The average dairy cow produces 82 pounds of manure daily. For elephants, that number is up to 300 pounds. According to researchers at the University of Vienna, all that dung represents an untapped resource that has the potential to change the way we make paper.
The team of scientists presented their findings at a meeting of the American Chemical Society on March 21. Waste from cows and elephants, they say, is rich in the same cellulose that's required to make paper products. What's more, the cellulose in manure has been broken down by digestion, making it easier for paper manufacturers to process.
"Animals eat low-grade biomass containing cellulose, chew it and expose it to enzymes and acid in their stomach, and then produce manure," researcher Alexander Bismarck said in a statement. "Depending on the animal, up to 40 percent of that manure is cellulose, which is then easily accessible."
Bismarck first got the idea to make paper from manure after seeing goats graze on dry grass in a small village in Crete. As he watched the plant matter go in, he wondered if that same matter wouldn't be suitable for making paper once it came out the other end. Today most paper is made by grinding down raw wood into nanocellulose, a process that takes a lot of power. The cellulose in dung has already been chewed and worn down by acid and enzymes in the animal's digestive system, cutting out the need for all that grinding.
Following Bismarck's goat manure–inspired revelation, he and his team began working with waste from horses, cows, and now elephants. Thanks to cattle farms and elephant parks around the world, this material is an abundant sustainable resource. The dung they collect is treated with a sodium hydroxide solution to remove lignin, the glue that holds cellulose fibers together (and can also be used as fuel). From there, they filter out other impurities like proteins and dead cells and bleach whatever's left with sodium hypochlorite to create a pure, white pulp that's ready to be made into paper.
The research team is currently exploring potential applications for the material. For now, they say it could be used as reinforcement for polymer composites or as filters for wastewater. It can also be made into paper for writing, though it may be a while until you see notebooks made from elephant dung at your local office supply store.