The advance by a team of researchers from UCL, Edinburgh Napier University and Teesside University could help farmers overcome challenges presented by disposing of dung.
Published in The Journal of Cleaner Production, the study describes the new ‘pressurised spinning’ innovation and its potential to create cellulose materials more cheaply and cleanly than some current manufacturing methods, using dairy farm cow dung as the raw material.
The advance is the first time that manufacturing-grade cellulose has been derived from animal waste.
Common material
Cellulose is found in the cell walls of plants and was first used to create synthetic materials in the mid-19th century.
Today it can be found in products including cling film, surgical masks, paper products, textiles, foods and pharmaceuticals. Though it can be extracted organically, it is also often produced synthetically using toxic chemicals.
Pressurised spinning (or pressurised gyration) is a manufacturing technology that uses pressure and rotation simultaneously to spin fibres, beads, ribbons, meshes and films from a liquid jet of soft matter. The technology was invented in 2013 by a team from UCL Mechanical Engineering led by Professor Mohan Edirisinghe.
In a statement, senior author Professor Edirisinghe said: “Our initial question was whether it could be possible to extract the tiny fragments of cellulose present in cow manure, which is left over from the plants the animals have eaten, and fashion it into manufacturing-grade cellulose materials.
“Extracting the fragments from dung was relatively straightforward using mild chemical reactions and homogenisation, which we then turned into a liquid solution. But when we tried to turn the fragments into fibres using pressurised spinning technology, it didn’t work.
“By a process of trial and error, we figured out that using a horizontal rather than a vertical vessel containing surface nozzles and injecting the jet of liquid into still or flowing water caused cellulose fibres to form. We were then able to change the consistency of the liquid to create other forms, such as meshes, films and ribbons, each of which have different manufacturing applications.
“We’re still not quite sure why the process works, but the important thing is that it does. It will also be fairly easy to scale up using existing pressurised spinning technology,”
The new horizontal nozzle-pressurised spinning technique is said to be an energy efficient process that does not require the high voltages of other fibre production techniques such as electrospinning.
The team said that adapting existing pressurised spinning machines to the new process should be relatively straightforward. The greater challenge is likely to be the logistics of sourcing and transporting the raw material, but that the environmental and commercial benefits of doing so would be significant.
Ms Yanqi Dai, first author of the study from UCL Mechanical Engineering, said: “Dairy farm waste such as cow manure is a threat to the environment and humans, especially through waterway pollution, the release of greenhouse gases into the atmosphere when it decomposes, and the spread of pathogens. It is also often a burden on farmers to dispose of properly.
“Horizontal nozzle-pressurised spinning could be a huge boost to the global dairy farming industry, by putting this problematic waste product to good use and perhaps creating a new source of income.”
The research team is currently seeking opportunities to work with dairy farmers to take advantage of the technology and scale it up.
Core pressurised spinning research at UCL was made possible by grants awarded by UK Research and Innovation (UKRI).
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