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One element of our agricultural cycle is the production of biogas and biofertilizer from agricultural residues through anaerobic digestion. We have investigated the biogas potential of of all lignocellulosic biomasses within the ReMe-diation project, with reeds from constructed wetlands showing particularly high potential. By treating the reeds with hot steam, biogas production could also be accelerated.

In order to further test the applicability of biogas production from reeds, we established two continuous anaerobic fermentations on a 5 L scale as the next scaling step (see the photo below). Both have now been running in parallel for 150 days, one plant with untreated reeds, the other plant with reeds that have been treated with hot steam. In addition, we add some chicken manure, another agricultural residual stream, to ensure the supply of nitrogen. For 150 days now, we have been feeding the plants with reeds every day and extracting a certain amount of digestate ever day. The result: 4-5 liters of biogas per day from around 20 g of feed per day. The fermentation residues are examined, for example with regard to their fertilizing effect. We also test the stability of the system by varying the parameters. How stable is the system and is it all worthwhile? That’s what we want to find out and our evaluations will follow. Both reactors are still running and we will further let them run for a while. Let’s see who gives up sooner – us or the microorganisms?