Waste algae from municipal wastewater-treatment plants is typically sent to landfills, but a new process offered by Gen3Bio, Inc. (West Lafayette, Ind.; www.gen3bio.com) aims to convert it into specialty chemicals using a proprietary blend of enzymes to break open — but not digest — the microalgae. “This releases the internal lipids, proteins and carbohydrates to provide a filtrate containing monosaccharides and soluble proteins and a precipitate with lipids, insoluble proteins and algal cell walls,” explains CEO Kelvin T. Okamoto.
As an alternative to landfilling, waste algae streams are sometimes processed via hydrothermal liquefaction, but this process involves much higher operating costs when compared to Gen3Bio’s method, continues Okamoto. “The process is greater than 90% efficient in lipid, protein and carbohydrate recovery, thus allowing for several specialty-chemical revenue streams to be produced from the algae,” he says. The starting algae strain or strain mix will determine the ratio and type of end specialty chemicals that can be produced, and the process can handle most algae strains that do not have a thick cell wall. “The filtrate can be fermented to produce ethanol, succinic acid, itaconic acid or any other byproduct of fermentation. Succinic acid is the first target for fermentation due to a large global demand for biosuccinic acid that is not presently being met,” explains Okamoto. The precipitate can be further separated into lipids (to produce biodiesel, omega-3 fatty acids or glycerol), proteins (which can be hydrolyzed to produce peptides and amino acids) and algal cell walls (which can yield glycolipids, glycans and phospholids).
So far, the enzymatic process has been demonstrated in a 55-L mobile plant, and recent funding awards will allow the process to be further developed at a wastewater-treatment plant in Roberts, Wisconsin this summer in association with Clearas Water Recovery, Inc. (Missoula, Mont.; www.clearaswater.com).