# RPSEA Final Report

08122

- 36.Final

Produced Water Pretreatment for Water Recovery and Salt Production

08122

- 36

January 26, 2012

Principal Investigator: James M. Silva
Senior Chemical Engineer
General Electric Global Research Center

1 Research Circle Niskayuna, NY 12309ii Legal Notice

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## Produced Water Pretreatment for Water Recovery

and Salt Production

James M. Silva

, Hope Matis

, William L. Kostedt IV, and Vicki Watkins

Abstract :

Horizontal drilling and slickwater hydrofracturing have enabled shale gas to become a significant contributor to the United States’ energy supply. Hydrofracturing typically requires

2MM

– 6.5MM gallons of water per shale gas well. About 15

- 25% of this wa ter returns to the surface as “flowback” within 30 days after hydrofracturing. “Produced water” continues to flow at a much reduced rate, e.g. 2

- 10 bbl/day, for the life of the well. In addition to high salinity and hardness levels (Mg, Ca, Sr, Ba), much Marcellus produced water also contains significant levels of naturally occurring radioactive materials (NORM), particularly radium. The near absence of disposal wells in Pennsylvania initially forced much of the produced water to be trucked into Ohio for disposal by deep

- well injection (UIC). Currently up to 95% of the flowback and produced water is reused in subsequent hydrofracturing operations. However, eventually the supply of flowback and produced water is expected to exceed the reuse capacity.

At this point, a growing vo lume of high

- TDS produced water must either be deep

- well injected, or water and salt recovery is required. The objective of this study is to identify cost

- effective softening technologies, primarily for barium and radium removal, that enable thermal recovery of distilled water and a salable salt product from produced water.

Current technology utilizes evaporation to recover about 56% of the produced water as distilled water and a salt concentrate, which is disposed of by UIC (de sign case). To achieve 80

- 95% water recovery, it is necessary to generate a solid salt (NaCl) product. For use as road salt, the salt product TCLP extract must contain no more than 100 mg/L barium. It is also assumed that the salt product must also meet 226 Ra specifications for disposal of solids as nonhazardous solid waste, which is 25 pCi/gm in Pennsylvania. Based on a pilot study by GE Water and Process Technologies (GEWPT) of Marcellus produced water evaporation and salt crystallization, we
defined a map of pretreatment needs as a function of the produced water barium and radium concentrations. We concluded that produced waters containing less than a specific barium concentration ([Ba] max , about 1,000

- 2,000 mg Ba/L) and essentially arbitrary radium activities do not require barium removal prior to NaCl crystallization (“Type I” produced water). Produced water with a barium concentration greater than [Ba] max and very low radium activity (<200

- 1,000 pCi 226 Ra/L; upper limit depends on the produced water barium concentration) may be economically treated for barium removal by sulfate precipitation (“Type II” produced water) prior to NaCl crystallization. Produced water with a barium concentration greater than [Ba] max and higher radium activity (>200

- 1,000 pCi 226 Ra/L; lower limit depends on the produced water barium concentration) requires barium removal by a method other than direct sulfate precipitation prior to NaCl crystallization (“Type III” produced water). We focused on defining economical pre treatment processes for Type III produced water.iv

Selective removal of radium from Type III produced water in order to enable barium removal by sulfate precipitation is not practical. We found that the radium capacity of DOWEX TM RSC, a commercially availa ble ion exchange resin for radium removal from aqueous streams, is too low
to be economical.

We defined two pretreatment processes to remove both barium and radium from Type III produced water. Each process generates a barium and radium concentrate was te stream that may be disposed of by UIC. The first process utilizes a modified lime

- soda softening process to completely soften produced water. Magnesium, calcium, and strontium are first selectively precipitated to yield a solid sludge that may be disp osed of as nonhazardous waste in a RCRA

- D facility. This is followed by precipitation of barium and radium as carbonates. The carbonates from the second precipitation step are redissolved with HCl to yield a liquid concentrate that can be disposed of by UIC. For the design case, about 0.05 bbl of concentrate for UIC disposal
and about 25 lb. RCRA

- D solid waste are generated per bbl raw produced water. For this case, the materials and disposal cost is estimated to be $3.5/bbl produced water. Further

dev elopment work is needed to maximize the selectivity of the first precipitation step for
calcium and strontium over barium and radium and to reduce the materials cost.

The second process utilizes high surface area, HCl

- regenerable MnO 2 as an adsorbent for barium and radium. The estimated materials and disposal costs for this process are in the range of $1.7

- $2.3 per bbl produced water for the design case produced water (10, 5 cycles of adsorbent life, respectively). Because this process utilizes micron or submicron MnO 2 particles, further work is required to define cost

- effective particle

- water separation processes for both produced water treatment and MnO 2 regeneration. In addition, MnO 2 regeneration requires dilute HCl (ca. 0.1N), but the regeneration p roduct for UIC disposal is a BaCl 2 - RaCl 2 concentrate.
MnO 2 regeneration with a solution of dilute HCl and concentrated BaCl 2 - RaCl 2 needs to be demonstrated in the laboratory.

Both processes have undergone preliminary laboratory scoping studies with field produced
waters. It is recommended that the modified lime

- soda process be further developed in the laboratory in preparation for pilot

- scale testing. It is also recommended that the further laboratory development of the MnO2 adsorption process be conduc ted. This process has potential for lower treatment and disposal costs than the modified lime

- soda process. It is also recommended that additional laboratory and pilot evaporation and crystallization studies be conducted with field produced waters to bet ter define [Ba]max.

Signature and Date Stampv



## THIS PAGE INTENTIONALLY LEFT BLANKvi

Table of Contents

Abstract

................................ ................................ ................................ ................................ ... iii

I. Introduction

................................ ................................ ................................ ........................ 1

II. Produced Water Composition

................................ ................................ ............................. 4

A. Literature Data

................................ ................................ ................................ ................. 4

B. Produce d Water Samples

................................ ................................ ................................ . 5

III. Current Processes for Produced Water Recovery

................................ ................................ 6

A. GEWPT Pilot

- Scale Evaporator/Crystallizer Trials with Marcellus Produced Water

............ 7

B. Produced Water Pretreatment Map

................................ ................................ ................. 9

IV. Type III Produced Water Pretreatment Process Options

................................ .................... 11

A. Ion Exchange

................................ ................................ ................................ .................. 11

B. Nanofiltration

................................ ................................ ................................ ................. 12

C. Sulfate Coprecipitation of Barium and Radium

................................ ............................... 12

D. Lime

- Soda Precipitation

................................ ................................ .............................. 15

E. Modified Lime

- Soda Process

................................ ................................ ........................... 16

1. Introduction

................................ ................................ ................................ ............ 16

2. Aspen Plus  /OLI Simulations

................................ ................................ ................... 17

3. Modified Lime

- Soda Pretreatment Process Cost Calculations

................................ .. 18

4. Laboratory Tests of Modified Lime

- Soda Process

................................ ..................... 19

F. MnO 2 Barium and Radium Adsorption Process

................................ ............................... 22

1. MnO 2 Characterization and Capacity Screening

................................ ....................... 22

2. MnO 2 Regeneration Process

................................ ................................ .................... 23

3. PNNL

- C Adsorbent Capacity and Regenerability

................................ ...................... 25

4. MnO 2 Barium and Radium Adsorption

- Regeneration Process

................................ .. 26vii

V. Conclusions

................................ ................................ ................................ ....................... 29

VI. Recommendations

................................ ................................ ................................ ............ 31

VII. Acknowledgements

................................ ................................ ................................ ........... 31

VIII. References

................................ ................................ ................................ ........................ 32

Appendix I. Selective Radium Removal from Produced Water

................................ ............. AI

- 1

Appendix II. Produced Water Softening by Ion Exchange

................................ .................... AII

- 1

Appendix III. Produced W ater Softening by Nanofiltration

................................ .................. AIII

- 1

Appendix IV. Modified Lime

- Soda Process Analysis and Experimental Results

..................... AIV

- 11



## Produced Water Pretreatment for Water Recovery

and Salt Production

James M. Silva

, Hope Matis

, William L. Kostedt IV, and Vicki Watkins



## I. Introduction

Horizontal drilling and slickwater hydrofracturing have enabled shale gas to become a significant contributor to the United States’ energy supply. Developed largely in the Barnett shale, these technologies have more recently been applied to the Marcellus shale, which has the potential to become the second largest natural gas field in the world 1

. Hydrofracturing a shale gas well typically requires 2M M

– 6.5 MM gallons of water . About 15

- 25% of this water

returns to the surface as “flowback” within 30 days after hydrofracturing. “Produced water” continues to flow at a much reduced rate, e.g.

, 2

- 10 bbl/day, for the life of the well. It is
estimated th at in Pennsylvania, in 2011, about 25 MM bbl of flowback and produced water will be generated 2

. A potential limitation to developing the Marcellus is the disposal cost of hydrofractu ring flowback and produced water, which are collectively referred to as “ frac” water in this report

. In addition to high salinity and hardness levels (Mg, Ca, Sr, Ba), much Marcellus produced water also contains significant levels of naturally occurring radioactive materials (NORM), particularly radium. The near absence of di sposal wells in Pennsylvania initially forced
much of the produced water to be trucked into Ohio for disposal by deep

- well injection (UIC 3 ). The cost of trucking from eastern Pennsylvania to Ohio and disposal by UIC is in the range of $10

- 12/bbl 4

.

Sinc e 2009, there has been a significant increase in frac water reuse for subsequent hydrofracturing jobs. Current estimates of Pennsylvania Marcellus frac water reuse ( after various forms of pretreatment ) range from about two

- thirds 5 to about 95% 2

. Because flowback
water has much lower TDS 6 than produced water, flowback water is more likely to be reused in subsequent hydrofracturing operations than produced water. Recovered frac water is often
reused wit h significant dilution by fresh water. Even assuming 95% reuse , the re is still an average of approximately 0.15

- 0.3 MM gallon s per day of produced water in the Pennsylvania Marcellus shale gas play that must be disposed of by UIC 7 . As the number of shale gas wells within a given geographic region (e.g. a county) grows, the supply of produced water with high TDS levels (viz. TDS levels at or above about 125,000 ppm) also grows. This increase is due to the lengthy production lifeti me of the shale gas wells, each of which continually yields produced water. Reuse also increases the TDS level of the produced water. Based on an analysis by Hayes 8 , for a given geographic area, sometime after the rate of hydrofracturing and refrac opera tions peaks, the supply of produced water is expected to exceed the reuse capacity. At this point, a growing vo lume of high

- TDS produced water must either be deep

- well injected, or water and salt recovery is required.2

There has been much recent regulator y activity with respect to frac water disposal, particularly in Pennsylvania. For example, since May 19, 2011, in Pennsylvania, shale gas drillers have been directed by PADEP to cease delivering wastewater to the 15 wastewater treatment plants that
had be en accepting it and had been granted “grandfather” status with respect to PADEP’s 2010 Total Dissolved Solids regulations. These wastewater treatment plants include Publicly Owned Treatment Works (POTW) and Centralized Wastewater Treatment (CWT) facilitie s 9

.

The purpose of this study is to identify pretreatment technologies that enable economic recovery of distilled water and a salable salt product from high

- TDS Marcellus shale gas produced water. The high TDS levels in the produced water require ther mal processes (evaporation and crystallization) for economic water and salt recovery. P retreatment technologies include both softening ( primarily barium removal) and NORM removal. Softened produced water enables a higher recovery of both distilled water and salt product, compared
with non

- softened water. Consistent with these higher recoveries, the crystallizer purge stream

, which must be disposed of by UIC, is smaller with softened water than with non

- softened water.

In produced water, soluble NORM species comprise 226 Ra and 228 Ra, which are daughter products of naturally occurring 238 U and 232 Th, respectively. 226 Ra is of principal interest because of its long half

- life (1600 years), its water solubility as a divalent cation, and its status as a known carcinogen 10

, 11

. 226 Ra is an alpha emitter (4.781 MeV) and a gamma emitter (186.2 keV). The 228 Ra activity 12 was typically less than 10% of the 226 Ra activity for the water samples analyzed from the Marcellus Shale formation 13

. For removal processes, it is expected that 226 Ra
and 228 Ra will behave similarly. Therefore, with respect to NORM, this study is focus ed on 226 Ra.

We defined a “ design case” produced water composition based on data from the literature as
well as seven produced water samples that we obtained (six from the Pennsylvania Marcellus
and one from the Barnett). For the design case, current water recovery technology comprises evaporation to recover about 56% of the produced water as distilled water. This proce ss also yields a salt concentrate, which is disposed of by UIC.

To achieve 8 0

- 95% water recovery, it is necessary to generate a solid salt product. For use as road salt, the solid salt (NaCl) product must pass TCLP 14

, which includes the requirement that the TCLP extract of the salt product contain less than 100 mg barium/L. Although there is currently no radium specification for road salt in either New York or Pennsylvania 15

, it is
assumed that road salt must meet 226 Ra specifications for disposal of solids as nonhazardous solid waste, which is 25 pCi/gm in Pennsylvania.

Based on a GEWPT pilot study of Marcellus produced water evaporation and salt crystallization, we defined three types of produced water based on their barium and radium concentrations. Each type of produced water requires a different pretreatment process to enable recovery of a salt product. “Type I” produced waters contain less than a specific barium concentration, [ Ba ] max , (

~ 1,000

- 2,000 mg Ba/L) and are not restricted with respect to 226 Ra activity. Type I produced waters require neither barium nor rad ium removal prior to NaCl crystallization

.3

“Type II” produced waters contain a higher barium concentration than [ Ba ] max and very low radium activities ( <200

- 1,000 pCi 226 Ra/L; upper limit depends on the produced water barium

concentration ). Type II pro duced waters may be economically treated for barium and radium removal by conventional sulfate precipitation prior to NaCl crystallization

.

“Type III” produced waters contain a higher barium concentration than [ Ba ] max and higher
radium activities (>200

- 1, 000 pCi 226 Ra/L; lower limit depends on the produced water barium

concentration ). Type III produced waters require barium removal using a method other than
direct sulfate precipitation prior to NaCl crystallization. In this project, we focused on defining
economical barium and radium removal pretreatment processes for Type III produced waters.

We explored several classes of ad sorbents to selectively remo ve radium from produced water

, which would en able barium to be subsequently removed by sulfate precipitation. DOWEX TM RSC (radium

- specific complexer) has been utilized to remove radium in municipal water
systems 16 . However, we found that the 226 Ra capacity for RSC (and all other adsorbents screened) was too low to economically remove radium from produced water.

W e considered ion exchange and nanofiltra tion as potential methods of softening Type III produced water. Based on the design case produced water composition, we found that neither

process was economically attractive

. For ion exchange, the cost of regeneration chemicals and waste disposal was over $6 /bbl produced water. In addition, the ion exchange regeneration
waste volume would be comparable to the volume of produced water being treate d. For softening by nanofiltration, simulations showed that t he water recovery fraction would be too low to be economical.

