Revolutionizing recycling: New uses for waste

Millions of tonnes of fabric and forestry waste are generated every year. At the same time water scarcity is rapidly becoming one of the most pressing issues of our time.

Published: Tue 2 Jan 2024 10:13 CEST
Revolutionizing recycling: New uses for waste
Lignin is a major waste product from forestry- and until now, we've thrown much of what we could reuse away. Photo: Getty Images

The question of whether the waste we create, both as consumers and as part of the manufacturing process, could be reused is rapidly moving from the theoretical to an essential part of our future planning.   

Two of Stockholm University’s leading teachers and researchers in the Department of Materials and Environmental Chemistry are at the heart of this dialogue.

Both are involved in projects that are taking the organic waste of several essential industries and turning them into revolutionary new products, disrupting established technological processes from water filtration to wound care. 

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Bringing cellulose back in style 

For Professor Aji Mathew, the journey towards her project has more closely resembled an evolution. 

“I have a background in chemistry. Earlier, when I was doing my Postdoctoral research almost 20 years back, the focus was on pure nanotechnology, working with biobased nanoparticles.””

“However, over the last fifteen years, there’s been a transition. I noted the same materials I was working with could be looked at as sustainable, renewable materials.”

The material in question is cellulose, an organic polymer found in plants. Specifically, Professor Mathew is currently interested in how the cellulose in cotton could be reclaimed to serve several pressing needs.

“Cotton is a source of high quality - it contains a lot of cellulose, but it’s also highly crystalline, so it’s very interesting from a research perspective.”

“However, it’s also important that we find a use for the cotton which is already taken out from agriculture, as it is a very water consuming and land consuming product. We can’t simply throw it out after one use.”

Professor Mathew’s team are currently investigating how current technologies can be applied to extract nanocellulose from recycled clothing. This particular material has a host of applications, including insulating foams for construction or for providing 3D printed water filtration to communities in dire need. The technology by itself is scalable and reasonably low cost and resulted in a start up from the group.

“From recovering cellulose, our goal is to put it back into the manufacturing loop. It may not be coming back to the same location, although that's also a possibility. However, we are visualising a cascading use - to have it re-used five or so times, to the fifth generation.”

“The technology by itself is scalable and reasonably low cost, using bio-based materials. In fact, we’re seeing that we have peers in South Africa and India, who are already running pilot projects.” 

Professor Mathew now oversees a group conducting several projects that investigate the use of cellulose in applications across a wide variety of industries - with more areas of research opening up as discoveries are made. 

Stockholm is a leading centre of materials research, proactively tackling the resource challenges of tomorrow. Learn more

Professor Aji Mathew. Photo: Supplied

New life for lignin

According to Assistant Professor Mika Sipponen, lignin, another organic compound, holds great promise. 

“My project is related to one particular substance – that is lignin, which comes from the forestry industry, in wood chips and bark. It’s something that researchers have been looking at, both at Stockholm University and across Sweden, for about a hundred years.

“Different grades of lignin are used already today in a number of applications, from concrete to different plastics and chemicals. For example, there are also some sunscreens that it's an active ingredient in, and it’s also used in animal feed. 

“What we want to do now is apply a more entrepreneurial mindset to it. Traditionally lignin has been regarded as a low-value material, but we want to market it as a more functional material.” 

“It can also be used as a natural glue, for instance in fully bio-based adhesives for sticking paper or wood pieces together.”

“I also see traction in taking this approach and working jointly with companies that explore these new applications. It’s an area that is rapidly expanding, with one startup originating from my group.”

The next challenge, Professor Sipponen believes, is to further develop the means by which the lignin can more easily reused following its reclamation. 

“This is what we’re working on. It goes back to the field of materials chemistry. We need to design these materials so you simply take them apart and put them together again - thinking of them like Lego blocks.”

Assistant Professor Mika Sipponen, of the Department of Materials and Environmental Chemitry at Stockholm University. Photo: David Falk / Unique Talents

A reusable future 

Both Professors Mathew and Sipponen are amazed at the increased focus towards their areas of research, both within Stockholm University and across the world. 

Professor Mathew reflects: “When I first did my research as a postdoc on nanocellulose, that was in the very beginning of its study, and I never thought it would turn into such a crucial area of research and interest in it has exploded. 

“Now, I’ve been able to build a career in the field, most recently here at Stockholm University. That’s because the question of and the need for sustainable practices has become more important. It’s going to be an area of interest for a long time to come.”

Professor Sipponen has similar sentiments: “I’m amazed at the tremendous growth of the group, not just in terms of numbers, but in our support from Swedish society. I'm obviously super grateful for that support. 

He continues: if I look forward now, I think we have lots of inspiring projects developing fantastic products. We are also collaborating internationally and building great relationships with Swedish and Nordic industries.  That’s how we’ll develop a sustainable way for reclaiming a lot of what we’d otherwise simply waste.”

Stockholm University offers several Master’s programmes degrees in the field of Climate, Environment and Sustainability


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