Generation and biological collection efficiency of MS2 bioaerosol for the evaluation of aerosol filtration devices

Abstract

Desarrolla una configuración experimental para evaluar la eficiencia de remoción del virus MS2 de un filtro de tela de fibra de carbón activado. La exposición a bioaerosoles en ambientes interiores está asociada a efectos adversos a la salud. Existe la necesidad de desarrollar dispositivos de control que permitan remover bioaerosoles de los flujos de gases en sistemas de ventilación y calefacción. Esta investigación consistió en el desarrollo de un generador LSA modificado para producir un flujo estable de aerosol. Asimismo, se determinó la eficiencia de recolección del bacteriófago MS2 a través del BioSampler, utilizado para caracterizar la eficiencia de remoción biológica del filtro ACFC mediante la captura del bioaerosol en un medio líquido antes y después del filtro. Se empleó una membrana de 100k Dalton para recolectar partículas aerosolizadas de MS2 en la entrada del BioSampler. El ensayo de infectividad permitió cuantificar las partículas infecciosas de MS2 en el filtro de membrana y en el medio de recolección del BioSampler. Con flujos de 1 y 6 slpm (20 ºC, 1 atm) en el filtro y BioSampler, respectivamente, y 50% de humedad relativa, se obtuvo una eficiencia de recolección biológica en base a 3 pruebas independientes, de 7.9 ± 0.42%. Finalmente, se evaluó la capacidad de remoción física del AFCF con partículas nanométricas estándar de 40 y 95 nm, obteniéndose 97 ± 0.07%.

Exposure to bioaerosol in indoor environments is associated with adverse health effects. There is need to develop control devices to separate bioaerosols from gas streams in heating and ventilation systems to protect human health and enhance national security. The goal of this research is to develop an experimental setup to evaluate the virus removal efficiency of an electrothermally regenerated activated carbon fiber cloth (ACFC) filter. MS2 bacteriophage was used as a model virus. Three tasks were conducted. The first task involved the development of a modified Liquid Sparging Aerosolizer (LSA) generator, which was fabricated to produce a stable supply of tested bioaerosol. The second task involved the determination of the biological collection efficiency of the SKC BioSampler for bacteriophage MS2. The BioSampler is used to characterize the biological removal efficiency of the ACFC filter by capturing the bioaerosol in a liquid medium before and after the ACFC filter. The biological collection efficiency of the BioSampler was calculated based on the results of infectivity assay. A 100 kDalton membrane was used to collect aerosolized MS2 particles at the inlet of the BioSampler. Infectivity assay was used to determine the infectious MS2 particles on the membrane filter and in the collection media of the BioSampler. Under 1 slpm (standard liter per minute) (20 °C, 1 atm) flow rate of the filter, 6 slpm (20 °C, 1 atm) flow rate of the BioSampler, and 50% relative humidity (RH), the biological collection efficiency calculated based on the results of the infectivity assays was 7.9 ± 0.42% based on three independent tests. The third task was to determine the ACFC’s ability to physically remove nanometer diameter particles. ACFC was tested with 40 nm and 95 nm diameter PSL beads. A particle physical removal of 97 ± 0.07% of the particles was measured based on the difference of the outlet and inlet particle number concentrations.