Polyhydroxyalkanoates (PHA) are a class of biodegradable plastic materials that can be produced via a range of biological processes. Due to their versatile production pathways and physical properties, they have become an emerging alternative to fossil-based plastics. A new production method for PHAs is being scaled up by Uluu (Perth, Western Australia; www.uluu.com.au) using seaweed, microbes and saltwater. “First, we hydrolyze the seaweed, breaking it down into fermentable sugars before separating the sugar-rich liquid from the remaining solids. We feed the seaweed sugars to salt-loving microbes that accumulate PHAs inside their cells. To extract the PHAs, we submerge the cells in freshwater, causing them to burst open through osmotic shock. Finally, we dry the polymer into a powder and compound it into pellets,” describes Uluu co-founder and co-CEO Michael Kingsbury.
Source: Uluu
The use of a regenerable and affordable feedstock like farmed seaweed is key for process scaleup. Uluu currently operates a test plant producing kilogram-scale quantities of pellets for customer trials. The next step is building a higher-capacity plant in Western Australia this year to increase production to 10 tons/yr, for which the company was recently awarded AU$16 million in Series A funding. “We’re targeting the build of our first commercial plant in 2028, and scaling up to 10,000 tons/yr by 2030,” notes Kingsbury. The process also yields a high-protein co-product, which holds promise for generating additional revenue in markets like soil treatment and animal feed.
Uluu has developed a novel saltwater fermentation process that is more efficient than standard freshwater fermentation, which also helps to close the gap in cost parity with conventional plastics. “The saline conditions limit contamination, greatly reducing the energy and downtime typically required for steam sterilization in conventional PHA production. Saltwater fermentation also provides the opportunity to extract PHAs through osmotic shock rather than relying on the harsh solvents used by other PHA producers (typically chloroform). This can eliminate hazardous waste streams and about 30% of the operating costs of traditional PHA production,” says Kingsbury.
Uluu’s PHA pellets behave like plastics, and can be processed using existing plastic-manufacturing equipment. Physical properties can be tailored for certain end-use applications. Initially, Uluu is focusing on two end markets for its PHAs: injection-molded packaging for cosmetic products; and textile materials for fashion markets. And although these markets are the company’s focus now, it has also demonstrated the ability to produce PHA films, foams and rubber-like materials.