Great idea! What happened to it? – High-tech fibers made from cow dung

Cow dung, which is now spread over fields as liquid manure, could serve as a raw material for the production of nanocellulose in the future. (picture alliance / Bildagentur-online / McPhoto)

Alexander Bismarck and Kathrin Weiland are experts in animal excrement. The professor and doctoral student from the University of Vienna can tell immediately whether a heap of manure comes from a cow, horse or elephant – not only visually, but also from the smell. “Horse manure is drier, it may still smell strongly of ammonia, but that’s about it,” says Alexander Bismarck. Cow manure, on the other hand, is not that nice, not to mention elephant dung. Unless it is sterilized, Kathrin Weiland explains: “We practically use a pressure cooker – it just smells like herbal tea.”

Elephant dung as a model for other types of manure

This is also an advantage in the laboratory and one reason why the team began experimenting with elephant dung a few years ago – as a model for other types of manure. The idea: to use the cellulose fibers from partially digested hay and straw to produce nanocellulose, which is an increasingly popular material. Because: Nanocellulose fibers are biodegradable, about a thousand times thinner than human hair and as strong as steel. Among other things, they are suitable as raw materials for membranes, packaging and for fine-pored filter papers that hold back heavy metals or viruses.

Wood and coconut milk are used as raw materials today

Currently, nanocellulose is mainly ground from wood or produced with the help of bacteria. For example from sugar or coconut milk, says Alexander Bismarck: “For example Nata de Coco, which is fermented coconut milk. The process is just very slow. It takes up to seven days to create a one-centimeter layer. “

The fibers from the excrement of the herbivores can be converted more quickly. And with around 40 percent cellulose, they contain as much raw material as wood, which is currently the most important raw material for nanocellulose production. Animal dung could even help protect trees. In addition, the fibers from the manure were pre-ground using strong bits and treated with digestive juices. This saves chemicals and energy during processing.

But you can’t do without it, says Kathrin Weiland: “We actually use the traditional papermaking process. That means that practically everything has to be extracted there too that is not cellulose or that we do not need for paper production. First it is extracted alkaline and then bleached again so that you have these white cellulose fibers. “

The process is similar to classic papermaking

Then an electric mill is used so that, at the end of the day, material on the nanometer scale can be harvested, explains the doctoral student at the University of Vienna: “That means we basically have to grind it up and break the fibers apart so that we have very thin fibers. Then we can you practically filter and press it and then you have paper. “

In recent years, the researchers from Vienna have repeatedly produced nanocellulose paper from elephant dung, examined it under an electron microscope and tested it for tear resistance. And they have investigated whether the quality of the paper is still right after the manure has been pretreated in a biogas plant. In addition to nanocellulose, electricity and heat could then be produced and fertilizer for the fields.

The problem: Fluctuating quality

The team has just published the results in a specialist journal. According to this, the stability of the nanopaper depends, among other things, on the animal feed. The fluctuations in quality can be brought under control with larger quantities of manure from various sources, says Kathrin Weiland. Basically, the process is ready for practical use: “We get high biogas values ​​and a lot of cellulose out again. And right now we are in the process of seeing how it would work in practice with horses. Because we rather want to look at animal husbandry relevant to Europe, so to speak. “

The researchers also want to test cow dung as a raw material for nanocellulose, as well as poultry excrement and mixtures of different types of dung. However, it is still unclear whether an investor can be enthusiastic about the products made from animal manure, even if the unsavory raw material is nothing to see or smell at the end.

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