Zhao Sha, Feng Wenyue, Li Jinming, Zhang Xiaoguang, Liu Li, Li Hongyan
College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao, China.
Front Bioeng Biotechnol. 2023 Jun 28;11:1225187. doi: 10.3389/fbioe.2023.1225187. eCollection 2023.
Carbon sequestration by microalgae is an effective approach for achieving carbon neutrality owing to its high carbon capture efficiency and environmental friendliness. To improve microalgae CO fixation efficiency, various methods to enhance CO transfer at the gas-liquid interface have resulted in high energy consumption. In this study, a novel aeration device with bubble cutting slices was installed in a photobioreactor for CO supply, which could precisely separate bubbles into sizes on the way to rising after departure, achieving CO transfer enhancement without extra energy consumption. Subsequently, the bubble cutting dynamic behaviors in the photobioreactor were studied, and the effects of thickness, hydrophilicity, and arrangement of cutting slices on microalgal growth were analyzed. It was found that bubble cutting caused the maximum dry weight and biomass productivity of microalgae to improve by 6.99% and 33.33%, respectively, compared with those of the bioreactor without cutting units, owing to a 27.97% and 46.88% decrease in bubble size and rising velocity, respectively, and an 84.55% prolongation of bubble residence time. Parallel cut slices with a thickness and spacing of less than 3 mm successfully cut the bubbles. The hydrophobic slice surface prevented daughter bubble departure and prolonged the bubble residence time, impeding microalgae growth owing to bubble coalescence with subsequent bubbles. The optimal cutting slice parameters and culture conditions for microalgal growth were 1 mm slice thickness, less than 1 mm slice spacing, 5% inlet CO concentration, and 70 mL/min gas flow rate.
微藻固碳因其高碳捕获效率和环境友好性，是实现碳中和的有效途径。为提高微藻固定二氧化碳的效率，各种增强气液界面二氧化碳传递的方法导致了高能耗。在本研究中，一种带有气泡切割片的新型曝气装置安装在光生物反应器中用于供应二氧化碳，该装置能够在气泡离开后上升的过程中精确地将气泡切割成不同大小，在无需额外能耗的情况下实现了二氧化碳传递的增强。随后，研究了光生物反应器中气泡切割的动态行为，并分析了切割片的厚度、亲水性和排列对微藻生长的影响。结果发现，与没有切割装置的生物反应器相比，气泡切割使微藻的最大干重和生物量生产力分别提高了6.99%和33.33%，这分别是由于气泡尺寸和上升速度分别降低了27.97%和46.88%，以及气泡停留时间延长了84.55%。厚度和间距小于3毫米的平行切割片成功地切割了气泡。疏水的切割片表面阻止了子气泡的离开并延长了气泡停留时间，由于气泡与后续气泡合并而阻碍了微藻生长。微藻生长的最佳切割片参数和培养条件为切割片厚度1毫米、切割片间距小于1毫米、入口二氧化碳浓度5%和气体流速70毫升/分钟。