We identified two processes to remove barium and radium from Type III produced water 17 . The byproduct from each process is a conce ntrate d solution of barium and radium that may be disposed of by UIC. In the first process, the produced water is completely softened by a modified lime

- soda process. After magnesium is preci pitated as a hydroxide, calcium and strontium are precipitated as carbonates and disposed of as nonhazardous waste in a RCRA

- D 18

landfill

. A second step precipitates barium and radium as carbonates. After the se carbonate salt solids are removed from the produced water, they are redissolved by addition of HCl to
form an aqueous solution of BaCl 2 and RaCl 2 , which is disposed of by UIC. For the design case produced water, the cost of materials and di sposal for this process is $3.5 /bbl produced water.

In the second process , barium and radium are removed from produced water by adsorption

onto a MnO 2 adsorbent. This adsorbent is regenerated by dilute HCl treatment, which yields a
BaCl 2 - RaCl 2 concentrate for disposal by UIC. For the design case produced water, the cost of
chemicals and di sposal for this process is $1.7

- $2.3 /bbl produced water (based on 10 and 5 adsorption

- regeneration cycles, respectively). This report shows laboratory experimental
results and costs for both process es.4



## II. Produced Water Composition

A. Literature Data

Figure 1 shows volu me and TDS flowback profiles for a characteristic hydrofractured well in the Marcellus. This figure was constructed from flow and composition data presented by Vidic 19

. The flowrate is relatively high through Day 6 and then drops to a relatively constant rate through Day 22. The instantaneous TDS increases essentially monotonically throughout the first 17 days and then plateaus at about 150,000 mg/L . About 27% of the water used to hydrofracture the well returned within 22 days.

Figure 1 . Marcellus Shale Flowback and Produced Water Profiles

Two cumulative TDS levels are also plotted. Each point on the line labeled “Cumulative TDS (time zero start: Day s 0

- n)” represents the volume average TDS of the flow back and produced water between the beginning of flowback ( Day 0) and Day “n”. The value of this cumulative
TDS measurement for Day 15 is about 60,000 mg/L . Currently, in the Marcellus, much of the early flowback water is reused with minimal treatment (e .g. removal of suspended solids and bacteria, with optional softening). In this example, the cumulative TDS for the first five days is about 50,000 mg/L and represents about 80% of the water returned during the first 22 days.
This water could be minimall y treated and reused in subsequent hydrofracturing jobs.

Each point on the line labeled “Cumulative TDS (late start: Day s n

- 22” represents the volume average TDS for the time interval from Day “n” through Day 22. The value of this cumulative5

TDS measurement for Day 6 is about 130,000 mg/L . This value represents the volume average
TDS for flowback and produced water collected from Day 6 through Day 22. Flowback and produced water from this interval may be pretreated and thermally recovered as distilled water
and salt.

Keister 20 reported frac water compositions, giving values for low

- , medium

- , and high

- TDS frac water, as well as a “typical” frac water. Table 1 shows the values reported by Keister.

A private report of Ma rcellus frac water composition was prepared for the Marcellus Shale
Coalition 21 . This report surveyed frac waters from 19 locations during both the early flowback period (1

- 5 days) and later periods (14, 90 days). The range and median values of TDS and

sp ecific ion concentrations reported are consistent with values shown in Table 1 and in the samples that we obtained (discussed in Section II

- B below).

Table 1

. Marcellus Frac Water Compositions (all concentrations in mg/L)
Component Low

- TDS Medium

- TDS High

- TDS “Typical”

TDS 69,640 175,300 248,000 195,000 Mg 438 938 1,630 1,300

Ca 5,140 14,100 31,300 18,000

Sr 1,390 6,830 2,000 4,000

Ba 2,300 3,310 4,300 6,500

Fe 11.2 52.5 134 60

Mn 1.9 5.17 7 5.0



### B. Produced Water Samples

We obtained Marcellus shale gas produced water from horizontal wells in four Pennsylvania counties. Samples were obtained from either portable frac tanks adjacent to a recently hydrofractured well or from a permanent tank at a well site. In addition, one sample was taken from a salt water disposal facility in the Barnett Shale (T exas).

Table 2 shows the measured composition for these samples. All ionic species were measured by inductively coupled plasma (ICP). Only one sample (Well

- 4) had a measurable level of sulfates; the same sample had a very low bariu m level. The appearance of the frac water sample s when received ranged from clear to orange

- brown.

The level of 226 Ra in each sample was measured using gamma spectrometry. Several of the

226 Ra gamma spectrometry measurements were conducted both at GEGR and at the New York State Department of Health, with excellent agreement between the two sites. The GEGR results are reported in Table 2

.6

Based on the measured composition of the Marcellus produced water samples shown in Table

2 , we identified a design case produced water composition (“Design Case”). For the design case, each species concentration approximates the median of the measured concentrations.

Table 2

. Produced Water Compositions from Pennsylvania Marcellus Shale Gas Wells.

(all quantities mg/L except where noted)

Well

- 1 Well

- 2 Well

- 3 Well

- 4 Well

- 5 Well

- 6 Well

- 7 a Design

Case County Bradford Bradford Bradford Butler Tioga Washington pH b 7.3 6.3 5.4 5.8 5.9 6.2 6.6 7.0

TDS 98,294 155,705 199,242 68,439 149,188 122,562 124,421 132,460

Na + 26,500 38,200 51,800 19,200 39,000 32,300 33,900 35,000 Mg ++ 460 840 1290 570 1,000 800 1,170 800

Ca ++ 5,560 10,280 13,120 5,360 13,000 8,700 10,880 9,500

Sr ++ 2,030 3,670 4,580 1,290 2,600 2,340 1,750 2,500

Ba ++ 6,580 13,200 11,600 32 3,500 5,800 147 6,200

Fe ++ 26 74 123 55 32 75 47 50

Mn ++ 1.5 2.5 3.4 1.7 2.7 4.3 1.2 3
Cl - e 57,120 89,429 116,713 41,845 90,014 72,525 76,493 78,407

SO 4 = <10 <10 <10 57 <5 <50 <100 0

SiO 2 16.7 11 13 29 39 18 33 0
Hardness

as Ca ++ 9,167 17,196 20,727 6,899 16,860 12,782 13,653 13,772

226 Ra c 5,400 7,600 4,200 4,600 5,600 820 2300 5,000

TSS 202 282 500 62 520 210 898 0 Turbidity d 78 399 1160 17.4 192 45 164 0

TOC <10 11.8 11.8 72 151 160 88 0 PW Type f III III III I III III I III

a Produced water from Barnett Shale (TX)

b dimensionless

c pCi/Liter

d Turbidity units: NTU

e adjusted to force ion balance (prior analyses found other anions were <1% of the chloride on a molar basis)

f Produced Water Type (see Figure 4 below for map of produced water types)



## III. Current Process es for Produced Water Recovery

Figure 2 shows a schematic diagram of GE WPT ’s current mobile evaporation process for recovery of distilled water and a brine concentrate from produced water . In this figure, all quantities are based on the design case produced water composition . This is a very direct option for frac water recovery

, including h igh

- TDS produced waters that contain significant
levels of 226 Ra and/or barium. This results in limited water recovery, but avoids generating solids with high 226 Ra or barium level s

. Current methods for produced water pretreatment7

prior to thermal evaporatio n include oxidation and lime treatment, which precipitates iron and manganese and removes suspended solids 22

, 23

. Pretreatment for barium and radium is not required; barium and radium are carried along with the concentrate. Assuming that the

concentra te leaving the evaporator has 30 0,000 mg/L TDS, 0.56 bbl of distilled water is recovered per bbl feed produced water for the design case. Table 3 shows the concentration factor and the cost of transportation and disposal of the concentr ate, assuming transport from
north

- central Pennsylvania to Ohio and disposal by UIC in Ohio. The estimated cost for concentrate transportation from central Pennsylvania to Ohio and disposal by UIC is $11 /bbl.

In lab experiments with Marcellus produced waters, t he 226 Ra activity measured by gamma spectrometry in the pretreated produced water was identical to that of the untreated produced water, within the accuracy of the measurement. From this, we infer that the pretreatment sludge contains negligible 226 Ra activity.

The GEWPT mobile evaporator is currently undergoing field trials with produced water.

Figure 2 . Current Produced Water Recovery Process (Design Case Produced Water Composition )



### A. GEWPT Pilot

- Scale Evaporator/ Crystallizer Trials with Marcellus Produced

Water

GEWPT conducted pilot

- scale trials of Marcellus produced water evaporation in a vertical falling film evaporator and crystallization of the evaporator blowdown to generate a solid NaCl salt product and dist i lled water

. Table 4 shows the composition of the evaporator feed (pretreated produced water) and the crystallizer feed. The crystallizer product passed TCLP and met ASTM

D

- 635 standards for use as road deicing salt. Figure 3 contrasts the appearance of the original produced water, the distilled water product, and the recovered salt product.8 Table 3

. Produced Water Evaporation : Water Recovery

Well Number 1 2 3 4 5 6 7 Design

Case Feed TDS, mg/L 98,294 155,705 199,242 68,439 149,188 122,562 124,421 132,460
max water recovery: (wt H 2 O)/( wt feed ) b 0.902 0.844 0.801 0.932 0.851 0.877 0.876 0.868

Max water recovery: (vol H 2 O)/(vol feed) 0.970 0.947 0.930 0.981 0.950 0.960 0.959 0.956

Evaporation only:
fraction of maximum
water recovery c 0.705 0.522 0.376 0.796 0.543 0.628 0.623 0.597

concentration factor, ( V ol feed ) / ( V ol conc ) 3.05 1.93 1.51 4.38 2.01 2.45 2.41 2.26

bbl distilled water/
bbl feed 0.700 0.513 0.365 0.793 0.535 0.622 0.616 0.590

Concentrate disposal

cost a , $/bbl feed $ 3.93 $ 6.23 $ 7.97 $ 2.74 $ 5.97 $ 4.90 $ 4.98 $ 5.30

a Cost for transportation from north

- central Pennsylvania to Ohio and UIC disposal in Ohio

b 100% dry salt product

c Conc entrate: 30 0,000 mg/L TDS

Based on the measured barium concentration in the salt product and in the produced water

, we estimated the produced water barium concentration for which the result ing barium concentration in a TCLP extract would equal 100 mg/L , the maximum value permissible under TCLP. The estimated value, [ Ba ] max , is in the range of 1,000

- 2,000 mg Ba/L produced water.

Assuming that barium and radium behave identically in the NaCl crystal lization process, we estimate d the radium content in the sol id salt product for a specified radium activity in the produced water. This assumption is based on the fact that the ionic radii of Ba +2 (1.49 Å ) and

Ra +2 (1.62 Å ) are very similar , and that barium and radium behave essentially identically in all

c rystallization processes 24

.

The design case produced water contains 5,000 pCi 226 Ra/liter. For this case, the estimated

226 Ra activity in the salt product is well below 10 pCi/gm

.9 Figure 3

. GEWPT Pilot Trial Results for Thermal Recovery of

Water and Salt from Produced Water

This pilot test of produced water evaporation and crystallization demonstrates the feasibility of recovering distilled water and a salable salt product from produced w ater by thermal evaporation and NaCl crystallization. This pilot test also provides a basis for estimating [ Ba ] max . These pilot results support the assertion that for the design case produced water (5,000 pCi

226 Ra/L) as well as produced waters with sign ificantly higher radium activities , the estimated radium activity in the product salt is well below the permissible level for disposal as
nonhazardous waste in a RCRA

- D landfill (<25 pCi 226 Ra/gm in PA) and is therefore negligible.

Table 4

. Produced Water Composition for Pilot Ev aporator and Crystallizer Test

(all quantities mg/L except where noted)

Evaporator
Feed Crystallizer

Feed pH 6.0 5.9

TDS 122,000 271,000

Na + 30,800 68,100

Fe ++ <0.5 <0.5

Mn ++ <0.2 <0.2
Cl 70,200 155,000

SO 4 = <10 15

SiO 2 <10 42

TSS None None Turbidity , NTU <0.1 0.4



### B. Produced Water Pretreatment Map

We developed the pretreatment map shown in Figure 4 based on the results of the produced water evaporation and crystallization pilot study conducted by GEWPT described above and sulfate precipitation materi al balance calculations (Section IV.C , below)

. This map identifies
three “ types ” of produced water based on their barium concentrations and radium activities

. The produced water compositions analyzed in this study are superimposed on this map. Each10

type of produced water requires a different pretreatment for barium removal prior to NaCl crystallization

.

Type I: The produced water barium concentration is below [ Ba ] max ( a value in the range 1,000

- 2,000 mg/L ) and is not restricted with respect to 226 Ra activity. Type I produced waters require neither barium nor radium removal prior to NaCl crystallization

. Produced waters from Well

- 4 and Well

- 6 are of Type I

.

Type II: The produced water barium concentration is higher than [Ba] max . Barium removal is needed prior to NaCl crystallization. Pretreatment of Type II produced water by sulfate precipitation y ields a sulfate sludge that is safe for disposal in a RCRA

- D landfill because the 226 Ra activity in the sludge is below the limit established by the state (25 pCi 226 Ra/gm sludge in PA). The location of the
red line in Figure 4 depen ds on the RCRA

- D limit for 226 Ra activity in a particular state. It is assumed that the sulfate sludge is 45 wt% solids.

Type III: The produced water barium concentration is above [Ba] max . Therefore, barium removal is needed prior to NaCl crystallizati on. Because the 226 Ra activity
is above the red line in Figure 4 , a pretreatment process other than direct sulfate precipitation must be used.

Figure 4 . Map of Produced Water Types and Barium Removal Pretreatment Requirements

(symbols represent produced water compositions analyzed in this study)11



## IV. Type III Produced Water Pretreatment Process Options

To recover distilled water and a salable salt from Type III produced waters, it is necessary to remove barium by a method other than direct sulfate precipitation

. Sulfate precipitation for Type III produced waters would be acceptable if the radium is first removed from the produced

water. We sought methods to selectively remove radium from produced water, including

DOWEXTM RSC (radium specific complexer) resin. In Appendix I, we review the literature on RSC
resins and show the results of laboratory screening of a variety of adsorbents for selective
removal of radium from produce d water

. As described in Appendix I

, of the 60 adsorbents that
we screened , none was economically feasible. Therefore, we abandoned the effort to selectively remove radium from produced water.

As shown in Figure 5 , we analyzed six processes for removal of barium , radium, and other multivalent cations from high

- TDS brines. These include ion exchange, nanofiltration, sulfate precipitation, carbonate precipitation, the modified lime

- soda process , and MnO 2 adsorption

. Each process is reviewed in the following sections.

