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# NORM Removal from Hydrofracturing Water

JAMES SILVA, HOPE MATIS, WILLIAM KOSTEDT IV, and VICKI WATKINS
GE Global Research Center, Niskayuna, NYIWC 11

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KEYWORDS: Marcellus, hydrofracturing, NORM, radium, ion exchange, adsorption,
Radium

- specific comp lexer, shale gas, pretreatment

ABSTRACT

Naturally occurring radioactive material (NORM), particularly 226 Ra, is often found in hydrofracturing flowback water and produced water (both referred to as “frac” water) from shale gas wells. A key frac water di sposal option is to recover clean water by thermal evaporation and a salable salt product by thermal crystallization. In order to avoid radium contamination of the salt product, it is desirable to remove radium from the frac water prior to the thermal pro cesses. We screened a variety of adsorbents and ion exchange resins for their effectiveness in radium removal from frac water. Clays, barium sulfate, and inorganic oxides (adsorbents) as well as strong acid cation exchange
resins were found to be effecti ve at removing radium from certain frac waters. Commercially available radium

- specific complexing (e.g. DOWEX RSC) ion exchange resins have been used for removing radium from well water and softener regeneration brines. However, frac water typically con tains much higher levels of dissolved solids, including barium, than are encountered in softener regeneration brines. RSC resin radium capacity for field frac water was too low to be economical. Several inorganic
oxide

- based materials showed promising pe rformance.IWC 11

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INTRODUCTION

Since 2007, the Marcellus shale gas pla y has experienced rapid growth. Figure 1 shows the trend in shale gas well drilling activity in the Pennsylvania Marcellus. In 2010, over 1300
Marcel lus shale gas wells were completed in Pennsylvania. Based on 1 MM gal flowback and produced water (both referred to as “frac water”) per well, an average of about 3.5 MM gal per day of frac water needed to be reused or disposed of. The near absence of di sposal wells in Pennsylvania initially forced much of
the frac water to be trucked into Ohio for disposal by deep well injection. Th e cost of trucking from eastern Pennsylvania to Ohio and deep well injection di sposal is in the range of $10

- 12 /bbl 1 . Sinc e 2009, there has been a significant increase in frac water reuse for subsequent hydrofracturing jobs; currently,
about two

- thirds of the Pennsylvania Marcellus frac water is reused for hydrofracturing after various forms of pretreatment, often with signif icant dilution with fresh water. Even with such high levels of reuse, there is still an average of over 1 MM gallon per day of frac water in the Pennsylvania Marcellus shale gas play that must be disposed of by deep well injection. As the number of wells within a given geographic region (e.g. a county) grows, the supply of high

- TDS frac water also grows. This increase is due to the lengthy production lifetime of the wells, each of which continually yields modest flow rates of produced water.
Reuse also increases the TDS level of the frac water. Based on an analysis by Hayes 2 , for a given geographic area, sometime after the rate of hydrofracturing and refrac operations peaks, the supply of frac water is expected to exceed the reuse capacity. At this poi nt, a growing volume of frac water must either be deep

- well injected, or treated for wat er and salt recovery

. 0 200 400 600 800 1000 1200 1400

2007 2008 2008 2009 2009 2010 2010Number of Wells Drilled/year

Year Figure 1 . Trend in Marcellus Shale Gas Drilling Activity in Pennsylvania

Much of this frac wa ter contains Naturally Occurring Radioactive Materials (NO RM). The principal NORM specie s of

interest is 226 Ra because of its water solubility, its long half

- life (1600 years), and its status as a known carcinogen 3

. F igure 2 shows the
measured 226 Ra levels for flowback and produced water from seven wells in the Pennsylvania Marcellus. While these frac
waters have radium concentrations that are far in excess of the EPA drinking water standard (5 pCi/L) and surface wat er discharge standard (60 pCi/L), they do not pose a radiation exposure risk. In the laboratory, all f rac water samples
are treated with ordinary safety precautions such as gloves, safety glasses, and ventilation. For handling NORM

- containing frac water, the work area is periodically surveyed for residual
radiation contamination.IWC 11

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Figure 2 . Pennsylvania Marcellus Shale Gas Drilling Activity and Measured Radium Levels

The purpose of this report is to establish a
pretreatment met hod for removing radium from frac water prior to thermal water and salt recovery. This will enable recovery of distilled
water and radium

- free salt. The distilled water may be used for industrial applications or discharged to surface waters and the salt product could be used for, e.g., road de

- icing or water softening.

