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Sewage Plants Struggle To Treat Wastewater Produced By Fracking Operations

Environment: Water used in natural gas production may still contain high levels of contaminants, even after going through wastewater treatment plants

by Leigh Krietsch Boerner
March 18, 2013

Credit: Kyle Ferrar
Treated wastewater flows out of a sewage plant in Pennsylvania. Facilities like this one sometimes treat water produced during natural gas production.
Credit: Kyle Ferrar
Treated wastewater flows out of a sewage plant in Pennsylvania. Facilities like this one sometimes treat water produced during natural gas production.

When energy companies extract natural gas trapped deep underground, they’re left with water containing high levels of pollutants, including benzene and barium. Sometimes the gas producers dispose of this contaminated water by sending it to wastewater treatment plants that deal with sewage and water from other industrial sources. But a new study suggests that the plants can’t handle this water’s high levels of contaminants: Water flowing out of the plants into the environment still has elevated levels of the chemicals from natural gas production (Environ. Sci. Technol., DOI: 10.1021/es301411q).

In 2010, about 23% of U.S. natural gas production involved a process called hydraulic fracturing or fracking. Workers inject high volumes of water at high pressures into the ground to break shale rock formations and to release trapped natural gas. Up to 80% of that injected water returns to the surface, where it’s collected as wastewater.

Currently, companies deal with this leftover water by reusing it, injecting it into deep storage wells, or sending it through sewage treatment plants.

However, in May, 2011, the Pennsylvania Department of Environmental Protection 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. Scientists hadn’t definitively pinpointed fracking waste as the source of this pollution. In general, researchers haven’t studied how fracking wastewater affects the quality of water leaving sewage plants.

To learn more, Kyle J. Ferrar, a graduate student at the University of Pittsburgh, and his colleagues analyzed water from treatment facilities that initially processed fracking water and then later complied with the state’s recommendation. They took water samples from one private and two public facilities in Pennsylvania that treated water from the nearby Marcellus Shale region, the largest shale basin in the U.S. They collected samples both before and after the department’s request.

Using a variety of spectroscopic techniques, the team measured levels of chemicals found in gas production waste but aren’t typically present in other industrial wastewaters. Although levels of these chemicals varied widely among the three treatment plants, in general, concentrations dropped significantly after the plants stopped taking the fracking waste, Ferrar says. For example, at a municipal plant in Greene County, average barium concentrations fell from 5.99 to 0.14 mg/L.

But when the plants still handled the waste, levels of several of the chemicals exceeded drinking water standards set by the U.S. Environmental Protection Agency. At the Greene County plant, the levels of barium and strontium, two toxic metals found in fracking wastewater, were on average 5.99 and 48.3 mg/L, respectively. EPA drinking water standards for these metals are 2 and 4 mg/L, respectively.

Carl Kirby, a professor of geology at Bucknell University who studies the environmental impact of Marcellus Shale gas production, says the human health impact of elevated contaminant levels from processed fracking water is unclear, because the water the team sampled is not used directly as drinking water. However, he points out that fracking contaminants eventually could reach larger water systems used for drinking water, albeit at significantly diluted levels.

Ferrar agrees that there is no immediate public health concern over the pollutant levels. But he does worry about how the elevated levels affect aquatic ecosystems receiving water from treatment plants. He hopes researchers will study further the impact of disposing of produced waters via wastewater treatment plants.



