Utilization of renewable raw materials for biogas production and for the production of functional materials for textile and packaging applications (BigaTex)
Topic
The cascade use of fiber-rich residual materials and permanent crops such as hop grubbing chaff, alfalfa stalks and nettles as fiber and biogas substrate offers an opportunity to increase the economic efficiency of biogas plants, conserve resources, increase regional added value and reduce greenhouse gas emissions. Separating the fibers that are hardly degradable in the biogas process from the organic acids and saccharides that are degradable in the biogas process results in higher resource efficiency and another source of income. The separation is done by steam explosion pretreatment (STEX), deflaker and a solid/liquid separator. This produces quality-enhanced fibers and a hydrolysate. Due to the different properties of the hydrolysate compared to conventional biogas plant substrates, fermentation in fixed bed reactors lends to the acceleration of the gas formation rate and thus to an increase in economic efficiency. As a positive side effect of the harsh conditions of the STEX (approx. 160°C, 6 bar), there are hygienization effects that can counteract the spread of pathogens, such as the "citrus bark cracking viroid", and enable the use of the digestate as fertilizer. Malfermentation leads to lower methane yields and to odor formation that spreads into the fiber.
Goals
The aim of the project is to analyze and optimize the ensiling of the substrates (hop grubbing chaff, alfalfa stalks and stinging nettles) using different ensiling agents. Special focus will be placed on the formation of odor-intensive organic acids. Currently, a laboratory STEX is being set up for a more detailed investigation on the influence of temperature, pressure and residence time on the fiber and hydrolysate quality. The company Outlast Technologies GmbH and Hochschule der Medien will combine the fibers with functional additives in various processes such as wet flow process and fiber casting process to produce shoe insoles and packaging materials.
