Untersuchungen zur Entwicklung des pH-Wertes bei der Uferpassage in einem Wasserwerk am Rhein

For a long time riverbank filtration has been an essential part of water treatment in many waterworks along the River Rhine. Most of the processes linked to the underground passage have been investigated intensively. The pH-value and the calcite solution capacity are also influenced by biodegradation. With regard to the more rigorous requirements of the new drinking water guidelines relating to pH-value and calcite solution capacity, chemical analyses of the Rhine, not only from monitoring wells but also from a horizontal well close to Dusseldorf were assessed based on geochemical modelling. The present study was performed to determine the influence of various hydrogeochemical processes on the development of the pH-value and the calcite solution capacity. The simulation revealed that the variation of the pH-value and therefore of the calcite solution capacity depends on the amount of available oxygen and biodegradable substances. Because of the high oxygen saturation in the River Rhine, it was possible to rule out alterations in the calcite solution capacity at the investigated water well for the next few years.