Methodology for Modeling the Microbial Contamination of Air Filters

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.

Self-Sterilizing Laser-Induced Graphene Bacterial Air Filter

“…9 During filtration system operation, contaminants accumulate and captured microorganisms can proliferate inside filter media, leading to decreased filtration efficiency, increased energy cost, lower flow rate, penetration of smaller particles, impaired performance, and downstream airborne pathogen contamination. 7,10,11 Thus, air filters need to be regularly replaced, which adds to the maintenance cost of filtration equipment and systems. 7,10,11 The most common method of air disinfection is ultraviolet C-range (UV-C) radiation.…”

“…7,10,11 Thus, air filters need to be regularly replaced, which adds to the maintenance cost of filtration equipment and systems. 7,10,11 The most common method of air disinfection is ultraviolet C-range (UV-C) radiation. 12 UV-based air sterilization systems require a critical dose for bacteria death.…”

“…Particle capture relies on diffusion, electrostatic attraction, interception by adhesion, inertial impaction, and size-exclusion sieving . During filtration system operation, contaminants accumulate and captured microorganisms can proliferate inside filter media, leading to decreased filtration efficiency, increased energy cost, lower flow rate, penetration of smaller particles, impaired performance, and downstream airborne pathogen contamination. ,, Thus, air filters need to be regularly replaced, which adds to the maintenance cost of filtration equipment and systems. ,, …”

Low-Voltage Bacterial and Viral Killing Using Laser-Induced Graphene-Coated Non-woven Air Filters

“…Quaternary ammonium-functionalized polyurethane coatings applied to HEPA filters for bactericidal activity have been previous reported, and tannic acid-coated HEPA filters were shown to trap influenza viral particles . Copper and silver, known for their excellent antimicrobial properties against a variety of different micro-organisms, are among alternative surface coatings reported and can be effective for short-term use. − Generally, however, filter coatings tend to lose their effectiveness as bacterial deposits or dust buildup prevents necessary contact between the antimicrobial surface coating and micro-organisms . Other strategies to enhance the biological activity of air filters include the use of external stimuli or combined technological approaches such as UV disinfection coupled with filtration .…”

“…16−20 Generally, however, filter coatings tend to lose their effectiveness as bacterial deposits or dust buildup prevents necessary contact between the antimicrobial surface coating and micro-organisms. 21 Other strategies to enhance the biological activity of air filters include the use of external stimuli or combined technological approaches such as UV disinfection coupled with filtration. 22 For example, filters based on photocatalytic metal−organic frameworks proved inactivation of Escherichia coli under solar irradiation and also removed small particulate matter.…”