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Produced Water Management Technology Descriptions 

Fact Sheet - Ion Exchange

Salt is the key parameter that determines how produced water is managed 

onshore. A separate fact sheet describes membrane processes for 

removing salt. This fact sheet describes ion exchange, another common 

process that removes salt and other inorganic chemicals from produced 

water. 

Many consumers are familiar with home water 

softeners that remove iron and manganese from 

tap water. Water softeners use ion exchange 

columns filled with a specific type of resin. The 

resin is charged with sodium ions by passing a 

concentrated salt solution through the column. As 

water loaded with iron and manganese moves 

through the column, those ions are attracted to 

the resins, which prefer to bind with the iron and 

manganese. Sodium is released when the resin 

attaches to the iron and manganese. Once 

stripped of the undesirable iron and manganese, 

the water is piped into the home water supply. 

Periodically, the resin-exchange sites are all 

used. Then, the column is backwashed and 

regenerated with fresh salt solution. 

The water softener example is provided to explain the principle of ion 

exchange. Exchange resins can be designed to selectively remove different 

types of chemicals. IOGCC and ALL (2006) provide a description of the 

different types and applications of ion exchange resins. 

In the case of produced water, the most 

common use of ion exchange is to 

preferentially remove sodium. For that 

application, resins are chosen that are 

regenerated with hydrogen ions. As the 

produced water passes through the 

column, sodium ions are removed from the 

water. They replace the hydrogen on the 

resin's exchange sites. The treated water 

contains more hydrogen ions, and 

therefore its pH drops. Often the pH is 

raised by contact with calcium carbonate, which in turn helps to control the 

sodium adsorption ratio or SAR (for more discussion of the SAR, see the 

fact sheet describing agricultural use). 

However, ion exchange can be used to remove other contaminants too. At 

one treatment plant in the Powder River Basin, ion exchange is used to preferentially remove divalent cations 

which would otherwise form scale on the reverse osmosis membranes that do the bulk of the sodium removal. 

Further, special ion exchange resins have been developed to remove radium (NORM) from produced water. 

One version of ion exchange for treatment of coal bed methane produced water in the 

Rocky Mountain region is the "Higgins Loop." Dennis (2006) and IOGCC and ALL 

(2006) describe the process. The Higgins Loop uses a continuous countercurrent ion 

 

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Intro to Produced Water

Technology Descriptions

Basic Separation 

Mechanical Blocking Devices 

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Injection for Oil Recovery 

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Agricultural Use 

Industrial Use 

Domestic Use 

Discharge 

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Offsite Commercial Disposal 

Membrane Processes 

Capacitive Deionization 

Thermal Distillation 

Physical Separation 

Coalescence 

Flotation 

Physical/Chemical Processes 

Solvent Extraction 

Adsorption 

Combinations of Technologies

Feedstock 

Oxidation 

pH Adjustment 

Fed & State Regulations

Technology Identification

 

Home water softener 

column with salt tank 

for regenerating the 

column and sodium 

hydroxide tank for 

neutralizing low pH; 

Source: J. Veil, Argonne 

National Laboratory.

Ion exchange equipment at 

Argonne National Laboratory; 

Source: D&D - Nuclear 

Engineering Division of Argonne 

National Laboratory 

NETL: Produced Water Management Information System Page 1 of 2

http://www.netl.doe.gov/technologies/pwmis/techdesc/ionex/index.html 3/13/2012
exchange contactor for liquid phase separations of ionic components. The contactor 

consists of a vertical cylindrical loop, which contains a packed bed of resin separated 

into four operating zones by butterfly or "loop" valves. These operating zones - 

adsorption, regeneration, backwashing, and pulsing - function like four separate 

vessels. 

Produced water containing high sodium levels is fed to the adsorption zone within the 

Higgins Loop. There, it contacts strong acid cation resin, which accepts sodium ions 

in exchange for hydrogen ions. Treated water containing less than 10 mg/L sodium 

then exits the loop. In the lower section of the Higgins Loop, resin filled with sodium is

regenerated with either hydrochloric or sulfuric acid. This generates a small, 

concentrated spent brine stream. Regenerated resin is rinsed with water prior to 

reentry into the adsorption zone to remove acid from its pores. As resin in the upper 

layer of the adsorption zone becomes loaded with sodium, the flows to the Higgins Loop are momentarily 

interrupted. This allows advancement of the resin bed (pulsing) through the loop in the opposite direction of liquid 

flow. Liquid flows are restarted after resin pulsing is complete. 

Beagle (2006) reports that 17 ion exchange units are operating in Montana and Wyoming to treat produced 

water. Emit Water Discharge Technology uses a Higgins Loop as part of an overall treatment system to treat 

produced water for subsequent reuse or discharge. The volume of water treated in this fashion has steadily 

increased from a few hundred thousand bbl (barrel = 42 gal) in August 2003, to nearly 5 million bbl in August 

2006. 

The backwash stream from ion exchange treatment of produced water will contain high levels of sodium. 

Therefore, disposal requirements for the concentrated brine should be considered when selecting ion exchange 

treatment technologies. 

Other Versions of Ion Exchange Technologies

Other companies offer technologies that use ion exchange in different configurations. However, only a few have 

actually treated produced water. Descriptions of these technologies can be found in CSM (2009). Examples 

include: 

the Drake Process, a continous ion exchange process that targets sodium bicarbonate. 

the Eco-Tec: Recoflo® compressed-bed ion exchange process 

Additional versions of ion exchange technology may be part of combined treatment systems. 

References

Beagle, D., and R. Dennis, 2007, Continuous Countercurrent Ion Exchange Applied to CBM Produced Water 

Treatment in the Powder River Basin of Wyoming and Montana," presented at the 14th International Petroleum 

Environmental Conference, Houston, November 5-9. Available at http://ipec.utulsa.edu/Conf2007/Abstracts%

202007/Beagle_40.pdf [PDF]. 

CSM, 2009, “Technical Assessment of Produced Water Treatment Technologies,” prepared by the Colorado 

School of Mines as part of RPSEA Project 07122-12, November. Available at 

http://aqwatec.mines.edu/produced_water/treat/docs/Tech_Assessment_PW_Treatment_Tech.pdf [PDF} 

Dennis, R., 2006, "Coal Industry Turns to Ion Exchange Technology for Wastewater Minimization," Industrial 

WaterWorld, PennWell Corporation, Tulsa, OK, Sept. Available at 

http://ww.pennnet.com/Articles/Article_Display.cfm?

Section=ARTCL&PUBLICATION_ID=41&ARTICLE_ID=276178&C=colmn . 

IOGCC and ALL, 2006, "A Guide to Practical Management of Produced Water from Onshore Oil and Gas 

Operations in the United States," prepared for U.S. Department of Energy, National Energy Technology 

Laboratory, by the Interstate Oil and Gas Compact Commission and ALL Consulting, Oct. Available at 

http://www.all-llc.com/IOGCC/ProdWtr/ProjInfo.htm. 

Higgins Loop water 

treatment system; 

Source: Severn Trent 

Services 

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