Department of Chemical Engineering, Kocaeli University, Kocaeli, Turkey.
Department of Plant Protection, Kocaeli University, Kocaeli, Turkey.
Bioprocess Biosyst Eng. 2024 Feb;47(2):195-209. doi: 10.1007/s00449-023-02952-8. Epub 2024 Jan 16.
Microalgae are the most propitious feedstock for biofuel production due to their lipid and fatty acid content. Microalgae cultivation shares many features with bioreactors, such as thermal and pH regulation, feeding procedures, and mixing to enhance heat and mass transfers. Aeration and stirring speeds are important parameters to reduce the costs of producing microalgae. In this study, three different photobioreactor types (stirred tank, airlift, bubble column) were characterized and compared for microalgae production. Hydrodynamics, mass transfer, and power consumption were determined for various aeration rates (0.9, 1.2, 1.5 L/min), and stirring speeds (100, 200 rpm), and Chlorella sorokiniana growth performance was compared under the conditions that provided the highest volumetric mass transfer and the lowest mixing time. Photo-bioreactor homogenization was good as indicated by low mixing times (< 10 s). Bubble column had the highest volumetric mass transfer due to its sparger design. Gas holdup and volumetric mass transfer coefficient were found to increase with the air flow rate and stirring speed. For stirred tank, bubble column, and airlift photobioreactors, maximum specific growth rates of C. sorokiniana were 0.053, 0.061, 0.057 h, and biomass productivities were 0.064, 0.097, 0.072 gdw/L.day, respectively. Under the conditions tested, growth was limited by the volumetric mass transfer in the airlift and stirred tank and bubble column was the best option for producing microalgae. These findings pave way for more extensive use of these systems in producing microalgae and provide a basis to compare photobioreactors of different designs.
微藻由于其脂质和脂肪酸含量,是生物燃料生产最有利的原料。微藻培养与生物反应器有许多共同的特点,如热和 pH 值调节、进料程序以及混合以增强传热和传质。通气和搅拌速度是降低微藻生产成本的重要参数。在这项研究中,三种不同的光生物反应器类型(搅拌罐、气升式、鼓泡塔)的特点进行了表征和比较,以生产微藻。在不同的通气速率(0.9、1.2、1.5 L/min)和搅拌速度(100、200 rpm)下,确定了各种水力、传质和功率消耗,并在提供最高体积传质系数和最低混合时间的条件下,比较了小球藻的生长性能。光生物反应器的均匀性很好,混合时间很短(<10 s)。由于其喷头设计,鼓泡塔具有最高的体积传质系数。气含率和体积传质系数随空气流量和搅拌速度的增加而增加。对于搅拌罐、鼓泡塔和气升式光生物反应器,小球藻的最大比生长速率分别为 0.053、0.061、0.057 h,生物量生产力分别为 0.064、0.097、0.072 gdw/L·day。在所测试的条件下,生长受到气升式和搅拌罐中体积传质的限制,而鼓泡塔是生产微藻的最佳选择。这些发现为这些系统在生产微藻中的更广泛应用铺平了道路,并为比较不同设计的光生物反应器提供了基础。