scholarly journals Reversing membrane wetting in membrane distillation: comparing dryout to backwashing with pressurized air

2017 ◽  
Vol 3 (5) ◽  
pp. 930-939 ◽  
Author(s):  
David M. Warsinger ◽  
Amelia Servi ◽  
Grace B. Connors ◽  
Musthafa O. Mavukkandy ◽  
Hassan A. Arafat ◽  
...  
Keyword(s):  
Saline Water ◽  
Membrane Distillation ◽  
Feed Water ◽  
Membrane Wetting

Wetting of saline water through membrane distillation pores can be reversed with either drying out the membrane, or more effectively, by backwashing with pressurized air to force out wetting feed water.

scholarly journals Membrane Distillation of Saline Water Contaminated with Oil and Surfactants

Membranes ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 988
Author(s):  
Wirginia Tomczak ◽  
Marek Gryta
Keyword(s):  
High Salinity ◽  
Sea Water ◽  
Saline Water ◽  
Sodium Dodecyl ◽  
Membrane Distillation ◽  
Process Efficiency ◽  
Feed Water ◽  
Permeate Flux ◽  
Low Concentration

Application of the membrane distillation (MD) process for the treatment of high-salinity solutions contaminated with oil and surfactants represents an interesting area of research. Therefore, the aim of this study is to investigate the effect of low-concentration surfactants in oil-contaminated high-salinity solutions on the MD process efficiency. For this purpose, hydrophobic capillary polypropylene (PP) membranes were tested during the long-term MD studies. Baltic Sea water and concentrated NaCl solutions were used as a feed. The feed water was contaminated with oil collected from bilge water and sodium dodecyl sulphate (SDS). It has been demonstrated that PP membranes were non-wetted during the separation of pure NaCl solutions over 960 h of the module exploitation. The presence of oil (100–150 mg/L) in concentrated NaCl solutions caused the adsorption of oil on the membranes surface and a decrease in the permeate flux of 30%. In turn, the presence of SDS (1.5–2.5 mg/L) in the oil-contaminated high-salinity solutions slightly accelerated the phenomenon of membrane wetting. The partial pores’ wetting accelerated the internal scaling and affected degradation of the membrane’s structure. Undoubtedly, the results obtained in the present study may have important implications for understanding the effect of low-concentration SDS on MD process efficiency.

Experimental investigation of a pyramid type solar still with porous material: productivity assessment

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Naresh Yarramsetty ◽  
Naveen Sharma ◽  
Modumudi Lakshmi Narayana
Keyword(s):  
Porous Material ◽  
Saline Water ◽  
Base Plate ◽  
Hot Water ◽  
Feed Water ◽  
Solar Still ◽  
Absorber Plate ◽  
Content Type ◽  
Water Distillation ◽  
Clay Pots

Purpose This study aims to investigate the effect of porous material (clay pots) and it is facing on the productivity performance of a pyramid type solar still. The clay pots are placed in the basin facing up and facing down. The numbers of clay pots considered were 9 and 25, and its performance was compared with normal (0 clay pots) solar still. Design/methodology/approach The pyramid solar water distillation system has been designed, fabricated and tested under the actual environmental conditions of Kanchikacherla (16.6834 0N, 80.3904 0E), Andhra Pradesh, India. The solar still is used to produce the fresh water and hot water simultaneously from the brackish (i.e. containing dissolved salts) feed water for domestic applications. From open literature, it was established that the rate of evaporation is higher when the flowing water is held for a longer duration on the black color absorber plate, thereby leading to an increase in productivity of freshwater. Therefore, the pyramid solar still has been tested for smooth absorber plate and the absorber plate with porous heat storage material. Findings The porous material increases the production rate of freshwater compared to a base plate. However, the pyramid still with clay pots has higher productivity at a lower temperature because of the porosity effect. Originality/value The total dissolved solids, electrical conductivity and pH of the distilled water and the saline water have also been measured and compared.

Experimental and Numerical Study of Water Distillation Performance of Small-Scale Direct Contact Membrane Distillation System

2017 ◽  
Author(s):  
Danielle Park ◽  
Elnaz Norouzi ◽  
Chanwoo Park
Keyword(s):  
Water Temperature ◽  
Direct Contact ◽  
Membrane Distillation ◽  
Small Scale ◽  
Feed Water ◽  
Water Production ◽  
Water Distillation ◽  
Direct Contact Membrane Distillation ◽  
Feed Temperature ◽  
Feed Water Temperature

A small-scale Direct Contact Membrane Distillation (DCMD) system was built to investigate its water distillation performance for varying inlet temperatures and flow rates of feed and permeate streams, and salinity. A counterflow configuration between the feed and permeate streams was used to achieve an efficient heat exchange. A two-dimensional Computational Fluid Dynamics (CFD) model was developed and validated using the experimental results. The numerical results were compared with the experiments and found to be in good agreement. From this study, the most desirable conditions for distilled water production were found to be a higher feed water temperature, lower permeate temperature, higher flow rate and less salinity. The feed water temperature had a greater impact on the water production than the permeate water temperature. The numerical simulation showed that the water mass flux was maximum at the inlet of the feed stream where the feed temperature was the highest and rapidly decreased as the feed temperature decreased.

