Challenge
As a result of the October 2013 storm, a swimming pool was contaminated with leaves and other undissolved organic matter. This caused the water to discolour to a light brown. It was not possible to remove the water from the swimming pool as the swimming pool would then start to float. The water therefore had to be purified by means of recirculation.

Solution
A laboratory experiment looked into a system for purifying swimming pool water to make it clear once more and remove any undissolved matter and colour.

Results
It was shown that filtering the swimming pool water by means of bag-type filters had little effect on the presence of undissolved material. On the contrary, it appeared that there was actually more undissolved material in the water after filtration. A possible reason for this is that the filtration process breaks the larger undissolved organic matter up into smaller undissolved components. In addition to this, tests were carried out using UV/peroxide. The treatment with UV/peroxide seemed to be a good solution. After treating the water that was first filtered using a 25 µm filter, the water was treated in the water flow with UV/peroxide, which decreased the discolouration of the swimming pool water.