Figure 5 . Schematic Diagram of Type III Produced Water Recovery Process

and Pretreatment Options



### A. Ion Exchange

As shown in Appendix I I for the design case produced water , a pproximately one bed volume of chelating ion exchange resin is required to soften one bed volume of produced water. Thus, the ion exchange resin will be exhausted after it has processed one bed volume of produced water. The cost for regeneration chemica ls and disposal of waste streams by UIC is calculated
to be over $6 /bbl produced water. This cost is quite high, and it does not include the cost of sourcing or disposing of rinse water, which is needed after acid treatment and after caustic12

treatment. T he regeneration rinse waters could most likely be combined, neutralized, and sent

to an industrial wastewater treatment plant . Because of the high cost and need to handle significant volumes of rinse water, chelating ion exchange is not recommended for softening
Marcellus produced water

.



### B. Nanofiltration

Appendix II I shows simulation results for NF softening of produced water using WINFLOWS
software from GEWPT. Produced waters from both the design case and Well

- 5 were considered. Maximum softened water ( permeate) recovery calculations were based on a feed pressure upper limit of 600 psia. Table 5 shows the maximum permeate recovery calculated
from t he simulations for both cases.

Table 5 . Nanofiltration: S imulation Results

Well

- 1 Well

- 2 Well

- 3 Well

- 4 Well

- 5 Well

- 6 Well

- 7 Design

Case Maximum permeate recovery based on Winflows Simulation (%) 15 30

As noted above, the estimated cost for concentrate transportation from central Pennsylvania to Ohio and disposal by UIC is $11 /bbl. For the design case produced water , the maximum permeate water recovery was 30%. At this recovery level, the transportation and disposal cost for the concentrate is $7.7 0 per bbl feed produced water. Based on the lo w recovery and the resulting high disposal cost of the concentrate, it is recommended that NF technology not be

pu rsued for produced water softening.



### C. Sulfate Cop recipitation of Barium and Radium

This section describes produced water pretreatment by sulfate precipitation and shows ( through material balance calculations ) that direct sulfate precipitation should not be utilized to pretreat Type III produced waters.

Sulfate precipitation is currently practiced for treating produced water. ProChemTech

Intern ational, Inc. describes a chemical treatment process that pretreats produced water using three sequential precipitation steps 25 . The first step removes barium by precipitation as barium
sulfate 26 , which is non

- leaching by TCLP. The subsequent precipitation steps remove the remaining scale formers. ProChemTech also describes a process in which produced water is treated with sulfuric acid to precipitate a barium sulfate sludge followed by lime/soda softening to generate a calcium carbonate sludge 27

.

Veil 28 de scribes four commercial wastewater disposal facilities in Pennsylvania that, as of May, 2010, treated frac water and disposed of the treated water to either a POTW or a river under

NPDES 29 permits. At these facilities, f rac water is typically treated with sodium sulfate in order13

to precipitate barium, followed by lime treatment to precipitate magnesium and other hardness species. Precipitate from these steps is settled in a thickener and dewatered in a filter press. The sludge is sent to a local landfill.

Reserved Environmental Services 30 operates a 1.2 MGD produced water treatment fac ility in southwest Pennsylvania. TerrAqua 31 operates a 0.4 MGD facilit y in Williamsport, Pennsylvania.
Both facilities remove barium, strontium, iron, and suspended solids f rom produced water and
return the treated water to the customer for use in subsequent drilling and hydrofracturing operations. Because the sludge generated must pass TCLP, it is assumed that sulfate is used to precipitate barium and strontium as BaSO 4 and SrSO 4 , respectively. Precipitation of barium and strontium with sulfate is attractive because sodium sulfate is relatively inexpensive ($130

- 160/short ton, anhydrous) 32

, and BaSO 4 and SrSO 4 are nonhazardous

. These plants may be expanded to include thermal evaporation and crystallization to yield a saleable salt product and
distilled water. Additional frac water treatment plants are in operation in Pennsylvania.

D ozens of additional treatment plants are in th e planning stages and many have received permits 28

.



### a) Radium Solubility in Sulfate Environments

For radium

- containing produced waters, sulfate treatment yields a coprecipitate of barium

su lfate and radium sulfate (radio barite, Ba(Ra)SO 4 ) , which is a solid solution of RaSO 4 and

BaSO 4 . Radio barite is well

- known in the oil and gas industry. The EPA estimates that one

- third of all domestic oil and gas wells produce some radium

- contaminated scale 33 . Radium sulfate is
one of the least water

- soluble salts

. The solubility of RaSO 4 alone in water is 4.8x10 - 8 M (11 ppb /w Ra, or 11x10 6 pCi Ra/L ) 34 , which is about three orders of magnitude higher than the highest 226 Ra activity found in Marcellus pr oduced water (10,000 pCi/L)

. However, the presence of barium reduces the radium sulfate solubility significantly. Doener and Hoskins 35 , in 1925, confirmed that in the presence of sulfate ion, a solution of RaCl 2 and BaCl 2 coprecipitates

as RaSO 4 and BaSO 4 even when the concentrations of Ra ++ and SO4 = are far below the solubility
of RaSO 4 in water. They concluded that barium and radium coprecipitate to form a solid
solution of RaSO 4 and BaSO 4 . Under ideal solid solution conditions, the calculated solubili ty 36 of

RaSO 4 in equilibrium with a solid solution of (Ra,Ba,Ca, Sr ) SO 4 is 7 x 10 - 13 M, or 2 x 10 - 7 ppm /w 37

Ra. This calculated solubility of Ra is equivalen t to 200 pCi/L of 226 Ra. In GEGR laboratory experiments with Well

- 3 produced water, the radium activity in solution after addition of an excess of sodium sulfate (vs. barium) was non

- detectable by high purity germanium (HPGe) gamma spectrometry. The detection limit for 226 Ra was 17 pCi/liter.



### b) Material Balance for Barium and R adium Sulfate Precipit ation As noted above, s ulfate sludge may be safely and economically disposed of as nonhazardous
solid waste in a RCRA

- D landfill if the 226 Ra activity in the sludge is below 5

- 50 pCi/gm. The limit varies by state and i s 25 pCi/gm for Pennsylvania. The co st for sludge disposal as nonhazardous

waste in a RCRA

- D landfill is typically about $50/ton. Sludge that exceeds th is value must be disposed of as Low Level Radioactive Waste ( LLRW )

. Energy Solutions, Inc. (Utah) charges about $200/ft 3 (excluding transp ortation) for disposal of Class A LLRW, which can contain up to 10 nCi/gm 226 Ra.14

We conducted a simple material balance to estimate the radium activity in the (Ba, Ra ) SO 4 sludge. We assumed that on addition of a stoichiometric amount of Na 2 SO 4 to produced water,
all the barium and radium in the raw produced water precipitate as (Ba, Ra ) SO 4 sludge, and that no other components precipitate. We also assumed that the sludge would be dried to 45% solids before being transported to a landfill. Figure 6 shows the calculated radium activity in the wet sludge as a function of the radium activity in the produced water feed for six levels of
barium in the produced water 38

. Design case produced water contains 6,200 mg barium/L. For this barium concentration, the produced water 226 Ra activity must be below about 600 pCi/L for the resulting sulfate sludge to meet Pennsylvania’s RCRA

- D disposal criteria. F or all produced waters analyzed in this study , the calculated 226 Ra activity in a hypothetical (Ba,Ra)SO 4 sludge is above 25 pCi/gm , as shown in Table 6 . Therefore, the sulfate sludge would need to be either
blended with sufficient non

- radioactive solid waste to meet the RCRA

- D specification for 226 R a activi ty or treated as LLRW.

Table 6 also shows the amount of wet sulfate sludge generated per barrel of produced water, as well as the cost of disposing of this sludge as LLRW. The cost of sludge disposal as LLRW is prohibitive. Because Well

- 4 and Well

- 7 are Type I produced waters, they do not need pretreatment for barium removal prior to NaCl crystallization.

Table 6 . Material Balance for BaSO 4 - RaSO 4 Sludge (45 wt% solids)

Well Number 1 2 3 4 a 5 6 7 a De sign

Case

226 Ra Activity in wet Sludge, pCi/gm 217 152 95.9

- 424 37.4

- 213

Wet Sludge quantity lb/bbl Produced Water 8.71 17.5 15.4

- 4.63 7.68

- 8.21

LLRW Disposal Cost $/bbl Pr oduced W ater $18 $36 $32

- $10 $16

- $17

a Type I produced water15 Figure 6 . Calculated Sludge 226 Ra Activity for (Ra, Ba ) SO 4 Coprecipitation



### D. Lime

- Soda Precipitation

Treating produced water with lime and sodium carbonate precipitates magnesium as Mg(OH) 2 and calcium, stron tium, barium , and radium 39 as t heir corresponding carbonates

. Table 7 shows, for each produced water, the calculated 226 Ra activity for the wet carbonate sludge resulting from complete softening by lime

- soda treatment (sludge: 45 wt% solids) . Each of these activities is higher than the maximum level permitted for RCRA

- D disposal in Pennsylvania. These sludges would have to be disposed of as LLRW, and the cost for disposal would be prohibitive

.

Table 7 . Calcul ated Barium Concentration and 226 Ra Activity in Wet Carbonate Sludge

for Lime

- Soda Treated Produced Waters (45% solids)

Well Number 1 2 3 4 5 6 7 Design

Case pCi 226 Ra/gm wet sludge 87.2 64.7 31.4 143.2 56.9 10.3 31.2 58.0

Ba in wet sludge , ppm/ w 106K 112K 86.6K 848 35.5K 72.6K 2.00K 80.0K LLRW Disposal cost, $/bbl $45 $86 $98 $28 $72 $59 $54 $63 Produced Water Type III III III I III III I III

In addition, barium carbonate is easily leached with acid, and sludge that yields above 100 mg barium/L in a TCLP extract will not pass TCLP

. Table 7 shows that for all Type III produced
waters, the barium concentration in the precipitate is far too high to be suitable for disposal in16

a RCRA

- D landfill. Thus , lime

- soda softening and slud ge disposal of Type III produced water is not practical.



### E. Modified Lime

- Soda Process

1. Introduction

Table 8 shows the costs of disposal and restrictions on 226 Ra activity for three disposal options for pretreatment process byproducts . The low di sposal cost by UIC for waste that contains

226 Ra is a strong motivation to develop a process that yields an aqueous 226 Ra (and barium)

concentrate. According to the Ohio Department of Natural Resources, which manages the underground injection control (UIC) program, there is currently no official limitation on the

226 Ra activity or barium concentration in liquids disposed of by UIC. In addition, disposal by UIC is regarded as a safe method to avoid groundwater or aquifer contamination.

Table 8 . Disposal Costs (excluding transportation)

RCRA

- D Nonhazardous
Landfill UIC (Deep

- well Injection) Low

- Level Radioactive

Waste (LLRW)

Locations 50 sites in PA Ohio, WV Utah

Maximum 226 Ra pCi/gm 25 (in PA)

- 10,000 Disposal cost: $/short ton 50 11.5 6,400

Fig ure 7 shows a schematic diagram of the modified lime

- soda process to pretreat Type III produced water . Produced water is first oxidized and contacted with lime to precipitate magnesium as Mg(OH) 2 , iron as Fe(OH) 3 , and manganese as MnO 2 . Just over 1 mole Ca(OH) 2 per mole Mg results in essentially complete precipitation of Mg as Mg(OH) 2 . The pH in Precipitation S tage 1A is about 10.6

- 10.8. Sodium carbonate is then added to selectively precipitate calcium and strontium. The pH in Precipitation Stage 1B is about 11

- 11.3. Precipitation Stages 1A and 1B may be conducted in a single vessel. The precipitates from Stages 1A and 1B are nonhazardous and may be disposed of in a RCRA

- D nonhazardous landfill.

In Precipitation Stage 2, the produced water is treated with additional sodium carbonate to precipitate both barium and radium as carbonates. The Stage 2 precipitate is removed from the produced water and treated wit h concentrated HCl to convert BaCO 3 and RaCO 3 to CO 2 , BaCl 2 , and RaCl 2 . Carbon dioxide is vented to the atmosphere , optionally though a carbon adsorbent to trap radon gas. The HCl addition is adjusted to achieve a pH low enough to strip essentially all o f the carbonates from the aqueous concentrate stream (e.g. pH 2

- 4). This concentrate stream may be neutralized if desired prior to disposal by UIC.

After Precipitation Stage 2, the softened produced water still contains a significant
concentration of d issolved carbonates (about 450 ppm/w CO 3 = for design case produced water).
HCl is added to this stream to drive off CO 2 . The softened, decarbonated produced water may then be thermally treated to recover distilled water and a solid salt product.17 Fig ure 7 . Schematic Diagram of Modified Lime

- Soda Process

This process exploits the relative solubilities of the Group II metal c arbonates. Table 9 shows
that calcium and strontium carbonate are less soluble than either barium or radium carbonate and are thus expected to precipitate preferentially over barium and radium carbonate as
sodium car bonate is added to the system.

The produced water pretreated by this process is essentially completely softened. This enables very high water and NaCl recoveries. Further, the relatively pure salt product may be usable for higher value applications than road deicing. For example, the salt product may be used as feedstock for caustic and chlorine production or for indus trial water softening.

Table 9 . Water Solubility of Group II Metal Carbonates 40
Species Solubility, gm/100 gm H 2 O Temperature,  C MgCO 3 .5H 2 O 0.176 7 MgCO 3 0.0106 ~20

CaCO 3 (calcite) 0.0014 25

CaCO 3 (aragonite) 0.00153 25

SrCO 3 0.0011 18

BaCO3

- alpha 0.002 20

BaCO 3 - beta 0.022 18

BaCO 3 - gamma 0.0022 18

RaCO 3 more soluble than barium carbonate 24



### 2. A spen Plus  

### /OLI Simulations

We conducted Aspen Plus  /OLI simulations of the modified lime

- soda process. Figure 8 shows simulation results for the design case. Prior to Na 2 CO 3 addition, the magnesium has been essentially completely precipitated by li me addition. This figure shows that as Na 2 CO 3 is added to the system, CaCO 3 precipitates first, followed by coprecipitation of both CaCO 3 and SrCO 3
.18

Barium carbonate does not begin to precipitate until the calcium and strontium have been nearly completel y precipitated. At about 1.15 times the stoichiometric amount of Na 2 CO 3 , the barium precipitation is essentially complete. At this point, the solution contains about 50 ppm/w Ba (compared with over 5600 ppm/w in the feed solution). The target barium

con centration in Precipitation S tage 2 may be defined through additional laboratory and pilot testing. Appendix I V shows precipitation plots for each of the produced waters characterized in
this study

.

