| This purpose of this study was to examine the effects of carbon source and pH adjustment on the growth rate of the microalgae Neochloris oleoabundans. These effects were tested using batch nutrient supply from BG11 medium in a series of open trough systems under artificial lighting. Atmospheric carbon was supplemented in one of two ways; by the injection of gaseous CO2, or by the addition of sodium bicarbonate (NaHCO 3). The pH was adjusted by the addition of gaseous CO2, by the addition of phosphoric acid (H3PO4), or by the addition of hydrochloric acid (HCl). Peak biomass concentrations ranged from 870 mg L-1 to 1270 mg L-1, specific growth rates to reach peak concentration ranged from 0.31 to 0.15 days-1 , and doubling times ranged from 2.3 days to 4.7 days, respectively. The most rapid growth in all of the troughs occurred in the first three days. During this time specific growth rates ranged from 0.41 to 0.76 days -1, and doubling times ranged from 0.9 days to 1.7 days, respectively. Troughs that were injected with gaseous CO2 had the shortest doubling time whereas troughs receiving NaHCO3 and HCl had the highest peak concentration. The data collected in this study indicates that pH within the range of 7.0 to 7.5 supports the most rapid biomass production by N. oleoabundans. Injecting CO2 into the culture at a concentration sufficient to maintain the pH within the suggested range also provides sufficient bioavailable carbon to the system. |
