Harvesting of algal biomass presents a large barrier to the success of biofuels made from algae feedstock. Small cell sizes coupled with dilute concentrations of biomass in lagoon systems make separation an expensive and energy intense-process. The rotating algal biofilm reactor (RABR) has been developed at USU to provide a sustainable technology solution to this issue. Algae cells grown as a biofilm are concentrated in one location for ease of harvesting of high density biomass. A mathematical model of this biofilm system was developed based on data generated from three pilot scale reactors at the City of Logan, Utah wastewater reclamation plant. The data were fit using nonlinear regression to a modified logistic growth equation. The logistic growth equation was used to estimate nitrogen and phosphorus removal from the system, and to find the best harvesting time for the reactors. These values were extrapolated to determine yields of methane and biodiesel from algae biomass that could be used to provide energy to the City of Logan if these reactors were implemented at full scale. For transesterification into biodiesel, algae need to have high lipid content. Algae biofilms have been relatively unexplored in terms of cell lipid composition accumulation and changes with regard to environmental stressors. Results indicated that biofilm biomass was largely unaffected by nutrient stresses. Neither nitrogen limitation nor excess inorganic carbon triggered a significant change in lipid content. Biofilm algae grown with indoor lighting produced an average of 4.2% lipid content by dry weight. Biofilm algae gown outdoors yielded an average of 6.2% lipid content by dry weight.
| Identifer | oai:union.ndltd.org:UTAHS/oai:digitalcommons.usu.edu:etd-2076 |
| Date | 01 December 2011 |
| Creators | Woolsey, Paul A. |
| Publisher | DigitalCommons@USU |
| Source Sets | Utah State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | All Graduate Theses and Dissertations |
| Rights | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact Andrew Wesolek (andrew.wesolek@usu.edu). |
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