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CisT (March 18, 2013 7:02 PM)
Those are rather high levels for strontium and barium. In fact, for strontium, yikes!
Mary (May 3, 2013 11:57 AM)
Has cyanide been found in the treated wate water?
BMC (March 19, 2013 1:53 PM)
Why are the taxpayers paying to clean up their mess? These companies should be held accountable for their polluted runoff; it should not fall on the state wastewater treatment plants to clean.
Skoot Kanute (March 19, 2013 4:12 PM)
The companies should pay the majority of costs to clean this up, but users of the gas (including consumers) should not be let off the hook entirely.
wally12 (March 19, 2013 4:43 PM)
The tax payers are not paying for the treatment of industrial wastes. The company that owned the waste pays for it. In many of these treatment facilities the cost is based of X dollars per gallon of waste and there may be added charges if the waste needs additional treatment such as neutralization etc. However, If the waste treatment plants can't achieve the level of cleanliness required, the EPA is the agency usually instructs and/or demands that the company who produced the waste use a different treatment process/facility.
Kyle M (March 19, 2013 5:05 PM)
I would imagine the fracking companies set up contracts with the waste treatment facilities (those of which specifically treat industrial waste), and pay to have that waste treated. I guess you can say that tax payers are paying for part of it because like some industrial companies, these gas producers might be receiving some sort of government subsidy. However, it is not the tax payer paying wholly for cleaning the water.
Urrrbal (March 19, 2013 10:59 PM)
The taxpayers don't pay for it. The utilities charge the fracking companies to treat the wastewater for a profit, so it actually saves taxpayers money.
Rick January (March 20, 2013 8:03 AM)
This seems to follow the historical pattern of industry to create an environmental mess and then leave it for the public to clean up. Fracking should not be allowed until its risks are studied and proper handling methods developed - paid for by those who reap the economic benefit.
KoolThink (March 20, 2013 3:29 PM)
Treatment plants probably don't take wastewater without charging a fee, whether it is residential, industrial, or fracking. Fees paid by industrial wastewater sources (likely fracking too) often subsidize the cost of plants to hand residential sources; not the other way around. Plant operators might consider the fracking water a boon to their financial bottom line. The article doesn't state whether discharge limits were exceeded. Apparently not, since PA asked them to voluntarily stop taking the waste. If the concentrations are so bad, then their discharge permits ought to be changed.
Xlinkr (March 20, 2013 4:03 PM)
The generators of waste water pay the treatment plants according to the quantity of waste being treated. The treatment plants may need to enhance their treatment process and charge the fracking generators the cost of the upgrades.
Steven Hanifl (March 19, 2013 5:13 PM)
What price energy independence? Can't win on this one, may as well start building out what is left of our bus and train system, guaranteed to have the fracking industry closed down if they keep this up... where the heck is this strontium coming from in the first place???
Marian Smith (March 20, 2013 10:30 PM)
The water that flows back from the fracking goes through radioactive shales thus picking up the strontium. Thus frac water should be disposed of in saltwaterdisposal wells.

For more information read
Michael (March 22, 2013 2:15 PM)
Marian, it seem prudent it indicate the your link is for investment information. You fail to point out that if the HVHF activities in Michigan expand to the level of Penn., the resultant volume of flowback water could be on the order of several billion gallons. At ~9,900 gallons per tanker to haul the material, we would see an additional ~120,000 to 1.2 million tanker load in Michigan alone. All assuming single well stimulations, a poor assumption based on current practices.

--3,000 wells @ 8,000,000 gallons per well = 2.4x10^10 gallons (assumes single HVHF stimulation, conference proceedings indicated up to 18 stimulation can be completed)

a) 5% flowback (lower range)= 1.2x10^9 gallons/9,900 tankers = 121,000 loads
b) 13% flowback (Excelsior 1-25 HD1) = 3.1x10^10 gallons/9,900 tankers = 315,000 loads
c)50% flowback (upper range) = 1.2x10^10 gallons/9,900 tankers = 1,200,000 loads

Seems to be an excellent investment opportunity but not so wonderful for the communities around the 1,460 aging class II disposal wells here in Michigan. This also discounts that this water is no longer a component of our hydrologic cycle.

If the multiple well stimulations were taken to current end ranges, the total water needs could reach 4.3x10^11 gallons of water or 5.6 billion gallons of flowback (13%). The water use would be equivalent to 78 years of water for the City of Ann Arbor at the current municipal use rate of 15 MGD per day.
Not fooled (March 19, 2013 6:28 PM)
Clearly the public waste water treatment plant is not capable of removing adequate Barium and Strontium. This is not representative of all waste water treatment plants but simply means a different process is required.

