Download - seminar report on membrance technology
-
7/27/2019 seminar report on membrance technology
1/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 1
CHAPTER - 1
INTRODUCTION
Water contains beside of the necessary dissolved matters suspended and dissolved
impurities. The water sources often bear disease causing bacteria, viruses, and parasites and
this water must be treated and purified to meet human needs. Chemical disinfection is in
wide use to treat water but disinfection forms again disinfection by-products (DBP). To avoid
the generation of such DBPs it is necessary to remove natural organic matters efficiently prior
to disinfection. Pesticides and nitrates in ground water is a growing problem in agricultural
areas.
Beside of flocculatio, coagulation and clarification membranes have demonstrated
excellent results in natural organic matter separation and have gained a high potential in
future in the production of drinking water.
The major fields of membrane applications are in the treatment of different sources of
water and are shown in Fig.1. Membrane and membrane processes are generally alternative
ways to conventional techniques and it should be noted to choose the classical way when ever
this is technically and economically possible. Membrane processes are combined with a
relevant demand for electrical energy. The minimization of the energy demand of water
treatment systems is an important task facing our future water resources [4]. Membrane
processes need hydraulic pressure to force water through a semi-permeable membrane which
needs energy and if we are speaking of energy, we have to face the mass of CO2 which is
emitted therefore to get water in defined quality. If we count the quantity of CO2 which we
will emit to produce softwater out of ground water, we have to realize that we are emitting
between 200 to 500 g CO2 per produced 1000 l of product water. Its a relatively wide CO2
emission range which is a result of different process parameters and of the feed water quality.
However membranes are applicable for water sources which cannot be treated
anymore successfully by e.g. convetional techniques combined with disinfection chemicals.
Membranes exhibit the ability to reject most contaminants and have attained for these tasks a
high acceptance in the last 20 to 30 years and many membrane applications in watertreatment have been realized therefore and devepment of economically and ecologically
processes is needed.In the water industry there have been collected parallel to this
development experienced ways of operations in the treatment of different water sources. The
scale of application of membrane plants has grown as well and the sizes of membrane plants
will have further more a rising demand for developments to eneable the purifying water in
areas where water is available but the quality for human consumption is not given. The
challenge to apply membrane processes for the different raw water qualities is to make these
techniques applicable in respect to specific plant and energy costs. Certain plant concepts and
process combinations are inevitable to meet these designated targets and some of them will
-
7/27/2019 seminar report on membrance technology
2/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 2
be presented in this paper and practical experiences from field tests discussed. Variations of
this technology include reverse osmosis (RO), nanofilitration or low pressure RO,
ultrafiltration and microfiltration. As membrane plants need energy it is crucial to minimize
the energy consumption for this fast growing demand in water treatment applications also inview of climate change emission reduction.
-
7/27/2019 seminar report on membrance technology
3/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 3
CHAPTER- 2
MEMBRANE OPERATIONS
According to driving force of the operation it is possible to distinguish:
2.1Pressure driven operations microfiltration ultrafiltration nanofiltration reverse osmosis2.2Concentration driven operations
dialysis pervaporation forward osmosis artificial lung gas separation
2.3 Operations in electric potential gradient
electrodialysis membrane electrolysis electrodeionization electrofiltration fuel cell2.3Operations in temperature gradient
membrane distillation
http://en.wikipedia.org/wiki/Pervaporationhttp://en.wikipedia.org/wiki/Pervaporationhttp://en.wikipedia.org/wiki/Electrodialysishttp://en.wikipedia.org/wiki/Electrodeionizationhttp://en.wikipedia.org/wiki/Electrofiltrationhttp://en.wikipedia.org/wiki/Electrofiltrationhttp://en.wikipedia.org/wiki/Electrodeionizationhttp://en.wikipedia.org/wiki/Electrodialysishttp://en.wikipedia.org/wiki/Pervaporation -
7/27/2019 seminar report on membrance technology
4/32
-
7/27/2019 seminar report on membrance technology
5/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 5
purpose of softening (polyvalent cation removal) and removal of disinfection by-product
precursors such as natural organic matter and synthetic organic matter.[1][2]
Nanofiltration is also becoming more widely used in food processing applications suchas dairy, for simultaneous concentration and partial (monovalent ion) demineralisation.
2.1.4 REVERSE OSMOSIS
Reverse osmosis (RO) is a water purification technology that uses a semipermeable
membrane. This membrane-technology is not properly a filtration method. In RO, an applied
pressure is used to overcome osmotic pressure, a colligative property, that is driven by
chemical potential, a thermodynamic parameter. RO can remove many types
ofmolecules and ions from solutions and is used in both industrial processes and in
producing potable water. The result is that the solute is retained on the pressurized side of the
membrane and the pure solvent is allowed to pass to the other side. To be "selective," this
membrane should not allow large molecules or ions through the pores (holes), but should
allow smaller components of the solution (such as the solvent) to pass freely.
In the normal osmosisprocess, the solvent naturally moves from an area of low solute
concentration (High Water Potential), through a membrane, to an area of high solute
concentration (Low Water Potential). The movement of a pure solvent is driven to reduce the
free energy of the system by equalizing solute concentrations on each side of a membrane,
generating osmotic pressure. Applying an external pressure to reverse the natural flow of pure
solvent, thus, is reverse osmosis. The process is similar to other membrane technology
applications. However, there are key differences between reverse osmosis and filtration. The
predominant removal mechanism in membrane filtration is straining, or size exclusion, so the
process can theoretically achieve perfect exclusion of particles regardless of operational
parameters such as influent pressure and concentration. Moreover, reverse osmosis involves a
diffusive mechanism so that separation efficiency is dependent on solute concentration,
pressure, and water flux rate.[1]Reverse osmosis is most commonly known for its use in
drinking water purification from seawater, removing the salt and othereffluent materials from
the water molecules.
http://en.wikipedia.org/wiki/Valence_(chemistry)http://en.wikipedia.org/wiki/Cationhttp://en.wikipedia.org/wiki/Organic_compoundhttp://en.wikipedia.org/wiki/Nanofiltration#cite_note-WQ-1http://en.wikipedia.org/wiki/Nanofiltration#cite_note-WQ-1http://en.wikipedia.org/wiki/Nanofiltration#cite_note-FilmTec-2http://en.wikipedia.org/wiki/Nanofiltration#cite_note-FilmTec-2http://en.wikipedia.org/wiki/Nanofiltration#cite_note-FilmTec-2http://en.wikipedia.org/wiki/Food_processinghttp://en.wikipedia.org/wiki/Dairyhttp://en.wikipedia.org/wiki/Ionhttp://en.wikipedia.org/wiki/Semipermeable_membranehttp://en.wikipedia.org/wiki/Semipermeable_membranehttp://en.wikipedia.org/wiki/Membrane_technologyhttp://en.wikipedia.org/wiki/Filtrationhttp://en.wikipedia.org/wiki/Osmotic_pressurehttp://en.wikipedia.org/wiki/Colligative_propertyhttp://en.wikipedia.org/wiki/Moleculeshttp://en.wikipedia.org/wiki/Ionshttp://en.wikipedia.org/wiki/Solutionhttp://en.wikipedia.org/wiki/Solventhttp://en.wiktionary.org/wiki/porehttp://en.wikipedia.org/wiki/Osmosishttp://en.wikipedia.org/wiki/Osmotic_pressurehttp://en.wikipedia.org/wiki/Filtrationhttp://en.wikipedia.org/wiki/Reverse_osmosis#cite_note-water-1http://en.wikipedia.org/wiki/Reverse_osmosis#cite_note-water-1http://en.wikipedia.org/wiki/Reverse_osmosis#cite_note-water-1http://en.wikipedia.org/wiki/Water_purificationhttp://en.wikipedia.org/wiki/Seawaterhttp://en.wikipedia.org/wiki/Salthttp://en.wikipedia.org/wiki/Effluenthttp://en.wikipedia.org/wiki/Effluenthttp://en.wikipedia.org/wiki/Salthttp://en.wikipedia.org/wiki/Seawaterhttp://en.wikipedia.org/wiki/Water_purificationhttp://en.wikipedia.org/wiki/Reverse_osmosis#cite_note-water-1http://en.wikipedia.org/wiki/Filtrationhttp://en.wikipedia.org/wiki/Osmotic_pressurehttp://en.wikipedia.org/wiki/Osmosishttp://en.wiktionary.org/wiki/porehttp://en.wikipedia.org/wiki/Solventhttp://en.wikipedia.org/wiki/Solutionhttp://en.wikipedia.org/wiki/Ionshttp://en.wikipedia.org/wiki/Moleculeshttp://en.wikipedia.org/wiki/Colligative_propertyhttp://en.wikipedia.org/wiki/Osmotic_pressurehttp://en.wikipedia.org/wiki/Filtrationhttp://en.wikipedia.org/wiki/Membrane_technologyhttp://en.wikipedia.org/wiki/Semipermeable_membranehttp://en.wikipedia.org/wiki/Semipermeable_membranehttp://en.wikipedia.org/wiki/Ionhttp://en.wikipedia.org/wiki/Dairyhttp://en.wikipedia.org/wiki/Food_processinghttp://en.wikipedia.org/wiki/Nanofiltration#cite_note-FilmTec-2http://en.wikipedia.org/wiki/Nanofiltration#cite_note-WQ-1http://en.wikipedia.org/wiki/Organic_compoundhttp://en.wikipedia.org/wiki/Cationhttp://en.wikipedia.org/wiki/Valence_(chemistry) -
7/27/2019 seminar report on membrance technology
6/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 6
2.2 CONCENTRATION DRIVEN OPERATIONS
2.2.1 DIALYSIS
In medicine dialysis meaning through is a process for removing waste and excess
water from the blood, and is used primarily as an artificial replacement for lost kidney
function in people withrenal failure.[1]Dialysis may be used for those with an acute
disturbance in kidney function (acute kidney injury, previously acute renal failure), or
progressive but chronically worsening kidney functiona state known as chronic kidney
disease stage 5 (previously chronic renal failure or end-stage renal disease). The latter form
may develop over months or years, but in contrast to acute kidney injury is not usually
reversible, and dialysis is regarded as a "holding measure" until a renal transplant can be
performed, or sometimes as the only supportive measure in those for whom a transplant
would be inappropriate.[2]
The kidneys have important roles in maintaining health. When healthy, the kidneys
maintain the body's internal equilibrium of water and minerals (sodium, potassium, chloride,
calcium, phosphorus, magnesium, sulfate). The acidic metabolism end-products that the body
cannot get rid of via respiration are also excreted through the kidneys. The kidneys also
function as a part of the endocrine system, producing erythropoietin and calcitriol.
