Ataollah Kheyrandish

Ultraviolet (UV) light is an effective disinfection technology, able to inactivate a wide range of microorganisms, including bacteria and fungi. A safer UV wavelength of 222 nm, also known as far‐UVC, has been proposed to minimize these harmful effects while retaining the light’s disinfection capability. This study is aimed at exploring the antimicrobial activity of filtered far‐UVC (222 nm) on a panel of pathogens commonly found in nosocomial installations. A panel of Gram‐positive and Gram‐negative bacteria and yeast pathogens was tested. Microorganisms were deposited on a plastic surface, allowing them to dry before exposure to the far‐UVC light at a distance of 50 cm. Results showed that far‐UVC light successfully inhibits the growth of the tested pathogens, although at different exposure times. In conclusion, the results of this study provide fundamental information to achieve reliable disinfection performance with far‐UVC lamps with potential applications in healthcare facilities like hospitals and long‐term care homes.

Per- and polyfluoroalkyl substances (PFAS) are potential human carcinogens that have been ubiquitously detected in drinking water sources. Ion exchange (IX) resins offer promising potential for the treatment of water sources impacted by high natural organic matter (NOM) and PFAS concentrations. Several kinetic models such as the pseudo-first-order (PFO), pseudo-second-order (PSO) and intraparticle diffusion (ID) have been investigated to examine the PFAS uptake kinetics on IX resins. However, the kinetic parameters are strongly impacted by the sorption test conditions, especially the sorbate-to-sorbent ratio, which were highly variable in past studies, resulting in several discrepancies when comparing published data. This study examined the use of the homogenous surface diffusion model (HSDM) coupled with the equivalent background concentration (EBC) model as an approach to describe competitive uptakes of regulated long- and short-chain PFAS, NOM, and inorganic ions (such as sulphate and nitrate) with IX resins. Kinetic studies confirmed surface diffusion as the rate-limiting step in NOM-rich waters (Biot number >30), while the multicomponent equilibrium model demonstrated that the initial NOM concentration of approximately 0.35–0.95 μmol L⁻¹ (C₀ = 5 mg C per L) competed with PFAS for active exchange sites. More importantly, the HSDM (R² > 0.98)/EBC (R² > 0.95) models provided an adequate fit to describe PFAS removal in a recycled wastewater.