Biochar, an agricultural waste product that attracts and retains water, may be a safe and inexpensive way to treat flowback water from hydraulic fracturing (fracking), according to Texas researchers.
Independent testing laboratory Southwest Research Institute (SwRI) and the University of Texas at San Antonio (UTSA) collaborated on creating a specific type of biochar for the oilfield and found what may be an effective alternative for oil and gas companies to treat wastewater for reuse.
"This project extensively studied the adsorption capacity of different biochar for potential inorganic ions and organic contaminants," said SwRI engineer Maoqi Feng. "The adsorption capacity data is very useful for designing of large-scale adsorption beds for flowback water treatment."
Researchers led by Feng, UTSA professor Zhigang Feng and four UTSA students spent the past year creating biochar for flowback tests and using it in water samples. The biochar was created from materials such as wood chips, paper, leaves, soybean oil, corn oil and other types of agricultural waste that were heated to high temperatures in an oxygen-deprived environment. The biochar then was able to absorb impurities such as hydrocarbons, organics, biocides and certain inorganic metal ions.
The team compiled a preparation method, test process and data collection system for an exact type of biochar to filter out specific chemicals that oil and gas companies typically add to the water during the fracking process. Those chemicals, such as calcium chloride and magnesium chloride, are listed by the U.S. Environmental Protection Agency as being harmful to the environment.
"There are many variables that go into making different types of biochar to filter certain chemicals, including the material composition of the biochar and to what temperature it's heated," Zhigang Feng said. "Our research demonstrates that this is a product that can reduce the environmental impact of drilling in a way that is safe and inexpensive to industry."
Some types of biochar now are used commercially to improve soil quality by helping retain nutrients and water. The SwRI/UTSA scientists now plan to seek additional research funding and partnerships with biochar companies to commercialize the product’s use in the oil and gas industry.