Alternative disinfection technologies may overcome some of the limitations of conventional treatment applied in swimming pools: chlorine-resistant pathogens (e.g. Cryptosporidium oocysts and Giardia cysts) and the formation of chlorinated disinfection byproducts. In this paper, results of full scale validation of an alternative disinfection technology UVOX Redox® (hereinafter referred to as UVOX) that combines ozonation and UV irradiation are presented. The performance was assessed in terms of microbial inactivation, disinfection byproduct formation and micropollutant removal. UVOX was able to achieve 1.4–2.7 log inactivation of Bacillus subtilis spores at water flows between 20 and 76 m³/h. Lower formation of trichloromethane and dichloroacetic acid was observed with UVOX followed by chlorination when compared to chlorination alone. However, due to the use of ozone and the presence of bromide in the pool water, the formation of trihalomethanes and haloacetic acids shifted to more brominated byproducts. Chlorine alone was able to remove the target micropollutants: acetaminophen, atenolol, caffeine, carbamazepine, estrone, estradiol, and venlafaxine (>97% removal) after 24 h, with the exception of ibuprofen (60% removal). The application of UVOX in chlorinated water enhanced the removal of ibuprofen. The application of UVOX could lower the usage of chlorine to the level that provides an adequate residual disinfection effect.@en

The occurrence of 32 pharmaceuticals and 14 UV filters in swimming pools and spas was studied. Fifty-one water samples were collected from 17 pools located in sport centres and hotels in Catalonia, Spain. The samples were analysed by liquid chromatography-tandem mass spectrometry. The pharmaceuticals atenolol, carbamazepine, hydrochlorothiazide, metronidazole, ofloxacin, sulfamethoxazole, acetaminophen, ibuprofen, ketoprofen and phenazone were measured in water samples at concentrations higher than their limit of quantification (LOQ). The highest concentration of any individual pharmaceutical was measured for the diuretic hydrochlorothiazide (904 ng/L). The most frequently detected pharmaceutical was carbamazepine, as it was observed in more than half of all the water samples measured (53 %, 27/51). The UV filters at concentrations higher than LOQ in water samples were BP1, BP2, BP3, BP8, THB, 4DHB, 4MBC, OD-PABA, 1HBT, MeBT and DMeBT. The highest concentration of UV filter observed was 4MBC (69.3 ng/L) while the most frequent UV filters in the samples were 1HBT (59 %, 30/51). The results also showed that pharmaceuticals and UV filters were most frequently found in spas. Finally, from a water treatment technology perspective, the lowest occurrence of pharmaceuticals was in the pools applying sand filters followed by disinfection by sodium hypochlorite, while the lowest occurrence of UV filters was in the pools applying coagulation, sand filtration, UV and salt electrolysis.

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