Ultraviolet Irradiation To Preserve High Reverse Osmosis Water Quality

Aims: The use of ultrapure dialysate decreases hemodialysis patients' morbidity. Bacterial and endotoxin content of reverse osmosis (RO) water is usually lowered or eliminated by a combination of bacterial filtration and regular disinfection of the distribution. Whether bacterial filtration may be replaced by UV irradiation is unknown. Materials and methods: One, and subsequently two UV lamps were inserted in a complex RO water distribution circuit, devoid of bacterial filters. RO water bacterial content was checked weekly between RO water distribution disinfections. Results: With one UV lamp on the departure of the RO water circuit, bacterial results remained negative (<1 cfu/ml) till the second week after disinfection. Disinfection of the circuit was required every four weeks to comply with the AAMI Guidelines (<200 cfu/ml). Failure of the lamp was followed by bacterial growth (up to 500 cfu/ml), promptly aborted after replacement of the failed lamp. Subsequent addition of a second UV lamp on the return line of the water circuit kept bacteria <1 cfu/ml for up to five weeks. Endotoxin levels remained <0.125 EU. Conclusions: UV irradiation preserves a low RO water bacterial/endotoxin content in the distribution line and is not associated with a measurable endotoxin increase.