Coupling of membrane processes for brackish water desalination (original) (raw)
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Reverse Osmosis Membranes for Desalination of Brackish Water
University of Waterloo, 2020
Reverse osmosis (RO), which is commonly used for different water purification and desalination applications, is a remarkable process to separate dissolved inorganic and organic compounds from water. Over traditional methods of water treatment and purification, RO has many benefits such as production of high quality drinking water, simultaneous elimination of multiple pollutants, and simple operation procedure. As drinking water supplies are declining and demand for high quality water is increasing worldwide, RO membrane based water treatments will most probably continue to develop. This research was aimed at better understanding the behavior of the thin film composite (TFC) polyamide membrane used in RO process under various operating conditions. The performance of RO membrane was evaluated in terms of salt rejection and water flux to simulate brackish water desalination process. The operating conditions included salt concentrations ranging from 2000 to 6000 ppm and operating pressure ranging from 100 to 250 psi. Based on experimental results, the performance of the TFC polyamide RO membrane was estimated at higher operating pressures (300-1000 psi). Based on mass transfer coefficient , solute transport parameter and water permeability that is characteristic of the membrane. In addition, the potential of using the TFC RO membrane to process water during oil and gas productions (with 1.5-2.5 % salt by weight), was demonstrated in this study. Besides simulation, experiments were conducted using real water as the feed solution. Dedication This is dedicated to the one I love. v Table of Contents List of Figures viii List of Tables x List of Tables 2.1 Classification of pressure driven membrane separation processes[9].. .. . .
Frontiers of Membrane Desalination Processes for Brackish Water Treatment: A Review
Membranes, 2021
Climate change, population growth, and increased industrial activities are exacerbating freshwater scarcity and leading to increased interest in desalination of saline water. Brackish water is an attractive alternative to freshwater due to its low salinity and widespread availability in many water-scarce areas. However, partial or total desalination of brackish water is essential to reach the water quality requirements for a variety of applications. Selection of appropriate technology requires knowledge and understanding of the operational principles, capabilities, and limitations of the available desalination processes. Proper combination of feedwater technology improves the energy efficiency of desalination. In this article, we focus on pressure-driven and electro-driven membrane desalination processes. We review the principles, as well as challenges and recent improvements for reverse osmosis (RO), nanofiltration (NF), electrodialysis (ED), and membrane capacitive deionization (M...
Desalination, 1998
In this new approach to membrane and thermal seawater desalination processes developed by the Saline Water Conversion Corporation (SWCC), R&D Center, a nanofiltration (NF) membrane unit, which received non-coagulated filtered seawater feed, was placed ahead of the SWRO and the MSF pilot plant units to form, for the first time ever, fully integrated desalination systems of an NF-SWRO, NF-MSF, and NF-SWROreject-MSF. Preliminary results were presented at the IDA World Congress, Madrid '97. Further results obtained in this investigation at a pressure of 22 bars showed that the NF unit reduced turbidity and microorganisms, removed hardness ions of Ca++, Mg++, SO4=, HCO3−, and total hardness by 89.6%, 94.0%, 97.8%, 76.6% and 93.3%, respectively. The system also resulted in the reduction of the monovalent ions of Cl−, Na+, K+ each by 40.3% and the overall seawater TDS by 57.7%. The seawater (NF permeate water) produced by this process is considerably different in composition from (Gulf) seawater, and quality-wise is far superior to it as a feed to seawater desalination plants, and moreover without the problems normally associated with high concentration in seawater of scale forming ions, high TDS, high turbidity and microorganisms. This made it possible to operate both the SWRO and MSF pilot plants at high water recovery: 70% and 80%, respectively. It also allowed for the successful operation of the MSF unit at top brine temperature of 120°C without the addition to the make-up of antiscalant or acid or antifoam. The said desalination arrangements lead to significant improvement in the seawater desalination processes by lowering their energy consumption, by about 25–30%, and reducing chemical consumption thereby making the process more friendly to the marine environment. The observed increases in their product water output and recovery ratio by more than 70% resulted in the ultimate benefit of lowering the estimated cost of fresh water production by more than 27%. The SWRO permeate produced from the NF-SWRO arrangement has very low TDS, ≤200 ppm, making the requirement for a second-stage RO treatment of the SWRO permeate unnecessary. Moreover, the use of the desalination arrangement NF-SWROreject-MSF should allow for the conversion of up to 90% of the NF product into fresh water, where about 65% of the NF product is converted to fresh water by the SWRO unit and 25% of SWRO reject is converted by the MSF unit. Definitely, the achievement of the above results represents a milestone in seawater desalination technology. The paper describes the results obtained, the experimental approach used in this investigation along with description of the NF-SWRO, NF-MSF and NF-SWROreject-MSF pilot plants employed in this study. A simulated desalination model which compares the operation of existing SWRO plants with and without the NF modification is also described along with the technoeconomics of process analysis.
