Integrated treatment process using a natural Wyoming clinoptilolite for remediating produced waters from coalbed natural gas operations

Abstract

Coalbed natural gas (CBNG) development in western U.S. states has resulted in an increase in an essential energy resource, but has also resulted in environmental impacts and additional regulatory needs. A concern associated with CBNG development relates to the production of the copious quantities of potentially saline-sodic groundwater required to recover the natural gas, hereafter referred to as CBNG water. Management of CBNG water is a major environmental challenge because of its quantity and quality. In this study, a locally available Na-rich natural zeolite (clinoptilolite) from Wyoming (WY) was examined for its potential to treat CBNG water to remove Na + and lower the sodium adsorption ratio (SAR, mmol 1/2 L − 1/2 ). The zeolite material was Ca-modified before being used in column experiments. Column breakthrough studies indicated that a metric tonne (1000 kg) of Ca-WY-zeolite could be used to treat 60,000 L of CBNG water in order to lower SAR of the CBNG water from 30 to an acceptable level of 10 mmol 1/2 L − 1/2 . An integrated treatment process using Na-WY-zeolite for alternately treating hard water and CBNG water was also examined for its potential to treat problematic waters in the region. Based on the results of this study, use of WY-zeolite appears to be a cost-effective water treatment technology for maximizing the beneficial use of poor-quality CBNG water. Ongoing studies are evaluating water treatment techniques involving infiltration ponds lined with zeolite.