Biogenic waste streams are the base of producing high-quality compost and their utilisation is an important pillar for circular economy. A significant issue in this context is the problem of contaminants, especially plastics, in biogenic waste streams. In order to produce a high-quality compost out of biogenic waste, a cycle-oriented approach and an improvement of individual processes are essential.
On base of practical, large-scale investigations, various ways of pre-treatment with different aggregates (shredding aggregates, screening machines) and varying materials (freshly collected, pre-rotted) were carried out in this master thesis. The evaluation by means of mass and impurity balances as well as the determination of material and equipment-specific key data was intended to identify suitable machine combinations as well as to determine their functionality for impurity separation. Furthermore, the application of a sensor-based sorting machine in the wavelength range of near infrared light (NIR) was carried out for an improved separation of plastics from the various screening products of the pretreatment screen. This innovative method was tested in pilot plant trials.
The conclusions of this master thesis, which was developed within the framework of the Plastic Free Compost project in cooperation with the companies Holding Graz - Kommunale Dienstleistungen GmbH, Komptech GmbH, Binder+Co AG, Poschacher Kompost e.U. and Ingenieurbüro Wellacher e.U. at the Chair of Waste Processing Technology and Waste Management of the Montanuniversität Leoben, are the base for an optimized implementation concept of the pre-treatment plant for biogenic waste streams operated by Holding Graz - Kommunale Dienstleistungen GmbH. Furthermore, the question of optimized pre-treatment of biogenic waste streams from households for subsequent composting should be clarified in general.