Enhanced triacylglycerol accumulation in open cultivation of microalgae using an air self-sufficient aerator

https://doi.org/10.1016/j.biteb.2021.100916Get rights and content
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Highlights

The newly designed aerator was applied to the culture of microalgae.

The accumulation of TAG was achieved under high shear-stress condition.

High turbidity on early stage of growth decreased TAG yield by self-shading effect.

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.

Keywords

Microalgae
Open pond cultivation
Aerator
Fluid velocity
Triacylglycerol