Maintenance strategies for on-site water disinfection by ultraviolet lamps on dairy farms

Bacteria have been detected in many water supplies on dairy farms, and the water used to wash milking equipment should be free of bacteria. This study evaluated two ultraviolet (UV) technologies, with and without automatic sleeve cleaning device, as on-farm water disinfection system. No fouling was observed during 6 months of continuous operation of the self-cleaning UV system. The dose provided by a non self-cleaning UV lamp decreased by 41% and 96% after 30 and 60 days of continuous operation, respectively, at the maximum recommended water hardness and iron levels. However, when the lamp was operated 2 hours, twice daily, as on dairy farms disinfecting water solely to wash milking equipment, the dose decreased by 9% and 50% after 30 and 60 days, respectively. A UV system with self-cleaning capability is thus recommended for most farms, or monthly manual cleanings will be required to limit fouling and ensure water disinfection. Both UV technologies were efficient in disinfecting water containing high pathogen concentrations. A dose of 136 mJ/cm(2) completely deactivated 1090 and 595 CFU/100 mL of total and fecal coliforms, respectively. Under proper management, the use of UV lamps could thus provide bacteria-free water to wash milking equipment on dairy farms.