Using ultraviolet light for disinfection of finished water

Abstract

Ultraviolet light is now recognised to be very effective for inactivation of Cryptosporidium parvum oocysts; however, its application for disinfection of finished water necessitates validation of UV reactors prior to their installation. Although reactor performance will likely be assessed using non-pathogenic microorganisms as biodosimetry surrogates, it would be prudent for the water industry to simultaneously measure Cryptosporidium oocysts inactivation in controlled bench-scale studies using the water matrix intended for disinfection. The likelihood of that occurring is dependent upon the availability of infectivity measurement procedures that are more user-friendly than the mouse infectivity assays currently used. This study describes a modified cell culture procedure that would enable reliable measurement of changes in oocysts' infectivity following their UV treatment. Also, a number of different biodosimetry surrogates were examined and one selected for comparing the UV doses delivered between bench-scale and full-scale biodosimetry studies. Impacts of UV disinfection on production of disinfection byproducts, effects of lamp ageing on effectiveness of disinfection and the costs associated with employing this technology were also examined.

Molecular Characterization of the Cryptosporidium parvum IOWA Isolate Kept in Different Laboratories

“…O OCYSTS of the Cryptosporidium parvum IOWA or Harley Moon isolate (IOWA) are widely used by the research and regulatory community (Pohlenz et al 1978). IOWA has been used in key studies in the development of animal (Mead and You 1998;Novak and Sterling 1991) and cell culture infection models (Arrowood 2002;Rochelle et al 2002), evaluation of therapeutic drug candidates (Cama and Sterling 1991;Cama et al 1994;Jenkins et al 2004;Mead et al 2003) and disinfection methods (Bukhari et al 2000;Bukhari, Abrams, and LeChevallier 2004;Korich et al 1990;Rochelle et al 2004), immunological and human challenge studies (Chappell et al 1996;Priest et al 2000;Rochelle et al 2001), and more recently in the sequencing of chromosome 6 (Bankier et al 2003) and the whole genome of C. parvum (Abrahamsen et al 2004).…”

Pilot-scale evaluation of UV reactors' efficacy againstin vitroinfectivity ofCryptosporidium parvumoocysts

“…In a way, this method is comparable to counting of CFU, as used for bacteria. The results show that this method, previously used in bench‐scale experiments (Bukhari & LeChevallier, 2003; Bukhari et al , 2004), was appropriate and reproducible for testing a large number of samples and replicates in a large‐scale study.…”

Cryptosporidium and Giardia as water contaminant pathogens in Hungary

“…The multiple stresses that oocysts encounter in the environment and during treatment might limit the infectivity of the oocysts (Belosevic et al 1997, Medema et al 2006. Using animal infectivity, experiments showed that oocysts are sensitive to UV and short-duration pulsed-UV light is an effective disinfection measure for C. parvum (Bukhari et al 2004, Rochelle et al 2004, Lee et al 2008. (Medema et al 2006, Smith et al 1989).…”