Around 90% of the materials used in the beer brewing process ends up being waste at the end of the process. This organic waste goes mostly unused, and amounts to tonnes per year even in a single city like Brussels. Le Champignon de Bruxelles uses the waste from the brewing process of Belgian brewers to grow shiitake mushrooms in a cellar. Thus, local organic waste is being used as a ground for new foods to be produced. They produce up to three tonnes of mushrooms per year and plan to further upscale the production.