Using sludge from certified wastewater treatment plants is a way of recycling phosphorus and other plant nutrients to arable land. This requires that sources of pollution are identified, and eventually reduced, to obtain a fertilizing product that is acceptable in crop production.
Urban Water, in cooperation with the Käppala Association and Uppsala University, has developed a tool, Source Finder (SoFi), for upstream work with regard to heavy metals in wastewater. With SoFi, sources of cadmium, copper, chromium, mercury and zinc can be identified and their flows in wastewater calculated.
SoFi is implemented in Excel to make it easily accessible and user friendly, and is freely available for anyone to use. Development of the tool was financed by the Stockholm County Council and the Käppala Association.