Growth kinetics and lipid production using Chlorella vulgaris in a circulating loop photobioreactor

BACKGROUND: Compared with agriculture, microalgae culture promises to be a novel way of producing lipids for both food consumption and transportation fuel (biodiesel) purposes while using a minimal amount of land area. A circulating loop photobioreactor has been used to study the growth kinetics and lipid yield of Chlorella vulgaris growing on carbon dioxide as the sole source of carbon. RESULTS: Because of high photosynthetic active radiation (PAR) fluxes, C. vulgaris was observed to grow in exponential mode. The highest growth rate achieved was 0.049 h(-1) at the optimum growth conditions of 71.8 mW L(-1) PAR density, 10% CO(2) (v/v) in air and with an applied 8 h dark phase. The microalgae was observed to grow in a Monod fashion with a PAR density saturation coefficient of 2.8 mW L(-1). Light intensity showed the potential to significantly increase lipid yield, which reached a maximum of 30% (by mass) of cell dry weight. CONCLUSION: The circulating loop photobioreactor is a low-cost bioreactor technology capable of culturing photosynthetic microalgae at high PAR densities and with uniform mixing and lighting. C. vulgaris is able to grow exponentially in this bioreactor and produce lipids at concentrations up to 30% by cell dry weight. (C) 2011 Society of Chemical Industry