Upcycling: Cardboard into Mushrooms
Within the Caribbean region, cardboard accounts for about 20-30% of our municipal solid waste, and puts a strain on our landfill and dumpsite management due to its volume and lack of local recycling and processing facilities. As an organic waste stream, cardboard and paper provide a potential model for Integrated Waste Management, as this organic material can grow mushrooms that in turn food establishments can incorporate back into their business as a sellable product.
Fig. 1: CEI Research Scientist, Dorlan Curtis Jr., preparing shredded cardboard waste as a growth substrate for mushrooms.
In nature, the kingdom of fungi are considered primary decomposers and produce enzymes which degrade and recycle organic waste such as paper or cardboard into nutrients to sustain natural food webs. The most recognizable feature of fungi are mushrooms which are merely its fruiting body, and can be categorized as edible, medicinal or poisonous. Of the 20,000 mushroom-forming fungi, there are about 20 species reaching large-scale cultivation, namely Oyster mushrooms (Pleurotus ostreatus). Edible mushrooms have been cultivated for centuries for food and medicines as they are a good source of vitamin D, magnesium, protein and certain polysaccharides known to boost the immune system.
In urbanized areas and Small Island Developing States (SIDS) like The Bahamas, our communities are vulnerable to low or declining agriculture due to soil fertility and management practices, access to capital, and climate change. These factors contribute to local food insecurity and systems of food deserts. Nevertheless, mushroom cultivation provides a direct solution as they can be cultivated on readily available organic waste substrates such as cardboard and paper, spent coffee grounds, and wood chips. Mushrooms require no arable land or synthetic fertilizers, and can be produced indoors in low-tech climate controlled conditions.
Fig. 2: Oyster mushrooms growing (fruiting) from shredded cardboard material
At the Cape Eleuthera Institute (CEI) at The Island School, researcher Dorlan Curtis Jr., is utilizing oyster mushrooms for cultivation on cardboard and paper waste generated on campus (130 lbs/month). In the preliminary stages of this research, the team produced 5 pounds/week of Oyster mushrooms which were served in The Island School dining hall as part of communal meals with ‘farm-to-table’ cooking demonstrations (Fig. 2). In the first quarter of 2019, only 29% of food served in the school’s dining hall was sourced locally, whereas 40% of all non-meat protein was sourced from imported soy-based products.
Why is mushroom production important?
Climate change resilience and lower carbon footprint – Scientists have predicted that due to climate change, there will be an increase in Sea Surface Temperature (SST), global average temperatures and sea-level as well as decrease in annual rainfall will impact our agricultural and food systems. Oyster mushrooms can produce rapid harvest within 30 days which rival many of the agricultural crops traditionally produced in The Bahamas with harvest times of approximately 90 days, and livestock of 6-12 months. On a per pound basis, when comparing mushrooms only produce approximately 0.7 lbs CO2, while chicken meat manifests 3.1 lbs CO2. Additionally, as access to freshwater usage becomes a global concern, mushrooms require 1.8 gallons of water/pound while tofu requirements net at 219 gallons water/pound. Relative to all its agricultural counterparts, oyster mushrooms do not require significant natural resource inputs such as freshwater, synthetic fertilizers, soil and the need to induce deforestation. In this growing model at CEI, mushroom production features low-tech principles of cold sterilization of organic waste materials for substrates and mushroom fruiting in clean indoor shelters to conserve energy, space and water demands of production. These elements qualify mushrooms as a potential ‘climate-change resilient’ crop which proves beneficial as a model crop for innovative agriculture in The Bahamas.
Fig. 3: CEI Research Scientist, Dorlan Curtis Jr., preparing shredded cardboard waste as a growth substrate for mushrooms.
Oyster mushroom cultivation will contribute to achieving a 50% food security goal (sourcing foods from within The Bahamas) at The Island School and upcycling organic waste to food. This research will work toward both the carbon footprint mitigation of a primary vegan option (soy-based food products) and commercially farmed meat proteins. At a national level, provision of sustainable non-meat based protein promotes food sovereignty and community access to healthy food options to meet the mandate of U.N. Sustainable Development Goal (SDG) #12: Responsible Consumption and Production.
Dorlan Curtis Jr.
Assistant Director of Research and Innovation
Cape Eleuthera Institute