Student: Hannah Molitor, Graduate Student in Environmental Engineering, University of Iowa
Faculty Advisor: Jerald Schnoor
Microalgae as a nutritious cattle feed supplement to sequester carbon dioxide and recover nutrients from wastewater
Conventional agriculture places significant demands on natural resources and is generally inefficient. As organisms with tolerance for varied conditions, microalgae (single-cell photosynthetic microorganisms) are a promising alternative to conventionally grown soy for more rapidly and sustainably produced protein-rich animal feed. Microalgae can use carbon dioxide from combustion emissions and the nutrients from wastewater to produce biomass. However, there are significant barriers to growing nutritious salable microalgae, recovering nutrients from wastewater, and fixing carbon dioxide from power plant emissions in full-scale sustainable operations, which my research seeks to address. Specifically, I use a photobioreactor (vessel to grow microorganisms that use light for energy) to cultivate Scenedesmus obliquus, a nutritious green microalga. My previous work showed that this species can tolerate the high carbon dioxide levels characteristic of power plant or industrial emissions while maintaining favorable protein contents and amino acid profiles. My current work focuses on additional enhancements to the nutritional qualities of microalgae by leveraging the sulfur in combustion emissions, as a precursor for the biosynthesis of valuable sulfur-containing amino acids. Future work will address microalgal growth on wastewaters and energy-efficient harvesting of microalgal biomass from its culture media. Successful scale-up of this research could reduce fertilizer and freshwater resources use, prevent agricultural runoff contamination to natural water bodies and drinking water reservoirs, offset wastewater treatment costs, and mitigate greenhouse gas emissions.