MEMORANDUM

TO: Record

FROM: EPA

DATE: March 15, 2013

SUBJECT: Ion Exchange Vendors in the CBM Industry (DCN CBM00667)

EPA compiled information on all of the known ion exchange vendors in the CBM 

industry using information from existing sources, industry site visits, and the Detailed 

Questionnaire. This memorandum provides detailed information about each of the ion exchange 

technologies listed in Section 4 of the Technical Development Document for the 

Coalbed Methane (CBM) Extraction Industry (TDD).

1.0 HIGGINS LOOPTM PROCESS

In 2007, EPA visited an Exterran1

Figure 1-1

Higgins LoopTM Process unit operated by Fidelity 

Exploration and Production Company in the Powder River Basin (ERG, 2007). 

illustrates the Higgins LoopTM, designed by Severn Trent Services and operated by Exterran. The 

Higgins LoopTM targets the removal of sodium from sodium bicarbonate produced water. This is 

a single-resin system which does not remove anions such as chloride. Produced water in the 

Powder River Basin is ideal for treatment with the Higgins LoopTM system because the TDS is 

mostly sodium bicarbonate.

The Higgins LoopTM operates in two separate modes to maintain nearly continuous flow: 

normal operation and resin pulsing operation. The process uses a loop with two different zones,

divided by valves, called the adsorption zone and the regeneration zone. During normal 

operation, shown in Figure 1-1, all valves remain closed, separating the two zones. Influent 

wastewater enters the resin filled adsorption zone (1) where the ion exchange process occurs (2). 

Treated wastewater exits the adsorption zone at the bottom (3). Simultaneously, influent 

regeneration acid (4) is injected into the regeneration zone to regenerate spent resin (5). After 

regeneration, the spent acid leaves the loop as a regenerate waste stream (concentrated brine) (6). 

The Higgins LoopTM operates normally approximately 97 of the time, meaning the system has an 

effective operating time of 97 percent. 

Resin pulsing, shown in Figure 1-1 B, occurs to regenerate the resin as the resin 

performance in the adsorption zone gradually decreases (1). During resin pulsing, normal 

operation is briefly interrupted. All valves open and pulsing water is injected (2) to move a small 

portion of resin around the loop. When this happens, a portion of regenerated resin enters the 

adsorption zone (3) and a portion of spent resin enters the regeneration zone (4). 

The Higgins LoopTM is capable of the following average removals (%) (ALL, 2006; 

Beagle, 2007; Dennis, 2005):

• Bicarbonate: 78-95;

 1 Exterran Water Management Services was formerly known as EMIT Water Discharge Technology.
Memorandum

January 18, 2008

Page 2

• Magnesium: >92;

• Potassium: >93; and

• Sodium: 98.

Exterran indicated that their Higgins LoopTM treatment is priced on a dollar per barrel 

treated basis, which includes transporting the produced water (where necessary), treating the 

produced water, determining bypass rates, maintaining permitted discharge limits, and disposing 

of residual wastes (Beagle, 2012). 

Figure 1-1. Higgins LoopTM Flow Diagram

2.0 DRAKE COUNTERCURRENT PROCESS

The Drake Process uses a fluidized-bed ion exchange system in which resin beads 

circulate within a vessel between two separated reaction zones. Drake designed their process for 

Powder River basin produced water. The process selectively removes sodium and leaves the 

calcium and magnesium. 

According to Drake, in traditional ion exchange, as the resin becomes saturated with 

sodium ions, which adsorb first, calcium and magnesium ions begin to replace sodium ions on 

the resin. The adherence of calcium and magnesium ions to the resin reduces the sodium removal 

rates and increases the volume of waste in the regenerate waste streams. The preferential 

removal of calcium and magnesium would increase the sodium adsorption ratio (SAR)

2

Figure 2-1

making 

the effluent water unsuitable for potential use in irrigation. According to Drake, their system and 

operating design eliminates the need for SAR adjustment of the treated wastewater.

shows the flow diagram of the Drake process. First, the produced water enters 

equalization tanks and flows through filter screens to remove TSS. The Drake system meters the 

flow of resin beads and pretreated produced water into the sodium removal zone, controlling 

contact time between resin and produced water. During the contact time, sodium ions in the 

produced water exchange places with the hydrogen on the resin bead.