Figure 8 . Simulation Results for Modified Lime

- Soda Process: Design Case



### 3. Modified Lime

- Soda Pretreatment Process Cost Calculations

Table 10 shows the calculated chemical and disposal costs for the produced waters considered in this study. Table 10 reports both a minimum and maximum cost estimate for each produced water considered in this study. The minimum cost assumes that in both Precipitation Stages

1A

- 1B, and Precipitation Stage 2, equilibrium conditions prevail. Under equilibrium conditions, negligible amounts of barium and radium precipitate in Stages 1A

- 1B along with the magnesium, calcium, and strontium. Similarly, negligible amounts of magnesium, calcium, and strontiu m precipitate in Stage 2. For the design case produced water, the minimum cost for chemicals and disposal is $3.5/bbl produced water feed.

The maximum cost is based on no selectivity in the carbonate precipitation process. Thus, Precipitation Stages 1 B and 2 are combined. Calcium, strontium, barium, and radium precipitate together as a single mixture. In this case, no carbonates are disposed of as RCRA

- D waste. All carbonates are treated by HCl to generate a chloride concentrate for UIC disposal.19

F or the design case produced water, the maximum cost for chemicals and disposal is $5.8/bbl produced water feed.

Table 10 . Chemical and Disposal Costs for Modified Lime

- Soda Process
Well Number 1 2 3 4 5 6 7 Design Feed TDS, mg/L 98,294 155,705 199,242 68,439 149,188 122,562 124,421 132,460

Hardness as Ca ++ , mg/L 9,167 17,196 20,727 6,899 16,860 12,782 13,653 13,772 Feed Ba, mg/L 6,580 13,200 11,600 32 3,500 5,800 147 6,200 lb dry Ca(OH) 2 /bbl PrW a 0.489 0.918 1.45 0.589 1.01 0.870 1.24 0.876 lb dry Na 2 CO 3 /bbl PrW 8.56 16.8 21.0 6.71 14.9 14.6 13.1 13.2

Case 1: 100% Carbonate Precipitation Selectivity (Minimum Cost) lb dry HCl/bbl PrW 1.44 2.95 2.91 0.288 1.25 2.50 0.285 1.51

Chemicals & Disposal $/bbl Produced Water $2.45 $4.87 $5.78 $1.54 $3.77 $3.89 $2.98 $3.50

bbl UIC disposal/bbl Pr W 0.0307 0.0633 0.0606 3.3x10 - 5 0.0251 0.0301 5.2x10 - 4 0. 0305

lb wet solids to RCRA

- D/
bbl Produced Water 15.0 28.8 38.6 14.3 29.8 23.1 29.0 25.2

Case 2: 0% Carbonate Precipitation Selectivity (Maximum Cost) lb dry HCl/bbl PrW 5.68 11.1 13.78 4.19 9.94 8.07 8.60 8.74 Chemicals & Disposal $/bbl Produced Water $3.84 $7.53 $9.37 $2.93 $6.67 $6.09 $5.84 $5.91

bbl UIC disposal/bbl PrW 0.0944 0.185 0.227 0.0664 0.161 0.132 0.133 0.143

lb wet solids to RCRA

- D/
bbl Produced Water 0.83 1.59 2.51 1.01 1.74 1.47 2.14 1.49

a PrW: Produced water



### 4. Laboratory Tests of Modified Lime

- Soda Process

We conducted two exploratory laboratory experiments to test the modified lime

- soda process and one experiment in which NaOH was substituted for Na 2 CO 3 during Precipitation S tages 1A
and 1B

. Appendix I V shows the details of these experiments. In each of the first two experiments, a sample of produced water was added to a beaker and first treat ed with lime, followed by addition of Na 2 CO 3 , either portionwise or continuously. Samples of the supernatant were filtered and analyzed for residual radium by L iquid Scintillation Counting (LSC). For a given sample, the radium activity is proportional to the measured counts per minute (CPM). Results are reported as the fraction of the produced water CPM remaining in solution after a specific amount of Na 2 CO 3 has been added. Since barium and radium coprecipitate as carbonates, it is assumed that the frac tion barium remaining in solution is approximately equal to the fraction radium remaining in solution 24

.

Ideally, the fraction radium activity remaining in solution is unity until the number of moles of

Na 2 CO 3 added equals the number of moles of Ca ++ + Sr ++ in the feed solution, followed by a
decrease to zero as the number of moles to Na 2 CO 3 increases to about 1.15 times the number
of moles of Ca ++ + Sr ++ + Ba ++ in itially in the produced water. The 15 % molar e xcess carbonate
value is based on the simulation results for Well

- 5 produced water. According to the simulation,20

with 15 % molar excess Na 2 CO 3 addition, the residual barium concentration in solution is 59 ppm/w, which corresponds to a reduction of about 99 % vs. feed concentration.



### a) Experiment 20110826 with Well

- 5 Produced Water

We added one liter of Well

- 5 produced water and a magnetic stir bar to a beaker. After Ca(OH) 2 addition, Na 2 CO 3 was added to the agitated mixture in ten equal portions . Enough

Na 2 CO 3 was added to precipitate all of the calcium, strontium, and barium. Each portion was added essentially instantaneously. Approximately two minutes elapsed between Na 2 CO 3 additions.

Instead of the ideal behavior, Figure 9 shows t hat the fraction feed CPM decreased monotonically with increasing Na 2 CO 3 addition. This suggests that barium and radium precipitated in proportion to the amount of Na 2 CO 3 addition. Thus, under these conditions, the process showed no selectivity for the l ess soluble carbonates (Ca, Sr) over barium and radium. It is hypothesized that the Na 2 CO 3 addition rate was too high (for the mixing intensity afforded by the magnetic stir bar) for near

- equilibrium conditions to apply.

Figure 9 . LSC Results for Experiment 20110826



### b) Experiment 20110901 with Well

- 5 Produced Water

Experiment 20110826 was repeated with addition of a solution of Na 2 CO 3 to an agitated

mixture of Well

- 5 produced water at a constant rate over the course of 316 minute s. Figure 10 shows the results of this experiment. Although the ideal behavior was not achieved, this experiment shows that steady, slower Na 2 CO 3 addition resulted in much better selectivity than observed in experiment 20110826. Ad ditional tests are planned with improved agitation and other techniques to more closely approach ideal behavior.21 Figure 10 . LSC Results for Expt 20110901



### c) Experiment 20110708 with Well

- 5 Produced Water

This test utilized NaOH t o precipitate Mg, Ca, and Sr as the corresponding hydroxides, followed by Na 2 CO 3 to precipitate Ba and Ra as the carbonates. This approach is based on the relatively high solubility of Ba(OH) 2 (5.6 gm Ba(OH).8H 2 O per 100 gm H 2 O at 15  C 40 ), which serves to keep
barium and radium in solution while magnesium, calcium, and strontium precipitate as hydroxides.

NaOH was added portionwise to a beaker of Well

- 5 produced water and the supernatant was sampled after each aliquot for LSC analysis. After the last NaOH addition, the slurry was filtered through a 1  glass filter. The filtrate was placed back into the beaker and the agitation was restarted. Then a series of six portions of Na 2 CO 3 was added in the same manner, with sampling after each portion.

Figure 11 shows the results of this experiment. Here, the barium and radium remain in solution throughout the course of the NaOH addition. The total amount of NaOH was sufficie nt to precipitate all of the magnesium, calcium, and strontium. Although excess Na 2 CO 3 was added,

more Na 2 CO 3 may be necessary to completely precipitate the barium and radium as carbonates. This can be determined with further experimental and simulation studies. Although this process shows better selectivity toward Group II metals other than barium and radium in the first step, the cost of NaOH per equivalent is about 30% higher than the cost of Na 2 CO 3 per equivalent. Further, the precipitate obtained f rom the NaOH addition was very difficult to filter.22 Figure 11 . LSC Results for Experiment 20110708



### F. MnO 2 

### Barium and Radium Adsorption Process

We identified MnO 2 as an effective adsorbent for barium and radium removal from produced

water. We tested MnO 2 adsorbents that were made at Pacific Northwest National Laboratory ( PNNL ) and obtained from commercial sources.

We also demonstrated that barium and radium can be stripped from these adsorbents using
dilute HCl. This conce ntrate of RaCl 2 and BaCl 2 can be disposed of by UIC. We showed that regenerated MnO 2 adsorbent is effective for reuse. Alternatively, HCl

- treated adsorbent can be rinsed and disposed of as nonhazardous solid waste as long as it meets RCRA

- D disposal criteria

. On the basis of the materials and disposal costs, this process is less expensive than the modified
lime

- soda process. However, for adsorbents that hav e commercially practical barium and
radium capacity in pr oduced water applications , the particle size is in the micron or submicron

range . Additional development is required to define cost

- effectiv e methods of particle handling. Suitable methods must be developed for contacting th e particles with produced wate r, filtering the particles from the treated produced water, and recovering the particles for HCl treatment and disposal

. This process is currently under development at GEGR.



### 1. MnO 2 

### Characterization and Capacity Screening

For adsorbent capacity screening stu dies , we measured the radium capacity of each adsorbent by LSC. Adsorption experiments were also conducted in which both barium and radium capacities were measured . These experiments, in substantial agreement with an earlier study by Moon et al 41

, showed that MnO 2 adsorbs comparable percentage s of both barium and
radium from solution

.

We measured the 226 Ra adsorption capacity of both commercially available MnO 2 powder (Fluka Activated MnO 2 ) and 14 proprietary MnO 2 adsorbents obtained from PNNL

. All mater ials in this study were powders. The Fluka activated MnO 2 was pure MnO 2 powder. Each PNNL23

material was characterized by BET for surface area and by Energy Dispersive Spectroscopy (EDS) for bulk composition. As shown in Table 11 , t he materials from PNN L comprise various forms of

MnO 2 supported on silica. These materials are referred to as “resins”.

We first screened the PNNL materials for their 226 Ra capacity using Well

- 4 produced water. Even though Well

- 4 produced water is Type I, it was useful for these studies because it afforded significant 226 Ra capacity to each adsorbent, which enabled the use of LSC for capacity

measurements. Table 11 shows that PNNL samples C, D, F, G, I, K, and L have the highest 226 Ra capacities.

We also evaluated the adsorption and regeneration performance of material “C” for bot h 226 Ra
and barium

. For these studies, we measured 226 Ra activity by LSC and barium concentration by

ICP.



### 2. MnO 2 

### Regeneration Process
We conducted nine adsorption

- regeneration tests with Fluka activated MnO 2 , using Well

- 4 produced water and HCl for regenera tion. These tests focused on defining regeneration process conditions. The performance of a given regeneration condition was measured by both
the amount of 226 Ra removed from the adsorbent and the amount of 226 Ra capacity in the next adsorption cycle, as measured by LSC.

Table 11 . Characterization of PNNL Adsorbents

Resin:

PNNL

BET

Area,

m 2 /gm Principal Components

(EDS) 226 Ra Capacity,

pCi/gm resin with
Well

- 4 produced

water Morphology

A 32.1 Mn 69 ~100  , multi

- faceted particles; very little fine

structure B

<30 Mn 13

C 203 Mn, Si support, K 2350

Aggregates of ~100 nM particles; high surface

area D 75.7 Mn, Si support, K 2165

E 74.9 Fe 102

F 54 Mn, Fe 2015

G 280 Mn, Si support 2620

H 69.7 Fe 5

I 96.0 Mn, Fe 2120

J 82.6 Fe 619

K 149.2 Mn, Fe 2130

L 95.2 Mn, Fe 2220

M 107.7 Mn, Fe 253

N 65.82 Mn, Fe 41924

Each MnO 2 sample went through four complete adsorption

- regeneration cycles, followed by a fifth adsorption capacity test. The regeneration experiments utilized either 0.01N, 0.1N, or 1.0N HCl. These tests covered a factor of 400 in the amount of regeneration HCl per gram MnO 2 (0.2

- 80 mmol HCl per gm MnO 2 ).

Figure 12 shows the performance of Fluka activated MnO 2 with respect to 226 Ra adsorption and regeneration. The adsorption behavior was essentially unchanged from cycle

- to

- cycle, but

surpr isingly, the regeneration effectiveness increases in each subsequent cycle.

Figure 12 . Adsorption and Regeneration Study for Fluka Activated MnO 2

Figure 13 shows the effect of rege neration HCl usage on the effectiveness of the regeneration for each of the four regeneration cycles. The amount of 226 Ra regenerated (desorbed) from

MnO 2 is roughly proportional to the log of the regeneration HCl usage, and is essentially independent of the HCl concentration. The results of Figure 13 suggest that 2

- 4 mmol HCl per gm MnO 2 is effective for regenerating the MnO 2 used in these tests.

The regeneration effectiveness may also be measured by the amount of 226 Ra that is adsorbed by the resin on Cycle 5. Figure 13 shows this value plotted against the regeneration HCl usage (mmol HCl/gm MnO 2 ). These r esults suggest that 0.8 mmol HCl per gram MnO 2 is sufficient to fully regenerate MnO 2 , even though at this loading the amount of 226 Ra desorbed (96 pCi in Cycle 5) is only about 60% of the amount adsorbed. Additional testing will be needed to define

an HC l treatment that enables tens or hundreds of adsorption

- regeneration cycles.25 Figure 13 . Effect of Regeneration HCl on Radium Removal Effectiveness



### 3. PNNL

- C Adsorbent Capacity and Regenerability

We conducted a series of experiments to test the adsorption capacity and regenerability of

PNNL

- C adsorbent

. Table 12 shows the overall performance of PNNL

- C adsorbent for both
barium and 226 Ra adsorption and regeneration by HCl. We used Well

- 4 produced water in each loading cycle and 0.1N HCl as a regenerant. For a regeneration control, we used DI H 2 O. Experiments 10

- 12 utilized one batch of PNNL

- C adsorben t ; Experiment 13 utilized a second, larger, batch of PNNL

- C adsorbent

.

Table 12 shows that in these tests, the PNNL

- C adsorbent removed about 70

- 80% of the 226 Ra
and about 34

- 72 % of the barium from the Well

- 4 produced water. These results show that the

PNNL

- C adsorbent is only slightly selective toward radium over barium. The same behavior was
observed for Fluka MnO 2
. Moon et al 41 found no difference in selectivity between radium and barium for adsorption onto MnO 2
.

