Einfluss pflanzlicher Biofilmträger auf die Vergärung von Speiseresten
FacultiesFakultät für Naturwissenschaften
Due to their high amounts of carbohydrates, fats and proteins, wastes of the food industry have huge biogas potentials and quickly decompose while acidification. To avoid process instability these substrates only get digested in minor amounts resulting in less absolute yields of biogas. By fast and almost complete decomposition these substrates lack of required surface for microbial syntrophic growth. It was proven that the co-digestion with other substrates had a positive influence on the methane forming process (Sasaki et al. 2007, Wang et al. 2010). In this study laboratory-scaled experiments (4 x 10 L) were run to discover the effects of plant based biofilm-carriers while digesting higher loads of substrates rich in energy (e.g. food waste). In average of several batch experiments the specific methane yield could be increased up to 7 % and the grade of organic dry matter degradation up to 10 % when additional biofilm-carriers were supplied. Due to procedural conditions (feeding and mixing) of the laboratory biogas unit during continuous digestion the plant structures could not be mixed completely into the digestion liquid. For this reasons the positive effects attributed to the addition of biofilm-carriers in the previous batch-digestions could not be achieved. But it was possible to realise those findings successfully in a 300 m3 full-scaled digester of a co-digestion plant. Increasing the input of food waste and providing straw as a biofilm-carrier at the same time, the absolute yield of methane could be increased about 43 % and the specific one about 23 % without compromising the digestion process. Due to their slow decomposition plant biofilm-carriers were sufficient even in small amounts to stabilise the digestion process, to provide prior methane formation and in most instances higher gas yields at increased organic loads.
Subject HeadingsBiofilm [GND]