Raw Power: This Purple Bacteria Turns Sewage Into Clean Energy

Raw Power: This Purple Bacteria Turns Sewage Into Clean Energy

November 16, 2018

Scientists in Spain have discovered a new way to turn human waste into energy. The secret: a purple bacteria that can break it down into hydrogen gas.

Household sewage is swimming with organic compounds that hold potential as sources of energy — but they’re hard to extract. Now, researchers say they’ve found an eco-friendly and cost-effective solution: purple bacteria.

“One of the most important problems of current wastewater treatment plants is high carbon emissions,” says Daniel Puyol of King Juan Carlos University, Spain, co-author of his team’s study appearing in Frontiers In Energy Research. “Our light-based biorefinery process could provide a means to harvest green energy from wastewater, with zero carbon footprint.”

The phototropic bacteria (they can store energy from light) at play here have a unique metabolism: They use organic molecules and nitrogen gas rather than CO2 and H20 to provide carbon, electrons and nitrogen for photosynthesis. “This means that they grow faster than alternative phototrophic bacteria and algae, and can generate hydrogen gas, proteins or a type of biodegradable polyester as byproducts of metabolism,” according to Science Daily.

The team upped the voltage on the purple bacteria by applying an electric current to maximize their rate of synthesis, and minimize the release of C02. “This demonstrates that purple bacteria can be used to recover valuable biofuel from organics typically found in wastewater — malic acid and sodium glutamate — with a low carbon footprint,” said study co-author Abraham Esteve-Núñez of University of Alcalá.