The primary goal of this research is to conduct a long-term field test of a prototype Surfactant-Modified Zeolite/Vapor-Phase Bioreactor (SMZ/VPB) treatment system for removing dissolved organics from produced water prior to demineralization to yield water that can be used by utilities or other industrial users.
Department of Civil, Architectural, & Environmental Engineering, University of Texas at Austin, Austin, TX
Department of Earth & Environmental Science, New Mexico Institute of Mining and Technology, Socorro, NM
Los Alamos National Laboratory, Los Alamos, NM
The major achievement of this project has been the development of an integrated treatment system for produced water that can remove dissolved organics to levels that would make downstream reverse osmosis treatment cost-effective and allow for a range of water reuse applications. A treatment system consisting of a SMZ column coupled with a VPB can be used to remove the BTEX constituents from produced water. A field test of this coupled system performed well over repeated feed and regeneration cycles demonstrating the viability of the process for BTEX removal. Regeneration of the SMZ using air sparging was found to be sufficient in the field to maintain the SMZ adsorption capacity and to allow continuous operation of the system. As expected, the BTEX concentrations in the regeneration off gas streams were initially very high in a given regeneration cycle. However, a GAC-fixed bed adsorption column placed upstream of the VPB reduced the peak BTEX concentrations to acceptable levels for the VPB. Compared to the effective removal of BTEX in the SMZ/VPB system, the organic acids or carboxylates present in the produced water were not effectively removed; therefore, an additional biological treatment system was added to achieve additional organic acid removal. The need for this process would depend on the desired reuse application.
The combined process consists of three major components: surfactant modified zeolite (SMZ) adsorption, vapor phase bioreactor (VPB) off-gas treatment system, and a membrane bioreactor (MBR). The specific results for the performance of each of these components and the overall project include the following:
The increasing need for broader areas of beneficial reuse of produced water and other lower-quality waters has become apparent, given water supply and cost issues. As water becomes scarce in many regions of the country, particularly the arid western states, the valuation of water resources is expected to increase. Beneficial reuse of water normally not considered to be usable, such as produced water, is expected to increase proportionally. The results of this laboratory and pilot-scale program suggest that the SMZ/VPB system may contribute significantly to this trend. The most recent results from the prototype organic acid treatment system suggest that the effluent water quality is suitable for downstream treatment using reverse osmosis. This would allow for a greater range of reuse options for the produced water.
Coproduced water from the oil and gas industry is, by some estimates, one of the largest single waste streams in the United States. Over the past 5 years researchers involved with this project have been working under previous DOE contracts to develop a technology for treating produced water.
The process consists of an SMZ system developed under DOE Contract No. DE-AC26-99BC15221, Treatment of Produced Oil and Gas Waters with a Surfactant-Modified Zeolite, combined with a VPB developed under DOE Contract No. DE-FC26-02NT15461, Treatment of Produced Waters using a Surfactant Modified Zeolite/Vapor Phase Bioreactor.
The process involves use of SMZ and biodegradation to remove BTEX and other organic contaminants. SMZ is an innovative filtration/sorption medium that can be produced cost-effectively using naturally occurring zeolites and commercially available surfactant. Researchers have demonstrated the potential of SMZ for BTEX removal at laboratory and pilot scale. They also have demonstrated the potential for VPB treatment of off-gas from the SMZ regeneration process. In addition, the researchers have demonstrated the potential for biodegradation of BTEX and organic acids in produced water via a membrane bioreactor system.
Researchers determined that SMZ could remove BTEX from produced water and be regenerated over numerous cycles without loss of BTEX capacity. They developed a VPB system that can treat the vapor-phase BTEX released during regeneration of the SMZ. The VPB system was tested for its ability to withstand spikes in influent concentration and periodic shutdowns. The system was found to be resilient to spikes; however, a small passive GAC column was found to be beneficial for attenuating spikes if necessary. The recovery time after periodic shutdowns was dependent on the length and frequency of the shutdown. The VPB acclimated to the frequent shutdowns, and the performance of the system was maintained. Laboratory studies also verified that a membrane bioreactor could be used to remove both BTEX and organic acid/carboxylates from a synthetic produced water under conditions representative of field conditions.
