A novel upper-room UVC-LED irradiation system for disinfection of indoor bioaerosols under different operating and airflow conditions

• Published in: Journal of hazardous materials Vol. 396; p. 122715
• Main Authors: Nunayon, Sunday S., Zhang, Hui H., Lai, Alvin C.K.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05-09-2020
• Subjects: Aerosols; Bacteria; Disinfection; Disinfection bioaerosols; Escherichia coli; IAQ; LED; Ultraviolet Rays; Upper-room UVGI; UVC; IAQ; LED; UVC; Disinfection bioaerosols; Upper-room UVGI
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2020.122715

[Display omitted]
•A novel rotating UVC-LED device was invented to improve air quality.•Efficacy of static irradiation was 53–79 % lower in poorly- than well-mixed rooms.•Using moving irradiation in a poorly-mixed room could enhance efficacy by 22–50 %.•A more compact and safe disinfection system is possible with UVC-LED.
The potential of inactivating indoor bacteria aerosols using a novel rotating ultraviolet-C (UV-C) light-emitting-diode (LED) system was investigated. The system was installed in the upper level of a full scale chamber and its effectiveness against aerosolized E. coli, S. marcescens, and S. epidermidis under the well-mixed with stationary UV-LED scenario was initially tested. The estimated susceptibility values were 1.068, 1.148, and 0.156 m2/J for E. coli, S. marcescens, and S. epidermidis, respectively. Three additional scenarios of experiments were conducted, in which E. coli was aerosolized into the test chamber and then allowed to decay under (i) poorly-mixed condition with stationary system, (ii) well-mixed with rotating system, and (iii) poorly-mixed conditions with rotating system. Our results showed no significant difference between the performance of stationary and rotating UR-UVGI-LED systems under a well-mixed condition. While the performance of the stationary UR-UVGI-LED system under a poorly-mixed condition decreased by 52.90–79.38 % compared to a well-mixed condition, rotating the UR-UVGI-LED system under a poorly-mixed condition, compared to the stationary system, enhanced its performance by 22.36–49.86 %. Thus, our proposed rotating irradiation offers great potential for application in environments where bioaerosols are unevenly distributed in a built environment.