Finding ways to sort the smallest items for recycling

Finding ways to sort the smallest items for recycling

By Pamela Jolly  March 15th, 2023

A PhD candidate from MIT is creating a new standard for how small items can be and still get recycled at processing plants. 


Massachusetts Institute of Technology (MIT) PhD candidate, Alexis Hocken, knew early on she wanted to work in engineering, but it wasn’t until she was exposed to a class on sustainable plastics that she discovered her passion for finding ways to sort even the smallest plastic items like flossing picks for recycling.  

As a child Hocken spent many hours with her dad as he worked as an electrical engineer designing biomedical devices. She loved seeing him working to create solutions to complex problems.  

Studying chemical engineering at university Hocken worked on polymers and their additives for 3D plastics printing with little thought to their end-of-life impact. That all quickly changed when a lecturer shared statistics on the mounting problem of plastic waste.  

The UN environment programme reports plastic production has risen exponentially in the last decades and now amounts to some 400 million tons per year– a figure set to double by 2040. Only 9% of this figure has been estimated to be recycled. Australians used 3.4 tonnes of plastics in 2018-2019.  

This class had a huge impact on Hocken motivating her to find out more. With a new awareness to the depth of the problem she joined a trip to visit a recycling sorting centre. During the visit she could see smaller items literally falling through cracks in the processing plant.  

“Leaving that tour, I thought, my gosh! There’s so much improvement that can be made,” she says. “There’s so much impact that we can have on this industry.” 

Back in the lab Hocken set to work to see how these small plastic items could be captured. She is now working with a group of five companies to study packaging and waste products less than five centimetres, that could fit into your pocket, for identification and sorting to design a new retrofitted process for existing sorting machinery.  

“These are products that would be more recyclable if they were easier to sort,” she says. “The only thing that's different is the size. So you can recycle both your large shampoo bottle and the small travel-size one at home, but the small one isn’t guaranteed to make it into a plastic bale at the end.” 

In Australia, we know all about this size issue, with many small items or components of products like bottle lids unable to be processed by the machinery at many facilities.   

“It’s great to see women like Alexis Hocken wanting to make a change and working to find innovative solutions to improve the number of items that can be recycled at material recovery facilities,” said Alejandra Laclette, Senior Recycling Campaigns Manager at Planet Ark.  

“We need many brilliant minds not only working on how to sort elements but also further down the supply chain to find viable markets and opportunities to put materials back into circulation.“ 

Thanks to contributions like Hocken’s other female change makers have an impressive innovator to look to for inspiration.  

Planet Ark does not take responsibility for the accuracy of the original information and encourages readers to check the references before using this information for their own purposes.

Image: Melanie Gonick, MIT


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Pamela Jolly

Pamela is a Marketing Communications professional with over 10 years experience working for both agencies and organisations in communications, travel, finance and retail industries. Pamela loves to be in nature riding a bike, skiing, appreciating the trees at her local park or exploring wild places abroad with her family.

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