Subproducts resulting from disinfecting drinkable water

For his PhD thesis, Unai Iriarte Velasco analysed strategies for reducing levels of subproducts from the disinfection of drinkable water and their application in optimising the functioning of water treatment plants.

The thesis, recently presented at the University of the Basque Country, centres on the treatment of drinkable water. Currently it is known that the chlorine employed as disinfectant reacts with the natural organic material present in surface water. This interaction is responsible for the presence of certain undesirable substances known as disinfection subproducts. In fact, current legislation includes some of these disinfection subproducts amongst their criteria for the first time. The general aim of the thesis was to evaluate the factors that favour the formation of these subproducts and thus reduce the levels of exposition derived from the consumption of drinkable water.

The thesis has managed to establish the influence of the physicochemical characteristics of the supply water. The efficacy of the various treatments available was studied and new tools for the on-line control of the water purification plants have been developed. Moreover, according to the author, a higher quality product is not obtained using a greater amount of disinfectant.

Notable amongst the conclusions is the need to prepare made-to-measure water purification treatments, depending on the physicochemical nature of the supply water of the plant. The results obtained will be used to establish guidelines to follow in order to enhance existing purification treatments, as well as the design of future treatment plants. Companies such as PRIDESA and CETOLAR have already shown interest in the research.