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NORM Removal from Hydrofracturing Water

JAMES SILVA, HOPE MATIS, 

WILLIAM KOSTEDT IV, and VICKI WATKINS

GE Global Research Center, Niskayuna, NY
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KEYWORDS: Marcellus, hydrofracturing, NORM, radium, ion exchange, adsorption, 

Radium-specific complexer, shale gas, pretreatment

ABSTRACT

Naturally occurring radioactive material (NORM), particularly 226Ra, is often found in 

hydrofracturing flowback water and produced water (both referred to as “frac” water) 

from shale gas wells. A key frac water disposal 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 processes. 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 effective 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 contains 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 performance. 
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INTRODUCTION

Since 2007, the Marcellus shale gas play has 

experienced rapid growth. Figure 1 shows the 

trend in shale gas well drilling activity in the 

Pennsylvania Marcellus. In 2010, over 1300 

Marcellus 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 disposal 

wells in Pennsylvania initially forced much of 

the frac water to be trucked into Ohio for 

disposal by deep well injection. The cost of 

trucking from eastern Pennsylvania to Ohio and 

deep well injection disposal is in the range of 

$10-12/bbl1

. Since 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 

significant 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 Hayes2, 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 point, a growing 

volume of frac water must either be deep-well 

injected, or treated for water and salt recovery. 

0

200

400

600

800

1000

1200

1400

2007 2008 2008 2009 2009 2010 2010

Number of Wells Drilled/year

Year

Figure 1. Trend in Marcellus Shale Gas Drilling 

Activity in Pennsylvania

Much of this frac water contains 

Naturally Occurring Radioactive Materials 

(NORM). The principal NORM species of 

interest is 226Ra because of its water solubility, 

its long half-life (1600 years), and its status as a 

known carcinogen3

. Figure 2 shows the 

measured 226Ra 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 water discharge standard (60 

pCi/L), they do not pose a radiation exposure 

risk. In the laboratory, all frac 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.
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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 method 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 from 

dilute aqueous solutions such as well water 

with strong acid cation exchange resins. Wang4

showed the effectiveness of 18 different 

inorganic ion exchangers for removing radium 

from simulated wastewater containing about 

2100 ppm TDS, primarily CaSO4, and 5037 pCi/L 

226Ra, but not containing barium. Both Barite 

(as -100/+120 mesh granules) and powdered 

BaSO4 showed distribution coefficients5

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 solution 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 solution 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 BaSO4. 

Snoeyink7 et al measured the radium capacity 

of RSC under a wide 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 al8

Several metal oxides have been tested 

for removing radium from aqueous solutions. 

Nirdosh et al

measured 3,500 pCi 226Ra/gm for RSC 

resin for treating water softener regeneration 

brine, which had 40,600 ppm TDS and 1,181 pCi 

226Ra/L. These highly disparate results led us to 

conduct our own experimental study of the 

performance 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 226Ra solutions on oxides of Fe, 

Mn, Zr, and Ti. Several oxides showed good 

capacity for 226Ra.

10

demonstrated adsorption of radium from saline 

solutions onto hydrolyzed wood lignin, and 

Tsezos et al11

It is also of interest to consider 

regeneration of radium adsorbents for reasons 

of process economics. Elution of radium from a 

BaSO4 adsorbent is not efficient

investigated 226Ra adsorption on 

granular activated carbon for uranium mine 

tailings. 

12. For a BaSO4

column loaded with 140,000 pCi 226Ra, only 

38% of the radium was eluted with 20 bed 

volumes of 2M NH4NO3. Therefore, it is 

expected that regeneration of radium from RSC 

resin will also be inefficient.

PROPOSED PROCESS FOR NORM REMOVAL 

FROM FRAC WATER
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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 precipitate 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 NORMfree 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 proportional 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 of 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 large 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 NORM 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 (226Ra), which would 

normally feed the shorter half-life daughter 

products. For a typical frac water sample, the 

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 226Ra daughter product 

concentrations to stabilize within a few 

percent.

