From muck heap to materials: the engineers turning horse dung into packaging films

A stable yard in Essex may seem like an unlikely place for an engineering innovation to spring from, but that’s where this story begins.

Perry Robinson owns a business clearing waste from stable muck heaps. He told Reuters in February that he collects 150 to 200 tonnes of horse manure a week. Some of this can be composted or sent to farmers to use as a fertiliser.

But only so much can be stored for this purpose, as nutrient runoff from manure piles can pollute waterways. The rest is just solid waste, and with its disposal regulated by the Environment Agency, excessive manure can become a logistical burden for stable and farm owners.

As he searched for other ways to use the waste, Robinson came across the work of Professor Mohan Edirisinghe OBE FREng, who is the Chair of Biomaterials in the Department of Mechanical Engineering at UCL. He reached out after reading Edirisinghe and his group's work on spinning cellulose from cow manure, in an article published in summer 2025 in the Journal of Cleaner Production. This demonstrated that cow manure could be processed into a precursor for packaging materials, through an approach known as pressurised spinning (invented by Edirisinghe and his team at UCL).

Spotting an opportunity, Robinson invited Edirisinghe to his farm in Essex to see the extent of the waste problem he was dealing with. Edirisinghe and one of his team, Dr Mehmet Onur Aydogdu, then set out to upcycle horse dung with their spinning approach as part of this new research theme, dubbed “waste to wonder”.

Turning horse dung into a circular material

Edirisinghe has been recognised for developing scalable manufacturing approaches for all types of polymers, winning the Royal Academy of Engineering’s Colin Campbell Mitchell Award in 2023.

In recent years, he has increasingly focused on ‘green’ polymers, which come from natural feedstocks and are biodegradable. He told Ingenia his group aims to create useful materials that are manufactured in an environmentally friendly way and based on circular principles.

“We generate a lot of waste. We’ve got to reuse that in one way or form,” says Edirisinghe. “And we’ve got to do that with the environment in focus. That’s been my mission in the last few years.”

The first stage of the process, developed by Edirisinghe’s collaborators at Edinburgh Napier University, begins by collecting and drying the dung (ideally by leaving it in the sun). Then it is ground up and treated to extract cellulose, a compound found in plant cell walls, from other biological molecules such as lignin, as well as proteins and carbohydrates.

However, the cellulose is not yet in a usable form. Having been partially digested on its journey through the digestive system, it’s made up of a mush of fibres, each only nanometres thick and a few micrometres long.

This is where Edirisinghe’s pressurised spinning technique comes in. The setup involves a rotating drum with small holes, designed and fabricated in-house in the UCL Mechanical Engineering workshop. Rapid rotation pushes a stream of pressurised nanocellulose liquid feedstock into a reservoir of water. Then, because it is hydrophobic, it doesn’t mix with the water. Instead, it either forms fibres, ribbons, or films, depending on the viscosity of the nanocellulose feedstock.

The characteristic of being hydrophobic is also what makes cellulose a good packaging material for transporting goods: so our parcels don’t get wet. Edirisinghe has identified this as the key application for the cellulose films, once scaled up beyond the small amounts made in lab tests. It is also biodegradable, which is another advantage compared to synthetic polymers often used for this purpose.

Scaling up the process from lab to farm

Edirisinghe’s group is currently liaising with partners in Turkey and India to determine the quality and structure of the pressure-spun materials. This detailed study of the material characteristics may reveal other possible long-term uses, such as in textiles.

While the quantities involved have been small so far, there is a precedent for industrial interest in waste-derived cellulose. Sri Lanka-based HDDES Extracts is funding a PhD student in Edirisinghe’s group, who is extracting cellulose from waste from the cinnamon industry, and pressure spinning it. (Seaweed is yet another potential feedstock the group is exploring.)

For the horse dung project, Edirisinghe plans to set up a project with the support of partners in the equestrian community such as Robinson, to find out how much cellulose they can produce and how they can further develop the process.

Robinson is currently fundraising for seed investment under the name Stable Future, and has set up a space on his farm to trial pressure spinning at a larger scale than the laboratory tests so far. The research programme will also aim to quantify the exact scale of the horse dung waste issue in the UK, and collaboration with – and value for – stable owners will remain at the core of the project.