Wastewater from industrial processes can be purified using bacteria in a way that also generates electricity, Norwegian researchers said last week.

Research organization SINTEF reported that Luis Cesar Colmenares and Roman Netzer had succeeded in getting bacteria to power a biological fuel cell, using wastewater as the fuel. The products of the process are pure water droplets and electricity.

"In simple terms, this type of fuel cell works because the bacteria consume the waste materials found in the water," Colmenares explained. "As they eat, the bacteria produce electrons and protons. The voltage that arises between these particles generates energy that we can exploit. Since the waste in the wastewater (organic material) is consumed and thus removed, the water itself becomes purified."

At the moment the energy generation process works on a small scale, but in the future the researchers hope it could be used to power the water purification process, which typically consists of several stages, including mechanical and energy-demanding decontamination steps at the start.

"Systems that we might compare ours with are usually much more complex," Netzer commented. "But for our wastewater, we've found a solution that makes it possible to utilize two types of bacteria. In combination, they accelerate biological energy production because the waste products of the first provide food for the second — while both produce electricity at the same time. It's important to remember that this all happens in a closed system — the process is anaerobic."

The absence of air means that as they consume the waste, the bacteria are forced to transfer the electrons they produce to an electrode, SINTEF said.

A similar technique can also be used to produce hydrogen.