Ultraviolet irradiation to preserve high reverse osmosis water quality

Abstract

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.