There is growing concern regarding the threat that fracking fluids pose to drinking water sources, especially groundwater sources in aquifers deep below the surface. A recent study highlights a new threat to our drinking water, that of treated fracking wastewater that still may be contaminated. The study, published in the American Chemistry Society's journal Environmental Science & Technology, shows that discharging fracking wastewater into rivers, even after being treated at a wastewater treatment facility, could be contaminating the water, posing a risk to inhabitants of cities further downstream that are dependent on these rivers for their drinking water supply.
The researchers note that hydraulic fracturing by its very nature, is a process that utilizes vast quantities of water mixed with a variety of chemicals, which is injected underground under pressure to force out the oil and gas held within. The disposal of millions of gallons of this tainted wastewater presents a major challenge to oil companies that utilize this technique.
Treatment of Fracking Wastewater
Fracking wastewater contains high concentrations of heavy metals and halide salts, and it is also highly radioactive. As a result it poses a threat to drinking water supplies unless adequately treated. Consequently, fracking wastewater is often treated in commercial or municipal treatment plants before being released into rivers or surface water systems. However, these treatment facilities do not adequately remove halides (such as bromide, chloride and iodide), raising fears that halide-contaminated water can produce toxic byproducts when it is treated with conventional water treatment methods used to treat drinking water supplies. So the research team set about finding out whether these fears are well founded to ascertain whether or not there is indeed cause for concern.
Wastewater Treatment Study
The scientists diluted samples of river water where fracking wastewater is discharged from fracking operations in Arkansas and Pennsylvania, simulating environmental conditions experienced as wastewater enters the environment. Then, in the laboratory, they treated the water samples with conventional water treatment methods used to disinfect drinking water. They discovered that even at extremely low concentrations per volume of fracking wastewater, a number of toxic byproducts were produced.
Based on these findings, the scientists recommend that either current fracking wastewater treatment methods should be updated to include the removal of halides, or fracking wastewater should not be discharged into rivers and other surface water systems at all.
Up until now, there has been grave concern regarding contamination of drinking water wells situated near sites where fracking is occurring, but according to this latest study, the implications could be more widespread, affecting the drinking water of those downstream from fracking wastewater discharge sites -- including discharge sites of treated wastewater -- as well.
Kimberly M. Parker, Teng Zeng, Jennifer Harkness, Avner Vengosh, William A. Mitch. Enhanced Formation of Disinfection Byproducts in Shale Gas Wastewater-Impacted Drinking Water Supplies. Environmental Science & Technology, 2014; 140924125647003 DOI: 10.1021/es5028184