Erythropoietin is involved in the production of red blood cells and calcitriol plays a role in
bone formation.[3]Dialysis is an imperfect treatment to replace kidney function because it
does not correct the compromised endocrine functions of the kidney. Dialysis treatments
replace some of these functions through diffusion (waste removal) and ultrafiltration (fluid
removal).[4]
2.2.2 MEMBRANE GAS SEPARATION
Membrane technologies are not as well developed as other gas separation techniques
and as a result they are less widely used. Manufacturing challenges mean the units are better
suited for small to mid scale operations.
The use partially permeable membranes which allow "fast" gases to pass through and
be removed, while "slow" gases remain in the airstream and emerge without the original
http://en.wikipedia.org/wiki/Bloodhttp://en.wikipedia.org/wiki/Renal_replacement_therapyhttp://en.wikipedia.org/wiki/Renal_functionhttp://en.wikipedia.org/wiki/Renal_functionhttp://en.wikipedia.org/wiki/Renal_failurehttp://en.wikipedia.org/wiki/Dialysis#cite_note-1http://en.wikipedia.org/wiki/Dialysis#cite_note-1http://en.wikipedia.org/wiki/Dialysis#cite_note-1http://en.wikipedia.org/wiki/Acute_kidney_injuryhttp://en.wikipedia.org/wiki/Chronic_kidney_diseasehttp://en.wikipedia.org/wiki/Chronic_kidney_diseasehttp://en.wikipedia.org/wiki/Renal_transplanthttp://en.wikipedia.org/wiki/Dialysis#cite_note-Pendse-2http://en.wikipedia.org/wiki/Dialysis#cite_note-Pendse-2http://en.wikipedia.org/wiki/Dialysis#cite_note-Pendse-2http://en.wikipedia.org/wiki/Kidneyhttp://en.wikipedia.org/wiki/Metabolismhttp://en.wikipedia.org/wiki/Endocrine_systemhttp://en.wikipedia.org/wiki/Erythropoietinhttp://en.wikipedia.org/wiki/1,25-dihydroxycholecalciferolhttp://en.wikipedia.org/wiki/Dialysis#cite_note-3http://en.wikipedia.org/wiki/Dialysis#cite_note-3http://en.wikipedia.org/wiki/Dialysis#cite_note-3http://en.wikipedia.org/wiki/Diffusionhttp://en.wikipedia.org/wiki/Ultrafiltrationhttp://en.wikipedia.org/wiki/Dialysis#cite_note-4http://en.wikipedia.org/wiki/Dialysis#cite_note-4http://en.wikipedia.org/wiki/Dialysis#cite_note-4http://en.wikipedia.org/wiki/Dialysis#cite_note-4http://en.wikipedia.org/wiki/Ultrafiltrationhttp://en.wikipedia.org/wiki/Diffusionhttp://en.wikipedia.org/wiki/Dialysis#cite_note-3http://en.wikipedia.org/wiki/1,25-dihydroxycholecalciferolhttp://en.wikipedia.org/wiki/Erythropoietinhttp://en.wikipedia.org/wiki/Endocrine_systemhttp://en.wikipedia.org/wiki/Metabolismhttp://en.wikipedia.org/wiki/Kidneyhttp://en.wikipedia.org/wiki/Dialysis#cite_note-Pendse-2http://en.wikipedia.org/wiki/Renal_transplanthttp://en.wikipedia.org/wiki/Chronic_kidney_diseasehttp://en.wikipedia.org/wiki/Chronic_kidney_diseasehttp://en.wikipedia.org/wiki/Acute_kidney_injuryhttp://en.wikipedia.org/wiki/Dialysis#cite_note-1http://en.wikipedia.org/wiki/Renal_failurehttp://en.wikipedia.org/wiki/Renal_functionhttp://en.wikipedia.org/wiki/Renal_functionhttp://en.wikipedia.org/wiki/Renal_replacement_therapyhttp://en.wikipedia.org/wiki/Blood -
7/27/2019 seminar report on membrance technology
7/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 7
contaminants. Membrane technology is most often used for moisture removal, hydrogen
removal and nitrogen enrichment.
2.2.3 FORWARD OSMOSIS
FIG.2.2.3 Osmotic Membrane Processes
Forward osmosis is an osmoticprocess that, like reverse osmosis, uses a semi-
permeable membrane to effect separation ofwaterfrom dissolved solutes. The driving force
for this separation is an osmotic pressure gradient, such that a "draw" solution of
high concentration (relative to that of the feed solution), is used to induce a net flow of waterthrough the membrane into the draw solution, thus effectively separating the feed water from
its solutes. In contrast, the reverse osmosis process uses hydraulic pressure as the driving
force for separation, which serves to counteract the osmotic pressure gradient that would
otherwise favor water flux from the permeate to the feed. The simplest equation describing
the relationship between osmotic and hydraulic pressures and water flux is:
where is waterflux, A is the hydraulic permeability of the membrane, is the
difference in osmotic pressures on the two sides of the membrane, and P is the difference
in hydrostatic pressure (negative values of indicating reverse osmotic flow). The
modeling of these relationships is in practice more complex than this equation indicates, with
flux depending on the membrane, feed, and draw solution characteristics, as well as the fluid
dynamics within the process itself.[1]
http://en.wikipedia.org/wiki/Osmosishttp://en.wikipedia.org/wiki/Reverse_osmosishttp://en.wikipedia.org/wiki/Semi-permeable_membranehttp://en.wikipedia.org/wiki/Semi-permeable_membranehttp://en.wikipedia.org/wiki/Separation_processhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Osmotic_pressurehttp://en.wikipedia.org/wiki/Solutionhttp://en.wikipedia.org/wiki/Concentrationhttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Fluxhttp://en.wikipedia.org/wiki/Hydraulic_permeabilityhttp://en.wikipedia.org/wiki/Hydrostatic_pressurehttp://en.wikipedia.org/wiki/Fluid_dynamicshttp://en.wikipedia.org/wiki/Fluid_dynamicshttp://en.wikipedia.org/wiki/Forward_osmosis#cite_note-1http://en.wikipedia.org/wiki/Forward_osmosis#cite_note-1http://en.wikipedia.org/wiki/Forward_osmosis#cite_note-1http://en.wikipedia.org/wiki/File:Osmotic_Processes_Diagram.jpghttp://en.wikipedia.org/wiki/File:Osmotic_Processes_Diagram.jpghttp://en.wikipedia.org/wiki/File:Osmotic_Processes_Diagram.jpghttp://en.wikipedia.org/wiki/File:Osmotic_Processes_Diagram.jpghttp://en.wikipedia.org/wiki/Forward_osmosis#cite_note-1http://en.wikipedia.org/wiki/Fluid_dynamicshttp://en.wikipedia.org/wiki/Fluid_dynamicshttp://en.wikipedia.org/wiki/Hydrostatic_pressurehttp://en.wikipedia.org/wiki/Hydraulic_permeabilityhttp://en.wikipedia.org/wiki/Fluxhttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Concentrationhttp://en.wikipedia.org/wiki/Solutionhttp://en.wikipedia.org/wiki/Osmotic_pressurehttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Separation_processhttp://en.wikipedia.org/wiki/Semi-permeable_membranehttp://en.wikipedia.org/wiki/Semi-permeable_membranehttp://en.wikipedia.org/wiki/Reverse_osmosishttp://en.wikipedia.org/wiki/Osmosis -
7/27/2019 seminar report on membrance technology
8/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 8
An additional distinction between the reverse osmosis (RO) and forward osmosis
(FO) processes is that the water permeating the RO process is in most cases fresh water ready
for use. In the FO process, this is not the case. The membrane separation of the FO process in
effect results in a "trade" between the solutes of the feed solution and the draw solution.
