Converting human urine into clean energy: Researchers optimize the process - Energy & Green Tech - Hi Tech & Innovation

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Researchers at McGill University have improved the efficiency of a method for converting human urine into clean energy. The method employs microbial fuel cells (MFCs), which use bacteria to turn organic waste into electricity, providing a sustainable and low-cost means of treating wastewater while generating energy from an abundant source.

The McGill research, published in the journal Results in Chemistry, provides insights into which urine concentrations are optimal for this process. The paper is titled "Investigating microbial interactions in dual chamber microbial fuel cells using a hybrid substrate of synthetic wastewater and human urine."

"While MFCs are known to clean wastewater and generate electricity, the specific effects of different urine concentrations on their electrochemical function, pollutant removal efficiency and microbial community behavior are still not well understood," explained Vijaya Raghavan, study co-author and professor of bioresource engineering.

"This study addresses that gap by systematically examining how varying urine proportions affect the electrochemical and biological performance of MFCs," he said.

Raghavan said the method could be used to generate clean energy in contexts such as rural sanitation, disaster relief camps and off-grid communities. Moreover, because their electrical signals change in response to organic pollution levels, MFCs may also work as low-cost biosensors to monitor wastewater quality without complex equipment.

Higher urine concentrations improve fuel cell performance

The researchers built four dual-chamber microbial fuel cells and fed them with mixtures of synthetic wastewater and human urine at 20%, 50%, and 75% concentrations. They then tested the MFCs over two weeks, monitoring energy output, pollutant removal, and water treatment performance, and conducting electrochemical testing.

They found that higher urine concentrations (50–75%) improved electricity generation, and that urine provides essential nutrients that help microbes grow.

"Urine contains essential ions and organic compounds that support rapid microbial activity, which improves power generation and pollutant breakdown," Raghavan explained.

Although all of the microbial fuel cell systems contained a mix of bacteria, the researchers found that Sediminibacterium and Comamonas were the dominant groups. Sediminibacterium was more common when urine made up 50% of the mixture, while Comamonas became dominant at higher concentrations (75%).

Because microorganisms like these help break down organic pollutants and transfer electrons within fuel cells, changes in which species dominate may help explain differences in how much electricity the systems generate, the researchers suggested. It also shows that the amount of urine added strongly shapes which microorganisms thrive and how effectively the system works, they said.

Raghavan said the findings represent an important step toward a more circular economy.

"Using urine as a resource supports sustainable sanitation and nutrient recovery, reducing pressure on freshwater systems," he said. 

Provided by McGill University   

by McGill University

edited by Sadie Harley, reviewed by Robert Egan 

Source: Converting human urine into clean energy: Researchers optimize the process