Effects of light and nutrient availability on the biomass production CO2 fixation and bioethanol production potential of Thermosynechococcus sp in flat plate photo?bioreactors

  • 蘇 峙銘

Student thesis: Doctoral Thesis

Abstract

The concept of CO2 chemo?absorption by sodium hydroxide in a wet scrubber followed by microalgae cultivation was used potentially as a means to reduce the major greenhouse gas CO2 This study accepted the idea by utilized dissolved inorganic carbon as carbon source to cultivate thermophilic cyanobacteria strain Thermosynechococucs CL?1 (TCL?1) and designed flat plate photobioreactors for cultivating this strain without excess energy input for cooling the flat plate photobioreactor as other researchers did In order to apply TCL?1 in biomass production CO2 fixation and bioenergy production and more close to reality of cultivation the strain outdoors light emitting diodes array were used as the light source with strong illumination Effects of aeration rates illumination intensities and biomass concentrations were examined in advance under designed light path to evaluate how light availability affects TCL?1 Results suggest that most of these parameters play major roles in biomass production CO2 fixation and carbohydrate production However aeration rate of 0 5 vvm is adequate because no significant improvement of biomass production can be observed under greater aeration rates In addition the biomass productivity CO2 fixation rate and carbohydrate productivity reached 116 170 and 67 mg L?1 h?1 respectively in 1 5 cm light path photobioreactor and under optimal biomass concentration of about 3 g biomass L?1 Illumination intensity of 1 000 or 2 000 μE m?2 s?1 had minor effects when under optimal biomass concentration Moreover the biomass productivity can’t be increased furthermore when biomass concentration was greater than 3 g L?1 After the investigation of the light availability effects effects of nutrient availability were also examined under dense culture to test whether the biomass production CO2 fixation and bioenergy production potential could be further increased In addition glycogen instead of carbohydrate which may involve other hard fermentable pentose or hexose sugars were analyzed to have more accurate evaluation of bioethanol production potential Results show that among all the examined nutrients concentrations of sodium ion NaNO3 and CaCl2‧2H2O should be decreased as the MgSO4‧7H2O concentrations should be enhanced to obtain higher biomass productivity or persistence of the growth Most of the carbon contents in TCL?1 remain stable about 40% (w/w) under various nutrient levels In addition Su and Chu’s medium was reorganized by picking up the nutrient concentrations resulting from the biomass production The adoption of the new medium for cultivating TCL?1 exhibits the superior biomass productivity CO2 fixation rate and glycogen productivity of 138 7 221 5 and 75 9 mg L?1 h?1 respectively under 2 000 μE m?2 s?1 illumination in the 1 5 cm light path flat plate photobioreactors The high biomass productivity CO2 fixation rate and glycogen productivity indicate that the use of Su and Chu’s medium exhibits high potential for applying TCL?1 in CO2 fixation and bioethanol production potential in the flat plate photobioreactors
Date of Award2019
Original languageEnglish
SupervisorHsin Chu (Supervisor)

Cite this

Effects of light and nutrient availability on the biomass production CO2 fixation and bioethanol production potential of Thermosynechococcus sp in flat plate photo?bioreactors
峙銘, 蘇. (Author). 2019

Student thesis: Doctoral Thesis