Two pilot-scale studies of the SMZ/VPB system have been completed at a facility in Farmington, NM, to assess the potential of this technology under field conditions. The facility is a produced-water disposal facility. The infrastructure was established for evaluation of the SMZ/VPB/MBR system: a building to house the system, onsite laboratory facilities, and an 8,800-gallon produced-water storage tank and associated piping. Data collected during the pilot-scale studies included influent and effluent water compositions, water and gas flow rates, SMZ adsorption and regeneration capacity, gas-phase VOC concentrations, BTEX removal in the VPB, as well as BTEX and organic acid/carboxyalte removal from a membrane bioreactor. Data from the pilot-scale study indicate that the combined SMZ/VPB/MBR system is capable of removing organic constituents from produced water and providing an effluent quality suitable for downstream reverse osmosis treatment.
All project activities have been completed. The final report is listed below under "Additional Information".
Critical evaluation of the pilot-scale data indicates that several design modifications to the field-scale improved performance of the system. These design changes included modifying the hydraulics of the SMZ columns and incorporating the MBR technology into the process scheme to optimize the system for subsequent reverse osmosis treatment. The results of the laboratory and field trials suggest that BTEX and organic acids can be removed from the process. Researchers are in the process of applying for a patent application for the combined process. We are currently completing the final report and have applied for a patent for the technology. The final report will include the following details:
SMZ columns treating produced water at the McGrath salt water disposal facilities.
This project was selected in response to DOE Solicitation DE-PS26-04NT15460-02, Focused Research in Federal Lands Access and Produced-Water Management in Oil and Gas Exploration and Production.
$243,536 (20% of total)
Other Government Organizations Involved: Los Alamos National Laboratory
Final Project Report [PDF]
Altare, C., Bowman, R.S., Sullivan, E.J., Katz, L.E., and Kinney, K.A., “Removal of Organic Contaminants from Produced Water Using a Surfactant-Modified Zeolite System,” presentation (abstract only) at the Geological Society of America Annual Meeting & Exposition, Salt Lake City, UT, October 16-19, 2005.
Darby, E.B., Katz, L.E., Kinney, K.A., Bowman, R.S., and Sullivan, E.J., “New Opportunities for Re-use of Produced Water—Water Quality and Permitting Issues,” presentation (abstract only) at the Geological Society of America Annual Meeting & Exposition, Salt Lake City, UT, October 16-19, 2005.
Darby, E.B., “Engineering and Economic Assessment of a Surfactant Modified Zeolite/Vapor Phase Biofilter Process for Treatment of Produced Water,” Masters of Science & Engineering Report, Civil, Architectural & Environmental Engineering Department, University of Texas at Austin, TX, May 2006.
Noris, F. and Kinney, K.A., “Investigation of Bioaerosol Emissions of Bacteria and Fungi from Vapor Phase Biofilters,” Q-386, abstract only, Abstracts from the 106th General Meeting of the American Society for Microbiology, Florida, May 2006.
Altare, C., Bowman, R.S., Sullivan, E.J., Katz, L.E., and Kinney, K.A., “Application of Surfactant-Modified Zeolite for Oilfield Produced-Water Treatment: Examining Regeneration and Long-Term Stability,” poster presentation at the 7th International Conference on the Occurrence and Utilization of Natural Zeolites, Socorro, NM, July 6-9, 2006.
Sullivan, E.J. L. Katz, K. Kinney, S. Kwon, L.J. Chen, E. Darby, R. Bowman, and C. Altare, “Pilot-scale test of a produced-water treatment system for organic compounds,” 14th International Petroleum Environmental Conference, October 17-20, 2006, San Antonio, TX.
Darby, E.B., L. Katz, K. Kinney, R. Bowman, and E. Sullivan, “Assessment of a surfactant-modified zeolite/vapor phase biofilter process for treating produced water,” In Proc. Texas Section American Society of Civil Engineers, October 11-14, 2006, San Antonio, TX.
Bowman, R.S., E.J. Sullivan, L.E. Katz, and K.A. Kinney, “Treatment of oilfield wastewaters with surfactant-modified zeolite,” accepted for the 15th International Zeolite Conference, August 12-17, 2007, Beijing, China.
Altare, C., C., Bowman, R.S., Katz, L.E., Kinney, K.A. and Sullivan, E.J., “Regeneration and Long-Term Stability of Surfactant-Modified Zeolite for Removal of Volatile Organic Compound from Produced Water,” submitted to Microporous & Mesoporous Materials.