Inactivation modeling of human enteric virus surrogates, MS2, Qβ, and ΦX174, in water using UVC-LEDs, a novel disinfecting system

Abstract

In order to assure the microbial safety of drinking water, UVC-LED treatment has emerged as a possible technology to replace the use of conventional low pressure (LP) mercury vapor UV lamps. In this investigation, inactivation of Human Enteric Virus (HuEV) surrogates with UVC-LEDs was investigated in a water disinfection system, and kinetic model equations were applied to depict the surviving infectivities of the viruses. MS2, Q beta, and Phi X 174 bacteriophages were inoculated into sterile distilled water (DW) and irradiated with UVC-LED printed circuit boards (PCBs) (266 nm and 279 nm) or conventional LP lamps. Infectivities of bacteriophages were effectively reduced by up to 7-log after 9 mJ/cm(2) treatment for MS2 and Q beta, and I mJ/cm(2) for Phi X 174. UVC-LEDs showed a superior viral inactivation effect compared to conventional LP lamps at the same dose (1 mJ/cm(2)). Non-log linear plot patterns were observed, so that Weibull, Biphasic, Log linear-tail, and Weibull-tail model equations were used to fit the virus survival curves. For MS2 and Q beta, Weibull and Biphasic models fit well with R-2 values approximately equal to 0.97-0.99, and the Weibull-tail equation accurately described survival of Phi X 174. The level of UV-susceptibility among coliphages measured by the inactivation rate constant, k, was statistically different (Phi X 174 (ssDNA) > MS2, Q beta (ssRNA)), and indicated that sensitivity to UV was attributed to viral genetic material.