EFFECTS AND CONSEQUENCES OF ELECTRIC TREATMENT IN PREVENTING SCALING OF DRINKING-WATER SYSTEMS

Scale, which is a hard adherent mineral, is generally composed of calc ium carbonate and poses many problems in water distribution networks, An alternative treatment using a physical process to prevent scaling h as been in existence for many years, However, the potential efficiency of this process is still controversial. When electric devices were in stalled in water distribution networks in the centre of France, a stud y was carried out using both in situ observations and laboratory tests . Two analytical tests were designed to determine the effects of the d evices on scaling. The devices increased the precipitation of calcium carbonate which was mainly present in form of fine particles in the tr ial heater tanks. Moreover, there was a decrease in the adherent depos its when water was treated. The in situ observations were confirmed by the analytical laboratory tests, and showed that in water treated wit h electric devices there was an increase in crystallisation of calcium carbonate in the liquid phase and a decrease in heterogenous nucleati on on metal surfaces. However, the effects of the devices varied from one month to another.