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Bioplastic research comes to an end at Rivergate

Rivergate has played an instrumental part in a Queensland-based bioplastics field study that could unveil key findings about the way biodegradable plastics break down in our waterways.

Wanting to delve further into the world of marine pollution and bioplastics, University of Queensland PhD Candidate Tracey Read has conducted an ‘epic’ field trial across four southeast Queensland research sites, including Rivergate’s Marina.

A research expedition sailing from Japan to Hawaii through the Great Pacific Garbage Patch was the catalyst for Tracey to dive into this line of research.

“I was working in Hong Kong for an environmental charity I co-founded – Plastic Free Seas,” she said.

“We focused on plastic marine pollution education in schools and took action with companies and the community.

“During a research expedition I participated in, sailing from Japan to Hawaii through the Great Pacific Garbage Patch on ‘Sea Dragon’, I saw for myself the extent of this global plastic problem. The middle of the ocean contained not only indiscriminate large plastic items but also a smog of microplastics, which we were sampling over the 4-week sailing period.”

After moving back to Australia, Tracey decided to undertake a PhD in Chemical Engineering with a focus on bioplastics, researching how these materials biodegrade in marine environments and determine their lifetimes.

The scope of Tracey’s research was to identify how quickly biodegradable plastics break down in waterways, testing its viability as a partial solution to the world’s growing plastics problem.

To achieve this, Tracey established an 18-month field trial – dubbed the ‘epic’ field trial due to the scale and complexity – across four different sites that met safety, accessibility, and environmental requirements.

These sites were Rivergate Marina, Spinnaker Sound Marina, Dunwich, and Sea World.

“Rivergate Marina was ideally positioned for estuarine conditions,” Tracey said.

“However, it was the most difficult to design as the research rig was attached with ropes to the cleats on the floating pontoon, and also to concrete blocks to hold it onto the riverbed.”

Using these sites, Tracey tested how three different biodegradable materials reacted in the water across the four different sites. These materials were polyhydroxyalkanoate (PHA) – made by bacteria and used in some food packaging, polylactic acid (PLA) – made from plants and commonly used in cold drink cups and cutlery, often labelled ‘compostable,’ and polybutylene adipate terephthalate (PBAT), a fossil fuel-based bioplastic used in pet waste bags.

Because these three materials are manufactured in different ways, with varying thickness and shape, Tracey’s research aims to determine the lifetimes of each material when submerged in aquatic environments. She is also testing the effect of two different ‘additives’ to determine how these impact bioplastic biodegradation– a ‘filler’, often added to bulk out plastic, and a ‘plasticiser’, added to help make the bioplastic more flexible.

“I wanted to determine the lifetimes of each bioplastic material and if the way we made plastic, as well as the thickness and shape, had an impact on the lifetimes of these materials as well as the effect of particular additives (such as a non-toxic plasticiser) that would be used in commercial products,” Tracey said.

Now that the field element of the trial has ended, Tracey can share that the PHA across the test sites was readily and rapidly biodegradable due to the high number of naturally occurring bacteria that can colonize and break down the bioplastic. The PBAT lifetimes varied considerably in each of the environments, and the PLA whilst it didn’t lose weight and get thinner like PHA and PBAT, after 18 months, it was breaking apart.

So, what comes next?

Tracey will be busy with data analysis before writing and publishing her next two research papers and submitting her thesis by the end of 2024. Rivergate will share some of her findings – stay tuned!

Rivergate’s commitment to promoting cleaner waterways

Rivergate is an accredited International Clean Marina and consciously makes an ongoing commitment to upholding environmentally sustainable practices.

Aside from hosting Tracey’s bioplastic research onsite, Rivergate has been a proud supporter of Ocean Crusaders, a team of leading waterway cleaning specialists in southeast Queensland. Ocean Crusader’s crew members are made up of passionate volunteers who crusade oceans and waterways in southeast Queensland to remove litter and debris that is harming our ecosystems.

To learn more, click here.