PRE-TREATMENT METHODS FOR URBAN LIGNOCELLULOSIC GREEN WASTE FRACTIONS FOR AN ENHANCED ENERGETIC USE

摘要

Purpose: Currently energy production from renewable resources is mainly based on substrates, such as energy crops, agricultural waste or waste wood. The present work aims on the utilization of organic wastes for energy and material production. Methods: Different biomass fractions are obtained from different waste streams in a district of the city of Hamburg. The material is purified by sieving and subsequently shredded in a chipper. Steam refining is performed in 10 l reactor with about 300 g of biomass per batch. Treatments are performed at 190-210℃ for 5-30 min with and without addition of acidic catalysts. After this treatment the products are characterized regarding yield, carbohydrate composition and lignin content. For the production of fermentable sugars the products after steam refining are hydrolyzed for 72 h with an enzyme system or subjected to biogas production tests. Results: The steam refining process for hardwoods is well established and enables a good accessibility of the products to enzymatic hydrolysis. In the ongoing project it turned out that municipal green waste fractions contain large proportions of softwood which require harsher steam pre-treatments under addition of acid catalysts, namely SO2. Conclusion: For green waste fractions the process has to be optimized for a joint utilization of hardwoods and softwoods. This complicates an efficient separation of C6 sugars and C5 sugars due to the different composition of the raw materials. These conclusions suggest that the utilization for biogas might be more attractive than for fermentable sugars. First biogas tests are currently under way.