Date of Award


Document Type


Degree Name

Master of Science (MS)

Legacy Department

Biosystems Engineering

Committee Member

Dr. Terry H. Walker, Committee Chair

Committee Member

Dr. David A. Ladner

Committee Member

Dr. William C. Bridges


Microalgae have received considerable attention as a potential source for the thirdgeneration biofuel. Various products including biodiesel could be obtained from the algalbiomass. In this study, the green algae Chlorella protothecoides was cultured inmixotrophic mode – under the light from a LED lamp and supplemented with organiccarbon and nitrogen sources. The carbon and nitrogen sources were selected for theircapabilities to sustain algae growth, and their low cost as industrial by-products. Crudeglycerol was derived from the biodiesel production process and the spent brewer’s yeastwas the remaining yeast after beer fermentation. Both were subject to certainpretreatment steps before being mixed with the culturing medium. To assess their effectson algae growth, both the glycerol and the yeast were evaluated based on their carbon (gC/L) and nitrogen concentration (g N/L). To study the effects of light intensity (μmol/m-2 s-1), carbon concentration in themedium (g C/L), and nitrogen concentration (g N/L), experiments were performed basedon a three-factor, three-level full factorial design, with algal biomass (g/L) as theresponse. Data was fitted into a response surface model to investigate the impact onbiomass of 3 factors. Initially a regular response surface model was obtained, yet the lackof fit was quite significant. Then another modified model was fitted to the data.Compared to the regular response surface model, the new model had better fit with theresponse from the experiment data.



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