Many people consider water conservation important, but the average consumer may not tie their water use to energy consumption or production. Research projects underway in the Midwest aim to purify wastewater while simultaneously generating clean electricity.

The power of bacteria

A researcher at Washington University in St. Louis recently tested a system that filters wastewater while creating electricity. It recovers organic materials in the water that can be fed to bacteria.

“Bacteria love them and can convert them into things we can use,” said Zhen (Jason) He, a professor in the Department of Energy, Environmental & Chemical Engineering, in a news release. “Biogas is the primary source of energy we can recover from wastewater; the other is bioelectricity.”

The system is set up like a microbial fuel cell, a battery that uses electrochemically active bacteria as a catalyst instead of the platinum in traditional fuel cells. A water filtration system is integrated into the microbial electrochemical system. When wastewater is pumped into the cell, bacteria “eat” the organic materials and release electrons, generating electricity. About 80% to 90% of the organic materials get filtered out of the water, making it clean enough to release into the environment or for reuse in non-drinking applications like irrigation and toilet flushing.

Hu’s process is different from other wastewater energy projects because it preserves the water for reuse. Other methods produce energy at the expense of the water. The innovation also can recover nutrients like nitrogen and phosphorus for use as fertilizers.

The process generates enough electricity to help offset the power consumed at a typical water treatment plant. “In the U.S., about 3% to 5% of electricity is used for water and wastewater activity,” Hu said.

Machine learning for innovation optimization

A different water project recently received $2 million from the U.S. Department of Energy to develop an artificial intelligence-assisted system for recovering electricity, nutrients, and filtered water from wastewater. Partners on that team include Argonne National Laboratory, the University of Chicago, Northwestern University, the Great Lakes Water Authority, The Water Council, Current, and others.

The AI and machine learning will assist with optimizing energy and nutrient recovery. The project also involves developing novel materials to efficiently generate solar steam and wireless sensors for real-time water quality monitoring. The innovation will reduce energy consumption and become energy positive when scaled. The concept should be applicable not just to municipal wastewater recovery, but also for other wastewaters such as agricultural and industrial.

This research team intends for the system it creates to benefit underserved communities in Chicago and other cities in the Great Lakes region, such as Detroit and Milwaukee. 

“Water is an indispensable resource of our society, as it is required for sustaining life and economic prosperity,” Junhong Chen, Argonne water strategist and University of Chicago professor, said in a news release. ​“Our future economy and national security greatly depend on the availability of clean water. However, there is a limited supply of renewable freshwater, with no substitute.”