granulation process.

Main Methods:

• A multiscale mathematical model was developed, treating granules as spherical free boundary domains with radial symmetry.
• Nonlinear hyperbolic PDEs described sessile microbial growth, while quasi-linear parabolic PDEs modeled substrate and invading species dynamics.
• Nonlinear ODEs governed soluble substrates and planktonic biomass in the bulk liquid. Numerical solutions were used for analysis.

Main Results:

• The model successfully reproduced the concentric layering and ecology of anaerobic granules observed experimentally.
• Numerical simulations confirmed the model's ability to predict granule dimensional evolution and substrate dynamics.
• The model demonstrated predictive power for factors like influent composition and granulation properties.

Conclusions:

• The developed multiscale mathematical model provides a robust framework for understanding and predicting anaerobic granulation.
• The model accurately captures the complex interplay of microbial ecology, biomass dynamics, and physical processes in granular biofilms.
• This tool can guide the optimization of bioreactor design and operation for enhanced wastewater treatment and bioprocessing.