### 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 i on 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 Devel opment Document for the Coalbed Methane (CBM) Extraction Industry (TDD).

1.0 H IGGINS L OOP TM P ROCESS

In 2007, EPA visited an Exterran 1 Figure 1

- 1 Higgins Loop TM Process unit operated by Fidelity Exploration and Production Company in the Powder River Basin (ERG, 2007)

. illustrates the Higgins Loop TM , designed by Severn Trent Services and operated by Exterran . The Higgins Loop TM t argets the removal of sodium from sodium bicarbonate produced water

. This is a single

- resin system which does not remove anions such as chloride. P roduced water in the Powder River Basin is ideal for treatment with the Higgins Loop TM system because the TDS is mostly sodium bicarbonate.

The Higgins Loop TM 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 r esin 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 Loop TM 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 r esin 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 spe nt resin enters the regeneration zone (4).

The Higgins Loop TM 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.

E xterran indicated that their Higgi ns Loop TM 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 w astes (Beagle, 20 12 ).

Figure 1

- 1 . Higgins Loop TM Flow Diagram

2.0 D RAKE C OUNTERCURRENT P ROCESS

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 remove s sodium and l eave s the

ca lcium 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 magne sium 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 unsuita ble for potential use in irrigation. According to Drake , their system and operating design eliminate s the need for SAR adjust ment 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

. S ulfuric acid provides h ydrogen ions that exchange with sodium ion s on the resin beads

, generat ing a sodium sulfate brine (Na 2 SO 4 ). 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, 2 007). 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 le arned 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, 201 2 ).

3.0 R ECO P UR TM P ROCESS

Eco

- Tec, in cooperation with PureTech, has developed a countercurrent ion exchange process that uses s maller 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 H 2 SO 4 Sodium Sulfate ( Glauber Salt) Na 2 SO 4 Spent

Resin Regenerated ResinMemorandum 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 pre treatment 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 R OHM AND H AAS C ROSS
- CURRENT I ON E XCHANGE P ROCESS

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 Petr oleum 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 col lect 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 E xterran Higgins Loop TM 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 pro duced 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, 2007 a ). resins that target calcium and magnesium first and then sodium. This differs from the Exterran and Drake sys tems
, which target the removal of sodium. Anadarko regenerates the res in by pumping hydrochloric acid through the resin in the direction opposite the water being treate d to flush out suspended solids and then rinsing the resin with clean water from the top down in the same direc tion 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 C ORP ’ S D YN I X TM P ROCESS
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 DynIX TM Process is capable of the followin g 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 R EFERENCES

1. ALL Consulting. 2006. A Guide to Practical Management of Produced Water from Onshore Oil and Gas Operations in the United States . O ctober 2006. Prepared for US DOE, National Petroleum Technology Office. EPA

- HQ

- OW

2008

- 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 Loop TM Technology (Ion Exchange) . (February). DCN CBM00623

. 4. Dennis, Richard. 2005. A Positive Trade

- off. (Aug ust). 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. Sho rt 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 Petrol eum 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 3 0, 2007. EPA

- HQ

- OW

- 2006

- 0771

- 0975.