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- Member of: Theses and Dissertations
The first chapter demonstrates the capability of two strains of Scenedesmus acutus to grow in ultra-high-density (>10 g L-1 dry weight biomass) cultures in flat panel photobioreactors for year-round production in the desert Southwest with record volumetric biomass productivity. The advantages and efficiency of high-density cultivation are discussed. The second chapter focuses on uptake and utilization of the volatile components of wastewater: ammonia and carbon dioxide. Scenedesmus acutus was cultured on wastewater from both municipal and agricultural origin and was shown to perform significantly better on flue gas as compared to commercial grade CO2 and just as well on waste nutrients as the commonly used BG-11 laboratory culture media, all while producing up to 50% lipids of the dry weight biomass suitable for use in biodiesel. The third chapter evaluates the feasibility of using gravity sedimentation for the harvesting of the difficult-to-separate Scenedesmus acutus green algae biomass followed by microfluidization to disrupt the cells. Lipid-extracted biomass was then studied as a fertilizer for plants and shown to have similar performance to a commercially available 4-6-6 fertilizer. Based on the work from these three chapters, a summary of modifications are suggested to help current and future microalgae companies be more competitive in the marketplace with traditional agricultural commodities.
This thesis evaluates the potential of algae multiproduct biorefineries for the production of fuel and high-value products to be economically self-sufficient and still contribute to climate change mandates laid out by the government via the Energy Independence and Security Act (EISA) of 2007. This research demonstrates:
1) The environmental impacts of algal omega-3 fatty acid production can be lower than conventional omega-3 fatty acid production, depending on the dewatering strategy.
2) The production of high-value products can support biofuels with both products being sold at prices comparable to 2016 prices.
3) There is a tradeoff between revenue and fuel production
4) There is a tradeoff between the net energy ratio of the algal biorefinery and the economic viability due to the lower fuel production in a multi-product model that produces high-value products and diesel vs. the lower economic potential from a multi-product model that just produces diesel.
This work represents the first efforts to use life cycle assessment and techno-economic analysis to assess the economic and environmental sustainability of an existing pilot-scale biorefinery tasked with the production of high-value products and biofuels. This thesis also identifies improvements for multiproduct algal biorefineries that will achieve environmentally sustainable biofuel and products while maintaining economic viability.
Biochar from HTL of G. sulphuraria at 300 °C showed 15.98 and 5.27 % of phosphorous and nitrogen, respectively. HTL products from the biomass were analyzed for major elements through ICP-OES and CHNS/O. N and P are macronutrients that can be utilized in growing microalgae. This could reduce the operational demands in growing algae like, phosphorous mined to meet annual national demand for aviation fuel. Acidic leaching of these elements as phosphates and ammoniacal nitrogen was studied. Improved leaching of 49.49 % phosphorous and 95.71 % nitrogen was observed at 40 °C and pH 2.5 over a period of 7 days into the growth media. These conditions being ideal for growth of G. sulphuraria, leaching can be done in-situ to reduce overhead cost.
Growth potential of G. sulphuraria in leached media was compared to a standard cyanidium media produced from inorganic chemicals. Initial inhibition studies were done in the leached media at 40 °C and 2-3 vol. % CO2 to observe a positive growth rate of 0.273 g L-1 day-1. Further, growth was compared to standard media with similar composition in a 96 well plate 50 μL microplate assay for 5 days. The growth rates in both media were comparable. Additionally, growth was confirmed in a 240 times larger tubular reactor in a Tissue Culture Roller drum apparatus. A better growth was observed in the leached cyanidium media as compared to the standard variant.
Temperature swing adsorption is a commonly used gas separation technique, and is being<br/>further researched as a method of carbon capture. Carbon capture is becoming increasingly<br/>important as a potential way to slow global warming. In this study, algae-derived activated<br/>carbon adsorbents were analyzed for their carbon dioxide adsorption effectiveness.<br/>Algae-derived carbon adsorbents were synthesized and then studied for their adsorption<br/>isotherms and adsorption breakthrough behavior. From the generated isotherm plots, it was<br/>determined that the carbonization temperature was not high enough and that more batches of<br/>adsorbent would have to be made to more accurately analyze the adsorptive potential of the<br/>algae-derived carbon adsorbent.
Bioluminescent algae has long fascinated humans as a beautiful natural phenomenon. This creative project uses bioluminescent algae to push the limit of biomimicry, using the algae not as a model but as a technology. Through experimentation with algae samples and industrial design, two potential applications of bioluminescent algae as a sustainable lighting technology were generated. One design focuses on indoor, private lighting, while the other focuses on outdoor, public lighting. Both outcomes attempt to solve problems generated by nighttime lighting including light pollution, wasted electricity usage, and negative impacts on human and environmental health while retaining the benefits of safety and convenience.