This beer-making waste may offer a new stream for cleaner water

Scientific American · Mary Randolph · 2026-10-10 11:00 UTC

The research offers yet another way the brewery industry might repurpose its myriad by-products

Scientists still haven’t cracked how to turn water into wine—but they might have figured out how to turn beer into clean water. From the literal ashes of breweries’ by-products, researchers made a charcoal-like substance that clings to bacteria, and they are using it to test a new way of filtering water.

In a recent study, scientists heated up a common waste product from beer making called spent malt rootlets, which are little sprouts that grow from barley during the malting process, to produce biochar, a porous material created from burned organic matter. They found that when they mixed this substance with sand and sent water through it, the biochar was able to remove around five times as much Escherichia coli bacteria as a filtration system that used only sand.

Sending water through sand filtered bacteria like a colander: by physically stopping microbes from moving through. But when the team used a sand mix that was 10 percent biochar, the biochar actively glommed on to slow microbes’ passage.

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