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.
In
order to improve microalgal biofixation of CO2 in
flue gas with trace impurities from coal-fired power plants, the effects
of SO2 impurity in simulated flue gas with 15% CO2 on dynamic bubble dissolution and Arthrospira photosynthetic growth were analyzed in detail. A higher initial
solution pH resulted in a smaller dynamic bubble diameter, implying
a faster CO2 dissolution due to more H2CO3 ionization into HCO3
– and CO3
2–. A higher concentration of SO2 impurity in flue gas inhibited CO2 dissolution due to
a lower solution pH. The dynamic bubble diameter decreased faster
with a higher solution pH value that resulted from the culture medium,
smaller initial bubble diameter, and higher biomass density. The photochemical
efficiencies (Fv/Fm and φPSII) of Arthrospira cells decreased and the proportion of PSII active reaction centers
(q
P) increased with increasing SO2 concentration. The biomass yield of Arthrospira photosynthetic growth increased by 24% to 5.04 g/L with 200 mg/m3 SO2 in simulated flue gas containing 15% CO2, compared to that without SO2 impurity. This study
presents the possibility of directly cultivating microalgae with real
flue gas containing SO2 impurity, greatly reducing the
cost of flue gas treatment and increasing the economic benefit of
carbon sequestration of microalgae.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.