KOBE - A Japanese sake brewer has found an unlikely use for brewing waste, turning it into cattle feed that reduces manure odors and gives new value to a material once costly to dispose of.
Kobe-based Hakutsuru Sake Brewing Co. drew inspiration from ancient Roman writings in its search for a new use for spent activated carbon.
The company says cattle readily consume the feed, which cuts odor-causing compounds in their manure by around 90 percent.
The initiative has turned an industrial waste product into a source of revenue, with other breweries in Japan's major sake-producing regions, including Nada in Hyogo Prefecture and Fushimi in Kyoto, joining the effort.
Activated carbon has been used in sake production since around the Taisho era (1912-1926) to help preserve the drink's color and aroma. The powdered substance is added to sake and later filtered out, with the spent material generally treated as industrial waste.
Japanese sake brewers use at least 1,000 tons of activated carbon annually, about 100 tons of which is used by Hakutsuru, according to the company.
Hakutsuru had long sought ways to reuse the material. Although the company previously sold the spent carbon as compost, its high moisture content from the sake limited its value as fertilizer.
While exploring alternative uses, the company came across ancient Roman writings describing how charcoal and wine were given to sick cattle to improve their health.
Drawing on the idea, Hakutsuru developed a feed combining spent activated carbon with pulp to make it easier for cattle to eat.
The company found that the feed helped maintain cattle health while reducing mercaptans, compounds responsible for much of the unpleasant smell of manure, by 92 percent and hydrogen sulfide by 87 percent.
Hakutsuru began selling the product around 2022.
Hiroyuki Nishi, 54, a cattle farmer in Kobe's Kita Ward, mixes the product with other feed and says it has made a noticeable difference.
"Because my farm is in an urban area, keeping odors under control is important. This feed really helps reduce the smell of the manure," he said.
Although cattle can be picky eaters, Nishi said his animals readily eat the product.
"They seem to really like it. Maybe the aroma of the sake has something to do with it," he said.
Hakutsuru has also devised a recycling scheme under which manure from cattle fed the product would be turned into compost and used to grow rice for sake production.
Under the plan, the compost would be spread on the company's rice paddies, with the harvested rice then used to brew sake, completing a cycle linking breweries, livestock farms and rice cultivation.
Six other sake brewers, including companies in Nada and Fushimi, have joined efforts to reuse activated carbon.
Ryuki Shishikura, a senior researcher at Hakutsuru who helped develop the feed, hopes the initiative will spread further.
"We want to tackle the environmental impact of waste at its source," he said. "I hope more regions will find ways to recycle and reuse their activated carbon locally."