Gamma spectrometry with a high purity 

germanium detector is effective for measuring 

226Ra activity in both solid and liquid samples. 

The advantage of gamma spectrometry is that 

it can discriminate among gamma-emitting 

species. On the other hand, gamma 

spectrometry does require larger sample sizes; 

500-1000 mL is typical for liquid sample 

analyses. 226Ra has a characteristic 186.2 keV 

gamma emission13, which can be counted 

directly as long as samples do not have 
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sufficient 235U to cause interference. We 

measured the uranium by ICP-MS and 

determined that the contribution from the 235U 

185.7 keV gamma14 was negligible. 

LABORATORY SAFETY

To develop safe laboratory handling techniques 

for NORM-containing frac water and NORM 

concentrates, we measured 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-containing building 

materials. By comparison with the typical 

radiation dose for a person in North America 

(about 300 mRem/yr or about 35 μRem/hr, 

excluding medical procedures15), the additional 

dose from working with laboratory quantities 

of NORM-containing frac 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); 226Ra was 

measured using gamma spectrometry. Several 

of the 226Ra 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 226Ra 

concentration

Dose, 

μRem/hr

Background - 8-12

Frac water in 5-

gallon plastic 

bucket

7600 pCi/liter 9a

NORM solid 

concentrate in 

500 mL plastic 

Marinelli Beaker

542±49 pCi/gm 30a

15b

a measured at container surface

b measured at 1 foot from container surface

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 filtered 

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 oxide and 

barium sulfate are the most effective 

adsorbents for radium removal from frac water 

with modest TDS and barium levels.
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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

Because of the difficulties reported in 

regenerating RSC resins12, 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/ft3. 

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 

Veil16, the maximum 226Ra 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 

226Ra 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/ft3 for disposal. Figure 5

shows the cost of both resin and disposal (as 

LLRW) for two levels of feed 226Ra activity as 

functions of the adsorbent capacity. This figure 

shows that by loading a resin at 10,000 pCi 

226Ra/gm, the resin plus disposal cost adds 

$1.25-$2.50/bbl to the cost of recovering water 

and salt from frac water, depending on the raw 

frac water 226Ra activity. Thus, a working target 

loading level is 10,000 pCi 226Ra/gm resin.

Table 2. Frac Water Compositions from Pennsylvania Marcellus Shale Gas Wells**.

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

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

SO4

= <10 <10 <10 57 <10 <50 <100 0

SiO2 15 10 15 <50 18 30 0

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

pCi/Liter **Frac water from Barnett Shale (TX)
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0

2

4

6

8

10

0 2000 4000 6000 8000 10000

5000

2500

Resin+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 226Ra 

Level

EFFECTS OF TDS AND BARIUM 

CONCENTRATION ON RSC RESIN 

PERFORMANCE

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 batch 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 BaCl2, 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 226Ra. We utilized RSC resin as 

a convenient form of BaSO4. The capacity was 

calculated based on the measured reduction in 

LSC counts per minute above background due 

to resin treatment and the measured feed 226Ra 

levels. Figure 6 shows that the resin 226Ra 

capacity with unspiked Well-4 brine is 

comparable to that reported by Snoeyink7, 

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-7

RSC Capacity (pCi/gm)

ppm Ba in Frac Water

Figure 6. Effects of TDS and Barium 

Concentration on RSC 226Ra 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 magnitude 

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 226Ra activity of about 5,000 pCi/L. Frac 
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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 226Ra). Based on a 

screening study of over 60 materials for their 

ability to remove 226Ra from frac water, we 

found that BaSO4 and inorganic oxides had the 

best performance. We found that the radium 

capacity for BaSO4-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 resins. 

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.
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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 cooperation 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-10-65.

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. Rachkova, 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 Radium-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 Development, 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 terrestrial, 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 Options, Costs Vary, Oil and Gas Journal, Vol. 97, Jan 4, 1999, pp. 

37-43.

 

 
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