Purple Bacteria Turn Human Waste Into Clean Energy, Minimizing Carbon Footprint

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Organic compounds that are in the household sewage are rich in potential source of energy, proteins for animal feed and bioplastics as well.

\On the other hand, without an efficient extraction method, treatment plants discard these as contaminants.

But, researchers managed to find an environmentally-friendly and cost-effective solution.

The study is published in Frontiers in Energy Research, and this is the first study to show that purple phototrophic bacteria storing energy from light, when getting electric current, can recover near 100% of the carbon from any organic waste.

It’s also important that, at the same time, the bacteria will generate hydrogen for electricity production.

“One of the most important problems of current wastewater treatment plants is high carbon emissions,” says co-author Dr. Daniel Puyol.

“Our light-based biorefinery process could provide a means to harvest green energy from wastewater, with zero carbon footprint.”

Purple bacteria capture energy from sunlight using a variety of pigments which turn the shades of orange, red and brown and also purple.

“Purple phototrophic bacteria make an ideal tool for resource recovery from organic waste,” Puyol explained.

The bacteria can use the organic molecules and nitrogen gas in order to provide carbon, electrons, and nitrogen for photosynthesis.

In other words, they grow faster than alternative phototrophic bacteria and algae, and they can also generate hydrogen gas, proteins, and biodegradable polyester as byproducts of metabolism.

The best conditions for maximizing hydrogen production

The most recent study analyzed the optimum conditions for maximizing hydrogen production by a mixture of phototrophic bacteria species. They also made sure to test the effect of a negative current on the metabolic behavior of the bacteria.

Their main exciting result showed that the nutrient blend cut the production of CO2.

“This demonstrates that purple bacteria can be used to recover valuable biofuel from organics typically found in wastewater with a low carbon footprint,” according to the study.

By capturing excess CO2 produced by purple bacteria, there will be benefits which include reduced carbon emissions and also refining biogas from organic waste for use as fuel.