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

Possible transmission pathways of fungi in indoor swimming pool facilities were assessed through fungal counting in different areas of the facilities and typing of the collected fungal isolates. Air, water and surface samples were collected from seven different indoor swimming pool facilities. Fungal species were identified based on their internal transcribed spacer (ITS) sequences. Maximum fungal concentrations of 6.2 CFU/cm2, 1.39 CFU/100 mL, and 202 CFU/m³ were found on surfaces, in water and air, respectively. In total, 458 isolates were obtained, belonging to 111 fungal species, of which 50 species were clinically relevant. Phialophora oxyspora (13.3%) and Trichosporon dohaense (5.0%) were the most frequently isolated species and were merely detected on floors, as were the dermatophytes, Trichophyton interdigitale and T. rubrum. Penicillium spp. and Aspergillus spp. were the dominant fungi in water and air. No typical patterns of fungal concentrations along the preferential pathways of pool visitors were observed, however, sites where pool visitors converge while moving from one room (e.g. dressing room) to another (e.g. shower room) and walking barefoot displayed the highest fungal concentrations thus posing the highest risk of contamination. The dispersal of fungi on floors is most likely facilitated by the pool visitors and cleaning tools. Clinically relevant fungi, including the ones rarely identified in nature, were widely detected on floors, in water and in air, as well as on cleaning tools and flexibeams. Preventive measures such as cleaning should minimize the prevalence of clinically relevant fungi in swimming pool facilities since these potentially pose health risks to those vulnerable for infections.@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.@en

The density of fungal contamination and the fungal diversity in an indoor swimming pool facility were assessed. A total of 16 surface samples and 6 water samples were analysed by using a combination of different (semi-) selective culture media. Isolated fungal colonies were identified to the genus or species level by sequencing of the internal transcribed spacer (ITS). The highest fungal counts in water and on surfaces were in the recreational pool (17 CFU/100 mL) and on a flexibeam (5.8 CFU/cm2), respectively as compared with low counts (<0.1 CFU/cm2) on the diving platform, bench tops and walls. The 357 obtained isolates belonged to 79 species and species complexes, 42 of which known as clinically relevant. Phialophora oxyspora (13.7%) and Phoma spp. (12.3%) were the most frequently identified groups. We demonstrated that despite chlorine treatment and regular cleaning of surfaces both water and surfaces were commonly infested with fungi, including many clinically relevant species.@en