BACKGROUND

Several types of organic resins and inorganic
materials have been used to remove radium from brines and ground waters. Since radium is a Group II metal, it is easily removed f rom dilute aqueous solutions such as well water with strong acid cation exchange resins. Wang 4

showed the effectiveness of 18 different inorganic ion exchangers for removing radium from simulated wastewater containing about 2100 ppm TDS, primarily CaSO 4 , and 5037 pCi/L

226 Ra, but not containing barium. Both Barite (as

- 100/+120 mesh granules) and powdered

BaSO 4 showed distribution coefficients 5

Previously, we suggested the possibility of using a commercial radium specific complexer (e.g. DOWEX RSC) for removing
radium from frac water for
radium of the order of 3000

- 4000. This is equivalent to a radium capacity of 3000

- 4000 pCi/gm for a soluti on containing 1000 pCi/L
radium. The mechanism for radium removal
from solution is described as a chemical exchange between the radium and barium ions at the crystal

- solution interface. Based on this mechanism, it is expected that barium in the

aqueous s olution will decrease the effectiveness of a given material for radium removal due to competition.

6 . RSC resin is a strong acid gelular cation exchange resin that has been fully ion exchanged with barium, followed by treatment with sulfuric acid to precipitate microcrystallites of finely dispersed BaSO 4
. Snoeyink 7 et al measured the radium capacity
of RSC under a wi de range of TDS levels. At 2,500 ppm TDS and with a feed radium concentration of 180 pCi/L, the measured radium capacity was 32,000 pCi/gm. However, at 40,000 ppm TDS and a feed radium concentration of 250 pCi/L, the radium capacity was only 300 pCi/gm. In contrast, Mangelson
et al 8

Several metal oxides have been tested for removing radium from aqueous solutions.
Nirdosh et al measured 3,500 pCi 226 Ra/gm for RSC resin for treating water softener regeneration brine, which had 40,600 ppm TDS and 1,181 pCi

226 Ra/L . These highly disparate results led us to conduct our own experimental study of the

per formance of RSC resin for radium removal from high

- TDS brines. The results of our study are given below.

9

In addition, carbonaceous materials
have been used to remove radium from saline solution. For example, Rachkova et al measured equilibrium isotherms for aqueous 226 Ra sol utions on oxides of Fe, Mn, Zr, and Ti. Several oxides showed good capacity for 226 Ra.

10
demonstrated adsorption of radium from saline

so lutions onto hydrolyzed wood lignin, and
Tsezos et al 11

It is also of interest to consider regeneration of radium adsorbents for reasons of process economics. Elution of radium from a

BaSO 4 adsorbent is not efficient investigated 226 Ra adsorption on granular activated carbon for uranium mine tailings.

12 . For a BaSO 4 column loaded with 140,000 pCi 226 Ra, only
38% of the radium was eluted with 20 bed
volumes of 2M NH 4 NO 3 . Therefore, it is expected that regeneration of radium from RSC
resin will also be inef ficient.

PROPOSED PROCESS FOR NORM REMOVAL

FROM FRAC WATERIWC 11

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Figure 3 shows the proposed process for pretreating frac water prior to thermal water and salt recovery. Frac water is initially treated with lime to precip itate iron and manganese, as well as suspended solids. The frac water is then subjected to NORM removal by adsorption or ion exchange. This yields substantially NORM

free frac water and a NORM concentrate. As discussed below, the NORM concentrate, which is technologically enhanced NORM (or TENORM), is then disposed of in an economical and environmentally acceptable manner.

Figure 3 . Proposed Frac Water Pretreatment

Process

NORM ANALYTICAL METHODS

We tested three techniques for measuring NORM: alpha

- beta proportional counting, liquid scintillation counting (LSC), and gamma spectrometry. Alpha

- beta proportional counting did not yield consistent results for frac water samples. During sample preparation for alpha

- beta proporti onal counting, a sample is dried on a piece of filter paper that is adhesively attached to a stainless steel planchet. As the sample dries, large salt crystals form because of the high TDS of the frac water. These salt crystals interfere with

emanation o f both alpha and beta particles from the sample, which leads to inconsistent results. Sample dilution resulted in insufficient sensitivity. We successfully measured NORM for liquid samples by both liquid scintillation counting (LSC) and gamma spectrometry , and both liquid and solid samples by gamma spectrometry. Each technique has its strengths and weaknesses. LSC requires only a small volume (1

- 10 mL) of sample and requires little sample preparation. LSC is thus very useful for rapidly screening a larg e number of samples for radioactivity. Depending on the sensitivity needed, the count time is in the range of 30

