The newly designed aerator was applied to the culture of microalgae.
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The accumulation of TAG was achieved under high shear-stress condition.
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High turbidity on early stage of growth decreased TAG yield by self-shading effect.
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Inhibition of early stage of growth by shear stress affects TAG yield.
Abstract
To improve energy production cost, it is necessary to operate bioreactors at a deeper depth to increase per unit area production; however, self-shading could be an inhibiting factor. Therefore, it is important to employ a variety of agitators so that microalgae in deep regions can be agitated, allowing sufficient aeration. We aimed to evaluate the effectiveness of a self-sufficient aerator in an open pond cultivation system for a microalga. Three experimental cases with different agitation velocities (high: Casehigh; low: Caselow; no agitation: Casezero) were evaluated. In Caselow, cells grew fastest in the early stage of cultivation due to reduced mechanical shear stress. However, the increased turbidity after 150 h reduced the cell density and increased chlorophyll a content, which could be attributed to low light intensity. The maximum TAG content was achieved in Casehigh. The findings suggest that strong agitation using an aerator can promote TAG accumulation.
