Integrating anaerobic co-digestion of dairy manure and food waste with cultivation of edible mushrooms for nutrient recovery.

State-level policies in the New England region of the United States require diversion of organic materials away from landfills. One management option for food waste is anaerobic co-digestion with dairy manure. In addition to biogas, anaerobic digestion produces separated solid and liquid digestates. Solid digestates in the region are typically recycled as animal bedding before returning to the digester and liquids are used to fertilize local soils. Repeated land application of nutrients can contribute to eutrophication risk over time and alternative models are needed to convert digestates into valuable export products. We tested solid digestates derived from dairy manure and food waste as substrate ingredients in the cultivation of Pleurotus ostreatus. We show these materials can be used to offset non-local substrate ingredients while achieving mushroom yields comparable to commercial recipes. This strategy could help divert nutrients away from land adjacent to digesters and into safe, protein-rich food, while producing useful spent mushroom substrate.