Hydrophobicity versus Pore Size: Polymer Coatings to Improve Membrane Wetting Resistance for Membrane Distillation

2020 ◽  
Vol 2 (3) ◽  
pp. 1256-1267 ◽  
Author(s):  
Allyson L. McGaughey ◽  
Prathamesh Karandikar ◽  
Malancha Gupta ◽  
Amy E. Childress
Keyword(s):  
Pore Size ◽  
Polymer Coatings ◽  
Membrane Distillation ◽  
Membrane Wetting

Superhydrophobic membrane with hierarchically 3D-microtexture to treat saline water by deploying membrane distillation

2020 ◽  
Vol 37 ◽  
pp. 101528 ◽  
Author(s):  
Guang Hui Teoh ◽  
Jing Yi Chin ◽  
Boon Seng Ooi ◽  
Zeinab Abbas Jawad ◽  
Hui Ting Lyly Leow ◽  
...  
Keyword(s):  
Saline Water ◽  
Membrane Distillation

A review of membrane wettability for the treatment of saline water deploying membrane distillation

Desalination ◽  
2020 ◽  
Vol 479 ◽  
pp. 114312 ◽  
Author(s):  
Minwei Yao ◽  
Leonard D. Tijing ◽  
Gayathri Naidu ◽  
Seung-Hyun Kim ◽  
Hideto Matsuyama ◽  
...  
Keyword(s):  
Saline Water ◽  
Membrane Distillation

scholarly journals Highly Saline Water Desalination Using Direct Contact Membrane Distillation (DCMD): Experimental and Simulation Study

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1575 ◽  
Author(s):  
Noor A. Mohammad Ameen ◽  
Salah S. Ibrahim ◽  
Qusay F. Alsalhy ◽  
Alberto Figoli
Keyword(s):  
Mass Transfer ◽  
Direct Contact ◽  
Saline Water ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Water Desalination ◽  
System Of Nonlinear Equations ◽  
Transfer Model ◽  
Transfer Resistance ◽  
Direct Contact Membrane Distillation

The path for water molecules transported across a membrane in real porous membranes has been considered to be a constant factor in the membrane distillation (MD) process (i.e., constant tortuosity); as such, its effect on membrane performance at various operating conditions has been ignored by researchers. Therefore, a simultaneous heat and mass transfer model throughout the direct contact membrane distillation (DCMD) module was developed in this study by taking into account the hypothetical path across the membrane as a variable factor within the operating conditions because it exhibits the changes to the mass transfer resistance across the membrane under the DCMD run. The DCMD process was described by the developed model using a system of nonlinear equations and solved numerically by MATLAB software. The performance of the poly-tetra-fluoroethylene (PTFE) membrane was examined to treat 200 g/L NaCl saline at various operating conditions. The simulation results in the present work showed that the hypothetical proposed path across the membrane has a variable value and was affected by changing the feed temperature and feed concentration. The results estimated by the developed model showed an excellent conformity with the experimental results. The salt rejection remained high (greater than 99.9%) in all cases. The temperature polarization coefficient for the DCMD ranged between 0.88 and 0.967, and the gain output ratio (GOR) was 0.893. The maximum thermal efficiency of the system was 84.5%.

scholarly journals Experimental evaluation of two consecutive air-gap membrane distillation modules with heat recovery

2020 ◽  
Vol 20 (5) ◽  
pp. 1678-1691 ◽  
Author(s):  
Mostafa Abd El-Rady Abu-Zeid ◽  
Gamal ElMasry
Keyword(s):  
Water Temperature ◽  
Flow Rate ◽  
Heat Recovery ◽  
Waste Heat ◽  
Water Flow Rate ◽  
Membrane Distillation ◽  
Air Gap ◽  
Feed Water ◽  
System Productivity ◽  
Air Gap Membrane Distillation