Also I wouldn't trust the validity or Independence of such results from a biased researcher.
Thinking For Myself (March 19, 2013 7:15 PM)
Matthew Trevett (March 19, 2013 8:51 PM)
Sewer districts require pretreatment of industrial wastes per the National Pretreatment Act. It is illegal to discharge "non-compatible wastes" which include any material which may pass through the treatment plant and be discharged into the receiving water causing environmental damage. Typical non-compatible wastes include heavy metals, cyanide, pesticides, herbicides, and other toxic organic compounds. Most municipal agencies have a division specifically dealing with Industrial Discharge/Pretreatment or a Source Control group.
Terry (March 19, 2013 11:00 PM)
A clear case of cost shifting from miners to the public taxpayer. Fracking is only economic if true environmental cost is not paid by the miner or the user of the gas. The miner needs to be responsible for all costs of extraction including current pollution and future environmental damage.
Bob (March 20, 2013 3:13 AM)
Another reason companies say the chemicals they use are proprietary. If nobody knows what you use, it is hard to prove that you are the source of contamination.
Marian Smith (March 20, 2013 10:28 AM)
Flow-back water from the fracking industry needs to be injected into salt water disposal wells where it flows into a permeable reservoir and is dissipated at depths that pose no problem to drinking water aquifers.

Water is contaminated with chemicals before it goes into the ground as frac fluids and as it returns to the surface it picks up more contamination from the shale including radioactivity. Flow-back water has no business in municipal water treatment plants as the outflow cannot be made safe by such methods. Deep salt water disposal, done at a rate that does not stimulate earthquakes is the way to go.
Poss (March 20, 2013 11:00 AM)
Majority of wells ever drilled in the world use barite (barium sulfate) as a weighting material. After the well is drilled is when then they begin to frac. Wouldn't there be residual barium (or strontium, since it occurs as a residual component in barite)in some of the frac fluid? That's not surprising.
Marian Smith (March 20, 2013 10:35 PM)
This is indeed possible but the strontium is more likely to be derived from the shale. The returning frac fluid picks up radioactivite elements from the shales.

The frac water is best injected into deep injection wells. For more information read
oldchemist4 (March 20, 2013 11:28 PM)
Barium sulfate is sufficiently insoluble that you can drink a fairly thick suspension of it (I have). It is also very radio-opaque so is used in a variety of radio-diagnostics (which is why I was drinking it). But the dissolved barium that would be present from barium sulfate would be a few tenths of a mg/L, well below the 5.99 mg/L quoted in the article and close to the level quoted (0.14 mg/L) found after the treatment of fracking fluids was stopped.

The high barium levels mentioned would thus not be due to the barium sulfate, but to other aspects of the fracking operation - possible reduction of the barium sulfate itself during the operation, or release of more soluble barium salts found in the geology.
cam (March 20, 2013 11:41 AM)
Once again, more questions need to be answered about the fracking process. Because of this, the quantity of water used & the undisclosed chemicals, all fracking should be halted until a more environmentally friendly fracking method is developed.
Michele Beckett (March 20, 2013 12:05 PM)
Thank you for the article, thank you for hopefully doing research to help our animals and children. If Adults cannot see how potentially dangerous this is on their shoulders.
I have been aware of hazards for over 15 years. Now with proposal to use on streets, and highways for snow melt only shows the utter ignorance of those in Leadership roles.
Thank you again
oldchemist4 (March 20, 2013 1:31 PM)
Leaving waste cleanup to the publicly-funded infrastructure is effectively a subsidy to the industry generating that waste.

