Trends in photobioreactor technology for microalgal biomass production along with wastewater treatment: Bottlenecks and breakthroughs

The rapid industrialization and urbanization over the years has resultant in increased pollution levels due to the emission of greenhouse gases and the discharge of hazardous wastewaters. In this context, beneficial wastewater treatment methods, such as the utilization of microalgae for bioremediation and carbon capture has gained huge attention due to its use as feedstock for the production of foods, biofuels, and bioactive compounds. These organisms utilize light and capable of CO₂ sequestration; thus, they are promising organisms which can be used to curb the menace of global warming. However, the use of these organisms in large scale has been hindered by reactor engineering shortcomings, with the typical open pond cultivation being prone to the risk of contamination and lack of control on the growth conditions. On the contrary, the closed photobioreactors assure improved control on microalgal growth parameters in terms of maximum exposure to natural light, pH of the growth media, CO₂ and water and nutrient supply. The advantage of using a photobioreactor is based on its ability to utilize CO₂ rich gas as a means of mixing and carbon supply for the growth of algae. Therefore, this chapter discusses basic design criteria regarding different photobioreactors; the parameters affecting CO₂ sequestration in photobioreactors for biomass production including the bottlenecks in the design of various photobioreactors for the generation of biomass.