Researchers Use Microbial Fuel Cells to Generate Electricity from Wastewater

Historically, solar rays dominate the the renewable energy source market. Two researchers, Xueyang Feng and Jason He, from Virginia Tech have developed a new technique to increase the amount of electric current that can be produced from the wastewater.

The research findings have been published in Scientific Reports. The article discusses an emerging sustainability movement to harvest energy from the available waste to introduce more energy-efficient treatment facilities.

The researchers detected the presence of bacteria, which enabled them to further understand that the working relationship between two individual substrates generated an increasing amount of energy than either did separately. This study will solve the puzzle on how energy is produced by electrochemically-active bacteria. It could also help to develop a novel treatment system known as microbial fuel cell.

Tracing the bacteria gave us a major piece of the puzzle to start generating electricity in a sustainable way. This is a step toward the growing trend to make wastewater treatment centers self-sustaining in the energy they use.

Xueyang Feng, Assistant Professor of Biological Systems Engineering, Virginia Tech

Jason He is an associate professor of environmental engineering, while Feng is in the College of Engineering and the College of Agriculture and Life Sciences.

This invention is significant because only very few organics execute the same job in a similar way. Some organics function because they are the main source of food for the electricity-generating bacteria, while others have good energy conducting features.

One substrate called lactate was mostly metabolized by its host bacteria to assist cell growth, and the other substrate called formate was oxidized to emit electrons to increase the generation of electricity.

The researchers discovered that the merging of these two substrates result in energy output that is much higher than when they are operating separately. The organics operate together with fuel cell receptors. Research using microbial fuel cells has been in existence for quite a long time, and this allowed Feng and He to use a unique kind of organics to generate electric current, as they were able to determine the symbiotic nature of two specific organics.

The methodology used by the researchers to detect the metabolic pathways of the varied bacteria strains, called carbon 13 pathway analysis, was considered to be the first time this particular type of isotope labeling process was utilized to estimate metabolism in bacteria. The analysis helps to develop a non-radioactive isotope on a carbon group that can be seen through a mass spectrometry.

Using energy generated from wastewater is a sustainable measure that has already been adopted by urban plants, like the wastewater treatment facilities built in Washington, D.C. Researchers are exploring many other ways to generate energy from waste, besides the ongoing process of using bacteria in microbial fuel cells to harness energy.

Currently, treatment plants are able to obtain methane from the solids present in sewage, permitting towns like Grand Junction, Colorado, to produce energy. Wastewater amounting to 8 million gallons is consumed by the plant, which is the first U.S. city to fuel its fleet of vehicles with energy generated from human waste.

He’s study also deals with gaseous elements, particularly ammonia. Ammonia is considered to be a pollutant in wastewater. Increasing amounts of ammonia released into a watershed can promote the growth of harmful algal blooms, which can destroy aquatic ecosystems.

Mohan Qin, a doctoral student doing his second-year in He’s lab, has constructed a system that helps to recover ammonia and remove other existing contaminants, while simultaneously generating electricity. Qin stated that this is the first time that ammonia-driven forward osmosis has been incorporated with an ammonia-generating microbial electrochemical cell.

The 2015 Innovation Award for Best Technological Advancement from the International Society for Microbial Electrochemistry and Technology was conferred to Qin for his innovative idea. Qin is from Shandong Province, China.

The research findings led to further advancements in microbial fuel cells, particularly system scaling up. Currently, the He lab is operating a 200-L microbial fuel cell system in a neighboring wastewater treatment plant for determining its prolonged performance with actual wastes.

However, He and Feng are not only demonstrating the significance of wastewater, like that of the Sun, but they are also assuring that generating energy from wastewater, whether it is organic waste or ammonia, should become part of a sustainability movement.

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