Assessment of oyster mushroom production employing urban-based materials in Stockholm Stad

Abstract: This thesis investigates the opportunities and challenges regarding urban oyster mushroomproduction (Pleurotus Ostreatus) employing urban-based materials in Stockholm Stad as agrowing medium. Additionally, the availability of the five most suitable substrates has beenfurther explored with the indicator’s availability in Stockholm Stad, and the Biologicalefficiency (BE%) for a suitable growing medium and the quantity of the substrates have beenmapped out. In response to climate change and an uncertain future, cities need to be resilientto disasters and meet essential needs like water, food, and energy. Due to the COVID-19pandemic, the Swedish government plans to increase self-sufficiency by developing the lawof public procurement to prioritize buying locally produced goods. However, imported foodis cheaper than Swedish goods, making it difficult for domestic products to compete.Moreover, a major part of Sweden’s waste management consists of the combustion of variouswaste, which is being on a lower priority on the Waste hierarchy. Therefore, assessing thepossible areas of use such as oyster mushroom cultivation could likely add further value tothe residual waste streams investigated. Using Material Flow Analysis (MFA), interviews,and literature review, relevant data and information was collected to locate the five mostsuitable substrates: (1) wood waste from arborists and wood workers, (2) paper waste, (3)cardboard waste, (4) Spent Coffee Grounds (SCG) from five of the biggest chains coffeeshops in Stockholm Stad, (5) garden waste collected from a collection company. Theestimated availability of each residual waste stream has been mapped out with paper wastebeing 15’805’567 kg, 20’560’580 kg (cardboard), 64’166’500 kg wood waste, 3’939’664,2kg garden waste, and 152’121,7 kg (SCG). The BE% is ranging from 18,61% for SCG, woodwaste to 64,69%, garden waste to 95,3%, paper to 112,4%, and cardboard with a BE% of117,5%. Moreover, the BE% will vary depending on the preparation of the substrate and thegrowing conditions of the mushrooms. The oyster mushroom's estimated kilo price is 245SEK/kg, with a potential yearly value of the oyster mushroom is estimated to beapproximately 128’333’000 SEK. This thesis highlights the potential of oyster mushroomcultivation potential where Stockholm Stad has the capacity to be locally self-sufficient whenlooking at the quantity of substrate available. Additionally, the results display the value ofusing residual waste streams as a resource in other ways than energy recovery.