ABSTRACT
Microalgae are widely mass-produced for applications such as nutritional supplements, protein sources, food colorants and pigments, pharmaceuticals, animal feed, biodiesel production, CO2 sequestration, and bioremediation. The most common methods of mass cultivation of microalgal biomass are open pond, closed bioreactor systems, and photobioreactors. Photobioreactors (PBRs) are a preferred mode of production due to their inherent advantages such as high yield, minimal contamination, better control on environmental parameters, continuous production capability throughout the year, and ability to use indoor controlled environments with natural or artificial lighting or outdoor cultivation using sunlight. This chapter focuses on current developments in the photobioreactors, as they hold promise for economic production and offer a continuous supply of biomass for biotechnological applications. PBRs are increasingly used in different modes like flat bed, tubular, and helical based on the type of microalgae being cultivated and parameters chosen for mass cultivation. Though the economics of biomass produced using PBR systems are considered to be high, the current developments in PBR-based technologies offer lower price than current estimates to produce phototrophic microalgal biomass, which can change the scenario for large-scale utilization of microalgae, such as biodiesel production. This chapter outlines the recent developments in the design, use of light source, harvesting of light source
6.6.4 CO2 Consumption 165 6.6.5 O2 Removal 165 6.6.6 Nutrient Supply 166 6.6.7 Temperature and pH 166
6.7 Advances in Microalgae Culture 166 6.7.1 Light Harvesting Complexes (LHCs) 166 6.7.2 Diatom Genomics 167 6.7.3 Radiation Breeding 167 6.7.4 Nitrogen Starvation 168 6.7.5 Freshwater Microalga 168 6.7.6 Growth Stimulant Lighting 168
6.8 Conclusion 169 References 169
for indoor applications, use of low-cost materials for PBRs, control of environmental conditions, automation in operation and control mechanisms, developments in harvesting methods, strain improvements on some of the most used microalgal strains, potential for new opportunities for finding suitable microalgal strains, extraction of biotechnologically important compounds, and the use of sustainable resources for microalgal biomass production.
