Jorge Alberto Vieira Costa* and Michele Greque de Morais

*Laboratory of Biochemical Engineering, College of Chemistry and Food Engineering,
Federal University of Rio Grande, Rio Grande, RS, Brazil

1.1 INTRODUCTION

Microalgal biotechnology has emerged due to the great diversity of products that can be developed from biomass. Microalgal biomass has been industrially applied in areas such as dietary supplements, lipids, biomasses, biopolymers, pigments, biofertilizers, and biofuels. To produce these compounds, microalgae can be grown using carbon dioxide and industrial wastes, which reduces the cost of culture medium nutrients and alleviates the environmental problems caused by these effluents. However, the high cost of production of microalgal bio­mass (compared to agricultural and forestry biomasses) is one of the major barriers that must be overcome in order for their industrial production to be viable.

Although efforts have been directed at the optimization of the medium and processes, the development of cultivation systems that are cost-effective and highly efficient must be signif­icantly improved for large-scale production to be viable (Wang et al., 2012; Wang and Lan, 2011). Microalgal cultivation on a large scale has been studied for decades (Lee, 2001).

The first unialgal cultivation was carried out with the microalga Chlorella vulgaris by Beijerinck in 1890, who wanted to study the physiology of the plants (Borowitzka, 1999). Dur­ing World War II, Germany, using open ponds, increased algal cultivation for use as a food supplement. With the onset of industrialization, some study groups at the Carnegie Institute in Washington, D. C., implemented algae cultures for carbon dioxide biofixation. In 1970 Eastern Europe, Israel, and Japan began commercial production of algae in open ponds to produce healthy foods (Ugwu et al., 2008).

Open pond cultivation systems are the most industrially applied because of their low cost of investment and operational capital. This system’s major difficulties are the control of operating conditions, which can cause low biomass productivity, and the control of contam­inants, which can be excluded by using highly selective species (Shu and Lee, 2003).

Compared to open ponds, closed photobioreactors may have increased photosynthetic ef­ficiency and higher production of biomass (Wang et al., 2012). However, closed photobioreactors have a high initial cost, and only microalgal strains with specific physiol­ogies may be used (Harun et al., 2010), which is why different types of closed photobioreactors have been developed in recent decades (Wang et al., 2012).

The objective of this study was to present the advantages and disadvantages of open ponds compared to other photobioreactors as well as to examine factors that affect the cultures and the bioproducts obtained.