Regeneration with 0.1N HCl removed about 37

- 55% of the 226 Ra and about 81

- 96 % of the barium that was adsorbed during the adsorption cycle. In con trast, DI H 2 O removed only 5% of
the adsorbed 226 Ra and 9 % of the barium that was adsorbed. Based on these experiments,

MnO 2 is effective for both barium and radium adsorption from Well

- 4 produced water; 0.1N HCl is effective for regenerating both barium and radium from MnO 2
.26

Table 12 . Summary of Adsorption

- Regeneration Tests with PNNL

- C MnO 2 Adsorbent

Test Regenerant 226 Ra

capacity, pCi/gm
adsorbent Fraction

226 Ra
adsorbed by MnO 2 Fraction

adsorbed

226 Ra removed by regen Ba

capacity, mg/gm
adsorbent Fraction

Ba
adsorbed by MnO 2 Fraction

adsorbed Ba removed by regeneration

10 0.1N HCl 3,240

3,490 a 0.76

0.82 0.55 15 0.50

0.72 0.96

11 DI H 2 O 3,300

2,880 a 0.77

0.68 0.05 15 0.5 0

0.34 0.093

12 0.1N HCl 3,150 0.74 0.37 15 0.50 0.81

13 0.1N HCl 3,460 0.81 0.40 16 0.52 0.83

a Tests 10 and 11 utilized two adsorption cycles , with a regeneration step between the two cycles . The first value is for the first cycle; the second value is for the second cycle.



### 4. MnO 2 

### Barium and Radium Ad sorption

- Regeneration Process

Figure 14 shows a schematic diagram of a hypothetical process for adsorbing barium and
radium from produced water onto MnO 2 , regenerating the MnO 2 with HCl to generate a BaCl 2 - RaCl 2 concentrate , and disposing of the BaCl 2 - RaCl 2 concentrate solution by UIC

. It is anticipated that a fraction of the MnO 2 inventory would be continuously or periodically removed from the separation step foll owing adsorption and regeneration

. This regenerated, “spent MnO 2 ”, may be disposed of as nonhazardous solid waste in a RCRA

- D landfill, assuming
that the barium concentration and 226 Ra activity meet RCRA

- D disposal criteria.

Figure 14 . Schematic Diag ram of MnO 2 Barium and Radium Adsorp tion

- Regeneration Process

Figure 15 shows a schematic diagram of a hypothetical regeneration process for MnO 2 adsorbent . A concentrated solution of BaCl 2 and RaCl 2 in dilute HCl is recirculated over the
loaded MnO 2 to desorb RaCl 2 and BaCl 2
. Concentrated HCl is added to the loop to maintain an
HCl concentration of about 0.1M. The stripped MnO 2 is rinsed with water , and returned to the adsorption process. The rinse water and a purge stream from the BaCl 2 - RaCl 2 - acid loop are
combi ned and neutralized with NaOH for disposal by UIC

.27

Based on the results shown in Table 12 , approximately equal percentages of barium and 226 Ra
adsorb from Well

- 4 produced water onto MnO 2 and desorb via HCl displacement from MnO 2
. For the design case produced water composition, the concentration of 226 Ra is 5,000 pCi/liter (5x10 - 6 mg/L). The concentration of barium is 6,200 mg/L. Thus, the concentration of barium is nine orders of magnitude greater than the concentration of radium. Therefore, the materials and disposal costs are estimated based only on the barium concentration in the produced

water.

We estimated the materials and disposal costs for this process for the design case produced
water. The materials cost for MnO 2 synthes is is based on a standard preparation for manganese oxide shown in equation ( 1 ) . Manganese sulfate can be used in place of manganese chloride, as shown in eq uation ( 2 )

.

( 1 )
( 2 )

In addition, we made the following assumptions.

 2.5 moles of HCl are required per mole of barium to remove barium during regeneration.

 Stripped MnO 2 is rinsed with twice its volume of clean water.

 The purge from the regeneration loop and the rinse stream are combined and
neutralized with 2.5 moles o f NaOH per mole barium.

 The neutralized mixture is disposed of by UIC.

Figure 15 . Schematic Diagram of MnO 2 Regeneration Process2 8

Table 13 shows the estimated costs for synthesis and regeneration of an MnO 2 - based adsorbent for barium and radium adsorption from produced water for the design case. The

MnO 2 is assume d to be usable for 5 adsorption

- regeneration cycles. The estimated barium capacity is based on the distribution coefficient of 2,800 repor ted by Moon 41 for both radium and barium adsorption on MnO 2 resin. Based on equation ( 3 ) , below, and a final barium
concentration in the treated produced water of 500 mg/L, the calculated barium capacity is approximately 1,400 mg/gm MnO 2 . To be conservative, we assumed a barium capacity of 1,000 mg/gm MnO 2
.

( 3 )

Figure 16 shows the estimated cost for chemicals and disposal for the MnO 2 adsorption

regeneration process as a function of the number of cycles for which the adsorbent is effective. In this figure, the final barium concentration refers to the barium concentration of the treated produced water leaving the MnO 2 adsorption step. For an adsorbent lifetime of 10 cycles, and a treated produced water barium concentration of 500 mg/L, the materials and disposal cost for barium and radium removal and disposal is $1.7/bbl produced water. For this case, the waste volume for UIC disposal is 0.05 bbl/bbl produced water.

Table 13 . Cost of Materials and Dispos al:

MnO 2 Barium and Radium Adsorption

- Regeneration Process (Design Case Produced Water; 5 Adsorption

- Regeneration Cycles)

Cost item Usage/bbl produced water $/bbl produced water

MnO 2 adsorbent consumption 180 gm $ 1.19 Disposal of spent adsorbent (MSW) 0.89 lb wet MnO 2 (45% solids) $0. 02 HCl to regenerate adsorbent 1.33 lb 100% HCl $0.32

NaOH for neutralization 0.91 lb 100% NaOH $0.25

BaCl 2 , NaCl for UIC disposal 4.6 lb

H 2 O in mixture for UIC disposal 17.2 lb Total UIC disposal 0.052 bbl $0.57 Total Materials and Disposal $2.3529

Figure 16 . MnO 2 Adsorption

- Regeneration Process Materials and Disposal Cost



## V. Conclusion s

For the Pennsylvania Marcellus in 2011, even with 95% produced water reuse, approximately

0.15

- 0.3MM gal/day of produced water must be disposed of by UIC. This volume will increase significantly as the s upply of produced water exceeds the demand for water in subsequent hydrofracturing operations. The objective of this study was to identify cost

- effective
pretreatment technologies that enable thermal recovery of distilled water and a salable salt product from Type III produced water s that would otherwise need to be disposed of by UIC.

For the design case produced water composition, c urr ent technology enables water evaporation in either a mobile or stationary evaporator to recover about 56% of the produced

water as distilled water and about 44% as a salt conc entrate. The salt concentrate is disposed
of by UIC . In 2011, GEWPT began testing its new mobile produced wa ter evaporator that utilizes mechanical vapor recompression and treats about 60 gpm produced water.

To achieve 80

- 95% water recovery, it is necessary to generate a solid salt product in a thermal crystallizer. For use as road salt, the salt product must be greater than 95 wt% NaCl and must pass TCLP. Thus, the barium concentration in the TCLP extract must be less than 100 mg/L. In the absence of a specification, it is assumed that the 226 Ra activity in the salt product must be no greater than the level permitted for disposal as nonhazardous solid waste, which is 25 pCi/gm in Pennsylvania.30

Based on a GEWPT pilot study of Marcellus produced water evaporation and salt crystallization, we developed a map of the produced water composition (barium concentr ation and 226 Ra activity) and the corresponding types of pretreatment required to obtain an acceptable salt product. We identified three types of produced waters. Type I produced waters contain barium concentrations less than [Ba] max (about 1,000

- 2,000 m g Ba/L) and are essentially unrestricted with respect to 226 Ra activity. Type I produced waters do not require barium or

226 Ra removal prior to NaCl crystallization.

Type II produced waters contain barium concentrations greater than [Ba] max and very lo w radium activities (<200

- 1,000 pCi 226 Ra/L; upper limit depends on the produced water barium concentration). These produced waters may be economically treated by sulfate precipitation prior to NaCl crystallization.

Type III produced waters have bari um concentrations greater than [Ba] max and higher radium activities (>200

- 1,000 pCi 226 Ra/L; lower limit depends on the produced water barium concentration). Type III produced waters should not be treated by direct sulfate precipitation prior to NaCl crys tallization because the resulting sulfate sludge 226 Ra activity would exceed state limits for disposal in RCRA

- D landfills, and disposal as LLRW would be cost

- prohibitive. This study focused on defining economical pretreatment processes for Type III produced waters.

The key to cost

- effective barium and radium removal from Type III produced water is to generate a barium and radium concentrate that may be disposed of by UIC. We identified two such processes and conducted laboratory testing and cost an alyses for each process.

The first pretreatment process is a modified lime

- soda process that completely softens the produced water. Magnesium, calcium, and strontium are first precipitated to yield a solid sludge that can be disposed of as nonhazardous waste in a RCRA

- D facility. This is followed by precipitation of barium and radium as carbonates. These carbonates are redissolved with HCl to yield a concentrate that can be disposed of by UIC. For the design case, about 0.05 bbl of
concentrate for UI C disposal and about 25 lb. RCRA

- D solid waste are generated per bbl raw produced water. For this case, the materials and disposal cost is estimated to be $3.5/bbl produced water.

The second process utilizes high surface area MnO 2 as an adsorbent for bar ium and radium.
The MnO 2 may be supported on mesoporous silica (as is the case for proprietary materials made by PNNL) or other supports. Alternatively, the MnO 2 may be in the form of activated

MnO 2 , which may be obtained commercially, or the MnO 2 may be prepared in

- situ. MnO 2 is regenerated by treatment with dilute HCl. The regeneration process yields a concentrated solution of barium and radium, which may be disposed of by UIC. In laboratory studies, we demonstrated adsorption of barium and 226 Ra ont o MnO 2 . We also demonstrated regeneration
of MnO 2 by HCl treatment to yield a reusable sorbent. For the design case produced water, we estimated the materials and disposal cost for a regenerable MnO 2 adsorbent to be in the range of $1.7 to $2.3 (adsorben t life 10 and 5 cycles, respectively) per bbl produced water. The31

volume of BaCl 2 - RaCl 2 concentrate for disposal by UIC for the design case is estimated to be about 0.05 bbl per bbl produced water. Assuming that the spent MnO 2 adsorbent can be stripped o f barium and radium sufficiently to be considered nonhazardous, the spent MnO 2 adsorbent may be disposed of in a RCRA

- D landfill.

This modified lime

- soda process is relatively simple and should be straightforward to scale up for commercial operation. Thi s process results in essentially complete softening of the produced water, which increases water recovery and yields a higher grade salt product. This process appears to be in the best position for near

- term implementation.



## VI. Recommendations

Based on this investigation, the following recommendations are made.

For the modified lime

- soda process, a series of laboratory tests should be conducted to define both an effective agitation intensity (power per unit volume) and a range of reagent addition rates that give sufficient selectivity in the first carbonate precipitation process (Stage 1B in Fig ure 7 ).

The MnO 2 adsorption process should be further developed in the labo ratory to establish the feasibility of this process. Identification of an effective means of separation of MnO 2 particles from produced water and from regeneratio n streams is needed. Secondly , the regeneration purge stream to be di sposed of must be concentrated (e.g. 20

- 30 wt% solids) for UIC , although the regeneration requires dilute HCl . The feasibility of using slightly acidic, concentrated BaCl 2 - RaCl 2 solutions for desorption of BaCl 2 and RaCl 2 from MnO 2 must be established.

Additional laboratory and pilot evaporation and crystallization studies should be
conducted with produced waters that contain higher barium concentrations (e.g. 1,000, 2,000, and 5,000 mg Ba/L) . This will enable a more robust estimate of the produced water barium concentration above which barium removal is needed.

A 226 Ra specifica tion for road deic ing salt should be established.



## VII. 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 DEAC2607NT42677.32



## VIII. References

1 Considine, T.J., Watson, R., and Blumsack, S., The Economic Impacts of the Pennsylvania Marcellus Shale Natural Gas Play: An Update, May 24, 2010.

2 Wendel, K., Shale Gas Wastewater Landscape in Pennsylvania, submitted to Oil and Gas Journal, 2011.

3 UIC: underground injection control (used interchangeably with deep

- well injection)

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

5 Rassenfoss, S., From Flowback to Fracturing: Water Recycling Grows in the Marcellus Shale, Journal of Petroleum Technology, July, 2011, p. 48

- 51.

6 TDS: total dissolved solids

7 0.3MM gal/day is based on 2,000 new wells/year with 1MM gal flowback and produced water per well and 95% reuse. This number does not include the volume of long

- term produced water from active wells drilled in earlier years. 0.15 MM gal/day is based on 5% of 25MM bbl frac water in 2011.

8 Hayes, Thomas, Techno

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

9 Garvin, S., EPA Re gional Administrator, in a letter to Michael Krancer, Pennsylvania Department of Environmental Protection, May 12, 2011.

10 Argonne National Laboratory, EVS, Human Health Fact Sheet, 2005.

11 United Nations Scientific Committee on the Effects of Atomic Radia tion (UNSCEAR) (1982): Ionizing Radiation: Sources and Biological Effects. http://www.unscear.org/unscear/en/publications/1982.html

. 12 One picocurie (pCi) of radium is equal to 10 - 12 gm radium.

13 The ratio of 226 Ra to 228 Ra will vary by location and it is not appropriate to assume that all waters within or
between different formations will have a ratio of 226 Ra to 228 Ra in the range of 10/1.

14 TCLP: Toxicity Characteristic Leaching Procedure (or Protocol)

15 Rice, T., NY State Department of Environmental Conservation; Allard, D., Pennsylvania Department of Environmental Protection, Dec., 2011, personal communication.

16 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).

17 Water Treatment Process for NORM Removal, US Patent Ap plication Serial No. 13/307656, filed 30 November

, 2011

. 18 RCRA

- D: Resource Conservation and Recovery Act, subtitle D , which addresses nonhazardous solid waste (EPA)

19 Vidic, R. D., Sus tainable Water Management for Marcellus Shale Development, Presented at Marcellus Shale Natural Gas Stewardship: Understanding the Environmental Impact, Marcellus Shale Summit, Temple University, Philadelphia, PA, 2010. http://www.temple.edu/environment/NR DP_pics/shale/presentations_TUsummit/Vidic

- Temple

- 2010.pdf

20 Keister, T., Marcellus Hydrofracture Flowback and Production Wastewater Treatment, Recycle, and Disposal Technologies, Presented at The Science of the Marcellus Shale, Lycoming College, January 2 9, 2010.

21 Hayes, T.L, Sampling and Analysis of Water Streams Associated with the Development of Marcellus Shale Gas, Final Report, December 31, 2009, cited by Dempsey, B., Pennsylvania’s Marcellus Shale Gas: Water Supply and Water Quality Issues, 2010 htt p://www.research.psu.edu/events/2010/penn

- state

- energy

- day

documents/Dempsey.pdf

. 22 Tinto, J. and Solomon, R., Water Recovery via Thermal Evaporative Processes for High Saline Frac Water Flowback, International Water Conference paper IWC

- 10

- 66, San Antonio , October, 2011.

23 Kimball, R., Key Considerations for Frac Flowback/Produced Water Reuse and Treatment, NJWEA Annual Conference, May, 2011, Atlantic City, NJ.

