Recycling of biowaste: Experience with collection, digestion, and quality in Germany

Abstract

Only cascading use can ensure higher sustainability in the recycling of biodegradable waste materials (biowaste) compared to pure thermal and/or energetic utilization types. Cascading use means, in a first stage, that energy is skimmed off by a fermentation process. In a second stage, products used as organic fertilizers and soil improvers are generated. This is usually done by composting. The separate collection of biowaste is a prerequisite for the production of high-quality organic fertilizers and soil improvers. The anaerobic treatment of biowaste and green waste in Germany has not gained the importance it deserves by far, owing to its ecological advantages. This is also evidenced by the high expansion and development potential afforded by the anaerobic treatment. There is a need for action in two areas: (1) increase the amount of biowaste collected by establishing a tightly meshed nationwide expansion of the organic waste bin system and increase the collection rates and (2) channel a large proportion of the biowaste currently only undergoing composting into fermentation as well. The potential for increasing fermentation in Germany is estimated at 5.4 million tons.