This thesis describes the occurrence of microbial and chemical contaminants in swimming pools and the investigation of an alternative disinfection technology, UVOX Redox® that could reduce reliance on chlorine and the formation of chlorinated disinfection byproducts (DBPs) in swimming pools. This technology was effective in inactivation of chlorine resistant microorganisms, represented by Bacillus subtilis spores, and in combination with chlorine generated lower concentrations of chlorinated DBPs compared to chlorination alone. It enhanced the removal of pharmaceuticals and personal care products (PPCPs), which were frequently present in indoor, outdoor and spa pools. Carbamazepine and 1H-benzotriazole were the most frequently detected PPCPs, while hydrochlorothiazide and 4-methylbenzylidene camphor were detected at the highest concentration. An investigation of seven different swimming pool facilities showed that clinically relevant fungi were omnipresent. Floors at the sites where the pool visitors converge, such as the exit leading to shower rooms, showed the highest fungal concentrations. The distribution of fungi inside the swimming pool facilities highlighted potential transmission pathways and a possible risk of fungal infections. Future swimming pool water guidance should include raising awareness among swimmers, pool operators and managers about hygienic behaviour and better hygiene measures, and application of alternative disinfection technologies such as UVOX.
2 Application of UVOX Redox® for swimming pool water treatment: microbial inactivation, disinfection byproduct formation and micropollutant removal
3 Occurrence of pharmaceuticals and UV filters in swimming pools and spas
4 Clinically relevant fungi in water and on surfaces in an indoor swimming pool facility
5 Potential transmission pathways of clinically relevant fungi in indoor swimming pool facilities
6 General discussion
IHE Delft PhD programme leads to a deepening of a field of specialisation. PhD fellows do scientific research, often with conclusions that directly influence their region. At IHE Delft, PhD researchers from around the world participate in problem-focused and solution-oriented research on development issues, resulting in an inspiring research environment. PhD fellows work together with other researchers from many countries dealing with topics related to water and the environment.
PhD research is often carried out in the ‘sandwich’ model. Preparation and final reporting – the first and last portion of the programme – are carried out in Delft, while actual research is done in the fellow’s home country, under co-supervision of a local institute. Regular contacts with the promotor are maintained through visits and long-distance communication. This enables researchers to employ solutions directly to problems in their geographical region.
IHE Delft PhD degrees are awarded jointly with a university. The degrees are highly valued and fully recognised in all parts of the world.