24 Kirby, H.W. and Salutsky, M., The Radiochemistry of Radium, National Academy of Sciences, 1964

. 25 Keister, T., Marcellus Gas Well Supply and Wastewater Disposal, Treatment, and Recycle Technology, ProChemTech TAB 1208, 2008.

26 McGinty, J., McHugh, T.E., Higgins, E.A., Barium Sulfate: A Protocol for Determining Higher Site

- Specific Barium Cleanup Le vels, SPE E&P Environmental and Safety Conference held in Galveston, Texas, U.S.A., 5

– 7 March 2007.33 27 Letter from ProChemTech in PADEP Regulatory Analysis Form, http://www.irrc.state.pa.us/Documents/SRCDocuments/Regulations/2806/AGENCY/Document

- 18068.pdf , pp. 353

- 355, Jan, 2010.

28 Veil, J., Final Report: Water Management Technologies Used by Marcellus Shale Gas Producers , NETL, July, 2010.

29 NPDES: National Pollutant Discharge Elimination System

30 R.E.S. June 11, 2010 http://www.prnewswire.com/news

- releases/pennsylvania

- dep

- secreta ry

- new

- treatment

plant

- showcases

- technology

- to

- meet

- stronger

- greatly

- needed

- water

- quality

- standards

- 96159224.html

. 31 TerrAqua Resource Management http://www.tarmsolutions.com/ (2010).

32 SRI Consulting, Chemical Economics Handbook, Sodium Sulfate, 2009.

33 Rood A

. S

. , White G

. J

. , Kendrick D .T., Measurement of 222 Rn Fl ux, 222 Rn Emanation, and 226;228Ra Concentration from Injection Well Pipe Scale, Health Phys ics 75:187

– 192 (1998)

. 34 Lind, S.C, Underwood, J.E., and W hittemore, C.F., The Solubility of Pure RaSO4, JACS 40 , No. 3, pp. 465

- 472 (1918).

35 Doener, H.A. and Hoskins, W.M., Co

- precipitation of Radium and Barium Sulfates, JACS 47 , pp. 662

- 675 (1925).

36 Bruno, J. et al, Chemical Thermodynamics of Solid Solutions of Interest in Nuclear Waste Management, A State

of

- the

- Art Report, OECD, p. 26, (2007).

37 ppm/w: microgram per gram (  gm/gm).

38 Silva, J.M., Matis, H., Tinto, J.V., NORM Removal from Frac Water in a Central Treatment Facility, International
Water Conferen ce paper IWC

- 10

- 65, San Antonio, TX, October, 2010.

39 Kirby, H.W. and Salutsky, M.L, The Radiochemistry of Radium, National Academy of Sciences, National Research Council, p. 8 (1964).

40 CRC Handbook of Chemistry and Physics, 57 th Edition, R.C. Weast, ed., 1976.

41 Moon, D.S., Burnett, W.C., Nour, S.

, Horwitz, E.P.

, and Bond A. , Preconcentration of Radium Isotopes from Natural Waters using MnO2 R esin, Applied Radiation and Isotopes, 59 (2003) 255

- 262

.AI

- 1



### Ap pendix I

. Selective Radium Removal from Produced Water

A. Literature Background The National Drinking Water Clearinghouse has reported ion exchange, lime softening, and reverse osmosis as the best available technologies for removing radium from groundwate r 1 . In addition, Deng 2 cites groundwater treatment for radium removal by
low

- pressure membrane filtration, manganese greensand filtration, MnO 2 - impregnated resins, acid

- washed sand filtration, and radium specific complexer (RSC) resins. Several
chemical techniques for radium removal have been reported. These include sulfate treatment to coprecipitate radium and barium as RaSO 4 with BaSO 4 , as discussed by

Doe ner and Hoskins 3 . Bader 4 describes a pressurized sulfate precipitation method to remove radium, b arium, and strontium from produced water. This method yields a solid sulfate product.

In an earlier study 5 , w e suggested the possibility of using a commercial RSC resin (e.g.

DOWEX RSC) to selectively remove radium from produced water. Snoeyink et al 6

m easured the radium capacity of RSC unde r a wide range of TDS levels. For example, a t 2,500 mg/L TDS and with a feed radium concentration of 180 pCi/L, the measured radium capacity was 32,000 pCi/gm. However, at 40,000 mg/L TDS and a feed radium

concentra tion of 250 pCi/L, the radium capacity was only 300 pCi/gm. In contrast, Mangelson et al 7 measured 3,500 pCi 226 Ra/gm for RSC resin for treating water softener regeneration brine, which had 40,600 mg/L TDS and 1,181 pCi 226 Ra/L

. The barium level

was not reported for the brines in the Mangelson study. 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.

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. Wang 8 showed the effectiveness of 18 different inorganic ion exchangers for removing radium from simulated wastewater containing about 2100

1 National Drinking Water Clearinghouse, Radionuclides, Tech Brief 13, March, 2000.

2 Deng, S., Polymeric Adsorbent for Radium Removal from Groundwater, Adsorption 11 : 805

- 809 (2005).

3 Doener, H.A. and Hoskins, W.M., Co

- precipitation of Radium and Barium Sulfates, JACS 47 , pp. 662

- 675 (1925).

4 Bader, M.S., Methods to Treat Produced Water, US P atent 7,963,338 , June 21, 2011.

5 Silva, J.M., Matis, H., Kostedt, W.K. IV, and Watkins, V., Hydrofracturing Water Pretreatment for Water and Salt Recovery, International Water Conference Paper IWC

- 11

- 7, November, 2011, Orlando, FL.

6 Snoeyink, V.L., Chamb ers, 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.

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

- 76 (1990).

8 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 Ch emistry, Articles, Vol 111, No. 2 (1987) 289

- 295.AI

- 2

mg/L TDS, primarily CaSO 4 , and 5037 pCi/L 226 Ra. Although most produced waters have significant levels of barium, the s imulated wastewater in the Wang study did not contain
barium

. BaSO 4 as

- 100/+120 mesh granules (barite) and powdered BaSO 4 both showed
distribution coefficients 9 for radium of the order of 3000

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

- 4000 pCi/gm for a solution co ntaining 1000 pCi/L radium. Wang describes the mechanism for radium removal from solution as a chemical exchange between the radium ions in solution and barium ions at the BaSO 4 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.

Several metal oxides have been tested for removing radium from aqueous solutions.
Nirdosh et al 10 measured equilibrium isotherms fo r aqueous 226 Ra solutions on oxides of Fe, Mn, Zr, and Ti. Among these oxides, only MnO 2 had significant adsorption capacity
for 226 Ra.

Patel and Clifford 11 reported several adsorbents, for example hydrous manganese oxides, manganese

- impregnated acrylic f ibers, BaSO 4 - impregnated alumina, untreated alumina, and iron and manganese precipitates for removing radium from groundwater. They found that water treatment by hydrous manganese oxide followed by
diatomaceous earth filtration was both economical and eff ective for radium removal
from radium

- spiked Houston groundwater.

Moon et al 12 describe “MnO 2 Resin” from PG Research Foundation that adsorbs radium and barium from aqueous solutions. This material was prepared by a proprietary method utilizing reductiv e precipitation to generate MnO 2 on a macroporous resin substrate. This material has been utilized to concentrate radium from ground water and sea water at the laboratory scale. Moon found that with MnO 2 resin, the distribution
coefficient for both radiu m and barium was 2.8 x 10 4 for adsorption from waters of a significant range of salinity (DI water, and waters containing 200, 3,500, and 35,000 mg/L TDS). Thus, MnO 2 showed no selectivity for radium over barium.

In addition, carbonaceous materials have been used to remove radium from saline
solution s . For example, Rachkova et al 13 demonstrated adsorption of radium from

9

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

- Desorption Studies on the 226Ra

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

- 248.

11 Patel, R. and Cli fford, D., Radium Removal from Water by Manganese Dioxide Adsorption and Diatomaceous Earth Filtration, EPA Project Summary EPA/600/S2

- 91/063 (March, 1992).

12 Moon, D.S., Burnett, W.C., Nour, S.

, Horwitz, E.P.

, and Bond A. , Preconcentration of Radium Isoto pes from Natural Waters using MnO2 R esin, Applied Radiation and Isotopes, 59 (2003) 255

- 262

. 13 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.AI

- 3

saline solutions onto hydrolyzed wood lignin. Tsezos et al 14 investigated 226 Ra adsorption on granular activated carbon for uranium mine tailings.

3M Corporation supplies EmporeTM disks to concentrate radium from water samples 15

. The active material is a crown ether covalently bound to inert substrate particles. This proprietary material has affinity for both radium and barium, and can b e regenerated with 0.25M EDTA, which would generate a concentrate of radium and barium for UIC. This material is proprietary, and is designed for laboratory analytical procedures.



### B. Adsorbent Screening
As shown above, m ost of the radium adsorption literatu re is focused on removing radium from groundwater or well water. To complement this information, we sc reened
about 60 materials for their ability to remove radium from produced water. We utilized liquid scintillation counting (LSC) to measure the perform ance of each material. Both the analytical techniques for NORM measurement and laboratory safety for handling

NORM

- containing produced water have been discussed previously 16 and are included in Appendix IV

. For this screening study , we utilized produced w ater from Well

- 4

. This produced water sample has significantly l ower TDS and barium levels than 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 , including MnO 2 . For each test, 20 mL of Well

- 4 produced water and approximately 115 mg of an adsorbent were placed in a vessel and agitat ed overnight. The feed and each filtered liquid were subsequently measured for residual radioactivity
b y LSC. The reduction in counts per minute (vs. feed) is plotted for each adsorbent in Figure AI

- 1 . This shows that among the mat erials screened, manganese oxide and
barium sulfate are the most effective ads orbents for radium removal from field produced water that has modest TDS and a low barium level

.

14 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.

15 Scarpitta, S.C., Evaluation of 3M E mpore Rad Disks for Radium Determination in Water, 42nd Annual Conference of BioAssay, Analytical, and Environmental Ra diochemistry, San Francisco, CA ( 1996 ).

16 Silva, J.M., Matis, H., Kostedt, W.K. IV, and Watkins, V., Hydrofracturing Water Pretreatment f or Water and Salt Recovery, International Water Conference Paper IWC

- 11

- 7, November, 2011, Orlando, FL.AI

- 4 Figure AI

- 1 . Radium Removal Performance for Screened Adsorbents



### C. DOWEX RSC Resin for Radium Removal from Produced Water We tested DOWEX RSC resin for selectively removing radium from produced water. Figure AI

- 2 shows a scanning electron micrograph of a resin b ead that was fractured by immersion in liquid nitrogen followed by a light tap with a hammer. The white spots represent BaSO 4 microcrystallites. The characteristic dimension of the microcrystallites is typically 20

- 40 nm 17

.

These bound BaSO 4 crystallites ion exchange with radium as shown in equation ( 1 )

.

( 1 )

Attempts have been made to regenerate RSC resin 18 . However, these attempts have been unsuccessful, primarily because RaSO 4 is so stable. Therefore, it is assumed that RSC resin is a single

- use ion exchange resin for radium removal. Spent RSC resin is typically disposed of as LLRW. RSC resin is often utilized to remove radium from brine that is used to regenerate water softening ion exchange resins in municipal water systems. In a demonstration study 19 , hardness (Mg ++ , Ca ++ , Sr ++ , Ba ++ ) and radium were removed from drinking water using a conventional gelular sulfonic acid ion exchange resin (sodium form). The softening ion exchange resin was regenerated with NaCl brine (average 40,600 mg/L TDS) to remove hardness and radium. The regeneration brine

17 Silva, J.M., Matis, H., Tinto, J.V., NORM Removal from Frac Water in a Central Treatment Facility, International Water Conference paper IWC

- 10

- 65, Sa n Antonio, TX, October, 2010.

18 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.

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

- 76 (1990).AI

- 5

leaving the ion exchange resin contained an average of 1180 pCi radium/liter (the barium level in this stream was not reported). Prior to disposal, this regeneration brine
was treated with RSC resin. The RSC resin rem oved an average of 99.2% of the radium from the softener regeneration brine. After one year of operation, the resin loading was 3,000 pCi/cc resin.

Figure AI

- 2 . SEM of DOWEX RSC Resin (50K magn ification)



### 1. DOWEX RSC Resin Economics

The cost of DOWEX RSC resin is approximately $500/ft 3

. W aste containing up to 10,000 pCi/gm can be disposed of as LLRW, which costs about $200/ft 3 for disposal. Figure AI

- 3
shows the cost of bot h resin and LLRW disposal for two levels of feed 226 Ra activity as functions of the adsorbent capacity 16 . 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 of recovering water and salt from produced water, depending on the raw produced water

226 Ra activity. Thus, for a non

- regenerable material such as RSC resin, the target loading level is 10,000 pCi 226 Ra/gm resin.



### 2. RSC Resin Performance

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

- 4. Therefore, we conducted two series of batch equilibrium capacity tests with produced waters that had been spiked
with various barium levels

. The details of both the capacity measurements and the equations for estimating 226 Ra capacity from LSC measurements are given in Appendix

IV. Produced waters from Well

- 4 (low TDS) and Well

- 7 (high TDS) were each spiked with
barium to measure the effects of TDS and barium concentration on the radium capacityAI

- 6

of DOWEX RSC resin. Barium was added to the produced water as BaCl 2 , which was
obtaine d from Sigma

- Aldrich 

.

Figure AI

- 3

. Resin and Disposal Cost Sensitivity to Adsorbent Capacity

and Produced Water Feed 226 Ra Activity

Figure AI

- 4 shows the effects of both TDS a nd Ba concentration on the apparent capacity of DOWEX RSC resin for 226 Ra. 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. This figure shows that the resin 226 Ra capacity with unspiked Well

- 4 brine is comparable to that reported by Snoeyink 6 . This measured 226 Ra capacity is far too low to be commercially practical , even for Well

- 4 produced water

. The radium 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

r esults led us to seek alternate sorbents, as well as alternate processes for remo ving
radium from produced water.AI

- 7

Figure AI

- 4

. Effects of TDS and Barium Concentration on RSC 226 Ra CapacityAI I

- 1



### Ap pendix I I

. Produced Water Softening by Ion Exchange

A. Background

In the chlor

- alkali industry, ion exchange (IEX) is used extensively for secondary sodium chloride brine purification prior to electrolysis in membrane electrolyzers. Chelating IEX

resins such as aminomethylphosphonic acid (AMP)

- and iminodiacetic acid (IDA)

- functionalized polystyrene are used to soften concentrated NaCl brine solutions. Figure

AII

- 1 shows a possible structure for the complex between a divalent cation and AMP

functionalized polystyrene 1 . The ion exchange capacity of commercially available AMP resins is typically 14 gm Ca per liter resin under chlor

- alkali purification conditions (60  C, 300 gm/liter NaCl, 15 mg/L Ca, pH 9.5, 10 bed volumes/hr) 2

. Prior to ion exchange resin treatment, the brine must be treated to remove suspended solids to below 10 microns 3

. In this application, the feed hardness level (calcium plus magnesium) is typically 1

- 10 mg/L; the treated product hardness level is below 20 μ g/L.

