Cultivation of algae biomass is a promising way to produce animal feeds and biofuels with a lower carbon footprint. Nevertheless, challenges remain before algal products can be commercialized. The high cost of algae cultivation is the primary impediment, and the present study addressed some of the major factors in this cost including: the efficiency of algal utilization of supplemental inorganic carbon such as carbon dioxide from flue gases; algal productivity; the energy use and effectiveness of pond mixing; and biomass harvesting and processing. This dissertation addresses these issues with (1) a literature review of algal carbon utilization, (2) a pilot-scale productivity and culture stability comparison of ten filamentous algal cultures including two local isolates, two polycultures, and six culture collection monocultures, (3) a hydraulic characterization of a full-scale wastewater treatment system with 13,200-15,000 m2 paddlewheel-mixed raceways, and (4) a bench-scale characterization of harvesting, dewatering, and drying of filamentous algae. The review of carbon utilization led to the conclusion that significant research is still needed at large-scale to demonstrate and maximize algal carbon utilization in paddlewheel-mixed ponds. In the algal culture study, a single locally–prospected monoculture of Tribonema minus exceeded productivity of the culture collection monocultures and one polyculture. In the hydraulic study the wire-to-water energy efficiency was 10-15% while mixing was low, indicating that this is an area for improvement. Despite this, the energy used for wastewater treatment was ~76% less than activated sludge. Finally, over 95% of filamentous algal biomass could be harvested by screening, and dewatering to 20% total solids was demonstrated using 75-55 µm mesh screens and a 1500-RPM dewatering device. This research advances understanding in several key gap-areas of algae biology and engineering.
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Doctor of Philosophy (Ph.D.)
College of Engineering and Computer Science
Civil, Environmental, and Construction Engineering
Length of Campus-only Access
Doctoral Dissertation (Campus-only Access)
Spierling, Ruth, "Algal Cultivation Systems: Productivity, Raceway Hydraulics, Harvesting and Dewatering, and a Review of Carbon Capture Literature." (2021). Electronic Theses and Dissertations, 2020-. 1160.
Restricted to the UCF community until February 2027; it will then be open access.