Superiority of Uv222 Radiation by in Situ Aquatic Electrode Krcl Excimer in Disinfecting Waterborne Pathogens: Mechanism and Efficacy

Abstract

Here, an in situ aquatic electrode KrCl excimer radiation with main emission wavelength 222 nm (UV222) was designed and used to disinfect model waterborne virus and bacteria. High inactivation efficacy and diversity of inactivation mechanisms of UV222 were proved by comparision with those of commercial UV254. UV222 could totally inactivate MS2, E. coli and S. aureus with initial concentrations of ~107 PFU or CFU mL−1 within 20, 15, and 36 mJ/cm2, respectively.  The protein, genomic and cell membrane irreparable damage contributed to the microbial inactivation by UV222. We found that UV222 damage nucleic acid with almost the same or even higher efficacy with UV254. Free base damage of UV222 in similar ways with UV254(dimer and hydrate). But due to the quantum yield of free base degradation of UV222 was greater than UV254. Excellent disinfection performance in UV222 irradiation was also achieved in real water matrices (WWTP and Lake). And it was proved that coexisting HCO3- or HPO42 – in real and synthetic water matrices can produce • OH to promote UV222 disinfection. This study provided novel insight into the UV222 disinfection process and demonstrated its possibility to take place of the conventional ultraviolet mercury lamp in water purification.

Keywords: excimer radiation, protein damage, genomic damage, free RNA bases, real water matrices