Researchers at Southwest Research Institute® (SwRI®) and The University of Texas at San Antonio (UTSA) have determined that biochar, a substance produced from plant matter, is a safe, effective and inexpensive method to treat flowback water following hydraulic fracturing, or fracking.
Flowback water treatment is a critical sustainability issue for the oil and gas industry. One to five million gallons of water mixed with sand and chemicals are required for the fracking of each well. Once the water is used, the flowback, or wastewater, must be treated to remove hazardous chemicals before it is stored, reused or disposed, which can be a costly endeavor. Using biochar could help oil and gas companies save money and responsibly treat flowback water for reuse. This is particularly important in areas where water resources are scarce.
UTSA mechanical engineering professor Zhigang Feng, senior research engineer in SwRI’s Chemistry and Chemical Engineering Division Maoqi Feng, and four UTSA students spent the past year creating biochar and testing it on water samples.
A stable charcoal-like solid that attracts and retains water, biochar absorbs impurities such as hydrocarbons, organics, biocides and certain inorganic metal ions. It is made from materials such as wood chips, paper, leaves, soybean oil, corn oil and other forms of agricultural waste heated to high temperatures in an oxygen-deprived environment.
“This project extensively studied the adsorption capacity of different biochar for potential inorganic ions and organic contaminants. The adsorption capacity data is very useful for designing of large scale adsorption beds for flowback water treatment,” SwRI’s Maoqi Feng said.
The research team developed the preparation method, tested the process and collected data that shows the exact type of biochar that filters out the specific chemicals oil and gas companies 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,” UTSA’s 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.”
Currently, biochar is used commercially to improve soil quality by helping soils retain nutrients and water. The research team plans to seek additional research funding as well as partnerships with biochar companies to help make the product marketable to the oil and gas industry.
This research initiative was funded by the Connect program, an annual UTSA-SwRI joint funding initiative established in 2010 to stimulate inter-organizational research between UTSA scholars and SwRI investigators in fields such as advanced materials, chemistry and chemical engineering, energy, the environment, security and manufacturing.
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