Singapore researchers using waste biomass for algae harvesting

In Singapore, waste biomass from fungal fermentation processes could be used to bind to and harvest microalgae being used in other biotechnology applications. A*STAR researchers have successfully demonstrated this procedure with fungal mycelium—the main vegetative part of a fungus such as the tangled mass of underground fibers beneath sprouting mushrooms.

The A*STAR team knew that less toxic natural materials such as starch could be used to precipitate and collect some freshwater microalgae, but this is not suitable for marine microalgae due to undesirable effects of the salty solutions. What is needed is a non-toxic and preferably natural and widely available material that can bind to, immobilize and precipitate both freshwater and marine microalgae. This led the researchers to investigate fungal mycelium, which they found was not only effective but could also add value by contributing to the total biomass in the combined and harvested material.

The team screened several varieties of fungi with varying results, in some cases achieving a harvesting efficiency of 97 per cent after several hours of mechanical mixing with four times the mass of wet mycelium. Detailed analysis indicated that the key to the binding and immobilizing effect is a simple ionic attraction between the differing electric charges on the surface of the microalgae and the fungal mycelium.