Integrated membrane –based desalination system
Desalination, 2007
A comparative study of an integrated hybrid membrane-based system with an earlier locally designed RO unit, such system comprises of Nanofiltration (NF), Reverse osmosis (RO) and Membrane Distillation (MD) subsystems. The comparison is essentially based on using the NF technique in pretreatment section, while the MD was contributed to concentrate the two brine streams from both NF and RO. The proposed system was economically evaluated and compared with the RO unit.
Desalination, 2015
Applicability of NF as a pre-treatment of SWRO desalination process • The highest permeate flux with NF90 + SW30-RO combination • The lowest permeate flux with NF270 + SW30-RO combination • The best permeate quality with NF90 + SW30-RO combination a b s t r a c t In this study, the applicability of nanofiltration (NF) was investigated as a pre-treatment stage of reverse osmosis (RO) process for seawater desalination. The desalination performance of such integrated system was checked. Previously, NF (NF90 and NF270) and SWRO (SW30) membranes were used individually in the close-loop operation. Next, the NF permeate was collected using NF membrane by a continuous operation and then this permeate was used as a feed for a closed-loop SWRO system. The performances of single SWRO, NF and NF + RO integrated systems were compared in terms of permeate qualities and quantities. The results showed that permeate recovery of NF270 membrane was higher than that of NF90 membrane. However, the salt rejection of NF90 membrane was better than that of NF270. The single SW30-RO membrane showed an average rejection of 98.2% for salinity, while the permeate recovery value was only 28% at 55 bar. Also the average permeate flux of single SW30-RO membrane was 30.1 L/h m 2 . For the integrated system experiments, the highest permeate flux was found with NF90 (30 bar) + SW30-RO (40 bar) combination. Similar permeate flux values were obtained with single SW30-RO and NF90 (30 bar) + SW30-RO (30) bar combination. The lowest permeate flux was found with NF270 (30 bar) + SW30-RO (40 bar) combination. Salinity was also highly rejected by all integrated system combinations. Permeate recovery values of integrated system combinations showed similar trend with permeate flux. Regarding permeate quality, it was seen that all integrated system combinations were better than single SW30-RO membrane. It was obtained that the permeate quality with NF90 + SW30-RO combination was better than that with NF270 + SW30-RO combination.
PloS one, 2018
Desalination of geothermal brackish water by membrane distillation (MD) provides a low recovery rate, but integrating MD with reverse osmosis (RO) can maximize the production rate. In this study, different design configurations of a hybrid system involving brine recycling and cascading are studied via simulations, and the performance improvement due to the process integration is substantiated via the increased recovery rate and reduced specific energy consumption. Brine recycling is also found to improve the recovery rate considerably to 40% at an energy cost of 0.9 $/m3. However, this achievement is only valid when the final brine is recycled to the RO feed: when the final brine is recycled to the MD feed, the overall performance degrades because the recycled brine cools the feed and causes a serious reduction in the driving force and the consequent production rate. Configuring the hybrid system in multiple stages connected in series increases the recovery rate to 90% and reduces t...
