Enhanced Growth of Microalgae and Production of Lipids via Electrostatically Controlled Photosynthesis

Lipid accumulation in microalgae is a renewable resource for the synthesis of biodiesel. Two microalgae, Spirulina and S. dimorphus, were subjected to the electrostatic conditions imposed by applying a dc voltage to the algal growth mixtures under different light intensities without inducing electrical currents. The electrostatic conditions increased the growth rates of the microalgae well above those due to natural photosynthesis. The enhanced growth was dependent on the magnitude of the applied voltage and the contact area of the algal growth mixture to the electrodes. The voltage also induced the flocculation of the algae on the electrodes. The lipid contents of S. dimorphus were analyzed and found to be increased by the electrostatic effect. The observed enhanced algal growth could be due to accelerated electron transport rates in the cellular processes of photosynthesis. The results presented here indicate that, even with deficient light intensities, the electrostatic method is able to increase the overall production of the microalgae consistently and significantly beyond the algal level caused by natural photosynthesis with the normal light intensity.