Researchers simplify oil and gas wastewater treatment

Engineers at the University of Colorado Boulder have invented a process that they claim simplifies the treatment of oil and gas wastewater by simultaneously removing salts and organic contaminants while producing energy.

The Colarado researchers have published a technique that uses a microbe-powered battery. “The beauty of the technology is that it tackles two different problems in one single system,” said University of Colorado Boulder associate professor of environmental and sustainability engineering and senior author of the paper Zhiyong Jason Ren. “The problems become mutually beneficial in our system–they complement each other–and the process produces energy rather than just consumes it.”

The new technology – microbial capacitive desalination – exploits the energy-rich hydrocarbons in the wastewater by deploying microbes that consume them and release their energy. The energy is used to create a positively charged electrode on one side of a cell and a negatively charged electrode on the other, essentially setting up a battery.

Lead author of the paper, Casey Forrestal, who is working to commercialize the technology said: “We use microbes to generate an electrical current that can then be used for desalination.”
Ren added: “Right now oil and gas companies have to spend energy to treat the wastewater. We are able to treat it without energy consumption; rather we extract energy out of it.”

Oil and gas operations in the US produce about 3.3 million Ml of wastewater a year. Its high salinity and organic contaminants make treatment difficult and expensive using conventional techniques. Some oil and gas wastewater is currently being treated and reused in the field, but that treatment process typically requires multiple steps and energy from diesel generators.

Because of the difficulty and expense, wastewater is often disposed of by injecting it deep underground. The need to dispose of wastewater has grown in recent years with the the production of shale gas and oil using hydraulic fracturing, or “fracking”. Injection wells that handle wastewater from fracking operations can cause earthquakes in the region, according to research by University of Colorado Boulder scientists and others.

The demand for water for fracking operations also has caused concern especially in arid regions of the US. Water for fracking operations in the West, for example, has become increasingly expensive for oil and gas companies.

To try to turn the technology into a commercial reality, Ren and Forrestal have co-founded a startup company called BioElectric Inc.