Abstract Two rectangular modules with a total interior membrane surface area of 13.53 m2 were consecutively combined to evaluate the use of heat recovery in an air-gap membrane distillation (AGMD) system. Several operating inlet parameters including feed water temperature, mass water flow rate and salinity were investigated. The experimental results revealed that the performance of the system was improved by virtue of efficient heat recovery resulting from combining two AGMD membrane modules in series. Under optimal inlet operating parameters of cooling water temperature of 20 °C, salinity of 0.05% and flow rate of 3 l/min, the system productivity (Pp) increased up to 192.9%, 179.3%, 176.5% and 179.2%, and the thermal efficiency (ηth) by 261.5%, 232.6%, 239.4% and 227.3% at feed water temperatures of 45 °C, 55 °C, 65 °C and 75 °C, respectively. Concurrently, the specific waste heat input (Ew.h.i) decreased by 6.7%, 4.7%, 5.6% and 2.7% due to the efficient heat recovery. The results confirmed that heat recovery is an important factor affecting the AGMD system that could be improved by designing one of the two AGMD modules with polytetrafluoroethylene (PTFE) hollow fibers with a flow length shorter than the other one having a salt rejection rate of 99%.

scholarly journals The Water Flux Dynamic in a Hybrid Forward Osmosis-Membrane Distillation for Produced Water Treatment

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 225
Author(s):  
Normi Izati Mat Nawi ◽  
Muhammad Roil Bilad ◽  
Ganeswaran Anath ◽  
Nik Abdul Hadi Nordin ◽  
Jundika Candra Kurnia ◽  
...  
Keyword(s):  
Water Treatment ◽  
Produced Water ◽  
Water Flux ◽  
Forward Osmosis ◽  
Membrane Distillation ◽  
Flux Dynamics ◽  
Flux Dynamic ◽  
Produced Water Treatment ◽  
Dynamic Hybrid ◽  
Membrane Wetting

Standalone membrane distillation (MD) and forward osmosis (FO) have been considered as promising technologies for produced water treatment. However, standalone MD is still vulnerable to membrane-wetting and scaling problems, while the standalone FO is energy-intensive, since it requires the recovery of the draw solution (DS). Thus, the idea of coupling FO and MD is proposed as a promising combination in which the MD facilitate DS recovery for FO—and FO acts as pretreatment to enhance fouling and wetting-resistance of the MD. This study was therefore conducted to investigate the effect of DS temperature on the dynamic of water flux of a hybrid FO–MD. First, the effect of the DS temperature on the standalone FO and MD was evaluated. Later, the flux dynamics of both units were evaluated when the FO and DS recovery (via MD) was run simultaneously. Results show that an increase in the temperature difference (from 20 to 60 °C) resulted in an increase of the FO and MD fluxes from 11.17 ± 3.85 to 30.17 ± 5.51 L m−2 h−1, and from 0.5 ± 0.75 to 16.08 L m−2 h−1, respectively. For the hybrid FO–MD, either MD or FO could act as the limiting process that dictates the equilibrium flux. Both the concentration and the temperature of DS affected the flux dynamic. When the FO flux was higher than MD flux, DS was diluted, and its temperature decreased; both then lowered the FO flux until reaching an equilibrium (equal FO and MD flux). When FO flux was lower than MD flux, the DS was concentrated which increased the FO flux until reaching the equilibrium. The overall results suggest the importance of temperature and concentration of solutes in the DS in affecting the water flux dynamic hybrid process.

scholarly journals An Experimental and Theoretical Study on Separations by Vacuum Membrane Distillation Employing Hollow-Fiber Modules

Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 947 ◽  
Author(s):  
Anthoula Karanasiou ◽  
Margaritis Kostoglou ◽  
Anastasios Karabelas
Keyword(s):  
Process Model ◽  
Flow Direction ◽  
Membrane Distillation ◽  
Water Desalination ◽  
Solution Temperature ◽  
Feed Water ◽  
System Productivity ◽  
Capillary Membrane ◽  
Vacuum Membrane Distillation ◽  
By Products

Vacuum membrane distillation (VMD) is an attractive variant of the novel membrane distillation process, which is promising for various separations, including water desalination and bioethanol recovery through fermentation of agro-industrial by-products. This publication is part of an effort to develop a capillary membrane module for various applications, as well as a model that would facilitate VMD process design. Experiments were conducted in a laboratory pilot VMD unit, comprising polypropylene capillary-membrane modules. Performance data, collected at modest temperatures (37 °C to 65 °C) with deionized and brackish water, confirmed the improved system productivity with increasing feed-water temperature; excellent salt rejection was obtained. The recovery of ethanol from ethanol-water mixtures and from fermented winery by-products was also studied, in continuous, semi-continuous, and batch operating modes. At low-feed-solution temperature (27–47 °C), ethanol-solution was concentrated 4 to 6.5 times in continuous operation and 2 to 3 times in the semi-continuous mode. Taking advantage of the small property variation in the module axial-flow direction, a simple VMD process model was developed, satisfactorily describing the experimental data. This VMD model appears to be promising for practical applications, and warrants further R&D work.

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