Evaluation of the Performance of Dialdehyde Cellulose Filters against Airborne and Waterborne Bacteria and Viruses

Abstract

The filtration efficiency and the inactivation performance of a dialdehyde cellulose (DAC) filter against airborne and waterborne bacteria and viruses were investigated. The DAC filter was synthesized by periodate oxidation of a cellulose filter. To evaluate the performance, the inactivation efficiency (determined by comparing the concentration of viable microbes obtained from control and experimental samples) and the relative survival fraction (calculated by comparing the viable microbes from an untreated filter and a treated filter) were introduced. For water filtration tests, the viable removal efficiency and the relative survival fraction of untreated and treated filters of different treatment times were investigated by testing with E. coli and MS2 bacteriophage. The treated filter presented a slightly higher viable removal efficiency and a significantly lower relative survival fraction as treatment time increased. Increasing the residence time by lowering the filtration velocity resulted in a higher viable removal efficiency and lower survival fraction. In air filtration tests, the physical removal efficiency, viable removal efficiency, and relative survival fraction of untreated and 12-h treated filters were investigated. The removal efficiency and relative survival fraction of the treated filter increased and decreased, respectively, with increasing relative humidity. The pressure drop of the treated filter was significantly lower than that of the untreated filter, which resulted in a higher filter quality. The DAC filter with sufficient moisture content had a higher removal efficiency, lower pressure drop, and better disinfection capability, which are all important attributes for practical biocidal applications.

Efficient collection of viable virus aerosol through laminar‐flow, water‐based condensational particle growth

“…Past studies (Woo et al . ; Zuo et al . ) showed that the aerosol produced by the Collison nebulizer at low RH had a mode size at approx.…”

Microwave-irradiation-assisted HVAC Filtration for Inactivation of Viral Aerosols

“…A study investigating bleach disinfection with 0.1% sodium hypochlorite aerosol and UV germicidal irradiation (UVGI) at a wavelength of 254 nm achieved 2-log SF of MS2; however, bleach and UVGI have limitations of chemical release and low penetration, respectively (Vo et al, 2009). Rengasamy et al (2010) and Woo et al (2011) confirmed the inactivation effect of biocidal filters incorporated antimicrobial agents, e.g., silver copper, oxygen species, titanium oxide and dialdehyde, but these filters did not reach 2-log SF within 30 mins. Compared to other filter disinfection technologies, the microwave-assisted filtration system was as or more effective without causing any filter damage and chemical formation.…”

Cellulose-based virus-retentive filters: a review

“…The treatment of a standard cellulose filter paper (Whatman TM Grade 50 filter paper) with sodium periodate improved its antiviral potency due to oxidation of some cellulose to dialdehyde cellulose inside the filter. Challenged with aerosols of MS2 enterobacteria phage at high relative humidity (90% at 23°C), the treated filter showed higher filtration efficiency than a control, untreated one, i.e., better removal of viable viral particles (Plaque Forming Units) joined to a lower resistance to air flow (pressure drop)-due to increased pore size distribution (Woo et al 2011). Higher inactivation of MS2 virus by the treated filter was also highlighted, confirming an improvement of its disinfection capability (Woo et al 2011).…”

“…Challenged with aerosols of MS2 enterobacteria phage at high relative humidity (90% at 23°C), the treated filter showed higher filtration efficiency than a control, untreated one, i.e., better removal of viable viral particles (Plaque Forming Units) joined to a lower resistance to air flow (pressure drop)-due to increased pore size distribution (Woo et al 2011). Higher inactivation of MS2 virus by the treated filter was also highlighted, confirming an improvement of its disinfection capability (Woo et al 2011). However, the filtration and inactivation of airborne viruses were less effective at lower moisture content of the filter, i.e., at air humidity levels commonly encountered in hospital settings, in particular operating rooms (Balaras et al 2007).…”