The University of New South Wales, alongside Sydney Water and Pacific Bio, is exploring whether algae that was used to clean wastewater could be used again to give discarded textiles new life.
The early-stage research is exploring whether the biomass can be converted into a binder and combined with underutilised materials such as discarded textiles to create new materials for manufacturing.
Textiles are an initial test case, with the researchers ultimately interested in how the binder could be used across a much wider range of manufacturing applications.
“The opportunity is to look at this algae biomass not as an end product of wastewater treatment, but as the starting point for something else,” said Mariëtte van Bueren, a research officer in UNSW’s School of Chemistry.
“We're exploring whether the unique properties of algae biomass can be used to create natural binders that could replace fossil fuel-based alternatives across a wide range of manufacturing applications.”
UNSW Associate Professor Anna Wang said developing a new material isn't just about whether the chemistry works. She said we also need to understand where the raw materials come from, how they can be processed and whether there's a useful application at the other end.
“Mariëtte's background in seaweed research, design and economics allows her to consider all those questions together,” Wang said.
The research builds on Sydney Water's innovative algae treatment trial at its Picton Water Resource Recovery Facility. Pacific Bio's RegenAqua technology uses native green macroalgae during the final stage of wastewater treatment to naturally remove nutrients such as nitrogen and phosphorus, improving water quality before it is reused or safely released into local waterways.
As the macroalgae grow, they capture nutrients from the water and convert them into harvestable organic biomass.
According to the project leaders, that biomass represents an important opportunity beyond water treatment.
The UNSW team are using the biomass to develop a natural binder, similar to a glue or resin, and testing how it performs when combined with discarded textile fibres and other materials.
“Wastewater treatment plants are called Water Resource Recovery Facilities because of the potential to harness the value of nutrients, energy and water supplies,” Sydney Water recycled water lead, Emma James, said. “But it is a big change to deliver a circular economy approach.
“It requires new partners and community support to unlock the value of materials previously considered 'waste'. It also requires science, research and new technologies to manage chemicals from our urban environment.”
Textiles could be an important test case for the potential of the new binder. Every year, more than 300,000 tonnes of clothing are either sent to landfill or exported from Australia.
Recycling textiles can be difficult because garments often contain blends of fibres, dyes, buttons and zips.
According to van Bueren, a broad range of chemicals are used in textile production processes, including PFAS, glues and dyes. She said these should be removed before recirculating the material, to enable sustainable textile recycling.
Rather than requiring perfectly sorted materials, the researchers are investigating processing methods robust enough to work with a wide variety of discarded textiles.
“If we're serious about reducing landfill, we need recycling processes that can deal with the reality of mixed textiles, not just the easy materials. That's the challenge we're trying to solve,” van Bueren said.
“This is a global challenge, and we're trying to contribute our part by identifying and researching different processing methods and pathways to produce the resin and new biocomposite materials.”
The textile application is just one potential pathway for the algae biomass. Pacific Bio is already exploring applications for RegenAqua biomass across areas including agriculture, energy and building products.
For the UNSW researchers, the next step is to understand what makes the algae-derived binder distinctive and where those properties could be most valuable.
“When you're working with something completely new, the first step is to understand its strengths and weaknesses,” van Bueren said.
“Once we know what it does well, we can identify where it can deliver the greatest value.”
The research is also exploring how processing could work at a local scale.
Many sources of biomass are available in relatively small quantities or can vary in quality, making them less suited to large, centralised commercial operations. Smaller processing technologies could potentially allow biomass to be converted into useful materials closer to where it is generated.
For councils, utilities and remote communities, that could reduce transport requirements while creating value from locally available resources.
“The vision is for local communities to turn their underutilised materials into something valuable,” van Bueren said.
“Rather than shipping materials across the country, we could create products close to where those materials are generated. It's a simpler way of thinking about recycling and a much more circular one.”
The project is approaching its conclusion, with the researchers aiming to produce a prototype resin and examples demonstrating potential applications.
Ms van Bueren said following that prototype resin, the next step is to secure more funding to work with Sydney Water and a textile industry partner to develop functional products, as well as build the technology needed to transform locally available biomass and other underutilised materials into valuable new resources.
The project received funding through the UNSW Science Translational Impact Seed Fund, which supports early-stage collaborations between researchers and industry, government, charities, not-for-profits, NGOs and foundations.
Ms van Bueren's research builds on her Master of Philosophy at UNSW, where she investigated seaweed valorisation under the supervision of Associate Professor Patrick Spicer from UNSW Chemical Engineering and A/Prof. Wang from UNSW’s School of Chemistry.