Identifier

etd-11092015-123040

Degree

Master of Science in Civil Engineering (MSCE)

Department

Civil and Environmental Engineering

Document Type

Thesis

Abstract

One of the most important factors controlling the growth of microalgae is light. Light quality and light quantity have a dramatic effect on the production of biomass, lipids and pigments of microalgae. In this research, a native Louisiana co-culture containing Chlorella vulgaris (microalgae) and Leptolyngbya sp (cyanobacteria) was studied to determine the effects of various wavelength distributions and irradiance levels on growth kinetics. Growth rates, biomass levels, lipid contents and chlorophyll-a production was examined in batch cultures to determine which color light was optimum for cultivation. At 80 µmol/m^2-sec the species shifted from microalgae dominant to cyanobacteria dominant. The impact of four different light colors (blue, green, red and white) on the growth at 400 µmol/m^2-sec revealed that red light produced the highest growth rate (0.41 1/d) and final biomass concentration (913 mg/L). Red light was chosen as the optimum wavelength at 400 µmol/m^2-sec. When red light was compared to white light at higher light intensities red light produced the highest growth rate (0.47 1/d). Red light had the highest photosynthetic efficiency (1.29 %), while white light had the highest chlorophyll-a production (1874 µg/L) and the highest biomass (1207 mg/L). Overall, red light was determined to be the optimum wavelength to grow this co-culture because of the higher growth rates and photosynthetic efficiency. This co-culture was also grown in a continuous flow hydraulically integrated serial turbidostat algal reactor (HISTAR) system. This study showed that different dilution rates can affect the final harvested biomass weight. Also, at high biomass concentrations, light penetration is reduced enough for cyanobacteria filaments to form, which will hinder the growth of the microalgae.

Date

2015

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Malone, Ronald

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