Ohio State researchers use electricity to boost fermentation of food waste

Adding a small electrical charge to the fermentation of industrial food waste can significantly speed up the process and increase yields of valuable chemicals, according to new research from The Ohio State University.

The team behind the study also discovered that pairing two bacterial species in this electro-fermentation system not only accelerated fermentation but enabled more targeted chemical production. Beyond the improved efficiency, the process produced hydrogen gas, opening the door to multiple revenue streams from a single feedstock.

The study, published in the Journal of Environmental Chemical Engineering, used ice cream and sour cream as the main food waste sources, though additional experiments have tested coffee grounds and lake algae. Researchers say the approach could provide a cost-effective and sustainable way to transform waste that would otherwise end up in landfills or incinerators into useful products.

“We are creating an industry from another industry’s waste,” said first author Beenish Saba, a research scientist in food, agricultural and biological engineering at Ohio State. “We’re making use of waste that a contractor charges businesses to take to a landfill, where it produces methane gas. We are suggesting that industries can put up a simple bioreactor in which they can produce other important byproducts.”

The research builds on earlier work by Saba and Katrina Cornish, professor emerita of horticulture and crop science and food, agricultural and biological engineering, who co-led the study. That earlier project assessed the physical and chemical properties of 46 types of food waste to identify promising candidates for conversion into chemicals and gases through different processes, including fermentation.

In the new study, the team compared conventional fermentation with electro-fermentation. In a conventional process, food waste and bacteria are combined in a bottle, nutrient levels are adjusted, and the mixture is incubated at 98.6°F. Electro-fermentation, by contrast, takes place at room temperature inside a bioreactor equipped with an electrode powered by minimal external voltage.

“In conventional fermentation, the bacteria are happily growing and they will produce some solvents and gases,” Saba said. “In the second step, we gave them a little tingling electricity so the bacteria can feel a little irritation, and the metabolism was fast. They were growing and happily eating, and they produced more byproducts – meaning we can increase the yield.”

That extra yield is not the only benefit. Experiments revealed that combining two bacterial species from the Clostridium family created a synergistic system. While C. beijerinckii is known to generate carbon dioxide as it converts food waste into alcohols, C. carboxidivorans consumes that CO2 and produces hydrogen gas and solvents in return.

“It means the waste product of one bacteria is utilized by the other bacteria,” Saba explained. “It was possible that there could have been an antagonistic relationship, but we tested growing them together and found there’s a synergistic relationship between these two bacteria that works well.”

This dual-bacteria approach reduces fermentation waste while producing an additional valuable product. “Carbon dioxide is still there, but most of it is consumed, and it gives us hydrogen gas – an additional product. We now have two valuable products and one waste product,” Saba said.

Hydrogen gas is increasingly recognized as a potential low-carbon energy carrier, while the solvents and platform chemicals produced can serve as inputs for a wide range of products, from biofuels to bioplastics. The prospect of generating both from food waste could make electro-fermentation particularly attractive for industries seeking to cut disposal costs while creating new revenue.

The research also aligns with wider efforts to valorize agricultural and biological residues. Governments and industries are looking for scalable methods to turn waste into valuable products, both to reduce environmental impacts and to support the growth of a bio-based economy.

“We are working on improving the yield, cost efficiency and scalability,” Saba said. “The government is asking for work in this area and industry is interested in getting value from waste and not paying for its disposal. So much material that is agricultural or biological in nature is just going to waste. It’s much better to utilize them and make valuable products.”

The work was supported by Ohio State’s President’s Research Excellence-Catalyst program and the Ohio Water Development Authority. Additional co-authors were Stephen Akinola, Ann Christy, and Thaddeus Ezeji, all of Ohio State.

For the researchers, the next challenge will be moving the system closer to commercial application. By refining the process, improving efficiency, and demonstrating scalability, the team hopes to show that electro-fermentation can become a practical tool for industries looking to convert food waste into high-value outputs.