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Although some organic compounds in domestic wastewater and industrial wastewater can be used as a source of energy, there was no effective extraction method to exploit their potential. But now researchers may have identified a cost-effective solution that could turn wastewater into electricity.
Dr. Daniel Puyol of King Juan Carlos University in Spain is one of the co-authors of the study.
"One of the most important problems of today's wastewater treatment plants is the high level of carbon emissions," Dr. Puyol said. "Our light-based biorefinery process could provide a way to harvest green energy from wastewater without a carbon footprint."
This study is the first to demonstrate that, when they are simply fed with electric current, purple phototrophic bacteria can recover nearly 100% of the carbon from any type of organic waste while generating hydrogen gas for the production of electricity.
Purple phototrophic bacteria capture the energy of sunlight by using a variety of pigments that give them orange, red, brown or purple hues. Scientists, however, are more interested in the versatility of their metabolism.
"Phototrophic purple bacteria are an ideal tool for recovering organic waste resources, thanks to their highly diversified metabolism," said Dr. Puyol.
Bacteria can use organic molecules and nitrogen, rather than carbon dioxide and water, to provide the carbon, electrons and nitrogen necessary for photosynthesis. This means that they can generate hydrogen gas, protein or a biodegradable type of polyester as a byproduct of metabolism.
The research team analyzed the best conditions to maximize the production of hydrogen by a mixture of species of purple phototrophic bacteria. They also tested the effect of a negative current on the metabolic behavior of the bacteria.
First, the experts found that the nutrient mix that produced the highest hydrogen production rate also minimized CO2 production.
"This demonstrates that purple bacteria can be used to recover valuable biofuel from organic materials commonly found in wastewater – malic acid and sodium glutamate – with a low carbon footprint," said the professor. Abraham Esteve-Núñez, co-author of the study.
The researchers also discovered that purple bacteria are able to use electrons from a negative electrode or a "cathode" to capture carbon dioxide through photosynthesis.
"The recordings of our bioelectrochemical system showed a clear interaction between the violet bacterium and the electrodes: the negative polarization of the electrode resulted in detectable electron consumption, coupled with a reduction in the production of carbon dioxide. carbon."
"This indicates that the purple bacteria used electrons from the cathode to capture more carbon from organic compounds via photosynthesis, so less CO2 is released."
Capturing the excess CO2 produced by purple bacteria would be useful for reducing carbon emissions or for refining biogas from organic waste and using it as fuel. According to Dr. Puyol, however, the main goal of the research remains to come.
"One of the initial objectives of the study was to increase biohydrogen production by donating electrons from the cathode to the metabolism of the purple bacterium. However, it seems that PPB bacteria prefer to use these electrons to fix CO2 instead of creating H2. "
"We have recently secured funding to pursue this goal through further research, and we will be working on it over the next few years. Stay tuned for more metabolic agreement. "
The study is published in the journal Frontiers in Energy Research.
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By Chrissy Sexton, editor of Earth.com
The original article can be found by clicking here
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