Microalgae cultivation in photobioreactors: sustainable solutions for a greener future

Microalgae cultivation in photobioreactors (PBRs) has emerged as a promising and sustainable approach to address various environmental and energy challenges, offering a multitude of benefits across diverse applications. Recent developments in microalgae cultivation in photobioreactors have contributed substantially to the development and optimization of sustainable bioprocesses. This review presents a comprehensive analysis of recent innovations and breakthroughs in the field of microalgae cultivation, with a specific focus on their application in photobioreactors, aimed at paving the way for a greener future. This study in-depth examines the advantages of microalgae cultivation in photobioreactors, concentrating on its effectiveness in wastewater treatment, CO₂ bioremediation, and the production of biofuels and high-value products. The review evaluates the effects of light, solar irradiation, temperature, nitrogen and phosphorus concentrations in culture media, CO₂ concentrations, and pH on microalgae growth performance, including specific growth and biomass productivity. The study also examines open systems like unstirred ponds, raceway ponds, and circular ponds and closed systems like horizontal tubular, vertical bubble-column, airlift, flat panel, and plastic-bag photobioreactors, comparing their pros and cons. To optimize microalgae cultivation, key factors in photobioreactor design, including photosynthetic efficiencies, light/dark (L/D) cycles, CO₂ concentrations, mass transfer, hydrodynamics behavior, and pH, are extensively investigated. In addition, the review outlines recent developments in large-scale photobioreactors and highlights the challenges and opportunities associated with photobioreactor scale-up and design parameter optimization, including genetic engineering and economic feasibility. This article is a vital resource for researchers, engineers, and industry professionals seeking sustainable bioprocesses and the application of microalgae-based technologies.