Measurement and Simulation of Biocontamination in an Enclosed Habitat

Abstract

Microbial aerosols can be used as model particles for examining the dispersion and deposition of particles as well as assessing the reliability of the simulation methods. For example, the computational fluid dynamics model (CFD) can be used in the evaluation of indoor microbial contamination and the possible spread of harmful microbes in spaces with high densities of people or in special hermetic environments. The aim of this study was to compare the results of the CFD simulation, which predicts the deposition of biological particles on the surfaces of a spacecraft, and real particle deposition, using Bacillus licheniformis/aerius bacterium particles as the model organism. The results showed that the particles were mainly deposited on floor surfaces, but also onto the supply air diffusers, where bacterial concentrations were higher than on the wall and ceiling surfaces. The CFD simulation showed similar trends with actual particle dispersal, conducted in this experiment with Bacillus particles.

Towards a passive limitation of particle surface contamination in the Columbus module (ISS) during the MATISS experiment of the Proxima Mission

“…Only Brownian motion, and electrostatic and phoretic 39 interactions allow the motion of the particles and finally their contact with surfaces. Modeling particle deposits, both the fluid dynamics computation and the experimental 40 , thus requires an aerosol model that is not yet fully updated in low-level activity environments in particular in the Columbus Module 38 , 41 . The maximum acceptable values for the airflow are <450 m 3 h −1 and for the concentration of particulate matter of the US Environmental Protection Agency of the National Ambient Air Quality Standards is 0.05–1 mg m −3 of particles <10 μm in aerodynamic diameter 42 .…”

Passive limitation of surface contamination by perFluoroDecylTrichloroSilane coatings in the ISS during the MATISS experiments

“…Evaluating hydrophobic coatings that limit the surface contamination by repulsing water droplets and floating condensates, prior to any microbial speciesdependent interaction, appears to be a promising approach 43 . Simulations under microgravity, and in the specific environment of ISS modules, have not yet been validated experimentally, although fluid dynamics computations are efficient in deciphering parameters and trends of bioaerosol contamination in an enclosed space 44 . Testing the ISS's true bioaerosol contamination on surfaces still requires exposing them in situ in the ISS.…”

Minimising exposure to droplet and aerosolised pathogens: a computational fluid dynamics study

“…CFD has also been used successfully in modelling biocontamination. The performance of CFD in predicting simulated aerosolised microbial (Bacillus licheniformis/aerius) deposition matched the final location of actual microbes on the internal surfaces of a spacecraft 5 .…”