(363d) Tri-Glyceride Production from Algae Grown on Dairy Anaerobic Digester Effluent

Persistent rises in fossil fuels are rendering bioenergy production on the farm an increasingly attractive alternative. In addition, increasing farm animal densities in the state of Washington are producing a concentrated manure surplus, which exceeds the amount usable on local agricultural lands as fertilizer.

In the context of the NSF MCCE IGERT fellowship (Multinational Collaboration on Challenges to the Environment, Integrative Graduate Education and Research Traineeship) at the University of Washington, our interdisciplinary team has looked at the integration of Anaerobic Digestion (AD) and biofuel (as Tri-Acyl-Glycerol or TAG) production on dairy farms. In this process, the evolved AD methane is combusted to produce electrical power, and the resulting carbon dioxide is used to enrich the algae reactor. The nutrient-rich AD effluent is fed to the algae, thus by-passing the need to purchase fertilizer. Preliminary feasibility studies were based on existing AD operations (Van derHaak dairy, WA) and pilot airlift photobioreactors (Greenfuel Co., MA).

Preliminary experiments have assessed the robustness of various algal strains documented in the 1998 NREL report: “A Look Back at the U.S. Department of Energy's Aquatic Species Program: Biodiesel from Algae” when given AD effluent as a nutrient source. In parallel, as developed in the NREL report, algae populations have been isolated from farm environments, fed on AD effluent, and sorted for fatty acid accumulation by flow cytometry. These results will be incorporated in the Puget Sound Energy photobioreactor pilot project in the state of Washington.