Growth of Chlorella vulgaris and Chlamydomonas reinhardtii for biodiesel production and carbon dioxide capture

The growth of two strains of green microalgae, Chlorella vulgaris (UTEX 2714) and Chlamydomonas reinhardtii (UTEX 90) was tested in three types of media; Tris Acetate Phosphate (TAP), Bushnell Haas Broth (BHB), and Wright\u27s Cryptophytes (WC buffered with either glycylglycine or Tris-base). Also, initial medium pH is ranging from 4 to 10, light intensity ranging from 100 to 600 micromol photons/m 2s, and CO2 concentrations ranging from 0.038% (ambient) to 12%, were tested. WC medium at pH 8 buffered with glycylglycine sustained the highest yield and best buffering capacity for growth of both C. vulgaris and C. reinhardtii. A light intensity of 200 micromol photons m-2s-1 provided for both good growth and electron transport rate (ETR). Both C. vulgaris and C. reinhardtii produced highest final yields when grown with 6% CO2. Also, lipid content increased with increasing CO2 concentration. Myristoleic acid (C14:1), palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1n9), linoleic acid (C18:2), and docosahexaenoic acid (DHA) were found in higher content when C. vulgaris was grown on 12% CO2, while the content of palmitoleic acid (C16:1), elaidic acid (C18:1t9), vaccenic acid (C18:1n7) were similar among all CO 2 concentration tested. CO2 capture was explored using two approaches: consumption of known quantities of CO2 in sealed serum bottles, and consumption of CO2 flowing through immobilized algal beads. In both cases, fixation rate decreased with increasing CO2 concentration. CO2 consumption generally decreased over the five day experiment. The rate observed using immobilized algae was 20% of the maximum obtained in liquid culture, indicating the need to future optimize this novel method for CO2 capture