(186b) Design and Operation of Novel Photobioreactors for the Cultivation of Microalgae for the Biofuels Sector

A major hurdle to the use of microalgae based biofuels is the lack of an economical method for the microalgae's cultivation. This problem is addressed by the development of two novel photobioreactors for algal growth. The first reactor is an external loop airlift reactor built with the capability of using either internal or external illumination. The riser diameter in this reactor is 6 inches while the downcomer is 2 inches. The second reactor is a 55 gallon bubble column designed with a novel mixing/ internal illumination mechanism. Both reactors were designed with automated control and monitoring systems. Dunaliella tertiolecta UTEX LB 999 grown in Erdschreiber's Medium and Chlorella minutissima UTEX 2219 in Modified Bold 3N Medium were used to study the operating parameters of both reactors. The effects of light intensity, photoperiod, and carbon dioxide concentration in the feed gas, gas flowrate and mixing on the microalgal growth were studied. The effects of the varying nutrient concentrations were also studied, and a procedure was developed to maintain the concentrations of the essential nutrients for algal growth. The microalgae were harvested at the end of each experiment and the algal oil was extracted and analyzed for biofuels potential.