Depending on the concentration of solutes in the feed (which dictates the necessary
concentration of solutes in the draw) and the intended use of the product of the FO process,
this step may be all that is required.
The forward osmosis process is also known as osmosis or in the case of a number of
companies who have coined their own terminology 'engineered osmosis' and 'manipulated
osmosis'.
2.2.4 PERVAPORATION
Pervaporation (or pervaporative separation) is a processing method for the separation
of mixtures of liquids by partial vaporization through a non-porous or porous membrane.
The term 'pervaporation' is derived from the two steps of the process:
(a) permeation through the membrane by the permeate, then (b) its evaporation into the vapor
phase. This process is used by a number of industries for several different processes,
including purification and analysis, due to its simplicity and in-line nature.
The membrane acts as a selective barrier between the two phases: the liquid-phase
feed and the vapor-phase permeate. It allows the desired component(s) of the liquid feed to
transfer through it by vaporization. Separation of components is based on a difference in
transport rate of individual components through the membrane.
Typically, the upstream side of the membrane is at ambient pressure and the
downstream side is under vacuum to allow the evaporation of the selective component after
permeation through the membrane. Driving force for the separation is the difference in
the partial pressures of the components on the two sides and not the volatility difference of
the components in the feed.
The driving force for transport of different components is provided by a chemical
potential difference between the liquid feed/retentate and vapor permeate at each side of the
http://en.wikipedia.org/wiki/Separation_of_mixturehttp://en.wikipedia.org/wiki/Separation_of_mixturehttp://en.wikipedia.org/wiki/Vaporizationhttp://en.wikipedia.org/wiki/Artificial_membranehttp://en.wikipedia.org/wiki/Permeationhttp://en.wikipedia.org/wiki/Permeatehttp://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Membrane_introduction_mass_spectrometryhttp://en.wiktionary.org/wiki/inlinehttp://en.wikipedia.org/wiki/Vaporizationhttp://en.wikipedia.org/wiki/Partial_pressureshttp://en.wikipedia.org/wiki/Volatility_(chemistry)http://en.wikipedia.org/wiki/Volatility_(chemistry)http://en.wikipedia.org/wiki/Partial_pressureshttp://en.wikipedia.org/wiki/Vaporizationhttp://en.wiktionary.org/wiki/inlinehttp://en.wikipedia.org/wiki/Membrane_introduction_mass_spectrometryhttp://en.wikipedia.org/wiki/Evaporationhttp://en.wikipedia.org/wiki/Permeatehttp://en.wikipedia.org/wiki/Permeationhttp://en.wikipedia.org/wiki/Artificial_membranehttp://en.wikipedia.org/wiki/Vaporizationhttp://en.wikipedia.org/wiki/Separation_of_mixturehttp://en.wikipedia.org/wiki/Separation_of_mixture -
7/27/2019 seminar report on membrance technology
9/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 9
membrane. The retentate is the remainder of the feed leaving the membrane feed chamber,
which is not permeated through the membrane. The chemical potential can be expressed in
terms offugacity, given byRaoult's law for a liquid and by Dalton's law for (an ideal) gas.
During operation, due to removal of the vapor-phase permeate, the actual fugacity of the
vapor is lower than anticipated on basis of the collected (condensed) permeate.
Separation of components (e.g. water and ethanol) is based on a difference in
transport rate of individual components through the membrane. This transport mechanism can
be described using the solution-diffusion model, based on the rate/ degree of dissolution of a
component into the membrane and its velocity of transport (expressed in terms of diffusivity)
through the membrane, which will be different for each component and membrane type
leading to separation.
2.3 OPERATIONS IN ELECTRIC POTENTIAL GRADIENT
2.3.1 ELECTRODIALYSIS
FIG 2.3.1Electrodialysis
Electrodialysis (ED) is used to transport salt ions from one solution through ion-
exchange membranes to another solution under the influence of an applied electric
potential difference. This is done in a configuration called an electrodialysis cell. The cell
http://en.wikipedia.org/wiki/Fugacityhttp://en.wikipedia.org/wiki/Raoult%27s_lawhttp://en.wikipedia.org/wiki/Dalton%27s_lawhttp://en.wikipedia.org/wiki/Salthttp://en.wikipedia.org/wiki/Ionshttp://en.wikipedia.org/wiki/Solutionhttp://en.wikipedia.org/wiki/Ion-exchangehttp://en.wikipedia.org/wiki/Ion-exchangehttp://en.wikipedia.org/wiki/Semipermeable_membranehttp://en.wikipedia.org/wiki/Electric_potentialhttp://en.wikipedia.org/wiki/Electric_potentialhttp://en.wikipedia.org/wiki/File:Edprinc.jpghttp://en.wikipedia.org/wiki/Electric_potentialhttp://en.wikipedia.org/wiki/Electric_potentialhttp://en.wikipedia.org/wiki/Semipermeable_membranehttp://en.wikipedia.org/wiki/Ion-exchangehttp://en.wikipedia.org/wiki/Ion-exchangehttp://en.wikipedia.org/wiki/Solutionhttp://en.wikipedia.org/wiki/Ionshttp://en.wikipedia.org/wiki/Salthttp://en.wikipedia.org/wiki/Dalton%27s_lawhttp://en.wikipedia.org/wiki/Raoult%27s_lawhttp://en.wikipedia.org/wiki/Fugacity -
7/27/2019 seminar report on membrance technology
10/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 10
consists of a feed (diluate) compartment and a concentrate (brine) compartment formed by
an anion exchange membrane and a cation exchange membrane placed between
two electrodes. In almost all practical electrodialysis processes, multiple electrodialysis cells
are arranged into a configuration called an electrodialysis stack, with alternating anion and
cation exchange membranes forming the multiple electrodialysis cells. Electrodialysis
processes are different compared to distillation techniques and other membrane based
processes (such as reverse osmosis) in that dissolved species are moved away from the feed
stream rather than the reverse. Because the quantity of dissolved species in the feed stream is
far less than that of the fluid, electrodialysis offers the practical advantage of much higher
feed recovery in many applications.
2.3.2 ELECTROFILTRATION
Electrofiltration is a method that combines membrane filtration and electrophoresis in
a dead-end process.
