Carbon Dioxide Capture & Conversion of Brewery Waste Stream for Microalgae (Nannochloropsis oceanica) Cultivation

Abstract

Developments in the use of microalgae as a plant-based protein and natural source of bioactive compounds in feeds, foods, and fuels are driving the growth of microalgal aquaculture. The biological demand for inorganic carbon needed to maintain dense cultures cannot be met simply through the natural exchange of carbon dioxide (CO2). Direct injection of concentrated CO2 or dissoluble carbon salts (bicarbonate) are common additives to increase dissolved inorganic carbon (DIC) concentrations. However, alternative methods for DIC supplementation are needed to increase the sustainability of microalgae aquaculture. This study investigates an approach utilizing a fermentation waste stream to demonstrate the capture and conversion of gaseous CO2 into bicarbonate, generating a high-DIC growth medium. The results of seven pairwise experiments cultivating Nannochloropsis oceanica indicate biomass development in the high-DIC medium was generally comparable to CO2 injection.