Produced water for use in once

- through steam generators (OTSG) has been demineralized using ion exchange technology 4 . For the OTSG application, the produced water TDS was in the range of 4,000

- 7,100 mg/L and the hardness level was 447 mg/L as

CaCO 3
. Both the TDS and hardness are about a factor of 20 lower than the corresponding frac water values.

Produced water from coal bed methane (CBM) extraction has also been purified using ion exchange technology. Marathon has a warded Eco

- Tec a service contra ct to utilize a Recoflo system to demineralize produced water from CBM in the Powder River Basin in Wyoming 5

. The system is designed to treat 1.5 MGD (36,000 bpd) produced water. The TDS range of the produced water to be treated was not specified, but a DOE survey of the Powder River Basin CBM produced waters utilized 1,500 mg/L TDS as a working value to compare the cost of Powder River Basin CBM produced water demineralization by ion exchange and reverse osmosis 6 . The TDS level for CBM demineralization is two orders of magnitude lower than the design case frac water TDS and an order of magnitude lower than the design case hardness level

.

1 Kiefer, R. and Hoell, W., Sorption of Heavy Metals onto Selective Ion

- Exchange Resins with

Ami nophosphonate Functional Groups, Ind. Eng. Chem. Res. 2001, 40, 4570

- 4576.

2 Wolff, J.J. and Anderson, R.E., Ion

- Exchange of Feed Brine for Chlor

- Alkali Electrolysis Cells: The Role of
Duolite ES

- 467, Presentation at AIChE Meeting, Orlando, Fl, Spring, 198 2.

3 Cocurek, D. and Woodside, G., Waste Treatment, Hazardous Waste, Kirk

- Othmer Encyclopedia of Chemical Technology, p. 8, (Dec. 4, 2000).

4 Krause, L., Sheedy, M., and Jones, K., Produced Water Recovery at Seneca Resources Using Short Bed Ion Exchange, I nternational Water Conference Paper IWC

- 10

- 21, San Antonio, TX, 2010.

5 PRNEWSWIRE, May 8, 2008. http://www.prnewswire.com/news

- releases/eco

- tec

- awarded

- cbng

produced

- water

- treatment

- system

- contract

- by

- marathon

- oil

- corporation

- 57216457.html

6 Bank , G. and Kuuskraa , V., The Economics of Powder River Basin Coalbed Methane Development

, Report prepared for DOE, 2008.AI I

- 2

A continuous IEX system, the Higgins Loop  , has been utilized commercially since 1955 for a variety of water softenin g and demineralization applications. Based on countercurrent contact between IEX resin and the feedwater, this process generates lower regeneration and rinse volumes than traditional co

- current flow systems 7

, 8 . No reference was found in which the Higgins Loop was applied to softening brines comparable to the design case.

Figure AII

- 1 . AMP

- Functionalized Polystyrene Resin

Chelating ion exchange resins (also referred to as weak acid cation exchange resins, or WAC) are reg enerated by a multiple step process. First, strong acid (2

- 4 M or 5

- 15 wt% HCl) is used to displace hardness from the resin with protons. Following a deionized (DI) water rinse, 2

- 4 M NaOH (5

- 15 wt%) is used to displace protons with sodium ions. The

res in is rinsed again with DI water and placed back into service. The regeneration solutions, comprising an acidic solution of concentrated alkaline earth metal chlorides (MgCl 2 , CaCl 2 , SrCl 2 , BaCl 2 ), and a basic solution of NaCl are typically mixed, neutral ized, and disposed of as wastewater.

The design case produced water contains the equivalent of 13,772 mg/liter of Ca ++ cations, which equals 0.687 gm

- equivalents of hardness per liter of frac water (109.3

gm

- equivalents per bbl frac water). The resin cap acity for removing hardness from frac water is assumed to be 14 gm Ca ++ (0.70 gm

- equivalents of hardness) per liter resin 9

. Based on this assumed capacity, 0.98 volumes of IEX resin are required per volume of frac water to soften frac water for the design case

. Thus, the ion exchange resin bed will become exhausted after the first bed volume of frac water passes through. Chemical costs and waste volumes for regeneration will therefore dominate the cost of using ion exchange to soften frac water. The cal culations given here represent a best case scenario; finite mass

- transfer zones for ion exchange unit operations will cause actual

7 Higgins, I.R., Treating Brackish Water for High Pressure Boiler Makeup For Thermal Flooding by Continuous Ion Exchange: A Case History At Coron ado Oil Company, Fall Meeting of the Society of Petroleum Engineers of AIME, 1

- 4 October 1967, New Orleans, Louisiana, 1967.

8 Higgins, I.R., Continuous Ion Exchange Equipment, Industrial and Engineering Chemistry, vol. 53, No. 8, August, 1961.

9 McKetta, J.J., Encyclopedia of Chemical Processing and Design: vol 51, Slurry Systems, Instrumentation
to Solid

- Liquid Separation, 1995, CRC Press.AI I

- 3

regeneration chemical usage and waste stream generation to be higher than those reported here.



### B. Acid Treatment

The first ste p in regeneration of a chelating ion exchange resin is an HCl treatment to strip divalent cations from the resin as their chlorides, as shown in equation ( 1 )

.

( 1 )

Equation ( 2 ) shows t he HCl usage for regeneration for this case.

( 2 )

Equation ( 3 ) shows the volume of concentrated (35.2 wt%) HCl required per bbl frac

water.

( 3 )

The cost of HCl (2009) is about $525/metric ton for 35.2 wt% HCl (100% basis) 10

. Assuming complete reaction of HCl for regeneration 11

, the cost of HCl for IEX regeneration is shown in equation ( 4 ) . For IEX regeneration, a 5

- 15 wt% HCl stream
would be recirculated between a tank and the IEX resin bed. The HCl concentration is maintained in the tank by addition of concentrated (e.g. 35.2 wt%) HCl to the HCl regeneration ta nk.

( 4 )

The HCl treatment generates an acidic chloride solution of the hardness cations. Based

on a target f inal CaCl 2 concentration of 30 wt% (as CaCl 2 ), the initial HCl concentration needs to be 22.2 wt% HCl. The amount of DI water required to make up this solution
from 35.2 wt% HCl feed is calculated below.

The amount of CaCl 2 generated per barrel frac wate r is given by equation ( 5 )

.

10 SRI Consulting, Chemical Economics Handbook (HCl: 2009; NaOH: 2008).

11 i.e. 100% of HCl added to system is used to displace hardness from IEX resin.AI I

- 4 ( 5 )

For a 30 wt% solution of CaCl 2 , the amount of H 2 O in the regeneration solution per barrel frac water is given by equation ( 6 )

.

( 6 )

The amount of water in the concentrated (35.2 wt%) HCl used for regeneration (per bbl frac water treated) is calculated in equation ( 7 )

.

( 7 )

The amount of DI water (or possibly filtered frac water or softened frac water) needed per barrel frac water is given by equation ( 8 )

.

( 8 )

The CaCl 2 (equivalent) concentrate will be disposed of by UIC. It is assumed that this concentrate is generated in North

- Central Pennsylvania and transported and dispo sed of in Ohio, at a cost of $11 /bbl (transportation plus UIC cost) . The volume of concentrate from the HCl regeneration step and the cost of dispo sal are calculated in equations ( 9 ) and ( 10 ) , respectively.

( 9 )

( 10 )



### C. Rinse
After the HCl treatment, the resin must be rinsed with at least one bed volume of a
neutral water stream. The purpose of the rinse ste p is to displace acid solution ( which
contains divalent cations such as Mg ++ , from the resin so that they do not precipitate during the subsequent NaOH treatment. In the chlor

- alkali industry, DI water is used forAI I

- 5

this rinse. In this application, a softened brine stream could be used. The volume of rinse is calculated in equation ( 11 )

.

( 11 )

For the design case, the rinse stream is essentially the same volume as the frac water being treated. Since the purpose of the rinse stream is to remove residual divalent cations from the resin, the rinse source stream must be substantially free of divalent

cations . Therefore, to con duct this rinse step, a clean source water stream is required

. Further, this rinse stream cannot be discharged to surface water because it may have

excess TDS and barium levels. The cost of disposal of this rinse stream by UIC is comparable to the cost o f disposal of the original frac water.



### D. NaOH Treatment The second step in regeneration of chelating ion exchange resin is to treat the resin with NaOH, as shown in equation ( 12 )

.

( 12 )

The NaOH usage is calculated in equation ( 13 )

.

( 13 )

For IEX regeneration, a 5

- 15 wt% NaOH stream is recirculate d between a tank and the IEX resin bed. The NaOH concentration in the tank is maintained by adding
concentrated (e.g. 50 wt%) NaOH to the tank. Equation ( 14 ) shows the vo lume of makeup 50 wt% NaOH required per bbl frac water.

( 14 )

The cost of NaOH is highly variable over time and g eography. The most recent price reported by SRI (2008) is $610/dry metric ton for 50 wt% NaOH 10 . Assuming complete reaction of NaOH for IEX regeneration, the cost of NaOH for IEX regeneration is shown in equation ( 15 )

.

( 15 )AI I

- 6

The NaOH regener ation brine stream is typically combined with the spent HCl regeneration stre am and disposed of by UIC. The NaOH regeneration brine stream comprises water from the original 50 wt% solution plus the water resulting from equation ( 12 ) , as well as residual NaOH

. Conceivable, some or all of this water may be
used to dilute the CaCl 2 stream generated by HCl treatment ( equation ( 8 ) )

.

( 16 )

The cost for disposal of this brine s tream is calculated in equation ( 17 )

.

( 17 )



### E. Rinse
After NaOH treatment, the resin bed must be rinsed with at least one bed volume of deionized or softened water rinse. This is to avoid precipitation of species such as Mg(OH) 2 on the resin bed after placing the ion exch ange system back into service after NaOH treatment. Again, the volume of this rinse will be comparable to the volume of frac water being treated.



### F. Summary

Table AII

- 1 shows the calculated chemical and disposal costs for both the ac id and base treatment steps. The cost of disposing the rinse water, while not included in this table, would be approximately double the cost of disposing all of the frac water by UIC. For brines with such high hardness levels as the design case, the use of chelating ion exchange resin is neither economical nor practical.

Table AII

- 1 . Regeneration Chemical Usages and Costs

Chemical Usage:

lb 100% chemical/
bbl frac water Usage:

gal solution/
bbl frac water Cost:

$/dry metr ic

ton Cost:

$/bbl frac water

HCl 8.78 2.54 $525 $ 2.09
HCl brine disposal $1.0 9

NaOH 9.63 1.52 $610 $2.67

NaOH brine disposal $0.44

Total $ 6.29A I II

- 1



### Ap pendix I I I. Produced Water Softening by Nanofiltration

A. Background Nanofiltration (NF) , shown schematically in Figure AIII

- 1

, was originally developed as a method to achieve higher water fluxes at lower differential pressures and t herefore lower energy costs than those associated with reverse osmosis (RO) membranes. NF provides an alternative to RO for applications where an extremely high

- quality permeate product is not required. NF rejects substances by two mechanisms: neutral

sp ecies are rejected by size (molecules larger than 200

- 300 gm/mole are rejected) and inorganic ions are rejected due to electrostatic interactions with the membrane 1

. Although the size range for rejection associated with NF overlaps those of ultrafiltrati on and reverse osmosis, the defining feature of NF is high rejection of multivalent ions combined with relatively low rejection of monovalent ions. This property makes NF attractive for water softening applications where desalination is not a key goal and it is desirable to achieve high removal of divalent ions such as calcium and magnesium while retaining high water flux

.

Because the permeability of monovalent ions through NF membranes is so much greater than with RO, the feed pressure to an NF system is much lower than the feed pressure to an RO system. The maximum operating pressures of NF membranes also tend to be
lower than tho se of RO

.

The use of NF membranes in drinking water applications has been reviewed by Thorsen
et al 2

. NF competes with tr aditional softening processes such as ion exchange and lime softening, especially at larger facilities. The product quality is better than that of lime softening due to the removal of color and turbidity, while process flexibility, lower footprint, and ze ro sludge production also make NF attractive. Also, recent advances in reducing operating pressure requirements continue to improve the cost

- effectiveness of

NF 3 . Potential issues include treatment and/or disposal requirements for the

concentrate stream, as well as membrane fouling and subsequent cleaning requirements. In addition, NF membranes are sensitive to both suspended solids and
dissolved oxidizers such as chlorine. Membrane fouling may occur both by scaling of inorganic compounds such as CaCO 3 or CaSO 4 as well as by deposition of or ganic compounds or biofouling.

Unlike ion exchange and lime softening, NF requires no regeneration chemicals and only minimal additives (e.g. antiscalants). The concentrate stream from NF processes is brine

1 Linde, K., Jonsson, A., Nanofiltration of Salt Solutions and Landfill Leachate, Desalination, 103 (1995)

223

- 232.

2 Thorsen, T. and Fl  gstad, H., Nanofiltration in Drinking Water Treatment: Literature Review, Techneau, D5.3.4B, December, 2006.

3 Li, N.N . et al., Advanced Membrane Technology and Applications, John Wiley & Sons, 2008.A I II

- 2

with a h igh concentration of multivalent species; this concentrate requires disposal by

UIC.

In a lab study with 1M brines (58,000 mg/L NaCl) comprising primarily monovalent anions, the retention of multivalent cations was higher than 70%, while the retention o f sodium ions was less than 10%. The flux was 50 L/m 2

- hr for a transmembrane pressure of only 435 psi 4 . The permeate recovery was not reported in this study.

NF has been used to selectively remove multivalent ions from aqueous feed streams in
water soft ening applications 5

. NF has been used, for example, to soften feedwater to seawater multistage flash units 6 and to remove divalent cations from concentrated
landfill leachate solutions 1

.

Figure AIII

- 1

. Schematic Diagram of NF Separation Process



### B. WINFLOWS Calculations

We utilized WINFLOWS 3.0 from GE Water and Process Technologies to simulate a NF application 7

. The NF membrane tested was GEWPT membrane HR8040. The maximum
allow able pressure was set to 600 psi. The objective of these calculations was to estimate the maximum permeate water recovery. Flux rates in each element were allowed to be outside of design guidelines.

4 Linde, K., Jonsson, A., op. cit.

5 Nanda, D., et. al., op. cit.

6 Awerbuch, L., ‘‘Nanofiltration: the Great Potential in Reducing Cost of Desalination’’ Proceedings of IDA World Congress Singapore, September 2005.

