Chapter 1 - Cultivation techniques

Abstract

Production of microalgal biomass usually takes place in open ponds or closed photobioreactors. Open systems (raceway and circular ponds) are cheaper and easier to construct and operate; thus they are chosen mainly for cultivation at industrial scales. However, they often depend on weather conditions, have poor culture parameters control (temperature, pH, dissolved O2 and CO2), and are prone to contamination with other microorganisms. As photobioreactors (tubular and flat-plate) achieve higher biomass productivity and to improve final product quality, hybrid systems could be a promising alternative. Therefore, a robust axenic inoculum would be obtained by first cultivating microalgae on a smaller scale followed by open ponds where stress conditions could be applied to increase a metabolite production, e.g., lipids. However, most studies that involve microalgae cultivation to attain different bioproducts are performed on a laboratory scale. Scaling up should then consider hydrodynamic limitations as well as its economic and environmental impacts.