If natural gas production were required to include all waste treatment within their business plans and resulting cost structures, what would that (full accounted) cost be, and what would the resulting market price be? A useful, if approximate, answer should be easy to calculate; construction cost of an appropriately sized and equipped waste-water treatment center, plus the cost of transporting spent fracking fluid to that site.
D. Frank (March 20, 2013 2:15 PM)
@BMC, the taxpayers don't pay for it. POTWs charge for any fluids or waste that dumped dumped at their facilities. However, the thrust of this article is correct in that POTWs generally utilize some sort of biological treatment and this waste stream is probably NOT something that should be dumped in a system designed for domestic wastes.
Gerri Wiley, RN (March 20, 2013 2:40 PM)
Please also consider the half-life of radium 226, the radioisotope commonly found in wastewater and sludge from fracking in the Marcellus shale is 1600 years. See:
See “Radioactivity in the Marcellus Shale” – by Marvin Resnikoff, Ph.D, Ekaterina Alexandrova, Jackie Travers – May 19, 2010
G Lewis (March 20, 2013 4:57 PM)
I agree. Municipalities should not be processing water from the oil & gas industry for money. They are ill equipped to handle these types of compounds found in frac flow back water. Apparently, these cities wanted a piece of the pie. You should not blame the greed of others on the oil & gas companies. These cities should be held accountable for accepting fluids that they had no business attempting to treat. The oil & gas companies are completely equipped to take care of their on non-hazardous oil field waste as it is classified by the EPA.
yomama (March 21, 2013 11:46 AM)
another reason to stay away from the East coast. Imagine feeling like you're taking a sip from a chemical lab beaker every time you drink water, or wash your vegetables.
ken osborn (March 23, 2013 12:43 PM)
POTW's (publicly owned treatment works) are designed to handle domestic waste and are not typically designed to handle waste from an industrial discharge. Pretreatment at the source is required for most industrial discharges to a POTW. Fees for industrial and other non-domestic sources are allocated based on flow and the total influent load from a given industry category. The purpose of the fee is to recover additional costs of treatment over what a domestic waste would require (e.g., adding an additional digester, secondary clarifier, etc). Source pretreatment is required so that the discharge to the POTW allows full treatment in compliance with the NPDES permit for the POTW.
Frieso Pouwer (March 25, 2013 8:50 AM)
There is a large problem that exists here and it is not the barium and strontium levels suggested in the waste water. These two chemicals can be captured very easily by a softener system believe it or not and then the backwash can be reused for more fracking if the oil company wanted to build such a beast for their work. No the real problem here is that no one wants the bad publicity without some sort of recompense. Oil companies aren't getting paid to recycle their waste water but municipalities are. The oil companies then can say they are ensuring proper disposal through a third party of their waste water making them look good. I would like to see someone come up with a great tech that could treat the water and re-harvest those chemicals at a high efficiency to be used again and again rather than passing the buck. Have the oil companies thought of a graphene water filtration system?
Dick Winschel (March 27, 2013 5:46 PM)
Did you all miss the point that this process of sending frac water to POTWs has STOPPED in Pennsylvania? This is old news. This is NOT the current practice, because the drillers (and the treatment plant owners) stopped it in response to the governor's request.
Sally L. Wright (March 27, 2013 11:25 PM)
I think it can somehow affect the aquatic ecosystems receiving water from water treatment plans. I totally hope too that the researchers will conduct further study of it's impact.

Eric (March 28, 2013 1:42 PM)
If the fracking companies are willfully lying about the content of their wastes, they are in violation. If they are using an industrial wastes facility to process their waster, they will provide the facility with the analysis of the waste (Ba, Sr, Ra226, gross alpha/beta, and the other RCRA metals) it is the facilities responsibility to process them correctly (as well as the fracking company to insure the waste facility is treating it as they are told). An industrial hygienist would be someone to speak to about this topic.
Nancy Shiffler (April 3, 2013 10:26 AM)
Oil and natural gas field wastes are currently not considered hazardous under RCRA and the Safe Drinking Water Act and, thus, are exempt from their disposal requirements.
Brian Oram (April 2, 2013 9:00 PM)
Study is a bit historic and dated- no flowback or brine water from Marcellus Shale or Utica goes to these treatment plants. There are other conventional oil and gas development that may go to some treatment plants, but this is not related to high volume hydraulic fracturing. These are non-Marcellus and non-Utica oil and gas brines from shallower formations going to wastewater treatment plants.

