Elsevier

Physics in Medicine

Volume 12, December 2021, 100039
Physics in Medicine

A Computational Fluid Dynamics (CFD) model to simulate the inactivation of Geobacillus stearothermophilus spores in different moist heat sterilization environments

https://doi.org/10.1016/j.phmed.2021.100039Get rights and content
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Highlights

  • A CFD model was developed using inactivation kinetics of bacterial spores and verified by performing measurements.

  • The inactivation kinetics were obtained from experimental data for wet steam, water and two kinds of dialysis solutions.

  • Simulations were designed to reveal the sterilization efficiency throughout the sterilization product.

  • The simulation of the multiphase flow allowed us to investigate the distribution of the NCGs in the sterilization product.

  • The developed CFD model allows researchers to improve the quality of sterilization processes and, therefore, product safety.

Abstract

The aim of this study was to develop a Computational Fluid Dynamics (CFD) model to simulate the inactivation of bacterial spores of Geobacillus stearothermophilus inside a Peritoneal Dialysis Bag System (PDBS). The presented CFD model has three significant modifications in comparison to current state-of-the-art simulations of sterilization processes. (i) The CFD simulation can be used to consider the multiphase flow (water, steam, different dialysis solutions, non-condensable gases (NCGS)) inside the PDBS, the natural convection as well as the steam penetration. (ii) Experimentally obtained inactivation kinetics were added to the CFD code to enable simulation of the inactivation of G. stearothermophilus spores. (iii) The inactivation process of G. stearothermophilus spores was simulated in different sterilization environments which are present inside a PDBS. The CFD model was verified with measurements using Biological Indicators (BIs). Results showed that on the pre-CFD-simulated “worst case locations” CFD simulations and the BI-based verification were in well accordance.

By using the presented CFD model, the simulation of a moist heat sterilization process can be performed for any given sterilization cycle. In addition, the model is a powerful tool that can be used to optimize steam sterilization processes and guarantee a high level of sterilization efficiency and product safety.

Keywords

Computational fluid dynamics (CFD)
Modelling
Moist heat sterilization
Bacterial spores
Microbial contamination

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