Bacteria purify wastewater while generating energy

Published on
September 10, 2015

Water treatment plants treat wastewater to make it safe for human use. As this process requires a great deal of electricity, Wageningen UR is exploring a new method which actually produces rather than requires energy. The secret? Deploying bacteria as battery chargers.

“The treatment of wastewater is currently an energy-intensive process,” explains Annemiek ter Heijne, scientist from the sub-department of Environmental Technology at Wageningen University. “This energy is required in order to pump oxygen for the cleaning process into the wastewater. We are exploring a totally new method which taps the energy that is already present in the water.”

Carbon granules

Ter Heijne and her colleagues deploy a method that uses carbon granules. “We add these particles to the wastewater where bacteria adhere to them and process the wastewater into carbon dioxide and electrons. The electrons are stored in the carbon granules, which can be discharged to generate electrical power.”

Reactor and discharger

To test the process, the scientists built a reactor in which wastewater was added to the carbon granules. The water was clean when it left the reactor. To tap the electricity produced, a discharging system was attached to the reactor which allowed the carbon granules to be discharged very rapidly. The video below shows exactly how this process operates

The principle works

Ter Heijne sees a bright future with a new, biobased reactor system in which electricity is generated quickly and efficiently by tiny microorganisms. “The principle works,” she says. “We have proven that this process allows a great deal of energy to be stored in the granules and the challenge now is to apply the principle on a larger scale. To really achieve a breakthrough, we must accelerate the process and make it more efficient.”

No more energy consumption

If the scientists succeed, treatment plants will no longer need energy to treat wastewater, Ter Heijne predicts. “, killing two birds with one stone.”

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