The use of ferrate for oxidation and disinfection
In drinking water production often FeCl3 is added as a coagulant as one of the first steps in DWT in order to remove colloidal particles. Furthermore, disinfection plays an important role in drinking water purification. During recent years it has become clear that sources for drinking water contain large numbers of organic micropollutants, in increasing concentrations. This mainly is the case for surface water, but also in ground water more and more micropollutants can be found. There are several ways to deal with such micropollutants. Adsorption by activated carbon in many cases is less effective, as these micropollutants often are relatively small, hydrophilic and sometimes even charged molecules. Membrane filtration is very effective for relatively large molecules, but it has the disadvantage that a concentrate is formed, which has to be dealt with, and that it is an energy intensive process. Oxidation, or advanced oxidation processes can be very effective in converting these micropollutants, which in principle can be mineralized completely (i.e. converted into CO2 and H2O). This is very expensive, and thus in most cases they are degraded into small, better biodegradable, compounds. Oxidation processes are becoming more and more important in water treatment.