The companies are recycling and some water is going to deep well injection and not POTW.

Additional Sources
The other sources

1. Other natural brine discharges or saline seeps into the water ways – the one in Susquehanna County has a bromide level of a few hundred mg/L
2. other industrial discharges directly into wastewater treatment plants from other industrial wastewater sources in the collection area.
3. Maybe related to geology
4. Bromides in fertilizers and pesticides
5. Emissions of 1,2 dibromethane
6. I think it is still used as an anti-knock in jet fuel.
7. Comment below - "It is equally possible the majority of the pollution is being caused by wastewater discharges from coal-fired power plants". (Source: article by same researcher team).

More Spin - where is the Science?

I agree Marcellus and Utica flowback and brine should not go to conventional treatment plants and it is not. This water should be recycled and reused and that is what is being done. Some amount is being deep well injected - it should be reused. Again facts in the article a little dated and lacking details.

Chemistry of flowback water and brines - go to and NO I do not work for any gas companies.

Sandra Bilek (April 10, 2013 6:19 AM)
Couple things: One, when chemicals are proprietary, and industry doesn’t have to disclose them, water companies and sewage treatment facilities cannot test for them, so no one knows if those chemicals are being discharged into waterways that eventually end up in drinking water systems. The effect on human health and the environment most assuredly will suffer.
Second thing: in Ohio, Lupo with D & L, just recently admitted to dumping fracking chemicals directly into a storm drain. This apparently occurred over quite some time. He and his company have recently been indicted. Of importance, the ODNR, who is in charge of regulatory affairs in that area viewed the dumping, but what they found was the chemicals migrated into the Mahoning River, which water directly feeds the Beaver River and Beaver Valley’s water supply. Neither the ODNR, nor the Ohio EPA saw fit to warn the Beaver community or the Beaver Falls Municipal Water Authority.
Municipal Water Authorities do not routinely check for any type of fracking chemicals when water is tested and deemed safe for consumption. According to the Environmental Working Group, who has done very extensive testing of municipal water supplies, it appears that a good majority of municipal water supply sources are not safe for drinking.
Who is making the determination of what is safe?
It seems that one remedy to solve the problem has been and continues to be, to raise the levels of acceptable chemicals, pollutants, pesticides, fertilizers and known carcinogens in public water supplies. It appears that radiation has been added to this list. See: “Whitehouse approves radical radiation rollback.”
danica (April 16, 2013 4:25 AM)
Industries who execute such pollutants should be responsible enough with their wastes. The sewage treatment plants are often the solution for this type of problem.
Sam Taylor (July 27, 2013 2:08 AM)
Well, you started with the discussion on the sewage elements that are extracted with natural gas. This type of problem is really very serious in its nature for the environment, but since human settlements are at far places from such areas, they hardly pose any threat to the health of human beings. However, it does not mean that we can let the oil and gas drilling companies to destroy our environment. The civil society and environment protection agencies should work together to force such companies to improve their infrastructures for the protection of environment. Sewage Water Treatment is a serious issue whether it relates to the human settlements or it relates to wildlife or our environment environment. And we must not let it go not-addressed.
JVB (June 20, 2014 11:21 AM)
I think the relevant point is that many pollutants that find their way into waste water treatment facilities are not removed completely and increase concentrations with each recycle through our aquifers. Many communities have sole source drinking water sources that are threatened by run off, waste water recycling back into the water sources and the migration of water through geological formations into saltwater bays and estuaries. Many of these chemicals interrupt the marine ecology's and fisheries.

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