Criteria to assess when biodegradation is kinetically limited by intraparticle diffusion and sorption

Area of Science:

• Environmental Science
• Chemical Engineering
• Biotechnology

Background:

• Pollutant biodegradation in porous aggregates is crucial for environmental remediation.
• Understanding the interplay between diffusion, sorption, and biodegradation is essential for accurate modeling.
• Existing models may not fully capture the influence of intraparticle processes.

Purpose of the Study:

• To develop a model that determines when intraparticle diffusion and sorption affect biodegradation rates.
• To establish a criterion for neglecting intraparticle diffusion in biodegradation studies.
• To provide a realistic description of pollutant biodegradation in porous media.

Main Methods:

• Governing partial differential equations for transient processes were formulated.
• The model incorporates local equilibrium sorption-desorption and intraparticle diffusion.
• Mass transfer from aggregate surfaces and external biodegradation were included.
• Illustrative calculations used a linear sorption isotherm and first-order kinetics.

Main Results:

• A dimensionless group was derived to predict the significance of intraparticle diffusion.
• The group combines diffusion coefficient, biodegradation rate, aggregate size, and adsorption capacity.
• Model calculations demonstrated the influence of intraparticle processes on biodegradation rates.
• The model accurately describes experimental data for pollutant biodegradation.

Conclusions:

• Intraparticle diffusion and sorption are critical factors in pollutant biodegradation within porous aggregates.
• The developed dimensionless group serves as a reliable criterion for simplifying biodegradation models.
• This research offers a more realistic approach to modeling biodegradation processes affected by internal aggregate dynamics.