Electrofiltration is regarded as an appropriate technique for concentration and
fractionation ofbiopolymers. The film formation on the filter membrane which hinders
filtration can be minimized or completely avoided by the application ofelectric field,
improving filtrations performance and increasing selectivity in case of fractionation. This
approach reduces significantly the expenses fordownstream processing in bioprocesses.
http://en.wikipedia.org/wiki/Anionhttp://en.wikipedia.org/wiki/Cationhttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Distillationhttp://en.wikipedia.org/wiki/Reverse_osmosishttp://en.wikipedia.org/wiki/Membrane_technologyhttp://en.wikipedia.org/wiki/Electrophoresishttp://en.wikipedia.org/wiki/Biopolymerhttp://en.wikipedia.org/wiki/Electric_fieldhttp://en.wikipedia.org/wiki/Filtrationhttp://en.wikipedia.org/wiki/Filtrationhttp://en.wikipedia.org/wiki/Downstream_processinghttp://en.wikipedia.org/wiki/Downstream_processinghttp://en.wikipedia.org/wiki/Filtrationhttp://en.wikipedia.org/wiki/Electric_fieldhttp://en.wikipedia.org/wiki/Biopolymerhttp://en.wikipedia.org/wiki/Electrophoresishttp://en.wikipedia.org/wiki/Membrane_technologyhttp://en.wikipedia.org/wiki/Reverse_osmosishttp://en.wikipedia.org/wiki/Distillationhttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Cationhttp://en.wikipedia.org/wiki/Anion -
7/27/2019 seminar report on membrance technology
11/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 11
FIG 2.2.4 ELECTROFILTRATION
Electrofiltration is highly innovative state of the art technique for separation,
respectively concentration of colloidal substances - for instance biopolymers. The principle of
electrofiltration is based on overlaying electric field on a standarddead-end filtration. Thus
the created polarity facilitates electrophoretic force which is opposite to the resistance force
of the filtrate flow and directs the charged biopolymers. This provides extreme decrease in
the film formation on the micro- or ultra-filtration membranes and the reduction of filtration
time from several hours by standard filtration to a few minutes by electrofiltration. In
comparison to cross-flow filtration electrofiltration exhibits not only increased permeate flowbut also guarantees reduced shear force stress which qualifies it as particularly mild technique
for separation ofbiopolymersthat are usually unstable.
The promising application in purification of biotechnological products is based on the
fact that biopolymers are difficult for filtration but on the other hand they are usually charged
as a result of the presence of amino and carboxyl groups. The objective of electrofiltration is
to prevent the formation of filter cake and to improve the filtration kinetic of products
difficult to filtrate.
http://en.wikipedia.org/wiki/Biopolymerhttp://en.wikipedia.org/wiki/Electric_fieldhttp://en.wikipedia.org/wiki/Dead-end_filtrationhttp://en.wikipedia.org/wiki/Biopolymerhttp://en.wikipedia.org/wiki/Filtrationhttp://en.wikipedia.org/wiki/Cross-flow_filtrationhttp://en.wikipedia.org/wiki/Biopolymerhttp://en.wikipedia.org/wiki/Biopolymerhttp://en.wikipedia.org/wiki/Biopolymerhttp://en.wikipedia.org/wiki/Biopolymerhttp://en.wikipedia.org/wiki/Cross-flow_filtrationhttp://en.wikipedia.org/wiki/Filtrationhttp://en.wikipedia.org/wiki/Biopolymerhttp://en.wikipedia.org/wiki/Dead-end_filtrationhttp://en.wikipedia.org/wiki/Electric_fieldhttp://en.wikipedia.org/wiki/Biopolymer -
7/27/2019 seminar report on membrance technology
12/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 12
2.3.3 MEMBRANE DISTILLATION
FIG 2.3.3 REM-image of a PTFE membrane
Membrane distillation is a thermally driven separational process in which separation
is enabled due to phase change. A hydrophobic membrane displays a barrier for the liquid
phase, letting the vapour phase (e.g. water vapour) pass through the membrane's pores. The
driving force of the process is given by a partial vapour pressure difference commonly
triggered by a temperature difference.
Principle of membrane distillation
FIG 2.3.3 Capilary depression of water on a hydophobic membrane
http://en.wikipedia.org/wiki/Membranehttp://en.wikipedia.org/wiki/Liquid_phasehttp://en.wikipedia.org/wiki/Liquid_phasehttp://en.wikipedia.org/wiki/Vapour_pressurehttp://en.wikipedia.org/wiki/File:Prinzip_MD.pnghttp://en.wikipedia.org/wiki/File:REM-Aufnahme_edited.jpghttp://en.wikipedia.org/wiki/File:Prinzip_MD.pnghttp://en.wikipedia.org/wiki/File:REM-Aufnahme_edited.jpghttp://en.wikipedia.org/wiki/Vapour_pressurehttp://en.wikipedia.org/wiki/Liquid_phasehttp://en.wikipedia.org/wiki/Liquid_phasehttp://en.wikipedia.org/wiki/Membrane -
7/27/2019 seminar report on membrance technology
13/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 13
FIG 2.3.3 MEMBRANE DISTILATION
FIG2.3.3
Schematic image of the membrane distillation process
Temperature and pressure profile through the membrane considering temperature
polarisation
State of the art processes that separate mass flows by a membrane, mostly use a
staticpressure difference as the driving force between the two bounding surfaces (e.g. RO), a
difference in concentration (dialysis) or an electric field (ED). Selectivity of a membrane is
produced by, either its pore size in relation to the size of the substance to be
retained,itsdiffusion coefficient orelectrical polarity. However, the selectivity of membranes
used for membrane distillation (MD) is based on the retention of liquid water with-at the
same time-permeability for free watermolecules and thus, for water vapour. These
membranes are made ofhydrophobic synthetic material (e.g. PTFE, PVDF or PP) and offer
pores with a standard diameter between 0.1 to 0.5 m. As water has
strong dipole characteristics, whilst the membrane fabric is non-polar, the membrane material
is not wetted by the liquid. Even though the pores are considerably larger than the molecules,
http://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Dialysishttp://en.wikipedia.org/wiki/Electric_fieldhttp://en.wikipedia.org/wiki/Diffusionhttp://en.wikipedia.org/wiki/Electrical_polarityhttp://en.wikipedia.org/wiki/Permeationhttp://en.wikipedia.org/wiki/Moleculeshttp://en.wikipedia.org/wiki/Hydrophobichttp://en.wikipedia.org/wiki/Dipolehttp://en.wikipedia.org/wiki/File:Dampfdruckprofil_MD.pnghttp://en.wikipedia.org/wiki/File:Schema_Membrandestillations-Prozess.pnghttp://en.wikipedia.org/wiki/File:Dampfdruckprofil_MD.pnghttp://en.wikipedia.org/wiki/File:Schema_Membrandestillations-Prozess.pnghttp://en.wikipedia.org/wiki/Dipolehttp://en.wikipedia.org/wiki/Hydrophobichttp://en.wikipedia.org/wiki/Moleculeshttp://en.wikipedia.org/wiki/Permeationhttp://en.wikipedia.org/wiki/Electrical_polarityhttp://en.wikipedia.org/wiki/Diffusionhttp://en.wikipedia.org/wiki/Electric_fieldhttp://en.wikipedia.org/wiki/Dialysishttp://en.wikipedia.org/wiki/Pressure -
7/27/2019 seminar report on membrance technology
14/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 14
the liquid phase does not enter the pores because of the high watersurface tension. A
convex meniscus develops into the pore. This effect is named capillary action. Amongst other
factors, the depth of impression can depend on the external pressure load on the liquid. A
dimension for the infiltration of the pores by the liquid is the contact angle =180 '. As
long as > 90 and accordingly ' > 0 no wetting of the pores will take place. If the
external pressure rises above the so-called wetting pressure, then = 90resulting in a bypass
of the pore. The driving force which delivers the vapour through the membrane, in order to
collect it on the permeate side as product water, is the partial water vapour pressure
difference between the two bounding surfaces. This partial pressure difference is the result of
a temperature difference between the two bounding surfaces. As can be seen in the image, the
membrane is charged with a hot feed flow on one side and a cooled permeate flow on the
other side. The temperature difference through the membrane, usually between 5 and 20 K,
conveys a partial pressure difference which ensures that the vapour developing at the
membrane surface follows the pressure drop, permeating through the pores and condensing
on the cooler side.[1]
http://en.wikipedia.org/wiki/Surface_tensionhttp://en.wikipedia.org/wiki/Meniscushttp://en.wikipedia.org/wiki/Infiltration_(medical)http://en.wikipedia.org/wiki/Membrane_distillation#cite_note-joako-1http://en.wikipedia.org/wiki/Membrane_distillation#cite_note-joako-1http://en.wikipedia.org/wiki/Membrane_distillation#cite_note-joako-1http://en.wikipedia.org/wiki/Membrane_distillation#cite_note-joako-1http://en.wikipedia.org/wiki/Infiltration_(medical)http://en.wikipedia.org/wiki/Meniscushttp://en.wikipedia.org/wiki/Surface_tension -
7/27/2019 seminar report on membrance technology
15/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 15
CHAPTER - 3
MEMBRANE SHAPES AND FLOW GEOMETRIES
There are two types of geometries.
