Inactivation of bacteria, virus and Cryptosporidium by a point-of-use device using pulsed broad spectrum white light

There are currently numerous point-of-use (POU) devices on the market claiming to inactivate micro-organisms including Cryptosporidium. In order to protect public health it is important that these devices be evaluated using the most sensitive and specific methodology available. A point-of-use device trade marked “PureBright®” that utilizes “pulsed light” was characterized using the United States Environmental Protection Agency Guide Standard and Protocol for Testing Microbiological Water Purifiers. The unit was challenged with Klebsiella terrigena, polio virus type 1 strain Lsc2ab, simian rotavirus SA11 and Cryptosporidium parvum. The unit was tested over 8 days which included two 48-h stagnation periods. The PureBright unit was run at the manufacturer’s recommended flow rate of 15.14 l/min (4 gal/min). Each microbial challenge consisted of 75.7 l of influent water containing 105 CFU/ml of Klebsiella, 104 PFU/ml of polio and rotavirus and 104 oocysts/ml of Cryptosporidium. Influent and effluent samples were collected and assayed using standard methods for the detection of viable bacteria (membrane filtration) and viruses (cell culture). Viable Cryptosporidium oocysts were determined using vital dyes, excystation, cell culture and animal infectivity. The PureBright unit was able to achieve a >7 log10 inactivation of Klebsiella, a >4 log10 inactivation of polio and rotavirus and a >4 log10 inactivation of Cryptosporidium parvum using relatively good quality influent water. Cell culture and animal infectivity analysis were shown to be equivalent in determining C. parvum viability.