The problem of foreign matter and impurities in biogenic waste has accompanied waste management since the introduction of separate collection and recycling in 1989 in Styria, for example. The recycling of source separated materials which are contaminated with impurities (especially organic waste) poses increasingly greater challenges for composting plant operators. It is necessary to meet the requirements of market, customer and law for a high-quality product. Up to about 60 percent of the impurities in biogenic waste consists of plastics, followed by metals, textiles, glass and ceramics. A complete separation for the production of quality-assured compost is not yet possible with the currently used technologies. The standard technology includes the screening of the compost as well as the magnetic separation and air separation of the oversized particles. In the course of the master thesis, which was created for the project "DeSort", a new process concept was tested and evaluated at large scale with regard to the mass and content output of plastics and stones. The concept consists of screening, air separation and sensor-based sorting during which an increase of the compost yield by 30 percent on average with at least the same compost quality was determined. Finally, based on the findings, a specification book for the plant manufacturer was derived.