It is estimated that humans have produced over 9200 million metric tonnes of plastic since its invention in the early 1900s. In theory, we have found ways to recycle plastics and expand their lifespan, changing the plastic into new forms. With approximately 400 million metric tonnes of new plastics produced each year, researchers are questioning whether we can keep up with the recycling demand, and how to lower the environmental impacts.
Dr. Nisha Singh, Visiting Research Fellow at Dalhousie University, and Dr. Tony Walker, Professor in the School for Resource and Environmental Studies at Dalhousie University, are tackling this issue head on, with the aim of identifying solutions to the global plastic overload. In a recent review article published in the scientific journal npj Materials Sustainability, they dive into the complexities of the plastic lifecycle. Research funding for the project was provided by the Ocean Frontier Institute, through an award from the Canada First Research Excellence Fund.
The realities of recycling
For many people across the world, recycling is a part of everyday life. Despite best efforts, however, only nine percent of plastic materials are recycled annually.
“With current technology, many types of plastics, like single-use plastics and multi-layer food packaging , cannot be recycled,” says Dr. Singh.
“Very few types of plastic polymers are actually able to be reused.”
Polymers are groups of molecules that are made from long chains of atoms. Plastic polymers are entirely synthetic, meaning that they are exclusively man-made and will not decompose in the environment.
The modern recycling process is complex. Current facilities utilise a system called mechanical recycling, where the plastic materials are sorted by their type and shredded. The resulting pulp is then repurposed into new items. These systems struggle to recycle materials with multiple types of plastic and cannot accept any recycling that has been contaminated with food.
Despite there being a multitude of plastics on the market, the only type that can readily be recycled is a simple plastic called polyethylene terephthalate (PET). PETs are clear and durable plastics, often making up plastic water bottles. These plastics can be recycled multiple times if they remain clean and are not mixed with other types of plastic.
“Unfortunately, plastic polymers are often downgraded in the recycling process,” explains Dr. Singh.
“A food grade plastic water bottle, it is often recycled into a textile material like clothing. Once the plastic ends up in this form, they are much more difficult to recycle further.”
Another deterrent to large scale recycling is the inputs required; large amounts of energy, funds, and resources are necessary to give plastic products a second life.
“Once you consider all of the energy and resources that go into recycling, it is actually cheaper to make virgin plastic directly from fossil fuels,” says Dr. Walker.
The future of plastics
Finding a solution to the global plastic problem is difficult and complex.
“With skyrocketing plastic production and a very small recycling rate, it is nearly impossible to create a balanced plastic system,” says Dr. Walker.
“Although recycling can in theory create a circular economy, the current model is not working and results in a leak in the system.”
Once plastics reach the end of their life, they either end up in the environment as pollutant, waste in a landfill, or incinerated, contributing to greenhouse gas emissions. This is the result of nearly all single-use plastics, which make up the majority of our plastic production.
Simplified plastic polymers are more likely to be recycled. When different polymers are mixed in a product, they become increasingly difficult to separate and most often end up discarded.
One proposed short-term solution is to focus on sustainably managing and creating new products. More research is needed to properly engineer easily recyclable materials and rework recycling systems to make them more effective. The best long-term solution is to cap plastic production and utilize alternate materials and methods.
“We wanted to put the plastic problem in the broader context of international policy,” says Dr. Walker.
"If people can agree upon standardized plastic polymers, international regulations can be built into future policy. This is an opportunity to at least highlight that current recycling is not working.”
Dr. Singh and Dr. Walker are continuing to collaborate on more projects relating to plastics of all sizes and their impact on the environment. Their goal is to improve the recycling industry to minimize plastic waste and reduce the amount of virgin plastic being produced.
