17. Drinking Water, Physical Processes for Nitrate Removal in Groundwater

The nitrate concentration of some groundwater wells is an issue for drinking water quality. This poses a serious health risk, since the intake of large nitrate quantities is harmful for the human health. In this context, physical processes for nitrate removal are very popular methods to counter this problem. Electrodialysis, reverse osmosis, and ion exchange have proven to be very efficient methods to lower the rising nitrate concentrations. Due to their relative simplicity, reliability, and high desalination, they are often implemented. Although excellent results can be achieved, correct process parameters are necessary. In electrodialysis, desalination is generally mainly dependent on voltage, although other parameters such as flow rate, limiting current, and temperature also affect membrane diffusion. Furthermore, for nitrate removal nitrate-selective membranes are preferably used. In case of electrodialysis and reverse osmosis, membrane scaling and fouling are major issues that need to be addressed. On the other hand, ion exchange has the disadvantage that the resins used must be regenerated at regular intervals, which increases the amount of chemicals required. In all this physical processes, brine disposal is an important topic and its safe discharge must be ensured. Possible solutions are safe disposal into a sewage system, a further treatment, or the use as irrigation water.