- 120 minutes. LSC is capable of detecting alpha and beta radiation using a conventional cocktail. However, LSC does not discriminate among NO RM species. Because LSC measures alpha and beta emission from all species, the total counts per minute for a given sample typically increases over time as the sample approaches secular equilibrium between
radium and its five short

- lived daughter products. However, some sample activities decreased over time after radium removal, which was due to the removal of the relatively long half

- life parent ( 226 Ra), which would normally feed the shorter half

- life daughter products. For a typical frac water sample, t he apparent equilibrium reading (counts per minute above background) was about 3 times the reading obtained immediately on sample preparation. This “ingrowth” process requires
about 2 weeks for 226 Ra daughter product
concentrations to stabilize within a f ew percent. Gamma spectrometry with a high purity germanium detector is effective for measuring

226 Ra activity in both solid and liquid samples. The advantage of gamma spectrometry is that it can discriminate among gamma

- emitting species. On the other ha nd, gamma spectrometry does require larger sample sizes;

500

- 1000 mL is typical for liquid sample analyses. 226 Ra has a characteristic 186 .2 keV gamma emission 13 , which can be counted directly as long as samples do not haveIWC 11

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sufficient 235 U to cause interfe rence. We measured the uranium by ICP

- MS and
determined that the contribution from the 235 U

185 .7 keV gamma 14 was negligible.

LABORATORY SAFETY

To develop safe laboratory handling techniques
for NORM

- containing frac water and NORM
concentrates, we meas ured the radiation dose for several samples using a dose meter equipped with a 2” x 2” sodium iodide
detector. Table 1 shows key results from this study. The background dose is due to cosmic rays as well as NORM

- cont aining building materials. By comparison with the typical radiation dose for a person in North America (about 300 mRem/yr or about 35 **μ** Rem/hr, excluding medical procedures 15 ), the additional dose from working with laboratory quantities
of NORM

- containing f rac water or NORM concentrates is insignificant.

FRAC WATER COMPOSITION

Table 2 shows the measured frac water composition from several Marcellus shale gas wells. All ionic species were measured by inductively coupled plasma (ICP); 226 Ra was measured using gamma spectrometry. Several
of the 226 Ra gamma spectrometry
measurements were conducted both at GE Global Research (GEGR) and at the New York State Department of Health, with excellent agreement between the two sites. These frac water samples have TDS and hardness levels far in excess of any waters used to test radium adsorbents or ion exchange resins reported in
the literature. Table 1 . Measured Radiation Dose from Frac Water Samples

Material 226 Ra

con centration Dose,

**μ** Rem/hr Background

- 8

- 12

Frac water in 5

- gallon plastic
bucket 7600 pCi/liter 9 a

NORM solid

concentrate in 500 mL plastic
Marinelli Beaker 542±49 pCi/gm 30 a

15 b

a measured at container surface

b measured at 1 foot from container surfa ce

ADSORBENT SCREENING

Based on the reported performance of the materials described above, we screened approximately 60 materials for radium adsorption capacity in frac water. For most of the testing, we utilized the frac water from
Well

- 4. This field frac water sample has significantly lower TDS and barium levels than any of the other samples and may be
considered a “best case scenario” for adsorbent screening. The screened materials included carbons, molecular sieves, clays such as montmorillonite, strong acid cation exchange resins, insoluble salts such as barium sulfate, and inorganic oxides. For each test, 20 mL of
Well

- 4 frac water and approximately 115 mg of an adsorbent were placed in a vessel and agitated overnight. The feed and each filtere d liquid were subsequently measured for residual radioactivity by LSC. The reduction in counts/minute (vs. feed) is plotted for each
adsorbent in Figure 4 . This shows that among the materials screened, an inorganic o xide and
barium sulfate are the most effective
adsorbents for radium removal from frac water
with modest TDS and barium levels.IWC 11

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0 10 20 30 40 50 60 70 80

0 10 20 30 40 50 60% CPM Reduction

Adsorbent Number Barium Sulfate

Amberlyst 15 Montmorillonite Inorganic Oxide

RSC
Resin

Figure 4 . Radium Removal Performance for
Screened Adsorbents

ECONOMICS

Beca use of the difficulties reported in regenerating RSC resins 12 , it is assumed that such resins will be used a single time and then disposed of. The cost of a radium adsorbent such as RSC resin is approximately $500 /ft 3

. Potential NORM disposal options include disposal as nonhazardous waste in a RCRA

- D landfill and disposal as low

- level radioactive waste (LLRW) in a special facility such as Energy Solutions’ facility in Utah. As reported by
Veil 16 , the maximum 226 Ra activity for a
material to be considered nonhazardous waste varies by state and ranges from 5