7 WINFLOWS 3.0 is available for download from: http://www.gewater.com/winflows.jsp

.A I II

- 3



### 1. Case I: Design Case Produced Water Softening The desig n case produced water was fed at 50 gpm to a two

- stage configuration. Four NF modules in parallel comprise the first stage, and 8 modules in parallel comprise the second stage. The feed pre ssure to the first stage was 514.9 psia, and the fee d to the

seco nd stage was 599.6 psia.

The selectivity for divalent cation rejection was significant (e.g. the Mg ++ concentration in the permeate was a factor of 10 .8 lower than in the feed). There was essentially no rejection of monovalent cations. The calculated w ater recovery is 30.0 percent

. Table

AIII

- 1 shows the results for this simulation.

Table AIII

- 1

. NF Simulation Results for Design Case Produced Water

(units mg/L except as indicated)

Component Feed Concentrate Permeate

TDS 132,460 149,886 96,986

Na + 35,000 34,948 35,085 Mg ++ 800 1,157 74.1

Ca ++ 9,500 13,305 1,767

Ba ++ 6,200 8,683 1,152

Sr ++ 2,500 3,500 467

Fe 50 70.0 9.37

Mn 3 4.20 0.56
Cl 58,008 88,218 58,431 pH 7.00 6.99 7.03 Rate (gpm) 50.00 35.01 14.99



### 2. Case II : Well

- 5 Produced Water Softening
The process configuration for Case I was also used in this case. Both the hardness and
TDS for Well

- 5 produced water are higher than the design case

. According to the simulation, t he maximum wat er recovery for this feed was 15.2 %. For water recoveries
above 15.2% , the required feed pressure exceeds the 600 psia limitation on the
membrane modules. Table AIII

- 2 shows the results for this simulation

. As in Case I,
there is essentially no rejection of monovalent cations. The Mg ++ concentration in the permeate was a factor of 7 lower than the corresponding concentration in the feed.A I II

- 4 Table AIII

- 2

. NF Simulation Results for Well

- 5 Produced Water

(units mg/L except as indicated)

Component Feed Concentrate Permeate

TDS 149,149 156,545 11,972

Na + 39,000 38,927 39,339 Mg ++ 1,000 1,176 141

Ca ++ 13,000 14,944 3,502

Ba ++ 3,500 4,024 942

Sr ++ 2,600 2,989 701

Fe 32.0 36.78 8.65

Mn 2.70 3.10 0.73
Cl 90,014 94,446 68,337 pH 5.90 5.85 6.13 Rate (gpm) 50.00 41.50 7.61



### 3. Operating Costs

Table AIII

- 3 shows the cost of electricity to operate a NF system for the two produced
waters considered here. The electricity cost is assumed to be $0.10 / kWh

.

Table AIII

- 3

. Key NF Softening Operating Costs

Produced

Water Electricity

Usage (kWh/bbl) E lectricity

Cost ( $/bbl ) Maximum

Permeate Recovery,
% Concentrate Transportation and Disposal Cost, $/bbl feed Design Case 0.19 0.02 30 7.7 0
Well

- 5 0.19 0.02 15 9.35

The dominant cost for produced water softening by NF arises from the low water recoveries predicted by the simulations. The NF concentrate stream would need to be disposed of by deep

- well injection ( UIC )

. The estimated cost for concentrate transportation from central Pennsylvania to Ohio and disposal by UIC is $11 /bbl

. This cost and the large amount of transportation required makes the use of NF for produced water softening impractical.AIV

- 1



### Appendix I V. Modified Lime

- Soda Process Analysis and Experimental Results

A. Equilibrium Material Balance Calculations with Aspen Plus/OLI

We utilized Aspen Plus with an electrolyte property package from OLI Systems for all material balance calculations described in this appendix. Figure AIV

- 1 shows the process flow diagram
for these calculations. Produced water is fir st treated with Ca(OH) 2 to precipitate magnesium as Mg(OH) 2 . The lime slurry (LIM

- SLRY) is filtered in FILTER

- 1 and the filtrate is sent to an optional NaOH precipitation step. No NaOH was added in any of the simulations reported here. Thus, the stream labeled OVERFLOW is the same as the stream labeled OH

- FLTRT. Sodium
carbonate is added in the block labeled CO3

- PPT to generate a carbonate slurry. This slurry is
filtered in the block labeled CO3

- FLTR to yield the softened produced water product, CO3FLT RT and the precipitate, CO3

- PPT. For all the disposal calculations, it is assumed that the precipitates are 45 wt% solids (balance water)

.

Figure AIV

- 1 . Process Flow Diagram for Aspen Plus/OLI Simulations

Table AIV

- 1 shows the flow rates of each feed component used in these calculations. The total flow rate was about 1 MGD (million gallons/day) for each produced water simulation. We conducted sensitivity studies in the lime precipitation step to define the amount of lime required to precipitate essentially all of the magnesium in the raw produced water . We fixed the lime usage at the lowest multiple of 25 lb/hr Ca(OH) 2 for which essentially all the magnesium precipitated as Mg(OH) 2 . For all cases, addition of 1.005

- 1.03 moles of Ca(OH) 2 per mole magnesium in the feed produced water was sufficient to precipitate essentially all of the magnesium in the feed produced water

.

With the Ca(OH) 2 addition rate fixed, w e conducted sensitivity studies in which we varied the
rate of Na 2 CO 3 addition to the lime

- treated produced water

. Figure AIV

- 2 through Figure AIV

- 9
show the calculated equilib rium composition of the produced water as a function of the
amount of Na 2 CO 3 added. For each case, as Na 2 CO 3 is added, essentially all of the calcium and strontium precipitate as carbonates prior to any barium (and therefore radium) carbonate precipitatio n. This selectivity is the basis for the modified lime

- soda process.AIV

- 2

Table AIV

- 1

. Produced water Component Feed Rates for Aspen Plus/OLI Simulations (all units lb/hr except where noted)

Well

- 1 Well

- 2 Well

- 3 Well

- 4 Well

- 5 Well

- 6 Well

- 7 Design

H2O 347622 327658 312522 358011 329934 339184 338543 335737
NaCl 23422 33764 45784 16970 34471 28549 29963 30935 MgCl2 627 1144 1757 776 1362 1090 1594 1090
CaCl2 5353 9898 12632 5161 12517 8377 10475 9147
SrCl2 1277 2309 2881 811 1636 1472 1101 1573
BaCl2 3469 6959 6116 17 1845 3058 78 3269
FeCl2 21 58 97 43 25 59 37 39
MnCl2 1 2 3 1 2 3 1 2
Total 381792 381792 381792 381792 381792 381792 381792 381792

MGD a 1.03 1.00 0.97 1.05 1.00 1.02 1.02 1.01

a MGD: million gallons/day

Figure AIV

- 2 . Simulation Results for Well

- 1 Produced WaterAIV

- 3 Figure AIV

- 3 . Simulation Results for Well

- 2 Produced Water

Figure AIV

- 4 . Simulation Results for Well

- 3 Produced WaterAIV

- 4 Figure AIV

- 5 . Simulation Results for Well

- 4 Produced Water

Figure AIV

- 6 . Simulation Results for Well

- 5 Produced WaterAIV

- 5 Figure AIV

- 7 . Simulation Results for Well

- 6 Produced Water

Figure AIV

- 8

. Simulation Results for Well

- 7 Produced WaterAIV

- 6 Figure AIV

- 9 . Simulation Results for the Design Case Produced Water



### B. Experimental Results for Modified Lime

- Soda Process

This section gives details of the experiments that were conducted to demonstrate the modified
lime

- soda process for softening produced water. We conducted all experiments under ambient conditions, using a magnetic stir bar for agitation. We utilized reag ent grade Na 2 CO 3 , Ca(OH) 2 , and NaOH for these experiments. The pH was measured with a Thermo

- Scientific Orion Five

Star pH meter and an Accumet 13

- 620

- 631 pH electrode. All experiments were conducted using Well

- 5 produced water.



### 1. Experiment 20110816 with Well

- 5 Produced water

We added one liter of Well

- 5 produced water to a 2

- liter beaker and placed the beaker on a stir plate. The initial pH of the solution was 5.68. To this solution, 43.29 gm 10 wt% Ca(OH) 2 solution was added, w hich increased the pH to 10.92 and precipitated the magnesium as Mg(OH) 2 . Then, 212.92 gm of 20 wt% Na 2 CO 3 solution was added to the agitated mixture in ten 10 mL increments. This is enough Na 2 CO 3 to precipitate all of the calcium, strontium, and
barium. Each increment was added essentially instantaneously. Approximately two minutes elapsed between Na 2 CO 3 additions. A sample was withdrawn from the beaker after every other

Na 2 CO 3 addition for LSC analysis. Table AIV

- 2 and Figure AIV

- 10 show the LSC results for the
filtrate for each amount of Na 2 CO 3 added.AIV

- 7

Table AIV

- 2 . Results for Experiment 20110826 with Well

- 5 Produced water

grams
Na 2 CO 3 (dry)
added mole Na 2 CO 3

per mole

Ca+Sr+ Ba mole Na 2 CO 3

per mole

Ca+Sr Counts/min

Above background Fraction feed

counts/min remaining

0 0 0 13.95 1

4.26 0.11 0.113 12.95 0.93

8.52 0.21 0.227 10.58 0.76

12.78 0.32 0.340 9.08 0.65

17.03 0.42 0.454 8.75 0.63

21.29 0.53 0.567 5.35 0.38

25.55 0.64 0.681 5.25 0.38

29.81 0.74 0.794 5.92 0.42

34.07 0.85 0.908 3.55 0.25

38.33 0.95 1.021 3.38 0.24

42.58 1.06 1.135 2.48 0.18

Figure AIV

- 10 . LSC Results for Experiment 20110826



### 2. Experiment 20110901 with Well

- 5 Produced water

We added one liter of Well

- 5 produced water to a 2

- liter beaker and placed the beaker on a stir plate. The initial pH of the solution was 5.9. To this solution, 37.35 gm 10 wt% Ca(OH) 2 solution was added, wh ich increased the pH to 10.62 and precipitated the magnesium asAIV

- 8

Mg(OH) 2 . Then, 424.9 gm of 10 wt% Na 2 CO 3 solution was added to the agitated mixture at a constant rate over the course of 316 minutes. This is enough Na2CO3 to precipitate all of the
calcium , strontium, and barium. Samples of the supernatant were removed periodically and filtered through 0.45  filters. The residual radium activity of each sample was measured using

LSC.

Table AIV

- 3 . Results for Experiment 201 10901 with Well

- 5 Produced water

grams Na 2 CO 3 solution
added mole

Na 2 CO 3 per mole

Ca+Sr+Ba mole

Na 2 CO 3 per mole Ca+Sr Counts/min

Above background Fraction

feed counts/min remaining

0 0.000 0.000 14.73 1.00

20 0.054 0.060 13.28 0.90

45.46 0.122 0.137 11.8 0.80

89.67 0.241 0.270 12.68 0.86

120.52 0.324 0.363 11.7 0.79

201.01 0.541 0.605 11.73 0.80

300.58 0.809 0.905 9.38 0.64

322.08 0.867 0.970 11.22 0.76

335.55 0.903 1.011 8.73 0.59

348.97 0.940 1.051 9.78 0.66

389.34 1.048 1.173 9.27 0.63

403.63 1.087 1.216 8.33 0.57

424.9 1.144 1.280 5.42 0.37

Table AIV

- 3 and Figure AIV

- 11 show the results of this experiment. Ideally, the fraction radium activity remaining in solution, as measured by the fraction of the feed counts/minute above background (column 5) remaining in solution, would be unity until the number of moles of

Na 2 CO 3 added equals the number of moles of Ca ++ + Sr ++ in the feed solution, followed by a
decrease to zero as the number of moles to Na 2 CO 3 increases to about 14% above the number
of moles of Ca ++ + Sr ++ + Ba ++ in the feed solution. The 14% molar excess carbona te value is based on the Aspen/OLI simulation results for W ell

- 5 produced water ( Figure AIV

- 6 ). According to the simulation, with 14% molar excess Na 2 CO 3 addition, the residual barium concentration in solution is 59 ppm/w, which corr esponds to a reduction of about 99% vs. feed concentration. Although the data show that this ideal behavior was not achieved, it is asserted that with improved agitation and other methods such as seeding and the judicial use of antiscalants, the
ideal beh avior may be approached closely enough to warrant further development. In this experiment, since it is known that radium and barium coprecipitate as carbonates, the fraction barium precipitation behavior may be inferred from the fraction radium precipitat ion 1

.AIV

- 9 Figure AIV

- 11 . LSC Results for Experiment 20110901



### 3. Experiment 20110708 with Well

- 5 Produced water
This experiment utilized NaOH to precipitate Mg, Ca, and Sr as the corresponding hydroxides, followed by Na 2 CO 3 to pre cipitate Ba and Ra as the carbonates. One liter of Well

- 5 produced

water was added to a 2

- liter beaker and agitated with a magnetic stirrer. Six aliquots of 50 wt% NaOH (7 mL per aliquot) were sequentially added to the beaker. After each addition, the

m ixture was allowed to agitate for 2

- 3 minutes. Then a sample was withdrawn, filtered, and prepared for LSC analysis. The LSC analyses were conducted on the day of the experiment and two weeks later (reported here). After the last NaOH addition, the slur ry was filtered through a

1  glass filter to remove the precipitate. The filtrate was added to the 2

- liter beaker and agitation was restarted. Then a series of six aliquots of 20 wt% Na 2 CO 3 solution were added in the same manner, with sampling after each increment.

Table AIV

- 4 and Figure AIV

- 12 show the results of this experiment. Here, the radium activity stays in solution throughout the course of the NaOH addition.AIV

- 10 Table AIV

- 4 . LSC Results from Experiment 20110708

Mole NaOH/ per mole Mg+Ca+Sr mole Na 2 CO 3

per mole Mg+Ca+Sr mole

NaOH/2+ Na 2 CO 3 per mole Mg+ Ca+Sr Counts/min

Above background Fraction feed

counts/min remaining

0 0 0 54.3 1

0.166 0 0.166 52.43 0.966

0.332 0 0.332 50.48 0.930

0.498 0 0.498 51.4 0.947

0.664 0 0.664 51.35 0.946

0.830 0 0.830 49.1 0.904

0.996 0 0.996 50.25 0.925

0.996 0.023 1.019 45.15 0.831

0.996 0.046 1.042 42.06 0.775

0.996 0.069 1.065 36.7 0.676

0.996 0.092 1.088 33 0.608

0.996 0.115 1.111 31.25 0.576

0.996 0.138 1.134 23.81 0.438

Figure AIV

- 12 . LSC Results for Experiment 20110708

1 Kirby, H.W. and Salutsky, M., The Radiochemistry of Radium, National Academy of Sciences, 1964.