Wednesday, November 7, 2007
307-6

Processes Using Zeolites for Treating Waters Produced from Coalbed Natural Gas Operations.

Hongting Zhao1, George F. Vance1, 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

Development of the coalbed natural gas (CBNG) industry in many parts of the western U.S., including the Powder River Basin in Wyoming and Montana, has resulted in the co-production of potentially saline-sodic waters, hereafter referred to as CBNG water. Management of CBNG water is a major environmental challenge because of its quantity and quality. In this study, the potential utilization of natural zeolites was examined for removal of sodium (Na+) from CBNG waters. Zeolite samples studied included a natural Na-rich zeolite from Wyoming as well as naturally Ca-rich zeolites from New Mexico, Idaho and an activated Ca-rich chabazite from Arizona. Surrogate CBNG water that simulated the water chemistry of CBNG waters was used. Wyoming zeolite was pretreated in 0.1 M CaCl2 solution and converted to a Ca-rich zeolite before use. Column studies indicated that one metric tonne (1,000 kg) of the Ca-Wyoming zeolite can treat ~1.2 x 105 L (~3.2 x 104 gallons) CBNG water to reduce its sodium adsorption ratio (SAR, mmol½ L-½) from 30 to an acceptable level of 10. Compared to results of the other zeolites (~1.6 x 104 and 6.0 x 104 L, respectively), it is suggested that water treatment with locally available Wyoming zeolite appears to be more effective and may be a promising and feasible treatment technology for maximizing the beneficial use of poor-quality CBNG in the Powder River Basin, Wyoming. Ongoing studies are evaluating water treatment techniques involving the direct application of zeolite to CBNG waters and development of a field scale prototype.

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