Substrates heavily polluted with ammonium, such as pig manure, digestate from biogas plants or process water from the protein-processing industry, emit unpleasant odours and contribute significantly to nitrogen emissions (NH3-N) into the atmosphere. Many of these substrates accumulate decentrally and/or seasonally. Their utilisation as organic fertilisers sometimes comes up against limits because supply and demand do not match in terms of quantity, nutrient content and form, as well as the content of accompanying substances.The industry partner aims to develop and market a process that solves this discrepancy. In a first step, ammonium / ammonia is depleted from the substrates mentioned by means of air stripping. This process step has been developed by the industry partner since 2015 to a high technology maturity level of TRL=8.In a second step, nitrogen is recovered from the ammonia-laden stripping air and made available as a highly concentrated, directly marketable renewable mineral fertiliser. The present project comprises the preliminary work for the technical development of this 2nd process step within the framework of an Innocheque.