- 50 pCi/gm. The tipping fee for nonhazardous waste disposal is typically $50/ton. However, for a
226 Ra concentration of 5000 pCi/liter in the raw
frac water and 50 pCi/gm resin loading, the cost of resin would exceed $350/bbl frac water. On the other hand, waste containing up to 10,000 pCi/gm can be disposed of as LLRW, which costs about $200/ft 3 for disposal. Figure 5
show s the cost of both resin and disposal (as LLRW) for two levels of feed 226 Ra activity as functions of the adsorbent capacity. This figure shows that by loading a resin at 10,000 pCi

226 Ra/gm, the resin plus disposal cost adds $1.25

- $2.50/bbl to the cost o f recovering water and salt from frac water, depending on the raw
frac water 226 Ra activity. Thus, a working target loading level is 10,000 pCi 226 Ra/gm resin.

Table 2

. Frac Water Compositions from Pennsylvania Marcellus Shale G as Wells **

. (all quantities ppm mg/L except for 226 Ra)

Well

- 1 Well

- 2 Well

- 3 Well

- 4 Well

- 5 Well

- 6 Well

- 7 ** Design

Case County Bradford Bradford Bradford Butler Tioga Washington

TDS 91,000 143,000 170,000 67,000 150,000 132,000 170,000 132,674

Na + 26, 000 38,000 53,000 19,200 39,000 32,000 35,000 32,355 Mg ++ 450 830 1,280 575 1,000 800 1,200 798

Ca ++ 5,500 10,280 13,120 5,350 13,000 9,000 11,000 8,693

Sr ++ 2,000 3,670 4,580 1,300 2,600 2,500 1,800 2,334

Ba ++ 6,600 13,000 11,600 30 3,500 6,000 150 5, 786

Fe ++ 26 74 123 50 32 <10 50 48

Mn ++ 1.5 2.5 3.4 1.7 2.7 <10 1.2 5
Cl - 55,000 83,800 95,000 12,500 77,100 72,000 97,000 72,612

SO 4 = <10 <10 <10 57 <10 <50 <100 0

SiO 2 15 10 15 <50 18 30 0

226 Ra * 5,400 7,600 4,000 4,900 5,400 350 2300 5,000

* pCi /Liter

** Frac water from Barnett Shale (TX)IWC 11

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0 2 4 6 8 10

0 2000 4000 6000 8000 10000 5000 2500Resin+Disposal Cost, $/bbl Frac Water Treated

Adsorbent Ra Capacity, pCi/gm Feed Ra activity, pCi/L

Resin: $500/ft3 Disposal: $200/ft3

Figure 5 . Resin and Disposal Cost Sensitivity to Adsorbent Capacity and Frac Water Feed 226 Ra
Level

EFFECTS OF TDS AND BARIUM

CONCENTRATION ON RSC RESIN

PERFO RMANCE

We selected RSC resin for further testing because it showed promising results in the screening tests and it is commercially available.
Much frac water has barium and TDS levels higher than those of Well

- 4. Therefore, we
conducted two series of ba tch equilibrium tests with frac waters that had been spiked with
various levels of barium. Frac waters from
Well

- 4 (low TDS) and Well

- 7 (high TDS) were each spiked with various barium levels to
measure the effects of TDS and barium on the radium capacity of RSC resin. Barium was
added to the frac water as BaCl 2 , which was obtained from Sigma

- Aldrich. Figure 6 shows the effects of both TDS and Ba concentration on the apparent capacity
of RSC resin for 226 Ra. We utiliz ed RSC resin as
a convenient form of BaSO 4 . The capacity was
calculated based on the measured reduction in LSC counts per minute above background due to resin treatment and the measured feed 226 Ra
levels. Figure 6 sh ows that the resin 226 Ra capacity with unspiked Well

- 4 brine is comparable to that reported by Snoeyink 7

, which is too low to be commercially practical. The capacity decreases significantly with increasing barium levels. For the higher TDS
brine of Well

- 7, the capacity is virtually negligible at all barium levels. These results led
us to seek alternate resins or materials for removing radium from frac water.

0 50 100 150 200 250 300 350 400

0 200 400 600 800 1000 1200 Well-4 Well-7RSC Capacity (pCi/gm)

ppm Ba in Frac Water

Figure 6 . Effects of TDS and Barium
Concentration on RSC 226 Ra Capacity

ALTERNATE ADSORBENTS

A series of experimental materials based on inorganic oxides was synthesized and tested for radium capacity with Well

- 4 frac water. These
materials show an order of m agnitude improvement in radium capacity compared with RSC resin. Further material development is in progress to increase capacity.

