Figuring Fracking

Just when it seemed like clean-water plants had enough challenges, here comes a new one: Dealing with water from natural gas extraction.

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So you’ve completed a plant upgrade. You’ve come into compliance with nitrogen and phosphorus limits — or have plans in place to do so. Now — if you happen to be in one of the nation’s natural gas boom areas — you may face a dilemma on what to do with wastewater from the process known as fracking.

North America is enjoying record high natural gas supplies, and thus record low prices, because of fracking (short for hydraulic fracturing). Here in Wisconsin, we’re not producing gas, but we are seeing an explosion of mining for the sand used in fracking operations in places like North Dakota — and concerns about the environmental effects of these loosely regulated mines have been raised.

In the gas-producing regions themselves, concern is growing over how best to handle fracking wastewater. If your plant is in one of those areas, Treatment Plant Operator would like to hear about your experiences with — and opinions on — the issue of treating this kind of influent. Do you do it? If not, why? If so, how does it affect your plant?

The basics

Fracking is used to extract natural gas from shale formations deep underground. The process involves drilling down, and most often also horizontally, to reach the shale layer. A mix of water, sand and chemicals is then injected at high pressure to fracture the rock and create pathways through which trapped natural gas can escape and be harvested.

As much as four-fifths of the injected water returns to the surface, where it is collected as wastewater. Some gas producers reuse this water. Others inject it into deep storage wells, and still others transport it to municipal wastewater treatment plants. Some plants accept this wastewater, which can contain high levels of pollutants like benzene (a human carcinogen) and barium; others do not.

In an article last spring, Chemical & Engineering News reported on a research study suggesting that treatment plants may not be able to handle this water adequately. The results seemed to indicate that effluent from plants that treat fracking water still contains elevated levels of chemicals from gas production.

The article noted that in May 2011, “the Pennsylvania Department of Environmental Protection (DEP) asked that the state’s treatment plants voluntarily stop processing fracking wastewater. The request came in response to public concern over elevated bromide levels in the Pennsylvania Monongahela River watershed, an area with facilities that treat water from natural gas production.”

Fracking waste has not been definitively cited as the source of the bromide, but there have been limited studies of how such wastewater affects effluent quality.

Looking deeper

The magazine reported that a graduate student and colleagues at the University of Pittsburgh analyzed water from Pennsylvania treatment plants that first took in fracking water and then later stopped, in line with the DEP request. Then they analyzed samples from plants in the state that treated water from the nearby Marcellus Shale region.

The researchers tested for substances that are found in fracking water but don’t normally appear in other industrial wastewater. Generally speaking, they found that levels of fracking contaminants dropped significantly once plants stopped taking fracking water.

“But when the plants still handled the waste, levels of several of the chemicals exceeded drinking water standards set by the U.S. EPA,” the magazine reported. At one plant, barium measured 5.99 mg/L on average (versus an EPA drinking water standard of 2 mg/L) and strontium at 48.3 mg/L (versus 4 mg/L.

Does that indicate a health risk? Not likely, because of course wastewater effluent is not used directly for drinking, and it would be significantly diluted in the receiving stream. But how might those elements affect aquatic ecosystems?

Your perspectives?

That question and others may need answers as fracking proliferates. I’m not in any informed position to weigh in against fracking. Its impacts concern me, but at the same time it’s because of fracking that natural gas for my home and propane for a seasonal cottage cost a lot less than a few years ago.

What are your thoughts — on fracking in general, but more importantly, on how fracking wastewater affects treatment? Send an email to editor@tpomag.com. I promise to respond, and we will report on the submissions in a future issue of the magazine.



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