Evaluation of photobioreactor for microalgae – A Review

The richness of high-value bio-compounds derived from microalgae has made microalgae a promisingand sustainable source of useful product. There has been increasing attention in recent years on the use ofphotobioreactors for various biotechnological applications, especially for the cultivation of microalgae.Microalgae cultivation has gained much interest in terms of the production of foods, biofuels, and bioactivecompounds and offers a great potential option for cleaning the environment through CO۲ sequestration andwastewater treatment. Although open pond cultivation is most affordable option, there tends to be insufficientcontrol on growth conditions and the risk of contamination. In contrast, while providing minimal risk ofcontamination, closed photobioreactors offer better control on culture conditions, such as: CO۲ supply, watersupply, optimal temperatures, efficient exposure to light, culture density, pH levels, and mixing rates. For a largescaleproduction of biomass, efficient photobioreactors are required.The bioreactors which are used for the purpose of growing algae are bubble column photobioreactor, airlift photobioreactor, flat panel bioreactor, horizontal tubular photobioreactor, stirred tank photobioreactor etc. Work is on fordeveloping hybrid type of bioreactors which may overcome the limitations of the developed photobioreactors. It is,therefore, highly desirable to understand the current state-of-the-art PBRs, their advantages and limitations so as toclassify different PBRs as per their most suited applications. The advancement in biomass production strategythrough photobioreactor engineering and enhancing cell biology through metabolic and genetic engineering are twomodern eras of research. This review paper describes general design considerations pertaining to photobioreactorsystems, in order to cultivate microalgae for biomass production. Also provides a holistic overview of the discreetfeatures of diverse PBR designs and their purpose in microalgae growth and also summarizes the recentdevelopment in use of hybrid PBRs to increase their working efficiency and overall economics of their operationfor the production of value-added products.

Keywords:

Microalgae , Photobioreactors , Biorefinery , Cultivation , Harvesting.