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Waste destroys microbes, squeezing more biogas from wastewater sludge

Few people are as excited about wastewater as Thomas Fudge. He has good reason: He and his colleagues believe they have found a way to turn sludge into gold.

Wastewater from breweries, food processing plants, and the like cannot be discharged into sewers; it must undergo special treatment, a costly undertaking that often occurs offsite. Fudge’s company, Wase, offers them another option: treat the water on-site and get some free energy to boot.

Collecting methane from organic waste and using it to generate electricity or heat is nothing new. Companies do this not only to squeeze some value out of the sludge, but also to reduce their carbon footprint, since the sludge can become a source of greenhouse gases as it breaks down on its own. Passing it through an anaerobic digester and burning the resulting methane can reduce a company’s carbon footprint.

What Wase is building isn’t your typical anaerobic digester, though. The UK-based startup says its system is significantly smaller and can squeeze around 30% more methane out of sludge. The volume of indigestible organic waste is reduced by 30% to 50%.

The company’s secret is electroactive microorganisms.

“They’re absolutely everywhere,” Wase founder and CEO Fudge told TechCrunch. “They’re in the soil underground, they’re in the wastewater sludge, they’re in the anaerobic digestion systems, but they don’t really have an environment where they can thrive.”

Basically, Gas built a device to make these bacteria happy.

In one of Wase’s systems, a stack of electrically charged fins called electrodes provide a place for electroactive bacteria to grow. At an electrode, something splits hydrogen ions from the sludge. Methane-producing bacteria, on the other hand, absorb hydrogen and use the extra electrons to attach it to carbon atoms stripped from carbon dioxide. The system needs to provide a small amount of power to keep things flowing in the right direction. “It’s more or less like a traffic light,” Fudge said. The end result is biogas.

Once the gas is produced, it is vented and burned to produce heat and electricity.

Because Wase uses microbes that are widely distributed and provides them with the electrons they need, the bacteria are happier in a wider range of conditions, Fudge said. Fudge said Wase’s system can operate at lower temperatures and in a wider range of acidic (or alkaline) conditions than the anaerobic digesters typically used to do the job.

“They grow faster and therefore are more efficient at breaking down organic compounds quickly.”

The colonies formed on the electrodes are constantly renewed. As the old bacteria die, they become food for living creatures. Each colony contains multiple species and strains that evolve over time as they become accustomed to the specific sludge they are processing.

Wase is developing a control system that will maintain wastewater flowing through the system to keep bacteria in optimal condition. As the bacteria draw electrons from the electrodes, the control system can monitor the current to determine how happy they are.

“You get real-time optimization,” Fudge said, which can be used to determine maintenance schedules, automate feeds and monitor overall system performance. “It gives operators a way to communicate with organisms and bacteria,” he said.

The startup recently closed an £8.5 million ($10.74 million) seed round, TechCrunch has learned exclusively. The round was led by Exantia Capital, with participation from Elbow Beach Capital, Empirical Ventures, Engie New Ventures, Hitachi Ventures and WEPA Ventures.

Wase will install a pilot system on a dairy farm in Wales this spring. The company also partners with two breweries.

Wase’s approach could potentially reduce the overall carbon footprint of the wastewater treatment process, although the company has yet to conduct a full accounting. Currently, the methane produced by its system will be burned on site, a smart move because it limits how far the gas must travel. Research shows that supplying it to the natural gas grid will make the climate benefits more ambiguous, as methane leaks along the way become a significant source of greenhouse gases.

However, it’s likely that the methane will be transported in some way. The European Union has set a target of 35 billion cubic meters of biogas production by 2030, which means that no matter how it is used, the young startup will have a lot to learn from.

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