The ion exchanger loop stripping process is a novel, hybrid process to obtain a nitrogen-rich product from ammonium-contaminated liquid digestates. The effluents from mechanical sludge dewatering at municipal sewage treatment plants can contain ammonium concentrations up to 3 g/l. During the ion exchanger loop stripping wastewater passes through a fixed bed of natural zeolite (main mineral: clinoptilolite), to which ammonium is bound by ion exchange. As a result, the treated water can be reused as process water. The loaded zeolite is regenerated repeatedly with a sodium hydroxide solution. Thus, ammonia is formed simultaneously, which is stripped from the NaOH-solution using a packed stripping column. Utilizing an ensuing acidic scrubber the expelled ammonia is fixed again and can be used as a marketable reducing agent for industrial NOx removal. In order to test the process in a real environment, a pilot plant was built and put into operation at a municipal sewage treatment plant (Knittelfeld). The separation rates for ammonium were determined by on-site tests. The most influential factors were identified, which are the feed concentration of ammonium, the bed volume, the grain size of the zeolite. Furthermore, the operational parameters for a sufficient regeneration of the zeolite bed were determined. In addition, the stability of the zeolite was tested in long-term-experiments with consecutive loading/regeneration cycles. The results of these experiments are presented in this thesis. In addition to a critical discussion of the findings, an outlook is given on the possibility of implementing an upscaled process at the sewage treatment plant Knittelfeld.