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Development of RO Membrane & Its Characterization
Project Presentation On:
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Tables Of ContentHistoryWhat is Reverse Osmosis?Membrane & Its typesReverse Osmosis Membranes & its comparisonMembrane MaterialsMembrane ModulesMembrane FoulingWork Plan of our ProjectTestingDesalinationBenefits Future Aspects
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HistoryThe first studies on osmosis were carried out as early as 1748 by the French scientist Nollet.
The early 1960's, Loeb and Sourirajan developed a method for making asymmetric Cellulose acetate membranes
In 1970, the development of new-generation membranes such as the thin-film, composite Membrane that can tolerate wide pH ranges, higher temperatures and harsh chemical environments.
An estimate indicated that sales of RO membrane products had grown to $280 million yearly in 2006
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What is REVERSE OSMOSIS?Osmosis is a natural phenomenon in which a solvent (usually water) passes through a semi permeable barrier from the side with lower solute concentration to the higher solute concentration side. As shown in Figure(a).
A reverse osmosis membrane acts as the semi permeable barrier to flow in the RO process, allowing selective passage of a particular species (solvent, usually water) while partially & completely retaining other species (solutes). As shown in Figure(b).
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Membrane & Its typesWater treatment processes employ several types of membranes. They include
MF membranes have the largest pore size and typically reject large particles and various microorganisms.
UF membranes have smaller pores than MF membranes and, therefore, in addition to large particles and microorganisms, they can reject bacteria and soluble macromolecules such as proteins. RO membranes are effectively non-porous and, therefore, exclude particles and even many low molar mass species such as salt ions, organics, etc.
NF membranes are relatively new and are sometimes called “loose” RO membranes
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Reverse Osmosis MembraneCellulose Acetate MembraneThin Film Composite Membrane
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CA MembraneThese initial RO membrane was made by the Loeb-Sourirajan
These CA membranes were asymmetric and exhibited NaCl rejection values of approximately 99.5%
The degree of acetylation describes the how many pendent OH groups are replaced acetyl groups, CH3COO.
It ranges from 0 to 3
they have excellent mechanical properties & resistant to chlorine.
CA membranes can tolerate up to 5 ppm
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Thin Film Composite MembraneThe first TFC RO membrane was developed by John Cadotte at North Star Research in 1972, based on aromatic polyamides.
interfacial polymerization are use to create a polyamide coating.
Most TFC membranes are made with a porous, highly permeable support.
Nowadays, This technique can also be used to produce Commercial RO membranes
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Comparison of Reverse Osmosis MembranesCA Membranes TFC Membranes
Rejection of Organic Low High
Rejection of low mol. weight organics
Low High
Water Flux Medium High
pH Tolerance 4-8 2-11
Temperature stability Max. 35c Max. 45c
Oxidant tolerance High Low
Compaction tendency High Low
Biodegradability High Low
Cost Low High
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Membrane Materials
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RO MembranesThere are typically
cellulose acetatePolysulfone coated with aromatic polyamides
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MF & UF MaterialsPoly (vinylidene fluoride)PolysulfonePoly (acrylonitrile)Poly (acrylonitrile)-poly(vinyl chloride) copolymersPoly (ether sulfone) is also commonly used for UF
membranespoly (tetrafluoroethylene).
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Membranes Modules
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Modules of membraneThere are four main types of modules:
plate-and-frame
Tubular
spiral wound
hollow fiber
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Membrane fouling
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Causes of Fauling Bio-fouling(it results from microbial contamination of feed water)
Scaling (It arises from the deposition of salts)
Organic(It comes from substances i.e. C-H which coat the surface)
Colloidal(It mainly stems from particles)
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Work Plan of Project
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Strategy of Work PlanMARKET SURVEY TO FIND THE AVAILBILITY OF
MATERIALS
STUDY AND ANALYZE ABOUT RO PROCESS TECHNOLOGY
CONSULT THE RELEVANT AUTHORITIES / ORGANIZATION
DEVELOPMENT OF RO MEMBRANE SAMPLES
TESTING OF MEMBRANE SAMPLES
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Testing of Membranes
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Major Tests of Membranes Non-Destructive Tests:1. Bubble test- test physical integrity of the membrane envelope 2. Membrane performance - flux, pressure and percent reject 3. Analysis of cleaning solution
Destructive Tests:1. Internal visual exam2. Coupon testing of membrane surface3. Metals analyses4. Digestion
Organic Analyses:1. FTIR Spectroscopy2. UV Spectroscopy
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Desalination
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Desalination Techniques Multi-effect distillation (MED)Multi-stage flash (MSF)Reverse osmosis (RO)Electro dialysis (ED)Capacitive deionization (CDI)Mechanical vapor compression (MVC)
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Benefits & Applications of Membrane
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CA membranes will reduce the cost of RO treatment processes
RO processes are used in the production of food and beverages, pharmaceuticals, and chemical products.
a new alternative to many areas where drinking water is in short supply.
RO technologies can make use of use an almost unlimited and reliable water source, the sea.
RO has a negligible environmental impact
RO technologies can be used to remove organic and inorganic contaminants.
Most economical process for salinity reduction associated with secondary effluent (or other wastewater source) TDS levels.
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Future Aspects
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Development of membranes that is less prone to fouling, operate at lower pressures, and require less pretreatment of the feed water.
Membranes able to remove hydrocarbons and salt could turn produced water.
Reduced fouling would make membranes even more cost effective by extending their operational lifetime.
focused on surface modification of membranes and increasing the pretreatment of the feed water.
Development of more energy-efficient technologies that are simpler to operate than the existing technology
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“End of Presentation”
DESIGNED BY:Adeel Fayyaz (12 – PE – 01)Rehan Hasan (12 –PE – 33)Zohaib Siddiqui(12 – PE – 44)