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.

scholarly journals Performance Investigation of O-Ring Vacuum Membrane Distillation Module for Water Desalination

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Adnan Alhathal Alanezi ◽  
H. Abdallah ◽  
E. El-Zanati ◽  
Adnan Ahmad ◽  
Adel O. Sharif
Keyword(s):  
Flow Rate ◽  
Membrane Distillation ◽  
Membrane Module ◽  
Water Desalination ◽  
Feed Flow Rate ◽  
Permeate Flux ◽  
Vacuum Degree ◽  
Flat Sheet ◽  
Vacuum Membrane Distillation ◽  
Feed Temperature

A new O-ring flat sheet membrane module design was used to investigate the performance of Vacuum Membrane Distillation (VMD) for water desalination using two commercial polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) flat sheet hydrophobic membranes. The design of the membrane module proved its applicability for achieving a high heat transfer coefficient of the order of 103 (W/m2 K) and a high Reynolds number (Re). VMD experiments were conducted to measure the heat and mass transfer coefficients within the membrane module. The effects of the process parameters, such as the feed temperature, feed flow rate, vacuum degree, and feed concentration, on the permeate flux have been investigated. The feed temperature, feed flow rate, and vacuum degree play an important role in enhancing the performance of the VMD process; therefore, optimizing all of these parameters is the best way to achieve a high permeate flux. The PTFE membrane showed better performance than the PVDF membrane in VMD desalination. The obtained water flux is relatively high compared to that reported in the literature, reaching 43.8 and 52.6 (kg/m2 h) for PVDF and PTFE, respectively. The salt rejection of NaCl was higher than 99% for both membranes.

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 Reverse Osmosis and Membrane Distillation for Desalination of Groundwater: A Review

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Bhausaheb L. Pangarkar ◽  
Mukund G. Sane ◽  
Mahendra Guddad
Keyword(s):  
Groundwater Quality ◽  
Reverse Osmosis ◽  
High Energy ◽  
Membrane Distillation ◽  
Water Desalination ◽  
Indian States ◽  
Strong Separation ◽  
High Energy Consumption ◽  
By Products ◽  
Disposal Problem

In recent years, the increasing threat to groundwater quality due to human activities has become a matter of great concern. The groundwater quality problems present today are caused by contamination and by overexploitation, or by combination of both, which are faced by many Indian states. Today, reverse osmosis (RO) membranes are the leading technology for desalination of groundwater because of their strong separation capabilities and exhibiting a great potential for treatment of waters worldwide. However, the RO process had some problems due to the formation of polarization films because high pressure operation and by-products which may generate bacteria and fouling. Also, high energy consumption and brine disposal problem is faced in RO process due to the limited recovery of water. These problems may be overcome by other membrane thermal process such as a membrane distillation (MD). This paper addresses the outline of RO and MD process for desalination. RO has developed over the past 40 years and MD is an emerging technology for brackish water desalination and yet is not fully implemented in industry. The MD is the better alternative to RO for desalination theoretically found in the literature.

scholarly journals Resistance of Polypropylene Membrane to Oil Fouling during Membrane Distillation

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 552
Author(s):  
Marek Gryta
Keyword(s):  
Membrane Distillation ◽  
Water Desalination ◽  
Feed Water ◽  
Permeate Flux ◽  
Feed Composition ◽  
Oil Emulsion ◽  
Thermally Induced ◽  
Polypropylene Membrane ◽  
Capillary Membranes ◽  
The Impact

The influence of oil emulsion presence in the water on the course of water desalination by membrane distillation was studied. The feed water was contaminated by oil collected from the bilge water. The impact of feed composition on the wetting resistance of hydrophobic polypropylene membranes was evaluated during long-term studies. Two types of the capillary membranes fabricated by thermally induced phase separation method were tested. It has been found that these membranes were non-wetted during the separation of NaCl solutions over a period of 500 h of modules exploitation. The addition of oil (5–100 mg/L) to the feed caused a progressive decline of the permeate flux up to 30%; however, the applied hydrophobic membranes retained their non-wettability for the consecutive 2400 h of the process operation. It was indicated that several compounds containing the carbonyl group were formed on the membranes surface during the process. These hydrophilic compounds facilitated the water adsorption on the surface of polypropylene which restricted the oil deposition on the membranes used.

Heat and mass transfer characteristics in vacuum membrane distillation for water desalination

2018 ◽  
Vol 132 ◽  
pp. 52-62
Author(s):  
Elham El-Zanati ◽  
Maaly Khedr ◽  
Ayman El-Gendi ◽  
Heba Abdallah ◽  
Eman Farg ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Membrane Distillation ◽  
Water Desalination ◽  
Transfer Characteristics ◽  
Vacuum Membrane Distillation

scholarly journals Produced Water Desalination via Pervaporative Distillation

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3560
Author(s):  
Jingbo Wang ◽  
Dian Tanuwidjaja ◽  
Subir Bhattacharjee ◽  
Arian Edalat ◽  
David Jassby ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Produced Water ◽  
Operating Mode ◽  
Porous Membrane ◽  
Membrane Distillation ◽  
Operating Conditions ◽  
Water Desalination ◽  
Feed Water ◽  
Water Composition ◽  
Salt Passage

Herein, we report on the performance of a hybrid organic-ceramic hydrophilic pervaporation membrane applied in a vacuum membrane distillation operating mode to desalinate laboratory prepared saline waters and a hypersaline water modeled after a real oil and gas produced water. The rational for performing “pervaporative distillation” is that highly contaminated waters like produced water, reverse osmosis concentrates and industrial have high potential to foul and scale membranes, and for traditional porous membrane distillation membranes they can suffer pore-wetting and complete salt passage. In most of these processes, the hard to treat feed water is commonly softened and filtered prior to a desalination process. This study evaluates pervaporative distillation performance treating: (1) NaCl solutions from 10 to 240 g/L at crossflow Reynolds numbers from 300 to 4800 and feed-temperatures from 60 to 85 °C and (2) a real produced water composition chemically softened to reduce its high-scale forming mineral content. The pervaporative distillation process proved highly-effective at desalting all feed streams, consistently delivering <10 mg/L of dissolved solids in product water under all operating condition tested with reasonably high permeate fluxes (up to 23 LMH) at optimized operating conditions.

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