Design and evaluation of a novel photobioreactor for mass cultivation of microalgae

From economical point of view microalgae can produce high value compounds using light energy and low value compounds such as CO٢. Microalgae are therefore applied in production of health foods, food additives, colorant agents as well as aquaculture and waste- water treatment. Microalgae are cultivated in different systems called open and closed systems. These systems have some drawbacks. The main goal of this study was design and construction of a noel photobioreactor with the unique ability for simultaneous production of biomass and fresh water as well as rectification sonic disadvantages of the conventional systems. The body of the photohiorcactor was constructed by Plexiglas and covered and closed by a soft plastic material. The photobioreacior included two compartments. The outer compartment was for microalgae cultivation and the inner compartment for condensation and accumulation of fresh water. Agitation of the system was performed by a controllable hydrostatic ٥٠ paddle. Aeration was done by two spargers instilled in the left and right sides of the photobiorcactor. The width of the outer part and the altitude of the cultivation media were designed in such a wa that the light zone of the reactor was increased from ٣٠٪ of open systems to ٥٥٪. Mass translèr rate (KLa) after optimization reached to ٤٫٨×١٠٣ s-١. which was in the range of closed systems. Because of having head space in the cultivation compartment no oxygen accumulation was observed. Fresh water production of the photobiorcactor was desirable (١ L. m٢.d. Therefore, it could he said that he novel phoiobioreactor has some advantages over open system such as, better control of cultivation parameters. high mass transfer rate, better light distribution, and lower contamination risk. This photobioreactor has also some advantages over closed systems such as avoiding oxygen accumulation, lower construction and operation costs, and easer scaling-up. The unique advantage of the system is fresh water production