Effect of selection of pH in swimming pool on formation of chlorination by-products

Chlorine is used as disinfection agent in public swimming pools, but also reacts with organic matter in the water forming chlorinat ed disinfection by-products. In order to evaluate the effect of choice of pHsetpoint in the pool we investigated the effect of chlorination of artificial body fluid analogue at different pH-values between 6 and 8.

The formation of trihalomethans, haloacetic acids and haloacetonitriles was measured. It was found that the formation of trihalomethans decreased with decreased pH. Haloacetic acid formation remained almost constant over the pH-range and haloacetonitrile formation increased with decreasing pH. As haloacetonitriles contributes the most to the genotoxicity of the water the predicted genotoxicity of the water was highest at the lowest pH value in the range tested.

Adding bromine in the experiments resulted in decreased haloacetic acids formation and increased formation of haloacetonitriles and trihalomethans. Addition of bromide in the experiments resulted in a shift in the formation of DBP to more brominated DBPs which contributed to that the predicted genotoxicity of the water increased significantly regardless of the pH-level.