 2 Sodicity is expressed as the sodium adsorption ratio, which is the ratio of sodium (Na) present in the water to the 

concentration of calcium (Ca) and magnesium (Mg).
Memorandum

January 18, 2008

Page 3

Figure 2-1. Drake Process Flow Diagram (U.S. EPA, 2007)

A separator removes the resin beads from the flow of CBM produced water to the 

regenerator. Sulfuric acid provides hydrogen ions that exchange with sodium ions on the resin 

beads, generating a sodium sulfate brine (Na2SO4). The sodium sulfate brine flows out from the 

system and the regenerated resin beads are put back into service in the sodium removal zone 

(U.S. EPA, 2007). A vendor advertisement indicated that the Drake process is capable removing 

between 40 and 75 percent of the sodium in influent waters (Drake, 2007).

EPA visited Drake’s pilot-scale CBM produced water treatment operations in the Powder 

River Basin in 2007 and 2009. Drake did not have any full-scale operations in the Powder River 

basin as of June 2009. According to recent telephone communications, ERG learned that Drake 

previously deployed a full-scale commercial IonFlo process in the Powder River Basin that 

treated produced water from two sites in Wyoming. However, Drake indicated that they do not 

currently have any ion exchange systems operating in the field and that their last water treatment 

contract fell through as a result of a drop in natural gas prices in Fall 2010 (Drake, 2012).

3.0 RECOPURTM PROCESS

Eco-Tec, in cooperation with PureTech, has developed a countercurrent ion exchange 

process that uses smaller resin beds in a slightly compressed state (Eco-Tec, 2008). This process 

has the following advantages over a conventional countercurrent ion exchange system:

• More compact treatment units compared to most ion exchange systems, which 

cost less, can be skid-mounted, and can be completely assembled prior to 

shipment;

• Lower use of total resin capacity during treatment adsorption cycle resulting in 

longer resin life and less chemical usage;

• Less channeling and ionic leakage through the system (i.e., less flow through 

isolated areas where resin becomes exhausted more quickly); and 

Typical Influent 

Concentration 

~920 mg/L Na+ Sodium 

Removal 

Zone

EQ Tanks 

& 

Screens

Typical Final Effluent 

Concentration 

< 115 mg/L Na +

pH>6.5

Produced 

Water from 

CBM Wells

Regenerator

Sulfuric Acid

H2SO4

Sodium Sulfate (Glauber Salt)

Na2SO4

Spent 

Resin

Regenerated Resin
Memorandum

January 18, 2008

Page 4

• Lower surge tank storage requirements due to shorter cycle times.

The only disadvantage to the compressed bed technology that Eco-Tec acknowledges is 

the increased need for pretreatment of suspended solids. Because the compressed resin beds do 

not have any freeboard (i.e. head space above the resin that can fill with water) where suspended 

solids can collect without disrupting the process, it is important to rigorously pre-treat influent to 

remove any suspended solids (Eco-Tec, 2006). 

4.0 ROHM AND HAAS CROSS-CURRENT ION EXCHANGE PROCESS

In October 2007, EPA visited a pilot-scale Rohm and Haas ion exchange unit designed to 

treat produced water from CBM wells operated by Anadarko Petroleum Corporation (Anadarko) 

in the Powder River Basin (PG Environmental, 2007a). The unit was not operating at the time of 

EPA’s visit, because limited gas pipeline capacity had forced Anadarko to cease production 

temporarily. As a result, EPA did not collect detailed information about the Rohm and Haas 

system. EPA does not have information on the current status of this system.

