At their mushroom farm near the Schiehaven in Rotterdam, Rotterzwam processes these waste streams into substrate for mushroom cultivation. Over the years, the team kept refining the process through hands-on experimentation, testing different growing methods, substrate compositions and mushroom varieties. Today, they work with climate-controlled growing units, collaborate closely with circular grower Gezwam in the The Hague region, and are scaling further through SPORO, a circular substrate factory focused on processing coffee grounds on a much larger scale. Alongside production, knowledge sharing remains an important part of the process through tours, workshops, grow kits and collaborations.