Three-Stage Shear-Serrated Aerator Broke CO₂ Bubbles To Promote Mass Transfer and Microalgal Growth

Abstract

A three-stage shear-serrated aerator (TSA) was proposed to break CO2 gas into smaller bubbles through the first-stage shear with horizontal sawteeth, second-stage shear with vertical sawteeth, and third-stage shear with oblique sawteeth on the serrated cylinder and conical head without additional power. The inlet gas flowed through the square throat to generate initial bubbles and then passed through gaps between triangular cones and broke into smaller bubbles at three-stage alternatively permutated sawteeth. The diameter of sheared bubbles at the TSA outlet reduced when side length of square throat decreased and numbers and height of three-stage sawteeth increased. When inclination angle of the aeration head increased from 20 to 60°, the diameter of sheared bubbles first decreased to a valley (inclination angle = 50°) and then increased. Accordingly, the diameter of sheared bubbles at the TSA outlet reduced by 62% to 2.4 mm, which resulted in an increased mass transfer coefficient (by 25.5%) and microalgal biomass yield (by 46.8%) in a raceway reactor.

Developing a Spiral-Ascending CO2 Dissolver to Enhance CO2 Mass Transfer in a Horizontal Tubular Photobioreactor for Improved Microalgal Growth

“…A decrease in the bubble generation time and diameter results in the generation of a great number of bubbles with a high gas–liquid contact area, which considerably enhances the mass transfer rate . Meanwhile, the generation of large amounts of small bubbles produces a stronger disturbance to the microalgal suspension flow, thereby strengthening the mixing effect …”

“…32 Meanwhile, the generation of large amounts of small bubbles produces a stronger disturbance to the microalgal suspension flow, thereby strengthening the mixing effect. 33 Dynamic Behavior of CO 2 Enriched Bubbles in the CO 2 Dissolver. In the presence and absence of the helical baffle, the bubble retention time in the CO 2 dissolver decreased from 1.67 to 0.71 s and from 3.39 to 3.13 s as the gas aeration rate increased from 0.1 to 0.5 vvm, respectively (Figure 4a).…”

SO2 Impurity in Simulated Flue Gas with 15% CO2 Affects Dynamic Bubble Dissolution and Arthrospira Photosynthetic Growth

“…The chlorophyll a and carotenoid contents were also measured spectrophotometrically . Each experiment was conducted in triplicate.…”

“…The chlorophyll a and carotenoid contents were also measured spectrophotometrically. 25 Each experiment was conducted in triplicate. gas with 15% CO 2 in N 2 (no SO 2 ), of which the initial diameter was 3.51 mm, is shown in Figure 2a.…”

Novel Flat-Plate Photobioreactor with Inclined Baffles and Internal Structure Optimization to Improve Light Regime Performance

“…Microalgae and the related high valuable products have been widely used in human food products, aquaculture, and the pharmaceutical industry . The high richness of biological oil in microalgae and photoautotrophic growth extended their applications in biofuel producing, carbon fixation, , and removal of nitrogen and phosphorus from wastewater . The wide application aspects of microalgae in supplying food and energy, as well as solving environmental problems posed challenges for microalgal high-density culture. ,, Photobioreactors (PBRs) have been regarded as the most potential devices for obtaining mass biomass , and plenty of novel PBRs have been developed and optimized since 2000 …”