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Date of Award
Master of Science in Chemical Engineering (MS)
College, School or Department Name
Department of Chemical Engineering
The microalga Haematococcus pluvialis was cultivated in MES-volvox medium at various light intensities and CO2 concentrations. It was found that CO2 concentrations of 10 and 15%, in combination with high irradiance at initial pH =6.7, accelerate astaxanthin accumulation in H. pluvialis cells but obstruct cell growth. The purpose of this research study was to devise a one-stage process consisting of the simultaneous cultivation of H. pluvialis and astaxanthin production using high light intensity and high CO2 concentration. This could be achieved at 200 µE/m2s and 15% CO2 in growth medium at initial pH = 4.3. Compared to the traditional two-stage H. pluvialis cultivation system, this one-step process can save up to 8-9 days of astaxanthin production time. The astaxanthin content in H. pluvialis cells induced with high light intensity only or with a combination of high light intensity and high CO2 concentration had comparable astaxanthin content; 94 and 97 mg/g dry biomass, respectively. However, it was extremely low in nitrate-free medium at high irradiance alone or combined with high CO2 concentration, with an average value of 4 mg/g dry biomass. Cell density was 40% less in cultures under discontinuous illumination compared to continuous illumination. This process could serve as a microalgal CO2 mitigation system after further understanding of the CO2 fixation ability of H. pluvialis has been gained.
Nkurunziza, Ornella, "ASTAXANTHIN PRODUCTION FROM HAEMATOCOCCUS PLUVIALIS UNDER VARIOUS LIGHT INTENSITIES AND CARBON DIOXIDE CONCENTRATIONS", Master's Thesis, Michigan Technological University, 2014.