Modelling chlorine decay in water networks with genetic programming

The disinfection of water supplies for domestic consumption is often achieved with the use of chlorine. Aqueous chlorine reacts with many harmful micro-organisms and other aqueous constituents when added to the water supply, which causes the chlorine concentration to decay over time. Up to a certain extent, this decay can be modelled using various decay models that have been developed over the last 50+ years. Assuming an accurate prediction of the chlorine concentration over time, a measured deviation from the values provided by such a decay model could be used as an indicator of harmful (intentional) contamination. However, most current chlorine decay models have been based on assumptions that do not allow the modelling of another species, i.e. the species with which chlorine is reacting, thereby limiting their use for modelling the effect of a contaminant on chlorine. This paper investigates the use of genetic programming as a method for developing a mixed second-order chlorine decay model.