Johannesburg - Treating wastewater from fracking could be vastly more complex than any water treatment South Africa mining has faced before, including acid mine drainage.
On Wednesday, the peer-reviewed journal Environmental Science & Technology published a study which found elevated levels of radioactivity, salts and metals at a site in the US where treated fracking water is released.
Hydraulic fracturing, or fracking, involves pumping high-pressure liquid into shale rock to crack it and release the natural gas within.
In the fracking process, about 50 percent of the water used stays underground, and is believed to be contained below the water table. However, the other half flows back up to ground level and must be disposed of.
Water specialist Carin Bosman said storing the water, rather then treating and releasing it, was not practical. She said coal mine wastewater was simple to treat in comparison to treating shale gas wastewater.
“It’s complex because you are not only putting in chemicals, you also dealing with the substances in the host rock.”
Some of the substances in the underground rocks can leech into the water during the fracking process. Bosman said because of South Africa’s unique geology, we could be dealing with contaminants in wastewater that have not been encountered in overseas shale gas recovery.
Researchers in the US found radium levels to be 200 times higher downstream from the treatment facility in Pennsylvania.
Dr Nathaniel Warner, one of the study’s authors, said that despite treatment removing some of the salts in the water, there could be a long-term legacy of radioactivity.
At some sites in the US, shale gas wastewater is injected into deep wells, but wastewater is frequently still discharged into the environment.
“It is clear that this practice of releasing wastewater without adequate treatment should be stopped in order to protect freshwater resources in areas of oil and gas development,” said Avner Vengosh, professor of geochemistry and water quality at Duke University’s Nicholas School of the Environment.
A report last year by the Water Research Commission warned of the dangers of cancer-causing chemicals used in the process.
Stellenbosch University’s Central Analytical Facilities has been analysing the water quality at sites across regions where fracking is proposed to have a baseline of water quality. - The Star