Journal of Membrane Science and Research, 2020
In this study, the applicability of nanofiltration (NF) membranes as a pretreatment prior to reverse osmosis (RO) in seawater desalination was investigated. The membranes used wereNF270 and NF90 as the NF membranes, while the brackish water (BW) RO membrane BW30 was used as the RO membrane. In desalination tests, permeates of the NF membraneswere collected and used as the feed to the BW30 membrane. The calculated permeate fluxes were 6.7 L/h.m2, 11.3 L/h.m2, 24.3 L/h.m2, and 36.6 L/h.m2 for single BW30-35 bar,NF270-30 bar + BW30-35 bar, NF90-30 bar + BW30-25 bar and NF90-30 BW30-35 bar, respectively. The calculated water recovery and rejected salt values were 51.6%, 41.4%,24.8%, 15.4% and 98.2%, 98.2%, 96.0%, 91.0% for NF90-30 bar + BW30-35 bar, NF90-30 bar + BW30-25 bar, NF270-30 bar + BW30-35 bar and single BW30-35 bar, respectively.The qualities of the product waters of integrated systems (NF+BWRO) and the single BWRO system were also investigated. Boron rejection was fairly well...
Journal of water process engineering, 2019
Membrane bioreactor (MBR) effluents of industrial wastewaters generally include high amounts of salinity, nitrate and hardness. Although MBR process can be applied for the production of low and/or medium quality water, nanofiltration (NF) or reverse osmosis (RO) processes are needed for removal of excess salinity from MBR effluent. Since the fouling is a unique problem for membrane systems, pre-treatment operations are gaining importance. Main objective of this study is to investigate the effect of NF system as pre-treatment before RO system in wastewater treatment. Feed solutions with two different conductivities were fed to the RO system for this purpose. In addition, change in the permeate quality was monitored and permeate quality increase was noticed in the NF pre-treatment study. Average normalized permeate fluxes of RO system were 32.3 L/m 2 .h and 28.7 L/m 2 .h for the study with NF pre-treatment and with only RO study, respectively. Treated wastewaters were also evaluated for the suitability of their reuse in cooling, steam generation as process water and agricultural irrigation. Experiments were performed in wastewater treatment plant of ITOB-Industrial Organized Zone (ITOB-OSB
Membrane desalination technologies in water treatment: A review
Water Practice and Technology
One of the most pressing problems worldwide is inadequate access to potable water. Many technologies have been applied to address this through research to find robust but inexpensive methods of desalination that offer high fluxes and use less energy, while reducing chemical use and environmental impact. Membrane desalination technology is universally considered to solve water shortage problems due to its high efficiency and lower energy consumption than distillation methods. This review focuses on the desalination performance of membrane technologies with consideration of the effect of driving force, potential technologies, membrane types, flux, energy consumption and operating temperature, etc. Pressure driven membrane processes (MF, UF, NF, RO), and their fouling propensity and major drawbacks are discussed briefly. Membrane characteristics and the effects of operating conditions on desalination are also covered. Organic-hybrid and inorganic membrane materials can offer advantages...
Characterization of nanofiltration membranes and their evaluation for RO desalination pre-treatment
2007
One of the most significant factors for a good performance and cost effectively operating a reverse osmosis desalination plant is the capacity of the pre-treatment to consistently produce high quality feed water. The use of low pressure filtration membranes pre-treatment become important in the last years because of the potential benefits compared with conventional, in terms of improved water quality, fewer RO cleanings and lower pressure drops. In the present work, different commercial NF membranes have been hydraulically characterized with synthetic seawater and analysed with FTIR-ATR, SEM, AFM and streaming potential. The results give us an evaluation of each membrane for their potential use as pretreatment for a RO desalination plant.