Fractional calculus as a generalized kinetic model for biochemical methane potential tests

Area of Science:

• Biochemical Engineering
• Anaerobic Digestion
• Renewable Energy

Background:

• Biomethane potential (BMP) assays are crucial for assessing anaerobic digestion efficiency.
• Existing kinetic models often struggle with substrate heterogeneity and complex degradation patterns.
• Accurate kinetic modeling is essential for optimizing biogas production.

Purpose of the Study:

• To introduce a generalized fractional calculus model for BMP assays.
• To evaluate the model's performance against conventional first-order kinetic models.
• To assess the model's applicability across diverse anaerobic digestion scenarios.

Main Methods:

• Development and application of a fractional calculus-based kinetic model.
• Comparison of fractional model fitting with first-order models using BMP assay data.
• Analysis of model performance with various substrate types and digestion conditions.

Main Results:

• The fractional calculus model demonstrated superior data fitting compared to first-order models.
• The model effectively managed substrate heterogeneity and complex BMP curve patterns (tailing, sigmoidal).
• Robust performance was observed in mono-digestion, co-digestion, and pre-treatment assays.

Conclusions:

• Fractional calculus offers a more accurate and versatile approach to modeling methane production kinetics.
• The model's ability to capture process complexities enhances its utility in anaerobic digestion research.
• Computational efficiency can be improved for fractional orders > 0.8 by using exponential functions.