Herek Clack

Dept. of Civil & Environmental Engineering - University of Michigan

Non-Thermal Plasma Air Sterilization: Recent Experimental Validation, Identified Challenges, and Comparisons to Conventional Air Treatment Technologies

Increasing recognition of the transmissibility of the SARS-CoV-2 virus between humans as airborne aerosols, and the limited options for respiratory protection against such transmission, have drawn attention to air purification products, with their relative advantages and disadvantages being closely considered. This presentation reviews recent experimental achievements in using non-thermal plasmas (NTPs) as an improvement upon HEPA filtration and ultraviolet irradiation for rapid inactivation of airborne viruses of the sort that is essential for the treatment of flowing air streams typical of ventilation systems. Studies considering both viral surrogates and actual viral pathogens known to cause animal disease are discussed. Particular challenges in conducting inactivation studies of viral aerosols are enumerated and current solutions described. Finally, performance comparisons between NTP air sterilization and the established technologies of UV irradiation and particle filtration are presented, showing the substantial promise for performance improvements that NTP approaches offer.

Selected Publications

[1] Clack, H.L. (2017). "Inhibition and Promotion of Trace Pollutant Adsorption within Electrostatic Precipitators." Journal of the Air & Waste Management Association 8, 881-888.

[2] Clack, H.L. (2018). "Lower Order Representations of Evolving Particle Size Distributions for Rapid Gas-Particle Mass Transfer Simulations during Electrostatic Precipitation." Fuel Processing Technology 178, 71-77.

[3] Clack, H.L. (2017). "Simulation of Electro-hydrodynamic Phenomena and Their Influences on Particulate Collection and Trace Pollutant Adsorption within Electrostatic Precipitators." Frontiers in Energy Research: Advanced Fossil Fuel Technologies, doi: 10.3389/fenrg.2017.00003 (Electronic ISSN: 2296-598X).

Herek Clack is an associate professor of civil & environmental engineering at the University of Michigan and co-founder and CEO of the start-up company Taza Aya. At U-M, his group focuses on chemical and biological aerosols and their interactions with electric fields and electrical discharges. He has served on numerous National Research Council committees addressing environmental issues ranging from the implications of changes to the regulations governing power plant emissions to the safe and ethical thermal destruction of both conventional munitions and chemical warfare agents by the U.S. military. He is the recipient of the XVI Distinguished Young Alumni/ae award (MIT, 2000), the NSF CAREER Award (NSF, 2004), the Harry J. White Award for Outstanding Achievement in the Science and Application of Electrostatic Precipitation (Int’l Soc. for Electrostatic Precipitation, 2013), and the Kenneth M. Reese Outstanding Research Scientist Award (Univ. of Michigan College of Engineering, 2019). He is vice-president and a member of the Board of Directors of the International Society for Electrostatic Precipitation (ISESP) and serves on the Mitigation and Control Technology working group, Awards Committee, and Representation & Equity Affairs Committee of the American Assoc. for Aerosol Research. He earned an S.B. in Aeronautical and Astronautical Engineering from MIT (1987) and an M.S. (1997) and Ph.D. (1998) in Mechanical Engineering from the University of California, Berkeley.