LONDON, UK — A new technique known as horizontal nozzle-pressurized spinning can extract cellulose from cow manure.

Mohan Edirisinghe, professor and chair of the Mechanical Engineering Department at University College London, invented pressurized gyration, or spinning, about 10 years ago. 

“[Pressurized gyration] basically takes a polymeric solution and then it spins it in a very simple vessel under pressure, so we apply pressure and rotation simultaneously,” he said. “The perforations on the circumference of the vessel then eject fibers. These fibers can be aligned by changing the processing parameters, and what we do then is make them for different functional purposes.”

In the case of extracting cellulose from manure, researchers dry the dung and use mild chemical reactions and homogenization to extract the small cellulose fragments present in the manure. The liquid solution containing these cellulose fragments is then placed into a vessel, where it is pressurized and spun, aiming to transform the fragments into fibers, a usable form of cellulose. After trial and error, Edirisinghe and his group found a configuration of the vessel that allowed them to create usable forms of cellulose from cow manure.

“Cow manure contains a very nice proportion of cellulose, and we have been able to get films, fibers, and actual ribbons of it,” Edirisinghe said.

The composition of untreated cow manure is between 14.2 and 32.3 percent cellulose, researchers estimate. 

Cellulose is widely used in manufacturing across various industries, including paper and cardboard, textiles, and pharmaceuticals. It’s a main component of surgical masks and cellophane and provides texture and controls viscosity in products like toothpastes and lotions. In a powdered form, cellulose is added to shredded cheese to prevent clumping.  Cellulose can also be chemically modified and mixed with other additives to form celluloid, a transparent plastic, although it isn’t in wide use today due to its flammability. 

Simply put, cellulose is a critical component of our everyday lives and the products that we use. While cellulose is often sourced from trees, the demand for the polymer can lead to increased tree logging for many industries, significantly impacting the environment. Sourcing cellulose from cow manure would reduce strain on natural plant resources. The technology invented by Edirisinghe uses less harsh processing than other techniques to extract cellulose, making it an eco-friendlier option. Additionally, the process is low-energy and doesn’t require high heat or electricity-intensive processes.

Additionally, sourcing cellulose from cow manure makes the waste valuable. 

“Cow dung is something [farmers] have to dispose of, and it isn’t environmentally friendly,” Edirisinghe said. “If we can convert [manure] into something that is economically of value, that’s a big bonus for the farming community and everyone else.”

A single dairy cow can produce between 80 to 150 pounds of manure per day, researchers estimate. While waste can be repurposed as fertilizer, farms are often left with more waste than they can use. Sometimes animal waste can end up in waterways, posing health risks to nearby human and animal communities. If manure could be repurposed as a source of cellulose, farmers would not only be able to make money, but they could also help prevent waste overflow.

There are still many processes to refine before the technology becomes widespread.

“We are dependent on having a sufficient stock of dung, and we haven’t taken [the technology] to the level of making it a commercial process yet,” Edirisinghe said. “The only drawback is that we’ve got to scale it up.”

Next, the group is working to put numbers to the process – if the team has 10 kilograms of dung, what is the output of cellulose? Additionally, they are working to transition the pressurized spinning technology from battery-powered to solar-powered. 

The lab is also working on other projects in the realm of pharmaceuticals and medicine. The group has a project with the School of Pharmacy at the university in creating fibers that can assist in drug delivery. The team is also creating antimicrobial filters, using natural materials like cinnamon and garlic, and exploiting other materials like alginate. 

“If you can do good things with materials like cellulose and alginate, say for example seaweed, I think we are helping our environment, which we must be doing to a very great extent,” Edirisinghe said. “I think synthetic materials that are made using a lot of chemical processing are not the future. We’ve got to try and exploit our natural materials, and that will be less harmful to the human community.”