Abstract:

To achieve higher microalgae carbon fixation efficiency without increasing energy consumption, multistage bubble cutting units were designed at different heights above the aeration device in microalgae photobioreactor in this study, and bubbles were precisely cut multiple times after departure from the orifice. The effects of multistage bubble cutting on bubble dynamics were visually studied and its effects on microalgae growth were also analyzed. The experimental results indicate that the bubbles are easier to be cut successfully, when the adjacent cutting units are cross-arranged and the spacing between the cutting units S is 100mm. As the cutting units region height H increases, the average diameter of the bubbles in the reactor decreases, and the bubble residence time increases, which is conducive to CO₂ dissolution and microalgae carbon fixation. However, the enhancement effect weakens, when H>65%. When H=65%, the maximum microalgae dry weight and productivity are 1.58g/L and 0.169g/(L·d), which increase by 68.1% and 44.4% compared with single-stage cutting, respectively.

Key words: microalgae carbon fixation, multistage bubble cutting, bubble behavior, photobioreactor, aeration device

摘要：

为了实现在微藻固碳过程中既不增加能耗又提高固碳效率的目的，在微藻光生物反应器内曝气装置的上方不同高度上设计了多级气泡切割单元，实现了在气泡脱离孔口后上升途中精准的多次切割，并采用可视化的实验方法研究了多级气泡切割对气泡动力学行为及微藻生长的影响规律。结果表明：相邻级切割单元交叉排列，级间间距S=100mm时，切割成功率最高；多级切割区域高度H越大，反应器内气泡平均直径越小，气泡停留时间越长，越有利于CO₂的溶解和微藻固碳，但当多级切割区域高度H>65%后提升效果减弱；H=65%时，微藻获得最大生物质产量和产率分别为1.58g/L和0.169g/(L·d)，较单级切割分别增长了68.1%和44.4%。

关键词: 微藻固碳, 多级气泡切割, 气泡行为, 光生物反应器, 曝气装置