A joint, $200,000 investment is being made by the organizations in the exploration of biochar for treating hydraulic fracturing flowback. Initial testing will be conducted on Eagle Ford Shale water samples.
Zhi-Gang Feng, assistant professor, mechanical engineering at the university, and Maoqi Feng, senior research scientist, are certain biochar derived from wood chips will prove an economical and environmentally friendly solution for these types of wastewaters, according to the San Antonio Business Journal.
Biochar is a solid material obtained from the carbonisation of biomass. […] This 2,000 year-old practice converts agricultural waste into a soil enhancer that can hold carbon, boost food security and discourage deforestation. The process creates a fine-grained, highly porous charcoal that helps soils retain nutrients and water. […] Biochar also improves water quality and quantity by increasing soil retention of nutrients and agrochemicals for plant and crop utilization. More nutrients stay in the soil instead of leaching into groundwater and causing pollution.
Although activated carbon is ideal for removing contaminants from water, notes the organization, it is costly to make and requires a large infrastructure investment. Various research continues into making biochar using traditional kilns as well as gasifer stoves able to reach temperatures between 650°C and 950°C to remove any naturally occurring tars and oils from the biomass.
Biochar is able to absorb chemical compounds including hydrocarbons, organics, and some inorganic metal ions.
During the yearlong research project, the researchers will prepare the appropriate biochar; test it on flowback water samples; and develop computer models of a possible biochar water treatment system as well as identify possible performance improvements.
Hydraulic fracturing, or fracking, is the process of extracting natural gas from shale formations that relies almost exclusively on water. The chemical mix — called flowback — that emerges at the well head is separated into gas and water. This water, which contains salt and other minerals picked up while coursing through the shale, is held for recycling. Some of these minerals, which might include barium, are naturally toxic and possibly radioactive substances. The water also still contains the frack water chemicals.
The handling of fracking wastewater continues to be a topic of debate among politicians at all levels of American government as natural gas drilling has boomed throughout the nation.
Drillers operating in the state of Texas have reportedly typically balked at reusing water, claiming using recycled and/or brackish water is not cost-effective. A handful of companies in the state are drilling without water. One reportedly uses propane for drilling.
This biochar treatment process, if successful, would be the second step in a two-step water purification process, say the Texas researchers. The first step is expected to consist of filtration to remove any solids before additional treatment. Once the process is complete, the water is expected to be reused or safe for disposal.
The research is being conducted through the Connect Program, a jointly funded program of UTSA and the Southwest Research Institute, an independent, nonprofit, applied research and development organization based in San Antonio. The program, which started in 2010, is undertaking research in disciplines including chemistry and chemical engineering, the environment, security, and manufacturing.
Image by The University of Texas at San Antonio.