The majority of commercial aquaculture facilities utilize fish feeds composed of fish oil and fishmeal sourced from marine catches or plant-based ingredients produced via industrial agriculture practices. Researchers have shown that microalgae are an attractive alternative to unsustainable forage fish-based and crop plant-based aquafeed ingredients. However, if microalgae production relies on inorganic fertilizers, then the unsustainable sourcing of inputs has not been improved, but rather shifted to another sustainability.

To address this issue, we have adopted a systems approach (pdf) to the food-energy-water nexus of aquafeed production. Some of our recent work with Alex Scalfani focuses on the sourcing of upcycled waste nutrients in order to displace some or all of the inorganic nutrients for cultivating microalgae on a commercial scale for aquafeed ingredients. We are focusing on brewery wastewater as a promising potential nutrient waste stream because it is widely available, contains dissolved forms of nitrogen and phosphorus, and is largely free of concerning pathogens or contaminants. Utilizing brewery wastewater for microalgae cultivation also has the potential to reduce energy inputs needed for standard domestic wastewater treatment, as well as energy embedded in inorganic microalgae fertilizers.

Alex Scalfani and other team members have reviewed the literature on brewery wastewater characteristics and composition. In early 2018 Alex collected wastewater samples from several regionally sized breweries, including Harpoon Brewery in Windsor, Vermont, and  Switchback Brewery, Burlington Vermont. Shortly after she conducted preliminary growth experiments of Nannochloropsis granulata microalgae using brewery wastewater as a nutrient media. The results of this experiment are now a manuscript in preparation with interesting conclusions. We are also developing a larger research effort in partnership with algal research facilities and breweries in Arizona.