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Methodology for modeling the microbial contamination of air filters.

Joe YH, Yoon KY, Hwang J - PLoS ONE (2014)

Bottom Line: The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively.It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases.The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter.

View Article: PubMed Central - PubMed

Affiliation: School of Mechanical Engineering, Yonsei University, Seoul, Republic of Korea.

ABSTRACT
In this paper, we propose a theoretical model to simulate microbial growth on contaminated air filters and entrainment of bioaerosols from the filters to an indoor environment. Air filter filtration and antimicrobial efficiencies, and effects of dust particles on these efficiencies, were evaluated. The number of bioaerosols downstream of the filter could be characterized according to three phases: initial, transitional, and stationary. In the initial phase, the number was determined by filtration efficiency, the concentration of dust particles entering the filter, and the flow rate. During the transitional phase, the number of bioaerosols gradually increased up to the stationary phase, at which point no further increase was observed. The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively. It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases. The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter.

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Bioaerosol number flux with various flow rates.(A) , (B)  (open symbol), and  (filled symbol) for Filter 2 when  = 0.5,  = 0, and  = 100 µg/m3.
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pone-0088514-g006: Bioaerosol number flux with various flow rates.(A) , (B) (open symbol), and (filled symbol) for Filter 2 when  = 0.5,  = 0, and  = 100 µg/m3.

Mentions: An increase in the flow rate caused an increase in the entering bioaerosols and dust particles concentrations. The effect of flow rate on will now be discussed. The values of with various flow rates when ηanti = 0.5,  = 0, and  = 100 µg/m3 are displayed in Fig. 6A. The value of with a higher flow rate was larger than the value obtained at a lower flow rate. For any flow rate, initially decreased, then increased with time before approaching a steady-state value. Fig. 6B shows that the initial amount of (open symbol) at a higher flow rate condition was larger than at the lower flow rate condition. However, for a higher flow rate, the increase in filtration by dust loading progressed more rapidly. Furthermore, at a higher flow rate, the starting time of the transitional phase was advanced, the value of (filled symbol) increased more rapidly in the transitional phase, and a large amount of was observed in the stationary phase. In this paper, was modeled as a product of , , and (see Eq. 7). The value of was assumed to be 3.0×10−10 1/m. When the flow rate was increased from 0.5 m3/s to 1.0 m3/s, the media velocity increased from 0.05 to 0.1 m/s. However, our calculation shows that was nearly independent of flow rate. Consequently, the changes of by flow rate were caused by changes of media velocity.


Methodology for modeling the microbial contamination of air filters.

Joe YH, Yoon KY, Hwang J - PLoS ONE (2014)

Bioaerosol number flux with various flow rates.(A) , (B)  (open symbol), and  (filled symbol) for Filter 2 when  = 0.5,  = 0, and  = 100 µg/m3.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921200&req=5

pone-0088514-g006: Bioaerosol number flux with various flow rates.(A) , (B) (open symbol), and (filled symbol) for Filter 2 when  = 0.5,  = 0, and  = 100 µg/m3.
Mentions: An increase in the flow rate caused an increase in the entering bioaerosols and dust particles concentrations. The effect of flow rate on will now be discussed. The values of with various flow rates when ηanti = 0.5,  = 0, and  = 100 µg/m3 are displayed in Fig. 6A. The value of with a higher flow rate was larger than the value obtained at a lower flow rate. For any flow rate, initially decreased, then increased with time before approaching a steady-state value. Fig. 6B shows that the initial amount of (open symbol) at a higher flow rate condition was larger than at the lower flow rate condition. However, for a higher flow rate, the increase in filtration by dust loading progressed more rapidly. Furthermore, at a higher flow rate, the starting time of the transitional phase was advanced, the value of (filled symbol) increased more rapidly in the transitional phase, and a large amount of was observed in the stationary phase. In this paper, was modeled as a product of , , and (see Eq. 7). The value of was assumed to be 3.0×10−10 1/m. When the flow rate was increased from 0.5 m3/s to 1.0 m3/s, the media velocity increased from 0.05 to 0.1 m/s. However, our calculation shows that was nearly independent of flow rate. Consequently, the changes of by flow rate were caused by changes of media velocity.

Bottom Line: The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively.It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases.The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter.

View Article: PubMed Central - PubMed

Affiliation: School of Mechanical Engineering, Yonsei University, Seoul, Republic of Korea.

ABSTRACT
In this paper, we propose a theoretical model to simulate microbial growth on contaminated air filters and entrainment of bioaerosols from the filters to an indoor environment. Air filter filtration and antimicrobial efficiencies, and effects of dust particles on these efficiencies, were evaluated. The number of bioaerosols downstream of the filter could be characterized according to three phases: initial, transitional, and stationary. In the initial phase, the number was determined by filtration efficiency, the concentration of dust particles entering the filter, and the flow rate. During the transitional phase, the number of bioaerosols gradually increased up to the stationary phase, at which point no further increase was observed. The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively. It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases. The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter.

Show MeSH