Nicola Everitt: 'People have shrimp waste they need to do something with, so why not make reusable bags'

Written by: Jo Gallacher | Published:
Dr Nicola Everitt. Photo credit: Shawn Ryan

Whether it’s gently roasted on the BBQ, providing stock for a seafood linguine or the key ingredient in a prawn cocktail starter, shellfish is one of the nation’s culinary favourites.

It has taken on a different role, however, for associate professor at the University of Nottingham Nicola Everitt, who is currently using the fish as the basis of a unique environmental experiment.

Everitt is currently researching how to make biodegradable ‘green’ shopping bags from shellfish food waste that would otherwise end up in landfill. And, surprisingly, the proposal isn’t as far-fetched as it sounds.

As with any great idea, it all started over the dinner table. Everitt’s Egyptian colleague Dr Irene Fahim was staying with the family in their Nottinghamshire home one summer when she commented on the stark difference between the UK and Egypt’s waste management strategies.

Fahim was amazed by the variety of bins for different materials, explaining how the Egyptian waste collection model doesn’t facilitate anything as complex.

This inspired Everitt to research the Egyptian waste management structure. Soon she realised not only is over half the country’s rubbish not recycled, but it doesn’t even get collected, often causing discarded rubbish to pile up on street corners.

Everitt began to contemplate how her research into testing the mechanical properties of materials could be used to help Egypt’s waste problem. Soon enough, she realised there was the potential to make biodegradable bags from a well-known ingredient found in shellfish: chitosan. RWW donned its chemist’s lab coat to find out more.

Everitt explains: “Crab shells and shrimp shells have within them a natural biopolymer called chitin, as well as calcium carbonate, which gives them their stiffness.

People have known this for a while and, in fact, the medical world has been quite interested in chitosan for a long time because of its anti-bacterial properties. It’s become well-known for its high-end uses, so technically we’re not doing anything new by make chitosan from the shells.

“The new step, if we can figure it out, is how we could make it into a cheaper product so that it can be used more widely for different purposes such as biodegradable food bags. People have shrimp waste they need to do something with, so why not make chitosan into something useful like degradable packaging.”

Everitt estimates that roughly one kilo of shrimp shell waste could produce enough chitosan to make 10-15 plastic bags. Although there are plenty of “ifs and buts”, given that Egypt produces 3,000-5,000 metric tonnes of shrimp shell waste per year, potentially 75 million degradable bags could be produced.

Why Egypt?

As Everitt began to look more into the potential of chitosan, research grant scheme the Newton Fund was appealing for new research projects to support. As part of the UK’s official development assistance programme, the Newton Fund finances scientific research which tries to help middle-income services.

It focuses on different countries in different years, and it just so happened that when the institute put its latest call out, Egypt was among the countries listed.

Everitt says: “The essence of the Newton grant is to try and help the country that you’re focused on get to a product that will be useful to them in a ten-year time frame. So far we hope in the end of the two years to have a prototype bag to show them that if you could put it into a manufacturing context, you could produce a bag with this material.”

Egypt also produces a set of conditions that would make the production of the bags much more likely. Everitt continues: “In order to get the polymer out of the shells and get it to the form we want, you have to use quite strong acids and alkalines. So they have a cost associated with them.

“In the UK, for example, it wouldn’t be viable as we don’t produce a huge amount of shrimp shell waste and our labour cost is a lot more. Whereas in places like Egypt, there’s more possibility.”

The Newton grant runs for two years, allowing Everitt and her team enough time to discover whether using chitosan to create the bags is a feasible proposition. After a busy year of research, the results look promising. “We are basically trying to evaluate chitosan composites to see if we can get films which look as if they have the sort of properties we’d want to make bags with. So far, we’ve produced some chitosan films with various fillers.”

Blue-sky thinking

There is also a second “blue sky” part of project, which uses the same research to create food packaging aimed to increase shelf life. Everitt argues there is potential for creating what she calls nano-chitosan, which takes the chitosan polymer and makes it into very small particles.

She says: “The plastic film which covers strawberries and other delicate fruit between the field and shelf contains lots of very small spaces where gas molecules can get out as the food ripens.

“If we could create a film where gas molecules are small enough to get out of the space but others can’t get in, then we are controlling the atmosphere. Essentially we would be trying to let the CO2 that the food produces as it ripens get out, but let stuff that you don’t want to get through, therefore extending a product’s shelf life. It’s yet another step on from having just got the polymer that I can make a plastic bag from.”

Changing attitudes

A bag derived from shellfish waste not only deals with food waste but also produces a biodegradable product, much preferred to the overuse of plastic bags which cause numerous detrimental effects to the environment. But there are still questions over the lifespan of the shellfish bags.

Everitt says: “Part of the research is to discover the rate at which the bags will degrade, and this all depends on how much moisture there is around and what temperature. Chitosan degradability depends on pH so it depends where the bag is degrading. For example, landfill or aerobic combustor would have different rates. At the end of the two years we hope to have a better answer.”

The potential is there, and now the next steps are to get investors involved, particularly the manufacturers of the bags and the consumers. Everitt says: “One would need to have a case to show people that they could get these bags at approximately the same cost, unless of course there was a government initiative.

“Look at the 5p bag in the UK; this changed behaviour overnight. It’s a good exemplar of how governments can get things going, but whether we will be able to get our voices loud enough in the Egyptian political scene for something like that to happen is questionable.

“At the moment there isn’t the same attitude over there, people just expect as we did ten years ago to go to the shops and what they buy gets put into a plastic bag for them to bring home.”

A fishy future

Everitt and her team still have one year left to develop their research into a prototype bag, but what happens once the funding has ended? She says: “It depends where we get to with the prototype bag, it might be that we continue as a research strand in an Egyptian lab, or if we’ve got it to a near enough marker product, we could start to move it out to Egyptian industry.”

Although Everitt remains optimistic that a material can be produced that has the right properties, she admits that making this economically viable may be more challenging. During the year ahead, and beyond, it will be Everitt’s natural curiosity which will continue to encourage progress within her research.

“It’s the research that keeps me going, I just like finding out about things. I’m a strong believer in the more knowledge you have, the more you can help things along.”


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