Purifying fracking water with bacteria
Together, BTI researchers Alptekin Aksan, associate professor of mechanical engineering, and Larry Wackett, a professor of biochemistry, molecular biology, and biophysics in the College of Biological Sciences, are developing a cutting-edge process that harnesses natural bacteria to purify water contaminated by hydrofracking.
Wackett specializes in biodegradation and bioremediation. He explores natural systems that can be employed to clean up waste products. Aksan specializes in biostabilization. He studies methods of preserving proteins, living cells, and tissues through processes such as cooling, drying, and the development of synthetic organic biomaterial devices.
“We want to take advantage of the natural ability of bacteria to eat these compounds by adding an engineering component.”
Aksan and Wackett began their collaboration more than two years ago over lunch one day. They discussed possible connections between their different areas of research, which led to the realization that Wackett’s expertise in biodegradation could be combined with Aksan’s in biostabilization.
The water used in hydrofracking is polluted with some 1,500 hydrocarbons. Currently, the only ways to treat this wastewater are to condense and landfill the hazardous waste or to inject the contaminated water deep underground. Wackett says naturally occurring bacteria could be used to chew up the chemicals— the same bacteria that helped clean up the oil spilled in the Deepwater Horizon disaster of 2010.
“Some of the same oily chemicals come up when water is used to release oil and gas in hydrofracking. We want to take advantage of the natural ability of bacteria to eat these compounds by adding an engineering component,” Wackett said.
The problem is that you can’t just dump the bacteria and fouled water together and hope for the best. The bacteria may not survive, they can’t be recaptured, and the water itself dilutes the bacteria so that they can’t efficiently clean up the hydrocarbons.
That’s where Aksan’s part of the collaboration comes in. Aksan has developed a process called bioencapsulation that captures the tiny oil-munching bacteria within a sponge made of silica, the same material that makes up sand. This sponge is essential to gaining control of the cleaning process.
Degrading the 1,500 types of contaminants that occur in hydrofracking water requires a combination of different types of bacteria. The complex interaction of contaminants and bacteria presents numerous bioengineering problems, but the silica sponge or matrix can act as a controlled filter. The bacteria are trapped within spaces in the sponge that are just large enough for the cells to move around without escaping. They break down the contaminants into safe byproducts. Aksan has already applied the process to clean up herbicide and pesticide contamination using genetically modified E. coli bacteria.
Though the project has been successful in the lab, work remains to scale it up for commercial application. The filtering system must be robust, economical, transportable, temperature-tolerant, and tolerant of human error. Wackett envisions other applications of the same process, such as an absorbent material filled with bacteria that could be spread over chemical spill sites.
“Currently, we have to scrape up contaminated soil and put it in a hazardous waste landfill. If this substance could be used to absorb and degrade the pollutants, we could simply spread it on the spill,” he said. “After the material had consumed the toxins, it would break down naturally and become part of the soil, which is our goal.”