FIELD EVALUATION OF A SURFACTANT-MODIFIED ZEOLITE SYSTEM FOR REMOVAL OF ORGANICS FROM PRODUCED WATER

Approximately 2.3 billion cubic meters (600 billion gallons) of wastewater (produced water) is generated each year as a byproduct of oil and gas operations in the continental USA. Disposal of this water represents about 10% of the cost of hydrocarbon production. Inexpensive treatment technologies can lower the cost of disposal and also generate higher quality water for other uses. Surfactant-modified zeolite (SMZ) has been shown to effectively sorb a variety of nonpolar organic compounds from water. SMZ was tested as a medium to remove benzene, toluene, ethylbenzene, and xylenes (BTEX) from produced water generated during extraction of coal bed methane. BTEX removal is necessary prior to surface discharge of produced waters or as a pretreatment for reverse osmosis.

We demonstrated in laboratory column experiments that BTEX-saturated SMZ is readily regenerated by air sparging. There was no loss in BTEX sorption capacity, and a minor decrease in the hydraulic conductivity of the SMZ, after 50 sorption/regeneration cycles. Based upon the laboratory results a pilot-scale produced-water treatment system was designed and tested at a reinjection facility in the San Juan Basin, New Mexico. The SMZ-based system was designed to treat up to 110 liters (30 gallons) of produced water per hour on a continuous basis by running two SMZ columns in parallel. The system performed as predicted based on laboratory results over repeated feed and regeneration cycles during the month-long operation. The BTEX-laden sparge gases were treated with a vapor-phase bioreactor system resulting in an emissions-free process.