Virginia Tech Invents Energy-Generating Ammonia Removal Technology

Researchers at Virginia Tech have developed a bacterial “battery,” that may offer both energy generation and ammonia removal and recovery to wastewater treatment facilities.

By combining a microbial electrochemical cell and a forward osmosis cell, a team of engineers, led by Virginia Tech doctoral student Mohan Qin, created a hybrid biological and electrochemical system, reports science news website Engineering.com.

The technology, according to Engineering.com, consists of a “microbial electrochemical cell which allows bacteria to conduct electron-shuttling chemical reactions, while the forward osmosis cell uses a highly concentrated mixture to pull clean water through a membrane to remove impurities.”

The microbial electrochemical cell, which Qin has coined a “bacterial battery,” harvests the microbial electrochemical reactions that naturally occur as the bacteria in the wastewater metabolizes. This electricity drives ammonium ions present in the wastewater to the other side of the cell, creating an ammonia-rich solution, according to Phys.org.

Energy that is pulled from the cell can be stored or can be moved to the electrical grid. The ammonia that is removed could potentially be sold for commercial-use as ammonia-based fertilizer, providing a source of income for the wastewater treatment plant.

Additional processes will still be required to remove the ammonia from the nitrogen completely. However, this technology is an energy efficient way to both clean wastewater and produce ammonia from nitrogen gas, a process that currently uses up 1 percent of the world’s electricity. By removing a significant portion of ammonia from the wastewater, this technology may also play a role in protecting aquatic ecosystems from algae blooms.

"We use so much energy to convert nitrogen gas into fertilizer, and then in wastewater treatment we consume a lot of energy to convert ammonia into nitrogen gas," said Jason He in an article for Phys.org. He, an associate professor of civil and environmental engineering in the College of Engineering, runs the lab where Qin created the technology. “A system that recovered the ammonia for later use, instead of just removing it, would be of great interest to sustainable wastewater treatment.”

Quin received the 2015 Innovation Award for Best Technological Advancement from the International Society for Microbial Electrochemistry and Technology for her invention. She is currently working to determine how to improve the performance of the technology using computer modeling studies. He is working with local water treatment plants to establish a research facility and build a pilot-scale model of the combined microbial electrochemical and forward osmosis cells.

“It's really hard to study a large-scale system in the lab,” He said. “You can build it, but you can't run it: there’s no wastewater. You need a place that can continuously supply wastewater.”