Anadarko explained that the ion exchange system is similar to the Exterran Higgins 

LoopTM process, but contains fewer moving parts. It consists of vessels packed with a 

combination of weak acid cation (WAC) and strong acid cation (SAC)

3

Anadarko blends CBM produced water that has been filtered for suspended solids with 

the ion exchange effluent. After blending, the water flows to a limestone-filled tank to raise the 

pH and then flows into the Powder River through a discharge outfall (PG, 2007a).

resins that target calcium 

and magnesium first and then sodium. This differs from the Exterran and Drake systems, which 

target the removal of sodium. Anadarko regenerates the resin by pumping hydrochloric acid

through the resin in the direction opposite the water being treated to flush out suspended solids

and then rinsing the resin with clean water from the top down in the same direction as the water 

being treated. After regeneration, the hydrochloric acid brine flows from the vessels to a 

limestone-filled tank for pH buffering, after which it is trucked to an injection well for disposal.

5.0 SET CORP’S DYNIXTM PROCESS

In 2008, RG Global (now SET Corp) completed construction of a water treatment facility 

for CBM produced water in the Powder River Basin. Unlike other ion exchange units which use 

SAC resin, SET Corp’s system uses WAC resin. WAC resins do not function well in ion 

exchange units with moving resin beds because they swell when they are exhausted. For this 

reason, SET Corp applied WAC resins to fixed resin beds. WAC resins require less acid for 

regeneration than SAC resins, so they generate smaller waste volumes and, therefore, have lower 

waste disposal costs. WAC resins also exhibit higher treatment efficiencies for sodium 

bicarbonate, the most common sodium compound found in CBM produced water. SET Corp’s 

DynIXTM Process is capable of the following removals (%)(Jangbarwala, 2008):

• Bicarbonate: 85;

• Calcium: >93;

• Magnesium: >67;

 3 See Section 4 of the Technical Development Document (TDD) for the Coalbed Methane (CBM) Extraction 

Industry (DCN CBM00669) for a general discussion of ion exchange technology.
Memorandum

January 18, 2008

Page 5

• Potassium: >67; and

• Sodium: 83.

6.0 REFERENCES

1. ALL Consulting. 2006. A Guide to Practical Management of Produced Water 

from Onshore Oil and Gas Operations in the United States. October 2006. 

Prepared for US DOE, National Petroleum Technology Office. EPA-HQ-OW2008-0517. DCN 10000.

2. Beagle, Douglas. 2007. Continuous Countercurrent Ion Exchange Applied to 

CBM Produced Water Treatment in the Powder River Basin of Wyoming and 

Montana - DCN 05158.

3. Beagle, Douglas. 2012. Notes from Telephone Conversation Between Steve 

Strackbein and Lori Weiss, ERG and Douglas Beagle, EMIT Higgins LoopTM

Technology (Ion Exchange). (February). DCN CBM00623.

4. Dennis, Richard. 2005. A Positive Trade-off. (August). DCN 02226.

5. Drake, Vivian. 2012. Email Conversation Between Brent Ruminski, ERG, and 

Vivian Drake, Drake Water Technologies. (January). 

6. Drake Water Technologies. 2007. Drake Process Technology: Scope and Pricing 

Summary. DCN 05283.

7. Eco-Tec. 2006. Short Bed Ion Exchange Technology Produces Ultrapure Water 

Without Using a Mixed Bed. DCN 06160.

8. Eco-Tec. 2008. Eco-Tec Awarded CBNG Produced Water Treatment System 

Contract – DCN 05530.

9. ERG, 2007. Final Site Visit Report: Fidelity Exploration & Production Co. 

Countercurrent Ion Exchange Treatment Decker, MT (Powder River Basin). 

EPA-HQ-OW-2006-0771-0974 (DCN 05201).

10. Jangbarwala. 2008. Custom-designed Process Treats CBM Produced Water. DCN 

6156.

11. PG Environmental. 2007a. Final Site Visit Report: Anadarko Petroleum 

Corporation Johnson County, WY (Powder River Basin), Coalbed Methane 

Detailed Study. (November). EPA-HQ-OW-2006-0771-1002 (DCN 05239).

12. U.S. EPA. 2007. Final Site Visit Report: Drake Water Technologies, Inc. Gillette, 

WY (Powder River Basin), November 30, 2007. EPA-HQ-OW-2006-0771-0975.