Biodegradable Plant-Based Plastic to Combat Ocean Waste

By Sarah MooreJun 1 2020

Image Credit: Romolo Tavani / Shutterstock.com

Plastic became widely used in the 1960s, with societies embracing the disposable lifestyle that offered them convenience and saved time.

Decades later, our dependence on plastic has become problematic. Our use has increased exponentially, with 2.3 million tons being produced in 1950, 162 million in 1993, to 448 million in 2015. A vast amount of plastic is added into circulation each year, and less than a fifth of it gets recycled. In the US specifically, the recycling rate for plastic is less than 10%.

The low recycling rate for plastic around the world, coupled with its durability, has resulted in a mounted volume of plastic polluting the world’s natural environments. Plastic can take hundreds of years to degrade naturally, with experts estimating it taking anywhere from 450 years to never.

Addressing the Exponential Growth of Plastic in Our Oceans

A large amount of plastic waste enters the world’s oceans each year. Although the exact figures cannot be known, experts estimate that as much as 5.3 million to 14 million tons of plastic are added to the oceans annually.

The result is that entire ecosystems are damaged. Ocean plastic pollution kills marine species, with around 700 species, some of which are already endangered, being detrimentally impacted by plastic pollution.

Around 40% of ocean surfaces around the globe have been converted into convergences of floating plastic waste. Current trajectories estimate that levels of plastic waste will overtake the weight of fish in the oceans by 2050, with roughly a truckload of plastic entering the water each minute.

The great pacific garbage patch has formed from the collections of trash in the East and West of the Pacific ocean. The spinning aquatic garbage dumps cover around 1.6 million square kilometers in total. What is even more concerning is that around 70% of the debris in the ocean sinks, meaning there is a huge amount of waste sitting below the Great Pacific Garbage Patch, on the ocean floor.

Video Credit: Monterey Bay Aquarium Research Institute (MBARI)/YouTube.com

How Does Plastic Pollution Affect Ocean Wildlife?

Fish in the North Pacific ocean are struggling to deal with these large amounts of plastic. It is estimated that around 12,000 to 24,000 tons of ocean plastic is ingested by fish each year, resulting in injury, death, and plastic accumulation in the food chain that leads to higher levels of plastic consumption by humans. A recent study revealed that as much as 25% of fish available for human consumption contain plastic microfibers.

Ocean plastic is also a major concern for other species. Sea turtles often die from consuming plastic debris. Meanwhile, thousands of seabirds are also estimated to ingest plastic, leading to starvation due to the plastic content in the bird’s stomachs causing them to feel full. Around 60% of seabirds have eaten plastic, a figure which is expected to rise to 99% by 2050.

The Possibilities of Biodegradable Plant-Based Plastic 

To address this problem, a team at Osaka University, Japan, developed a biodegradable plastic that breaks down in seawater. While a number of research teams have already created various plastics that break down in the ocean into harmless components, the problem with these plastics is that they are more expensive to produce and cannot, therefore, realistically be considered a viable material to switch a significant portion of plastic-based products to.

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In addition, they are also not as strong as conventional plastic products and are not water-resistant, limiting their potential use.

The Japanese team took the limitations of current biodegradable plastic into consideration and developed a plant-based plastic constructed from starch and cellulose nanofibers. Initial testing has revealed that the plastic has excellent water-resistant properties, strength, and, importantly, the plant-based plastic biodegrades easily over time if left floating in seawater.In addition, because the plastic is not made from petroleum, the production of biodegradable plastic, in theory, does not produce greenhouse gases.

A Biodegradable Plastic Made From Plants

The Osaka Blue Ocean Vision framework was laid out in 2019 at the G20 Summit in Osaka. Member countries of the summit agreed to the plans outlined in the document, which aimed to reduce plastic pollution in the world’s oceans to zero by 2050.

In response, researchers in Japan have focused on exploring ways to tackle plastic pollution by devising a plant-based plastic that is biodegradable in seawater and does not contribute to greenhouse emissions or add harmful components into the ocean once it is broken down.

In a paper published in late-2019, in the journal Carbohydrate Polymers, a team at Osaka University described how they developed plastic composed of starch and cellulose. The result was a low-cost, biodegradable plastic suitable for mass-production and, if used to replace conventional plastic, will tackle the issue of tons of plastic being introduced into the oceans each year.

The transparent plastic, made only from plant-based materials, is cheap to make because it relies on natural biological polymers that are low-cost and easy to access. Corn and potatoes are a common source of starch, and cellulose is found in a wide range of plants as it is the component that strengthens plant walls. The team demonstrates a simple production process that can be easily adopted at multiple worldwide locations to mass-produce the plant-based plastic.

Eco-Friendly Food Packaging

The starch component is used to create a strong plastic membrane that is reinforced with microscopic cellulose fibers. While it is water-resistant, it will slowly break down in water over time, taking roughly one month to be broken down into shreds. Seawater contains a large number of micro-organisms, which are believed to assist in the breakdown of the organic material.

The researchers predict that their innovation will have a major impact on the environment as it provides a realistic way to prevent more plastic waste from sticking around in the oceans.

Next, the team intends to trial the plastic as a food packaging material, a type of plastic that is often found in plastic debris in the sea. The plastic will then be trialed in different products and packaging types.

It is likely that future developments with continue to improve the properties and versatility of the plant-based plastic, which is predicted to be invaluable in future strategies to protect the world’s oceans.

References and Further Reading

Raghav Soni, Taka-Aki Asoh, Hiroshi Uyuma. (2020) Cellulose nanofiber reinforced starch membrane with high mechanical strength and durability in water. Carbohydrate Polymers. Available at: https://doi.org/10.1016/j.carbpol.2020.116203 

Center for Biological Diversity. Ocean Plastics Pollution. [Online] Available at: https://www.biologicaldiversity.org/campaigns/ocean_plastics/

Nami Sugiura. (2020) Osaka University creates plastic that decomposes in seawater. [Online] The Asahi Shimbun. Available at: http://www.asahi.com/ajw/articles/13222641

Ben Coxworth. Plant-based plastic biodegrades in the ocean. [Online] New Atlas. Available at: https://newatlas.com/environment/plant-based-plastic-biodegrades-ocean/

Greenpeace. Plastic Pollution. [Online] Available at: https://www.greenpeace.org.uk/challenges/plastic-pollution/

Prachi Patel. (2020) This new kind of plastic is made to degrade in seawater. [Online] Anthropocene Magazine. Available at: https://anthropocenemagazine.org/2020/03/this-new-degradable-plastic-could-be-the-relief-our-oceans-need/

Laura Parker. (2019) We Made Plastic. We Depend on It. Now We’re Drowning in It. [Online] National Geographic. https://www.nationalgeographic.co.uk/2018/05/we-made-plastic-we-depend-it-now-were-drowning-it

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