Tuesday, November 6, 2007 - 4:30 PM
230-19

Use of Zeolites for Treating Natural Gas Co-Produced Waters in Wyoming, USA.

George F. Vance1, Hongting Zhao1, Michael A. Urynowicz2, and Girisha Ganjegunte3. (1) Renewable Resources, University of Wyoming, 1000 E. University Ave., Laramie, WY 82071, (2) Civil and Environmental Engineering, University of Wyoming, 1000 E. University Ave., Laramie, WY 82071, (3) Crop and Soil Sciences, Texas A&M Agricultural Experiment Station, 1380 A&M Circle, El Paso, TX 79927

Water co-produced from coalbed natural gas (CBNG) operations is a major environmental challenge because of its quantity and quality. The concern associated with large volumes of CBNG water is due to its high sodium adsorption ratio (SAR, e.g., 30-70 mmol½ L). Calcium (Ca2+)-rich natural zeolites were studied for their ability to removal of sodium (Na+) from CBNG waters. Two zeolite samples were evaluated, one from the St. Cloud zeolite mine in Winston, NM and another from the Bear River (BR) zeolite mine in Preston, ID. The zeolite materials were used in adsorption kinetic/isotherm studies and column experiments. A surrogate CBNG water that simulated the water chemistry of CBNG waters was used in the various studies described herein. Results indicated that a Langmuir model fit the adsorption data well. The maximum adsorption capacities from the adsorption isotherms for ST-Zeolite and BR-Zeolite were 9.6 and 12.3 (mg/g), respectively, accounting for approximately 38% and 39% of their measured CEC values. Column studies indicated that a metric tonne (1,000 kg) of ST-zeolite and BR-zeolite can be used to treat 16,000 and 60,000 liters of CBNG water, respectively, in order to lower the SAR of the simulated CBNG water from 30 mmol½ L to an acceptable level of 10 mmol½ L. Based on the results of this study Na+ removal with zeolite appears to be a cost-effective water treatment technology for maximizing the beneficial use of poor-quality CBNG water.