Dead end geometry Cross flow geometry.
FIG 2.3.4 Dead end geometry
3.1 DEAD-END GEOMETRY:-
In cross-flow filtration the feed flow istangential to the surface of membrane,
retentate is removed from the same side further downstream, whereas the permeate flow is
tracked on the other side. In dead-end filtration the direction of the fluid flow is normal to the
membrane surface. Both flow geometries offer some advantages and disadvantages. The
dead-end membranes are relatively easy to fabricate which reduces the cost of the separation
process. The dead-end membrane separation process is easy to implement and the process is
usually cheaper than cross-flow membrane filtration. The dead-end filtration process is
http://en.wikipedia.org/wiki/Tangentialhttp://en.wikipedia.org/wiki/File:Dead-end.svghttp://en.wikipedia.org/wiki/Tangential -
7/27/2019 seminar report on membrance technology
16/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 16
usually a batch-type process, where the filtering solution is loaded (or slowly fed) into
membrane device, which then allows passage of some particles subject to the driving force.
The main disadvantage of a dead end filtration is the extensive
membrane fouling and concentration polarization. The fouling is usually induced faster at the
higher driving forces. Membrane fouling and particle retention in a feed solution also builds
up a concentration gradients and particle backflow (concentration polarization.
Flat plates are usually constructed as circular thin flat membrane surfaces to be used
in dead-end geometry modules. Spiral wounds are constructed from similar flat membranes
but in a form of a pocket containing two membrane sheets separated by a highly porous
support plate.[2]
Several such pockets are then wound around a tube to create a tangential flowgeometry and to reduce membrane fouling. Hollow fibermodules consist of an assembly of
self-supporting fibers with a dense skin separation layers, and more open matrix helping to
withstand pressure gradients and maintain structural integrity.[2]The hollow fiber modules
can contain up to 10,000 fibers ranging from 200 to 2500 m in diameter; The main
advantage of hollow fiber modules is very large surface area within an enclosed volume,
increasing the efficiency of the separation process.
FIG 3.1 Spiral wound membrane module.
http://en.wikipedia.org/wiki/Batch_productionhttp://en.wikipedia.org/wiki/Foulinghttp://en.wikipedia.org/w/index.php?title=Concentration_polarization&action=edit&redlink=1http://en.wikipedia.org/wiki/Gradientshttp://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Fiberhttp://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/File:Spiral_flow_membrane_module-en.svghttp://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Fiberhttp://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Gradientshttp://en.wikipedia.org/w/index.php?title=Concentration_polarization&action=edit&redlink=1http://en.wikipedia.org/wiki/Foulinghttp://en.wikipedia.org/wiki/Batch_production -
7/27/2019 seminar report on membrance technology
17/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 17
3.2 CROSS FLOW GEOMETRY:-
The tangential flow devices are more cost and labor intensive, but they are less
susceptible to fouling due to the sweeping effects and high shear rates of the passing flow.
The most commonly used synthetic membrane devices (modules) are flat plates, spiral
wounds, and hollow fibers.
FIG 3.2 Cross-flow geometry
CHAPTER - 4
http://en.wikipedia.org/wiki/File:Cross-flow.svg -
7/27/2019 seminar report on membrance technology
18/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 18
MASS TRANSFER:
Two basic models can be distinguished for mass transfer through the membrane:
thesolution-diffusion modeland thehydrodynamic model.
In real membranes, these two transport mechanisms certainly occur side by side, especially
during the ultra-filtration.
4.1 SOLUTION-DIFFUSION MODEL
In the solution-diffusion model, transport occurs only by diffusion. The component
that needs to be transported must first be dissolved in the membrane. This principle is more
important fordensemembranes without natural pores such as those used for reverse osmosis
and in fuel cells. During the filtrationprocess a boundary layerforms on the membrane.
This concentration gradient is created by molecules which cannot pass through the
membrane. The effect is referred as concentration polarization and, occurring during the
filtration, leads to a reduced trans-membrane flow (flux). Concentration polarization is, in
principle, reversible by cleaning the membrane which results in the initial flux being almost
totally restored. Using a tangential flow to the membrane (cross-flow filtration) can also
minimize concentration polarization.
4.2 HYDRODYNAMIC MODEL
Transport through pores in the simplest case is done convectively. This requires
the size of the pores to be smaller than the diameter of the to separate components.
Membranes, which function according to this principle are used mainly in micro- and
ultrafiltration. They are used to separate macromolecules from solutions, colloids froma dispersion or remove bacteria. During this process the not passing particles or molecules are
forming on the membrane a more or less a pulpy mass (filter cake). This hampered by the
blockage of the membrane the filtration. By the so-called cross-flow method (cross-flow
filtration) this can be reduced. Here, the liquid to be filtered flows along the front of the
membrane and is separated by the pressure difference between the front and back of the
fractions into retentate (the flowing concentrate) and permeate (filtrate). This creates a shear
stress that cracks the filter cake and lower the formation offouling.
http://en.wikipedia.org/wiki/Diffusionhttp://en.wiktionary.org/wiki/porehttp://en.wikipedia.org/wiki/Filtrationhttp://en.wikipedia.org/wiki/Boundary_layerhttp://en.wikipedia.org/wiki/Concentration_gradienthttp://en.wikipedia.org/wiki/Moleculehttp://en.wikipedia.org/w/index.php?title=Concentration_polarization&action=edit&redlink=1http://en.wikipedia.org/wiki/Fluxhttp://en.wikipedia.org/wiki/Convectionhttp://en.wikipedia.org/wiki/Macromoleculehttp://en.wikipedia.org/wiki/Solution_(chemistry)http://en.wikipedia.org/wiki/Colloidhttp://en.wikipedia.org/wiki/Dispersion_(chemistry)http://en.wikipedia.org/wiki/Filter_cakehttp://en.wikipedia.org/wiki/Cross-flow_filtrationhttp://en.wikipedia.org/wiki/Cross-flow_filtrationhttp://en.wikipedia.org/w/index.php?title=Retentate&action=edit&redlink=1http://en.wikipedia.org/wiki/Permeatehttp://en.wikipedia.org/wiki/Membrane_foulinghttp://en.wikipedia.org/wiki/Membrane_foulinghttp://en.wikipedia.org/wiki/Permeatehttp://en.wikipedia.org/w/index.php?title=Retentate&action=edit&redlink=1http://en.wikipedia.org/wiki/Cross-flow_filtrationhttp://en.wikipedia.org/wiki/Cross-flow_filtrationhttp://en.wikipedia.org/wiki/Filter_cakehttp://en.wikipedia.org/wiki/Dispersion_(chemistry)http://en.wikipedia.org/wiki/Colloidhttp://en.wikipedia.org/wiki/Solution_(chemistry)http://en.wikipedia.org/wiki/Macromoleculehttp://en.wikipedia.org/wiki/Convectionhttp://en.wikipedia.org/wiki/Fluxhttp://en.wikipedia.org/w/index.php?title=Concentration_polarization&action=edit&redlink=1http://en.wikipedia.org/wiki/Moleculehttp://en.wikipedia.org/wiki/Concentration_gradienthttp://en.wikipedia.org/wiki/Boundary_layerhttp://en.wikipedia.org/wiki/Filtrationhttp://en.wiktionary.org/wiki/porehttp://en.wikipedia.org/wiki/Diffusion -
7/27/2019 seminar report on membrance technology
19/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 19
CHAPTER-5
MEMBRANE PERFORMANCE AND GOVERNING EQUATIONS
-
7/27/2019 seminar report on membrance technology
20/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 20
The selection of synthetic membranes for a targeted separation process is usually
based on few requirements. Membranes have to provide enough mass transfer area to process
large amounts of feed stream. The selected membrane has to have high selectivity properties
for certain particles; it has to resist fouling and to have high mechanical stability. It also
needs to be reproducible and to have low manufacturing costs. The main modeling equation
for the dead-end filtration at constant pressure drop is represented by Darcys law:[2]
where Vp and Q are the volume of the permeate and its volumetric flow rate respectively
(proportional to same characteristics of the feed flow), is dynamic viscosity of permeating
fluid, A is membrane area, Rm and R are the respective resistances of membrane and growing
deposit of the foulants. Rm can be interpreted as a membrane resistance to the solvent (water)
permeation. This resistance is a membrane intrinsicproperty and expected to be fairly
constant and independent of the driving force, p. R is related to the type of membrane
foulant, its concentration in the filtering solution, and the nature of foulant-membrane
interactions. Darcys law allows to calculate the membrane area for a targeted separation at
given conditions. The solute sieving coefficient is defined by the equation:
[2]
where Cfand Cp are the solute concentrations in feed and permeate respectively. Hydraulic
permeability is defined as the inverse of resistance and is represented by the equation:[2]
where J is the permeate flux which is the volumetric flow rate per unit of membrane area. The
solute sieving coefficient and hydraulic permeability allow the quick assessment of the
synthetic membrane performance.