SUMMARY AND CONCLUSIONS

A survey of seven Marcellus frac water samples and a sample from the Barnett showed a
median 226 Ra activity of about 5,000 pCi/L. FracIWC 11

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water reuse currently accounts for about 2/3 of Marcellus frac water. However, as a given development area of the Marcellus matures, the need for thermal water and salt recovery will grow. To recover distilled water and
salable salt from NORM

- containing frac water, it will be necessary to pretreat the frac water to remove NORM (notably 226 Ra). Based on a screening study of over 60 materials for their ability to remove 226 Ra from frac water, we
found that BaSO 4 and in organic oxides had the best performance. We found that the radium capacity for BaSO 4 - based RSC resin was not economically attractive for use with the frac
waters of interest. We have obtained promising results from a series of inorganic
oxide

- based resin s.

ACKNOWLEDGEMENTS

This work was performed under Subcontract

01822

- 36 to Research Partnership to Secure Energy for America (RPSEA), a contractor to the United States Department of Energy under prime contract DEAC2607NT42677.IWC 11

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References

1. Gaudlip, A., Paugh, L., and Hayes, T., Marcellus Shale Water Management Challenges in Pennsylvania, Society of Petroleum Engineers Paper 119898, SPE Shale Gas Production Conference, November, 2008.

2. Hayes, Thomas

, Techno

- economic Assessment of Water Management Solutions, Marcellus Shale Gas Water Management Initiative, Canonsburg, PA, 2011.

3. Roper, W., Toxicity Profile for Radium, Agency for Toxic Substances and Disease Registry, U.S. Public Health Service, in co operation with US EPA, 1990. http://www.atsdr.cdc.gov/ToxProfiles/tp144.pdf

4. Wang, R.S., Chen, J.X., and Liu, Z. W., The Adsorption Behavior of Microamounts of Radium on Inorganic Ion Exchangers, Journal of Radioanalytical and Nuclear Chemistry, Articles, Vol 111, No. 2 (1987) 289

- 295.

5. 

## ( **) (**  **) (**  **) (**  **)** /

/ d Ra activity on solid gm solid K Ra activity in solution gm solution **=**

6. Silva, J.M., Matis, H., and Tinto, J.V., NORM Removal from Frac Water in a Central Treatment Facility, International Water Conference, 2010, San Antonio, IWC

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- 65.

7. Snoeyink, V.L., Chambers, C.C., Schmidt, C.K., Manner, R.F., Myers, A.G., Pfeffer, J.L., Richter, S.K., and Snyder, D.W., Removal of Barium and Radium from Groundwater, EPA Environmental Research Brief, Feb., 1987.

8. Mangelson, K.A. and Lauch, R.P., Removing and Disposing of Radium from Well Water, Journal of the American Water Works Association, 82 (6), 72

- 76 (1990).

9. Nirdosh, I., Trembley, W.B., and Johnson, C.R., Adsorption

- Desorption Studies on the 226Ra

- Hydrated Metal Oxide System, Hydrometallurgy, 24 (1990) 237

- 248.

10. Rachkov a, N.G., Shuktomova, I.I., and Taskaev, A.I., Sorption of Uranium, Radium, and Thorium from Saline Solutions on Hydrolyzed Wood Lignin, Russian Journal of Applied Chemistry, 2006, Vol 79, No. 5, pp. 715

- 721.

11. Tsezos, M and Keller, D.M., Adsorption of Radi um

- 226 by Biological Origin Adsorbents, Biotechnology and Bioengineering, Vol. 25, No. 1, January 1983, pp. 201

- 215.

12. Arnold, W.D and Crouse, D.J., Radium Removal from Uranium Mill Effluents with Inorganic Ion Exchangers, I&EC Process Design and Developme nt, Vol. 4, No. 3, July 1965.

13. Akovali, Y., Nuclear Data Sheets, 77, 271 (1996).

14. Browne, E., Nuclear Data Sheets, 93, 986 (2001)

. 15. The average exposure due to natural sources is 300 mRem/yr for the East coast (200 from Rn, 30 from cosmic, 30 from terre strial, 40 from diet); this annual estimate excludes exposure due to medical procedures. The NRC occupational exposure limit is 5 rem/yr. The NRC exposure limit for the public is 100 mRem/yr above background.

16. Veil, J. and Smith, K., NORM Disposal Optio ns, Costs Vary, Oil and Gas Journal, Vol. 97, Jan 4, 1999, pp.

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