Researchers create technique for generating renewable energy from human waste

The scientists, bioelectronics engineers, said they have created a strain of the deadly E-coli bacteria that can generate electricity as the microbe feeds on raw sewage.

The breakthrough could not only revolutionize sustainable energy efforts, but could also transform the more than 640 billion pounds of human waste produced each year into a literal gold mine for utility companies.

Electricity has often been generated from turbines driven by water, as in hydroelectric dams, or turbines driven by heated steam, as in nuclear power and some coal- and natural gas-fired plants.

But this new method, which immerses two electrodes in a stream of contaminated water, uses a new genetically enhanced version of the usual electrochemical activity of E-coli bacteria to generate an electrical current from wastewater to cables.

E-coli is a large and diverse group of bacteria that exists in both human and animal intestines, as well as in nature, where it feeds on decaying organic material.

The news comes amid increasingly surprising innovations in the field of sustainable energy, including CalTech’s MAPLE spacecraft that demonstrated, in a test made public in June, that it could transmit solar energy to Earth from space.

Mohammed Mouhib and Melania Reggente, the lead scientists of the study, posing in their laboratory at the Ecole Polytechnique Federale de Lausanne (EPFL)

The innovation could dramatically reduce carbon dioxide emissions that have warmed the climate from generating electricity from burning oil, coal and natural gas.

Researchers report that their unique bioengineered E-coli were three times better at generating electrical current than typical bacteria.

And unlike previous methods, this new strain could produce electricity by digesting or metabolizing a variety of organic substances, not just human feces.

“Although there are exotic microbes that produce electricity naturally, they can only do so in the presence of specific chemicals,” said Ardemis Boghossian, professor of chemical engineering at the Federal Polytechnic School of Lausanne (EPFL).

Boghossian, one of two EPFL bioelectronics experts who worked on the five-member project, published the results of this E-coli research on Friday in the peer-reviewed scientific journal. Joule.

He noted that the bacteria’s status as “the most studied microbe” is part of what makes these findings so significant.

‘MY. coli can grow in a wide range of sources, which allowed us to produce electricity in a wide range of environments,” Boghossian said, “including from wastewater.”

Boghossian and his team used a process known as extracellular electron transfer (EET) to engineer bacteria into highly efficient electrical microbes.

The researchers hope to see their results adapted to large energy production and waste treatment projects at the municipal level. Above, a common device used to transport human waste to modern sewage systems.

Creating this complete EET pathway within E. coli, a feat they report has eluded others, resulted in a bacteria that produced three times the electrical current generation of conventional strategies for bioelectric bacteria.

The group achieved this trick by integrating components from a type of bacteria famous for generating electricity, Shewanella oneidensis MR-1, with their E-coli.

The result was a microbe with an electrical pathway that spans both the internal and external membranes of each single-celled organism, expanding its electrical production.

“We have set a new record compared to the previous state of the art, which was based only on a partial pathway,” said the study’s lead author, Mohammed Mouhib, a doctoral assistant.

Unlike previous efforts to bioengineer such bacteria, the new E. coli strain proved capable of producing electricity while metabolizing a variety of organic substrates.

When the EPFL team tested their new microbe in brewery wastewater (from Les Brasseurs, a local brewery in Lausanne), the e-microbes thrived where previous strains had failed.

“The exotic electric microbes couldn’t even survive, while our bioengineered electric bacteria were able to thrive exponentially by feeding on this waste,” according to Boghossian.

They hope that their results will extend to large energy production and waste treatment projects at the municipal level.

“Instead of putting energy into the system to process organic waste,” Boghossian said, “we are producing electricity while processing organic waste at the same time, killing two birds with one stone.”

The EPFL team said the implications of their study extend beyond waste treatment.

They believe the engineered E-coli could help power microbial fuel cells and operate special biosensors.

“Our work is quite timely, as engineered bioelectric microbes are pushing the boundaries in more and more real-world applications,” Mouhib said.

He expressed hope that progress in this area would be more regular.

“With all the current research efforts in this field, we are excited about the future of bioelectric bacteria,” Mouhib said, “and we can’t wait for us and others to take this technology to new scales.”