Image: University illustration / Michael Osadciw

Many researchers agree that microbial fuel cells have a range of promising applications. However, before they can reach widespread applications, researchers need to make them both cheaper and more efficient.

A team of researchers from the University of Rochester believe they’re making progress on that front with the development of a paper electrode.

Microbial fuel cells drive electric current by using bacteria and mirroring bacterial interactions found in nature. In the 21st century, microbial fuel cells found new application in their ability to treat wastewater and harvest energy through anaerobic digestion.

This from University of Rochester:

Until now, most electrodes used in wastewater have consisted of metal (which rapidly corrodes) or carbon felt. While the latter is the less expensive alternative, carbon felt is porous and prone to clogging. Their solution was to replace the carbon felt with paper coated with carbon paste, which is a simple mixture of graphite and mineral oil. The carbon paste-paper electrode is not only cost-effective and easy to prepare; it also outperforms carbon felt.

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By: Mathew Wallenstein, Colorado State University

Walk into your typical U.S. or U.K. grocery store and feast your eyes on an amazing bounty of fresh and processed foods. In most industrialized countries, it’s hard to imagine that food production is one of the greatest challenges we will face in the coming decades.

By the year 2050, the human population is projected to grow from 7.5 billion to nearly 10 billion. To feed them, we will need to almost double food production within just three decades, all in the face of increasing drought, herbicide and pesticide resistance, and in a world where the best cropland is already being farmed.

From the 1960s through the 1980s, international initiatives referred to collectively as the Green Revolution dramatically increased food production, largely by breeding crop varieties that were able to take advantage of man-made fertilizer and developing powerful pesticides and herbicides. But as we intensified agriculture, we also intensified its environmental impacts. They include soil erosion, reduced biodiversity and the release of greenhouse gases that drive climate change.

Today our ability to continuously push these systems to produce more crops year after year has largely stagnated, and is not keeping pace with rising demand. Clearly, new innovations are needed to change the way we grow food and make it more sustainable.

I am part of a new crop of scientists who are harnessing the power of natural microbes to improve agriculture. In recent years, genomic technology has rapidly advanced our understanding of the microbes that live on virtually every surface on Earth, including our own bodies. Just as our new understanding of the human microbiome is revolutionizing medicine and spawning a new probiotic industry, agriculture may be poised for a similar revolution.

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A new study led by ECS member Haluk Beyenal reveals a novel type of cooperative photosynthesis with potential applications in waste treatment and bioenergy production.

The research details a unique metabolic process observed for the first time in a pair of bacteria, which could be used to engineer microbial communities. Beyenal and his team honed in on a bacterium known as Prosthecochloris aestaurii, which is able to photosynthesize by using sunlight and elemental sulfur or hydrogen sulfide.

This from Washington State University:

The researchers noticed that P. aestuarii tended to gather around a carbon electrode, an electricity conductor that they were operating in Hot Lake. The researchers isolated and grew P. aestuarii and determined that, similar to the way half of a battery works, the bacterium is able to grab electrons from a solid electrode and use them for photosynthesis. The pink-colored Geobacter sulfurreducens meanwhile, is known for its ability to convert waste organic matter to electricity in microbial fuel cells. The bacterium is also used in environmental cleanup.

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A new study published by researchers from Michigan State University reveals a new biofilm that can feed on waste and produce energy as a byproduct.

The novel biofilm was discovered and patented by ECS member and Science for Solving Society’s Problems grantee Gemma Reguera.

(MORE: Listen to our Science for Solving Society’s Problems Round Table podcast to hear how Reguera is applying microbial science to solving pressing issues in water and sanitation.)

Reguera’s biofilm works in a way very similar to the electric grid, where each cell acts as an individual power plant – generating electricity to be delivered to the underlying electrodes using a sophisticated microbial network. One part of that network, the cytochromes, act as transformers and towers that supply electricity to a city. The other part, the pili, acts as the powerlines connecting the towers so all have access to the grid.

“The pili do all of the work after the first 10 layers, and allow the cells to continue to grow on the electrode, sometimes beyond 200 cell layers, while generating electricity,” Reguera says, associate professor of microbiology at Michigan State University. “This is the first study to show how electrons can travel such long distances across thick biofilms; the pili are truly like powerlines, at the nanoscale.”

Each individual part of the biofilm is essential to the development of the working whole, much like the power grid.

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The cleaning of industrial wastewater is a persistent issue across the globe. If left untreated, these harmful waters could enter open watercourses, dispersing contaminants such as mercury and lead. Not only is this an immediate health risk, but it also threatens the entire ecosystem.

Modern wastewater treatment plants have been able to treat the water, but have not been very environmentally conscious. The typical plant produces CO₂ by burning fossil fuels for power and the general decomposition of the materials in the wastewater. Not to mention, these things require a lot of power. About 12 trillion gallons of wastewater gets treated each year in the United States along, consuming an alarmingly high 3 percent of the nation’s energy grid.

Researchers have already produced power from pee and made poop potable; so why not develop a new type of wastewater treatment device that significantly lessens the severity of CO₂ emissions and simultaneously captures greenhouse gases?

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