Basics of Algal Photobioreactors: Design and Engineering Aspects for Algal Cultivation

Microalgae cultivation has recently attracted considerable attention due to its sustainable approaches to tackle environmental and energy problems. Microalgae are photoautotrophic, unicellular microorganisms that use CO2 as a carbon source during photosynthesis to transform light energy into chemical energy more efficiently than plants. These organisms have gained prominence in various industrial sectors, including food production, pharmaceuticals, healthcare, cosmetics, and biorefineries due to their ability to generate lipids, nitrogen, and phosphorous through photoautotrophic processes, which can then be converted into beneficial food additives and biologically active compounds. Although both open and closed cultivation systems have been successfully used for algae cultivation, closed photobioreactors (PBRs) have emerged as the most versatile choice as it offers better quality products and controlled operations. Closed photobioreactors represent cutting-edge technology for microalgae cultivation, offering precise control over critical growth parameters such as carbon dioxide concentration, light exposure, and nutrient availability, creating optimal conditions for microalgal biomass accumulation and the production of sought-after compounds. This book chapter explores the fundamental principles of closed PBR design, materials used in its engineering, their operation and parameters or factors that affect in microalgae cultivation are discussed. A brief discussion on the variety of PBR from closed to open systems and their applications are also summarized. Although algal photobioreactors hold promise as sustainable platforms for biomass production, biofuel generation, and bioremediation, there are challenges such as huge capital-cost, operating-cost, and scalability issues that needs to be addressed for large scale microalgae cultivation.