CHAPTER-6
MEMBRANE SEPARATION PROCESSES
http://en.wikipedia.org/wiki/Binding_selectivityhttp://en.wikipedia.org/wiki/Foulinghttp://en.wikipedia.org/w/index.php?title=Mechanical_stability&action=edit&redlink=1http://en.wikipedia.org/wiki/Pressure_drophttp://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Flow_ratehttp://en.wikipedia.org/wiki/Dynamic_viscosityhttp://en.wikipedia.org/wiki/Intrinsichttp://en.wikipedia.org/wiki/Solutionhttp://en.wikipedia.org/wiki/Sievinghttp://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Fluxhttp://en.wikipedia.org/wiki/Fluxhttp://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Sievinghttp://en.wikipedia.org/wiki/Solutionhttp://en.wikipedia.org/wiki/Intrinsichttp://en.wikipedia.org/wiki/Dynamic_viscosityhttp://en.wikipedia.org/wiki/Flow_ratehttp://en.wikipedia.org/wiki/Membrane_technology#cite_note-O-2http://en.wikipedia.org/wiki/Pressure_drophttp://en.wikipedia.org/w/index.php?title=Mechanical_stability&action=edit&redlink=1http://en.wikipedia.org/wiki/Foulinghttp://en.wikipedia.org/wiki/Binding_selectivity -
7/27/2019 seminar report on membrance technology
21/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 21
Membrane separation processes have very important role in separation industry.
Nevertheless, they were not considered technically important until mid-1970. Membrane
separation processes differ based on separation mechanisms and size of the separated
particles.The widely used membrane processes
include microfiltration, ultrafiltration, nanofiltration, reverseosmosis, electrolysis,dialysis,
electrodialysis, gas separation, vapor permeation, pervaporation, membrane distillation,
and membrane contactors.[3]All processes except for pervaporation involve no phase
change. All processes except (electro)dialysis are pressure driven. Microfltration and
ultrafiltration is widely used in food and beverage processing (beer microfiltration, apple
juice ultrafiltration), biotechnological applications and pharmaceutical
industry (antibioticproduction, protein purification), water purification and wastewater
treatment, microelectronics industry, and others. Nanofiltration and reverse osmosis
membranes are mainly used for water purification purposes. Dense membranes are
utilized for gas separations (removal of CO2 from natural gas, separating N2from air,
organic vapor removal from air or nitrogen stream) and sometimes in membrane
distillation. The later process helps in separating of azeotropic compositions reducing the
costs of distillation processes.
TABLE OF DIFFERENT LIQUID TECHNIQUE
http://en.wikipedia.org/wiki/Microfiltrationhttp://en.wikipedia.org/wiki/Ultrafiltrationhttp://en.wikipedia.org/wiki/Nanofiltrationhttp://en.wikipedia.org/wiki/Reverse_osmosishttp://en.wikipedia.org/wiki/Electrolysishttp://en.wikipedia.org/wiki/Dialysishttp://en.wikipedia.org/wiki/Electrodialysishttp://en.wikipedia.org/wiki/Gas_separationhttp://en.wikipedia.org/wiki/Pervaporationhttp://en.wikipedia.org/wiki/Distillationhttp://en.wikipedia.org/wiki/Membrane_technology#cite_note-Pi-3http://en.wikipedia.org/wiki/Membrane_technology#cite_note-Pi-3http://en.wikipedia.org/wiki/Membrane_technology#cite_note-Pi-3http://en.wikipedia.org/wiki/Pharmaceutical_industryhttp://en.wikipedia.org/wiki/Pharmaceutical_industryhttp://en.wikipedia.org/wiki/Antibiotichttp://en.wikipedia.org/wiki/Wastewater_treatmenthttp://en.wikipedia.org/wiki/Wastewater_treatmenthttp://en.wikipedia.org/wiki/Wastewater_treatmenthttp://en.wikipedia.org/wiki/Wastewater_treatmenthttp://en.wikipedia.org/wiki/Antibiotichttp://en.wikipedia.org/wiki/Pharmaceutical_industryhttp://en.wikipedia.org/wiki/Pharmaceutical_industryhttp://en.wikipedia.org/wiki/Membrane_technology#cite_note-Pi-3http://en.wikipedia.org/wiki/Distillationhttp://en.wikipedia.org/wiki/Pervaporationhttp://en.wikipedia.org/wiki/Gas_separationhttp://en.wikipedia.org/wiki/Electrodialysishttp://en.wikipedia.org/wiki/Dialysishttp://en.wikipedia.org/wiki/Electrolysishttp://en.wikipedia.org/wiki/Reverse_osmosishttp://en.wikipedia.org/wiki/Nanofiltrationhttp://en.wikipedia.org/wiki/Ultrafiltrationhttp://en.wikipedia.org/wiki/Microfiltration -
7/27/2019 seminar report on membrance technology
22/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 22
Ranges of membrane based separations.
http://en.wikipedia.org/wiki/File:Cut-offs_of_different_liquid_filtration_techniques.png -
7/27/2019 seminar report on membrance technology
23/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 23
CHAPTER -7
PORE SIZE AND SELECTIVITY
The pore sizes of technical membranes are specified differently depending on the
manufacturer. One common form is the nominal pore size. It describes the maximum of the
pore size distribution[4]and gives only a vague statement about the retention capacity of a
membrane. The exclusion limit or "cut-off" of the membrane is usually specified in the form
ofNMWC(nominal molecular weight cut-off, orMWCO, Molecular Weight Cut Off,
Unit:Dalton). It is defined as the minimum molecular weight of a globular molecule which isretained by the membrane to 90%. The cut-off, depending on the method, can by converted in
the so-calledD90, which is then expressed in a metric unit. In practice the MWCO of the
membrane should be at least 20% lower than the molecular weight of the molecule that is to
be separated.
Filter membranes are divided into four classes according to their pore size:
Pore
size
Molecular
massProcess Filtration Removal of
> 10 "Classic" filter
> 0.1 m > 5000 kDa microfiltration < 2 barlarger bacteria, yeast,
particles
100-
2 nm5-5000 kDa ultrafiltration 1-10 bar
bacteria, macromolecules,
proteins, larger viruses
The form and shape of the membrane pores are highly dependent on the
manufacturing process and are often difficult to specify. Therefore, for characterization, test
http://en.wikipedia.org/wiki/Membrane_technology#cite_note-4http://en.wikipedia.org/wiki/Membrane_technology#cite_note-4http://en.wikipedia.org/wiki/Molecular_Weight_Cut_Offhttp://en.wikipedia.org/wiki/Dalton_(unit)http://en.wikipedia.org/wiki/Molecular_weighthttp://en.wikipedia.org/wiki/Filtrationhttp://en.wikipedia.org/wiki/Microfiltrationhttp://en.wikipedia.org/wiki/Microfiltrationhttp://en.wikipedia.org/wiki/Ultrafiltrationhttp://en.wikipedia.org/wiki/Ultrafiltrationhttp://en.wikipedia.org/wiki/Ultrafiltrationhttp://en.wikipedia.org/wiki/Microfiltrationhttp://en.wikipedia.org/wiki/Filtrationhttp://en.wikipedia.org/wiki/Molecular_weighthttp://en.wikipedia.org/wiki/Dalton_(unit)http://en.wikipedia.org/wiki/Molecular_Weight_Cut_Offhttp://en.wikipedia.org/wiki/Membrane_technology#cite_note-4 -
7/27/2019 seminar report on membrance technology
24/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 24
filtrations are carried out and the pore diameter refers to the diameter of the smallest particles
which could not pass through the membrane.
