0423_Desalination and Reuse of High-Salinity Shale Gas Produced Water: Drivers, Technologies...

ESEL Paper Review_20140423
By Hong Guo
Mail: hongguo@gist.ac.kr
Phone: (+82) (0)10 82276568
1, Title and Author
Title: Desalination and Reuse of High-Salinity Shale Gas Produced Water: Drivers, Technologies, and Future Directions
Journal: Environmental Science & Technology
Devin L. Shaffer, Laura H. Arias Chavez, Moshe Ben-Sasson, Santiago Romero- Vargas Castrillon, Ngai Yin Yip, and Menachem Elimelech*
Department of Chemical and Environmental Engineering, Yale University, P.O. Box 208286, New Haven, Connecticut 06520-8286,
United States
2. Summary of Paper
? In this study, the authors review the current state of practice for produced water management across the united states and discuss the interrelated regulator, infrastructure, and economic drivers for produced water reuse.
? Even though the desalination technologies are discussed to be the suitable technologies for reuse of produced water, expanding desalination for reuse is depend on the process and material for reduction of capital and operating costs for economic decision.
? Suitable technologies must be capable of desalinating high-salinity feed waters, have a low propensity for fouling, and be modular and scalable for on-site treatment at shale gas well sites. Ideally, produced water desalination technologies will use inexpensive, locally available alternative energy sources to reduce the energy costs of produced water treatment.
3. Results
? Unique challenges of shale gas produced water treatment
? Reducing the TDS concentration is the primary consideration for treating produced water to a quality suitable for discharge or for external reuse.
? In practice, multiple technologies that target removal of different constituents are often combined in commercial produced water treatment systems.
? Studies have concluded that the inorganic characteristics of produced water from natural gas production and from gas recovery from underground storage are controlled primarily by the geology of the surrounding rock formation.
? Produced water TDS concentrations reported in the database range from 1000 to 400 000 mg/L. high-salinity waters with TDS concentrations greater than approximately 35 000 mg/L, representing a TDS concentration of 70 000 mg/ L at 50% recovery, must be desalinated by more energy intensive thermal technologies
? Conventional thermal desalination technologies, such as multistage flash and multiple effect distillation, are well established. The high investment costs and the significant energy requirements and associated energy costs of these technologies limit their implementation.
? Membrane distillation
? Previous studies have focused on four main configurations: direct contact, air gap, sweeping gas, and vacuum MD. And in addition to being the simplest configuration, direct contact MD has been studied most extensively and is identified as the most suitable configuration for purification of feed streams non volatile solutes, such as desalination applications.
? Water flux rates in MD are only slightly sensitive to the feed salinity. For example, a study found that increasing the TDS concentration of the feed from 25000 to 75000mg/L reduces the resultant permeate flux by only 5%.
? This feature makes MD particularly suited to desalinate high-salinity sources, such as produced waters, without incurring substantial productivity penalties. Almost complete salt rejection has consistently been reported in the literature, even for very high salinity feeds.
? Although fouling is reduced in MD compared to conventional pressure-driven membrane processes, it can, nonetheless, have detrimental impacts on performance. Fouling clogs membrane pores, which leads to flux decline and pore wetting and imposes additional hindrance to heat and mass transfer.
? Mineral scaling is anticipated to be an important detrimental phenomenon given the high salinity of the produced water feed solution and the presence of salts close to their saturation concentration.
? Pretreatment to remove foulants, and periodic membrane cleaning, removal of components from the produced water feed that induce membrane pore wetting should be done for maintaining the productivity of desalination by MD.
? To meet product water quality standards, post-treatment might be required to remove volatile compounds and gases transported into the permeate from the feed solution.
? Future research for MD for produced water treatment: development of suitable membranes, optimization of operating parameters in membrane modules, and formulation of effective pre and post-treatment strategies.
? Forward Osmosis
? Recently, a pilot-scale operation of an FO system using ammonia-carbon dioxide draw solution demonstrated the potential for desalinating shale gas produced water. (73 000 mg/L from Marcellus shale gas region)
? The pilot successfully achieved 64% water recovery, desalinating produced water to achieved 64% water recovery, desalinating produced water to achieve a permeate TDS concentration less than 300 mg/L.
? The permeate had a very low concentration of total organic carbon (TOC), and the concentrations of major cations and anions reached potable water values. And the concentrated feed water had an average TDS concentration of 180000mg/L.
? Although reported water fluxes from the pilot study were relatively low (approximately 3 L/(m2 h)), further optimization and development in both membrane design and in module hydrodynamics are expected to improve the flux
? Despite the potential of the ammonia?carbon dioxide draw solution, it suffers from ammonia loss due to reverse solute flux through the FO membrane from the draw to the feed side. One way to resolve the ammonia reverse flux is stripping the ammonia from the feed stream after FO treatment in order to recycle it and to minimize the draw solute loss
? The relatively low specific energy consumption of FO, combined with advantages such as low propensity for irreversible fouling, modularity, and the potential to use low grade heat as the energy source, indicate that FO can be a potential desalination technology for external reuse of high salinity shale gas produced water.
4. Contribution:
This research give the guideline of research for the produced water treatment by using the desalination technology. Detail information from the pater would be greatly helpful for the future study.
5. Contact (Mail address): menachem.elimelech@yale.edu
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