Case Study: Composting and Drying & Pelletizing of Biogas Digestate

This chapter presents an analysis to support policy makers and other involved parties in the search for sustainable solutions to the problem of excess biogas digestate. It analyzes two plants in Flanders, one using composting and the other using drying and pelletizing processes to treat biogas digestates. The chapter also presents a case study, where the common practice of spreading digestate without any pre-treatment on agricultural land is taken as a baseline. This is compared with treatment of digestate of exactly the same characteristics through a tunnel composting plant and spreading of the product on agricultural land. As a second digestate treatment process, drying and pelletizing are analyzed. Spreading of digestate without any pre-treatment on agricultural land is taken as baseline scenario. The environmental evaluation of the different digestate treatment scenarios was conducted using the life cycle assessment method.