Growth Kinetics, Light Dynamics, and Lipid Production in Microalgae from Sugar-Mill Ponds

B. C. Benson, B. J. Meyer, R. Bajpai, D. D. Gang, S. T. Dufreche and M. E. Zappi

Abstract
Sugar-mill wastewaters have potential to support microalgal biomass production for use as a biofuel feedstock (lipid source). Growth kinetics, light dynamics, and lipid production in multispecies-microalgae cultures collected from a sugar-mill pond are reported in this paper. Lipid content of the microalgae collected from the pond water was 14.5 % (w/w). Culturing the same microalgae in a photobioreactor on the pond wastewater supplemented with Gillard’s F/2 and CO2, and irradiated with 151 to 337 μmol s–1 m–2 artificial light produced cells with lipid contents of 11 % (w/w) at 25 °C, 35 % (w/w) at 31 °C, and 28.6 % (w/w) at 33 °C. The maximum specific growth rates (μmax) at 25 °C, 31 °C, and 33 °C were 0.64 d–1, 2.5 d–1, and 2.7 d–1, respectively. Under these conditions, cell densities as high as 1020 g cell dry mass (CDM) m–3 were recorded. Total scalar irradiance attenuation coefficient (k0) was 0.275 m–1 in clear water and 30.5 m–1 in the dense culture. The attenuation coefficient of irradiance due to biomass (kB) was found to be a linear function of cell concentration in this work.

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Keywords
wastewater, Photo-bioreactor, Light Attenuation, Biofuels, Alternative Energy