Algae, once considered a nuisance and eco-threat, has emerged as a promising and sustainable resource for various applications, including biofuel production, wastewater treatment, and food and feed supplements. However, the efficient harvesting of microalgae remains a significant challenge due to the high cost and energy consumption associated with traditional methods like centrifugation and filtration. This has led researchers worldwide to explore innovative algae harvesting techniques that are cost-effective, energy-efficient, and environmentally friendly. One such promising approach is flotation.
Flotation: An Innovative Algae Harvesting Technique
Flotation is a separation technique widely used in the minerals industry to separate particles based on their differences in surface properties. In recent years, this technology has been adapted for algae harvesting with encouraging results. Flotation involves the attachment of air bubbles to algal cells, causing them to float to the water surface, where they can be easily separated and collected.
There are two main types of flotation processes used for algae harvesting: dissolved air flotation (DAF) and electro-flotation.
Dissolved Air Flotation (DAF)
DAF is a widely used method for the separation of solids from liquids in various industries, including wastewater treatment and food processing. In the context of algae harvesting, DAF involves dissolving air into water under pressure and then releasing the pressure to form micro-bubbles that attach to algal cells. The buoyant cell-bubble aggregates rise to the surface, forming a concentrated algae layer that can be easily skimmed off.
The efficiency of DAF for algae harvesting can be improved by using chemical coagulants or flocculants that promote aggregation of algal cells, making them easier to capture by air bubbles. However, the use of chemicals may not be desirable in some applications due to concerns about environmental impact or product contamination.
Electro-Flotation
Electro-flotation is an alternative flotation technique that generates bubbles in situ by electrolysis of water. In this process, an electric current is passed between submerged electrodes, producing hydrogen and oxygen gas bubbles. The bubbles attach to algal cells, causing them to float to the surface, where they can be removed and concentrated.
Electro-flotation offers several advantages over DAF for algae harvesting. It does not require the addition of chemicals or the use of compressed air, making it a more sustainable and environmentally friendly option. Moreover, electro-flotation can be easily scaled up or down to match the size and production requirements of different algae cultivation systems.
Revolutionizing Algae Harvesting Methods
The adoption of flotation techniques for algae harvesting has the potential to revolutionize the algae industry by significantly reducing the cost and energy consumption associated with traditional methods. This, in turn, could make algae-based products more competitive and attractive for various applications, from biofuels to bioplastics and beyond.
Several research groups and companies worldwide are actively working on the development and optimization of flotation techniques for algae harvesting. For example, a team at Wageningen University in the Netherlands has developed an innovative electro-flotation system that can efficiently harvest microalgae without using chemicals or additional energy input.
Similarly, US-based company OriginClear has developed a patented electro-flotation technology called Electro Water Separation™ (EWS) that can harvest microalgae rapidly and efficiently with minimal energy consumption. The company has successfully demonstrated its technology in pilot-scale projects for algae biofuel production and wastewater treatment.
In conclusion, flotation represents a promising and innovative approach to overcome the challenges associated with algae harvesting. By adopting cost-effective and energy-efficient flotation techniques, the algae industry can unlock the full potential of this versatile resource for a wide range of applications, contributing to a more sustainable future.