There is currently intense interest in the use of ultraviolet technology for helping to meet future regulations relating to improved microbial inactivation and decreased disinfection byproducts (DBPs).? Much of this interest has been fueled by recent research indicating the effectiveness of UV technologies for the inactivation of Cryptosporidium.? This scientific discovery, combined with proposed regulations concerning DBPs in the United States, has resulted in a need to evaluate the feasibility and effectiveness of UV irradiation for use as a disinfectant for drinking water.The objectives of this project were to:(1) develop and evaluate physical, chemical, and biological methods for calculating effective germicidal UV dose from medium-pressure (MP) and Pulsed-UV (P-UV) lamps;(2) establish a UV dose/log inactivation relationship for specific bacterial and viral indicators for MP and P-UV lamps;(3) determine the extent of photoreactivation and dark repair of heterotrophic bacteria after treatment by MP and P-UV lamps; and(4) compare the ability of MP and P-UV lamps to inactivate?Cryptosporidium.???Originally published by AwwaRF for its subscribers in 2003?This publication can also be purchased and downloaded via Pay Per View on Water Intelligence Online - click on the Pay Per View icon below
This study investigates the potential for biological repair in UV-irradiated oocysts, and it presents the results of concurrent lines of investigation to examine whether reactivation occurs following UV disinfection and also to determine if C. parvum has the genetic basis for repair. The primary objectives of the study included the following: Determine whether C. parvum oocysts of multiple isolates, irradiated with varying doses of UV light, can repair and regain infectivity under light or dark conditions using in-vitro cell culture with a human cell line. Confirm cell culture results with animal infectivity using a neonatal mouse model. Identify possible DNA repair genes in C. parvum by performing homology searches with sequence databases, polymerase chain reaction (PCR) assays, and sequencing clones from a genomic library. Measure the extent of UV-induced DNA damage by quantitative PCR. If reactivation is detected, evaluate the effects of both post-UV chemical disinfection on oocyst reactivation and determine the increased UV dosage necessary to inhibit repair. Originally published by AwwaRF for its subscribers in 2004.
There is currently intense interest in the use of ultraviolet technology for helping to meet future regulations relating to improved microbial inactivation and decreased disinfection byproducts (DBPs).? Much of this interest has been fueled by recent research indicating the effectiveness of UV technologies for the inactivation of Cryptosporidium.? This scientific discovery, combined with proposed regulations concerning DBPs in the United States, has resulted in a need to evaluate the feasibility and effectiveness of UV irradiation for use as a disinfectant for drinking water.The objectives of this project were to:(1) develop and evaluate physical, chemical, and biological methods for calculating effective germicidal UV dose from medium-pressure (MP) and Pulsed-UV (P-UV) lamps;(2) establish a UV dose/log inactivation relationship for specific bacterial and viral indicators for MP and P-UV lamps;(3) determine the extent of photoreactivation and dark repair of heterotrophic bacteria after treatment by MP and P-UV lamps; and(4) compare the ability of MP and P-UV lamps to inactivate?Cryptosporidium.???Originally published by AwwaRF for its subscribers in 2003?This publication can also be purchased and downloaded via Pay Per View on Water Intelligence Online - click on the Pay Per View icon below
This study investigates the potential for biological repair in UV-irradiated oocysts, and it presents the results of concurrent lines of investigation to examine whether reactivation occurs following UV disinfection and also to determine if C. parvum has the genetic basis for repair. The primary objectives of the study included the following: Determine whether C. parvum oocysts of multiple isolates, irradiated with varying doses of UV light, can repair and regain infectivity under light or dark conditions using in-vitro cell culture with a human cell line. Confirm cell culture results with animal infectivity using a neonatal mouse model. Identify possible DNA repair genes in C. parvum by performing homology searches with sequence databases, polymerase chain reaction (PCR) assays, and sequencing clones from a genomic library. Measure the extent of UV-induced DNA damage by quantitative PCR. If reactivation is detected, evaluate the effects of both post-UV chemical disinfection on oocyst reactivation and determine the increased UV dosage necessary to inhibit repair. Originally published by AwwaRF for its subscribers in 2004.