Microalgae have enormous potential for producing biofuels as they are aquatic organisms that require low energy inputs and can be grown in non-arable lands using high-salinity and wastewater streams. Microalgae are also well-known sources of proteins and lipids and are of high value to the food and pharmaceutical industries. Conventional harvesting methods (centrifugation, filtration, sedimentation, and flocculation), face efficiency, cost, and sustainability challenges. Although centrifugation and filtration achieve high recovery rates, they demand significant energy inputs and high operational costs, including requiring frequent maintenance to prevent clogging.
GW Researchers have developed a novel microalgae harvesting system that relies on low-energy physical biomass flocculation by avoiding the use of additives, contamination, and cell damage, representing a solution compatible with a combined co-production of nutraceuticals. The absence of additives allows the recycling of the growth medium, reduces resource consumption and does not affect product quality. The experiment shows that a simple slow tank rotation about a horizontal axis can aggregate dispersed microalgal cells (<50 μm) into flocs >1 cm within 3–4 hours, dramatically increasing their sedimentation rates by three orders of magnitude. It can also be adapted to virtually any microalgal species.
Figure 1: Proposed harvesting tank geometry (1000 L)
Figure 2: Algal culture before aggregation process (left) and after 3h low speed rolling (right).
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