The rejection can be determined in various ways and always provide an indirectmeasurement of the pore size. One possibility is the filtration of macromolecules
(often Dextran, polyethylene glycol oralbumin), and the measurement of the cut-off by gel
permeation chromatography. These methods are mainly for the measurement of ultrafiltration
membranes application. Another methods of testing are the filtrations of particles with
defined size and their measurement with a Particle Sizeror by Laser induced breakdown
detection (LIBD). A very vivid characterization is to measure the rejection ofDextranblue or
other colored molecules. Also the retention ofbacteriophage and bacteria, the so-called
"Bacteria Challenge Test", can provide statements of the pore size.
SIZES OF MICROORGANISM
Nominal pore size micro-organism ATCC root number
0.1 m Acholeplasma laidlawii 23206
0.3 m Bacillus subtilisspores 82
0.5 m Pseudomonas diminuta 19146
0.45 m Serratia marcescens 14756
0.65 m Lactobacillus brevis
To determine the pore diameter, physical methods such as porosimetry (mercury,
liquid-liquid porosimetry and Bubble Point Test) are also used, but a certain form of the pores
(such ascylindrically or concatenated spherical holes) is assumed. Such methods are used for
membranes whose pore geometry does not match the ideals, we get "nominal" pore diameter,
http://en.wikipedia.org/wiki/Dextranshttp://en.wikipedia.org/wiki/Polyethylene_glycolhttp://en.wikipedia.org/wiki/Albuminhttp://en.wikipedia.org/wiki/Gel_permeation_chromatographyhttp://en.wikipedia.org/wiki/Gel_permeation_chromatographyhttp://en.wikipedia.org/w/index.php?title=Particle_Sizer&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Laser_induced_breakdown_detection&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Laser_induced_breakdown_detection&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Dextranblue&action=edit&redlink=1http://en.wikipedia.org/wiki/Bacteriophagehttp://en.wikipedia.org/wiki/Bacteriahttp://en.wikipedia.org/wiki/American_Type_Culture_Collectionhttp://en.wikipedia.org/wiki/Acholeplasmahttp://en.wikipedia.org/wiki/Bacillus_subtilishttp://en.wikipedia.org/wiki/Pseudomonashttp://en.wikipedia.org/wiki/Pseudomonashttp://en.wikipedia.org/wiki/Serratia_marcescenshttp://en.wikipedia.org/wiki/Serratia_marcescenshttp://en.wikipedia.org/wiki/Lactobacillus_brevishttp://en.wikipedia.org/wiki/Lactobacillus_brevishttp://en.wikipedia.org/wiki/Physicshttp://en.wikipedia.org/wiki/Porosimetryhttp://en.wikipedia.org/wiki/Cylinder_(geometry)http://en.wikipedia.org/wiki/Spherehttp://en.wikipedia.org/wiki/Spherehttp://en.wikipedia.org/wiki/Cylinder_(geometry)http://en.wikipedia.org/wiki/Porosimetryhttp://en.wikipedia.org/wiki/Physicshttp://en.wikipedia.org/wiki/Lactobacillus_brevishttp://en.wikipedia.org/wiki/Serratia_marcescenshttp://en.wikipedia.org/wiki/Pseudomonashttp://en.wikipedia.org/wiki/Bacillus_subtilishttp://en.wikipedia.org/wiki/Acholeplasmahttp://en.wikipedia.org/wiki/American_Type_Culture_Collectionhttp://en.wikipedia.org/wiki/Bacteriahttp://en.wikipedia.org/wiki/Bacteriophagehttp://en.wikipedia.org/w/index.php?title=Dextranblue&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Laser_induced_breakdown_detection&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Laser_induced_breakdown_detection&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Particle_Sizer&action=edit&redlink=1http://en.wikipedia.org/wiki/Gel_permeation_chromatographyhttp://en.wikipedia.org/wiki/Gel_permeation_chromatographyhttp://en.wikipedia.org/wiki/Albuminhttp://en.wikipedia.org/wiki/Polyethylene_glycolhttp://en.wikipedia.org/wiki/Dextrans -
7/27/2019 seminar report on membrance technology
25/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 25
which characterize the membrane, but does not necessarily reflect their actual filtration
behavior and selectivity.
The selectivity is highly dependent on the separation process, the composition of themembrane and their electrochemical properties in addition to the pore size. By a high
selectivity, isotopes can be enriched (uranium enrichment) in nuclear engineering or
industrial gaseous like nitrogen be recovered (gas separation). Ideally, can be enriched with a
suitable membrane even racemics.
In the selection of the membrane selectivity has priority over a high permeability, as
can low flows easily offset by increasing the filter surface with a modular structure. For the
gas phase is to be noted that, in a filtration process different deposition mechanisms act, so
that particles having sizes below the pore size of the membrane can be retained as well.
FIG 7.1
The pore distribution of a fictitious ultrafiltration membrane with the nominal pore size
http://en.wikipedia.org/wiki/Gaseous_diffusionhttp://en.wikipedia.org/wiki/Gas_separationhttp://en.wikipedia.org/wiki/Racemic_mixturehttp://en.wikipedia.org/wiki/File:Porengr%C3%B6sse_und_Verteilung.pnghttp://en.wikipedia.org/wiki/Racemic_mixturehttp://en.wikipedia.org/wiki/Gas_separationhttp://en.wikipedia.org/wiki/Gaseous_diffusion -
7/27/2019 seminar report on membrance technology
26/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 26
CHAPTER-8
APPLICATIONS
FIG 8.1
Ultrafiltration for a swimming pool
FIG 8.2
Venous-arterial ECMO scheme
The particular advantage of membrane separation processes is that
2 They operate without heating and therefore use less energy than conventional thermalseparation processes (distillation,Sublimation orcrystallization).
3 This separation process is purely physical and because it is a gentle process, bothfractions (permeate and retentate) can be used.
http://in.ask.com/wiki/Distillation?qsrc=3044&lang=enhttp://in.ask.com/wiki/Sublimation_(phase_transition)?qsrc=3044&lang=enhttp://in.ask.com/wiki/Crystallization?qsrc=3044&lang=enhttp://in.ask.com/wiki/Permeation?qsrc=3044&lang=enhttp://in.ask.com/wiki/Retentate?qsrc=3044&lang=enhttp://en.wikipedia.org/wiki/File:Ecmo_schema-1-.jpghttp://en.wikipedia.org/wiki/File:Waldsassen_Ultrafiltration.JPGhttp://en.wikipedia.org/wiki/File:Ecmo_schema-1-.jpghttp://en.wikipedia.org/wiki/File:Waldsassen_Ultrafiltration.JPGhttp://in.ask.com/wiki/Retentate?qsrc=3044&lang=enhttp://in.ask.com/wiki/Permeation?qsrc=3044&lang=enhttp://in.ask.com/wiki/Crystallization?qsrc=3044&lang=enhttp://in.ask.com/wiki/Sublimation_(phase_transition)?qsrc=3044&lang=enhttp://in.ask.com/wiki/Distillation?qsrc=3044&lang=en -
7/27/2019 seminar report on membrance technology
27/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 27
4 Cold separation by means of membrane processes is commonly applied in the foodtechnology, biotechnology andpharmaceutical industries.
5 With the help of membrane separations realizeable that with thermal processes are notpossible. For example, because azeotropics orisomorphicscrystallization making a
separation by distillation orrecrystallization impossible.
6 Depending on the type of membrane, the selective separation of certain individualsubstances or substance mixtures is possible.
7 Important technical applications include drinking water by reverse osmosis (worldwideapproximately 7 million cubic meters annually), filtrations in the food industry, the
recovery of organic vapors such as gasoline vapor recovery and the electrolysis for
chlorine production.
8 Also in wastewater treatment, the membrane technology is becoming increasinglyimportant. With the help of UF and MF (Ultra-/Mikrofiltration) it is possible to remove
particles, colloids and macromolecules, so that wastewater can be disinfected in this way.
