No abstract

Alternative technologies to disinfect drinking water such as ultraviolet (UV) disinfection are becoming more widespread. The benefits of UV disinfection include reduced risk of microbial pathogens such as Cryptosporidium and reduced production of regulated drinking water disinfection byproducts (DBPs). The objective of this research was to determine if mammalian cell cytotoxicity and genotoxicity varied in response to different chlorination protocols with and without polychromatic medium pressure UV (MPUV) and monochromatic low pressure UV (LPUV) disinfection technologies. The specific aims were to analyze the mammalian cell cytotoxicity and genotoxicity of concentrated organic fractions from source water before and after chlorination and to determine the cytotoxicity and genotoxicity of the concentrated organic fractions from water samples treated with UV alone or UV before or after chlorination. Exposure of granular activated carbon-filtered Ohio River water to UV alone resulted in the lowest levels of mammalian cell cytotoxicity and genotoxicity. With combinations of UV and chlorine, the lowest levels of cytotoxicity and genotoxicity were observed with MPUV radiation. The best combined UV plus chlorine methodology that generated the lowest cytotoxicity and genotoxicity employed chlorination first followed by MPUV radiation. These data may prove important in the development of multibarrier methods of pathogen inactivation of drinking water, while limiting unintended toxic consequences.

Spiking studies underscore the important role filtration plays in removing protozoa from surface water. As part of a pilot‐scale examination of filtration media at the Cincinnati (Ohio) Water Works, heat‐inactivated Giardia cysts and Cryptosporidium oocysts were spiked into surface water that had already undergone coagulation and sedimentation. This spiked water was then introduced into pilot‐scale filters containing sand only, typical dual anthracite–sand, and deep dual anthracite–sand media configurations. All of the media types used in this study demonstrated similar removal capabilities, with average cyst removal ranging from 2.7 to > 4.5 logs and average oocyst removal of 2.7–3.9 logs. Endospore and polystyrene bead removals were similar to those of the protozoa, but turbidity and particle counts demonstrated substantially less removal capability.

No abstract

Advanced oxidation processes (AOPs) are finding key treatment niches in several applications, including groundwater remediation, water reuse, seasonal taste and odor control, and organic contaminant oxidation. AOPs are incorporated into a water treatment process train when traditional methods for the removal of organics such as coagulation, filtration, chemical oxidation, or ultraviolet (UV) photolysis alone are insufficient to remove specific contaminants.