This is needed if wastewater is discharged into sensitive outfalls, or in swimming lakes.
About half of the market has applications in medicine. As an artificial kidney to remove
toxic substances by hemodialysis and as artificial lung for bubble-free supply of oxygen in
the blood. Also the importance of membrane technology is growing in the field of
environmental protection (NanoMemPro IPPC Database). Even in modern energy recovery
techniques membranes are increasingly used, for example in the fuel cell or the osmotic
power plant.
http://in.ask.com/wiki/Food_technology?qsrc=3044&lang=enhttp://in.ask.com/wiki/Food_technology?qsrc=3044&lang=enhttp://in.ask.com/wiki/Biotechnology?qsrc=3044&lang=enhttp://in.ask.com/wiki/Pharmaceutical?qsrc=3044&lang=enhttp://in.ask.com/wiki/Azeotrope?qsrc=3044&lang=enhttp://in.ask.com/wiki/Isomorphism_(crystallography)?qsrc=3044&lang=enhttp://in.ask.com/wiki/Recrystallization_(chemistry)?qsrc=3044&lang=enhttp://in.ask.com/wiki/Reverse_osmosis?qsrc=3044&lang=enhttp://in.ask.com/wiki/Food_industry?qsrc=3044&lang=enhttp://in.ask.com/wiki/Chloralkali_process?qsrc=3044&lang=enhttp://in.ask.com/wiki/Dialysis?qsrc=3044&lang=enhttp://in.ask.com/wiki/Extracorporeal_membrane_oxygenation?qsrc=3044&lang=enhttp://in.ask.com/wiki/Blood?qsrc=3044&lang=enhttp://in.ask.com/wiki/NanoMemPro_IPPC_Database?qsrc=3044&lang=enhttp://in.ask.com/wiki/Fuel_cell?qsrc=3044&lang=enhttp://in.ask.com/wiki/Osmotic_power_plant?qsrc=3044&lang=enhttp://in.ask.com/wiki/Osmotic_power_plant?qsrc=3044&lang=enhttp://in.ask.com/wiki/Osmotic_power_plant?qsrc=3044&lang=enhttp://in.ask.com/wiki/Osmotic_power_plant?qsrc=3044&lang=enhttp://in.ask.com/wiki/Fuel_cell?qsrc=3044&lang=enhttp://in.ask.com/wiki/NanoMemPro_IPPC_Database?qsrc=3044&lang=enhttp://in.ask.com/wiki/Blood?qsrc=3044&lang=enhttp://in.ask.com/wiki/Extracorporeal_membrane_oxygenation?qsrc=3044&lang=enhttp://in.ask.com/wiki/Dialysis?qsrc=3044&lang=enhttp://in.ask.com/wiki/Chloralkali_process?qsrc=3044&lang=enhttp://in.ask.com/wiki/Food_industry?qsrc=3044&lang=enhttp://in.ask.com/wiki/Reverse_osmosis?qsrc=3044&lang=enhttp://in.ask.com/wiki/Recrystallization_(chemistry)?qsrc=3044&lang=enhttp://in.ask.com/wiki/Isomorphism_(crystallography)?qsrc=3044&lang=enhttp://in.ask.com/wiki/Azeotrope?qsrc=3044&lang=enhttp://in.ask.com/wiki/Pharmaceutical?qsrc=3044&lang=enhttp://in.ask.com/wiki/Biotechnology?qsrc=3044&lang=enhttp://in.ask.com/wiki/Food_technology?qsrc=3044&lang=enhttp://in.ask.com/wiki/Food_technology?qsrc=3044&lang=en -
7/27/2019 seminar report on membrance technology
28/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 28
CHAPTER-9
ADVANTAGES AND LIMITATIONS OF MEMBRANE PROCESSES
In many applications, e.g. water desalination and purification the membrane
processes compete directly with the more conventional water treatment techniques.
However, compared to these conventional procedures.
Membrane processes are often energy efficient. More simple to operate and yield a higher quality product. The same is true for the separation, concentration, and purification of drugs and food
products or in medical and pharmaceutical applications.
These membrane processes have in addition to high energy efficiency, simpleoperation, easy up and down scaling the advantage of operating at ambient
temperature avoiding any change or degradation of products.
In water desalination reverse osmosis or electrodialysis can be used. Depending on
local conditions, including water quality, energy cost and the required capacity of the
desalination plant, either electrodialysis or reverse osmosis can be the more efficient
process. For very large capacity units and in case a power plant can be coupled with the
desalination unit, distillationis generally considered to be more economical. For surface
water purification and waste-water treatment membrane processes, micro- and ultrafiltration
are competing with flocculation, sand bed filtration, carbon adsorption, ion-exchange and
biological treatment. In these applications the membrane processes are usually more costly
but generally provide a better product water quality. Very often a combination of
conventional water treatment procedureswith membrane processes results in reliable and
cost-effective treatment combined with high product water quality.
ADISADVANTAGE OF MEMBRANE PROCESSES
It is that in many applications, especially in the chemical and petrochemical industry,
their long-term reliability is not yet proven. Furthermore, membrane processes sometimes
-
7/27/2019 seminar report on membrance technology
29/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 29
require excessive pretreatment due to their sensitivity to concentration polarization and
membrane fouling due to chemical interaction with water constituents. Furthermore,
membranes are mechanically not very robust and can be destroyed by a malfunction in the
operating procedure. However, significant progress has been made in recent years,
especially in reverse osmosis seawater desalination, in developing membrane.
-
7/27/2019 seminar report on membrance technology
30/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 30
CHAPTER-10
COST CONSIDERATIONS AND ENVIRONMENTAL IMPACT
Membrane processes are considered as very energy efficient compared to
many other separation processes. However, the energy requirement of a process is only one
cost determining factor.
CURRENT MARKET AND FORECAST :-
The global demand on membrane modules was estimated at approximately 15.6
billion USD in 2012. Driven by new developments and innovations in material science and
process technologies, global increasing demands, new applications, and others, the market is
expected to grow around 8% annually in the next years. It is forecasted to increase to 21.22billion USD in 2016 and reach 25 billion in 2018.
-
7/27/2019 seminar report on membrance technology
31/32
MEMBRANE TECHNOLOGY
S.S.G.B.C.O.E.&T. BHUSAWAL Page 31
CONCLUSION
It begins with the definition of terms and provides a description of membrane structures and
membrane processes that are used today in mass separation, in (bio)chemical reactors, in
energy conversion and storage, and in the controlled release of drugs.The advantages as well
as the limitations of membrane processes are indicated. Major applications of membranes are
described and their technical and commercial relevance pointed out.A short overview over
the historical development of membrane science and technology is given and possible future
developments and research needs are indicated.
-
7/27/2019 seminar report on membrance technology
32/32
MEMBRANE TECHNOLOGY
REFERENCES
1 Aptel Ph., Neel J., Pervaporation, in Synthetic Membranes: Science, Engineering
and Applications, edts., Bungay, P.M., Lonsdale, H.K., de Pinho, M.N., pp. 403-436.
2. D. ReidelPubl. Company, Boston 1968.
Baker R. W., Membrane Technology and Applications, J. Wiley& Sons, Chichester, U.K.
2004.3.Bechhold H., Durchlssigkeit von Ultrafilter, Z. Phys. Chem. 64 (1908) 328.
4. Bhattacharyya D., Butterfield D. A., New Insights into Membrane Science and
5.Technology: Polymeric and Biofunctional Membranes, Elsevier, Amsterdam 2003.
Bray T. D., Reverse Osmosis Purification Apparatus, US-Patent 3 417 870 (1968).
6. Cadotte J. E., Petersen R.I., Thin Film Reverse Osmosis Membranes: Origin,
Development, and Recent Advances, in Synthetic Membranes, ACS Symposium
Series Vol. I, Desalination, edts. Turbak, A.F. pp. 305 -325, Washington, D.C.:American Chemical Society 1981.
7.Donnan F. G., Theorie der Membrangleichgewichte und Membranpotentiale bei
Vorhandensein von nicht dialysierenden Elektrolyten, Z. fr Elektrochemie und
angewandte physikalische Chemie 17 (1911) 572.
8. Drioli E., Giorno L., Biocatalytic Membrane Reactors: Application in Biotechnology and
the Pharmaceutical Industry, Taylor & Francis Publisher, London, UK 1999