presentation 1 28th may

8/8/2019 Presentation 1 28TH MAY

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INTRODUCTION TO MEMBRANE FILTRATION TECHNOLOGY

Prepared By:

Faraz Nazar

Environmental Engr. (National Environmental Consultants)

28th May, 2009


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What is MEMBRANE FILTRATION

Membrane filtration is a technique which is used to separate

particles from a liquid for the purpose of purifying it.

Microfiltration, Ultrafiltration, Nanofiltration, and Reverse

osmosis are all membrane filtration techniques.

The range of particle sizes is extended to include dissolved

constituents (typically 0.0001 to 1.0 micron range).


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http://www.porex.com/by_function/by_function_filtration.cfm

http://www.porex.com/by_function/by_function_filtration/part_size_def.cfm

Particle Size Definition

The unit of measure generally associated with filterable particles is microns. One

micron equals 1/25,400 of an inch (or one millionth of a meter).

Human hair for example has an average diameter of 90 microns.

Particles smaller than this often times require the use of a microscope.

However, even with a microscope, a particle less than 1 micron in diameter is difficult to

see.

Tobacco smoke, for example, typically ranges in size from 0.01 to 1.0 microns.

When the naked eye "sees" tobacco smoke, it is actually seeing the light that is beingreflected or scattered from millions of small particles.

The wavelength of such light is in the ultraviolet range, hence the blue haze normally

associated with a smoke-filled room.

As particles such as tobacco smoke become very small, they cease to behave as

particles. Instead, they begin to behave more like gas phase molecules.

Traditional methods of separation do not apply to particles below .01 microns and

removing them from air requires techniques reserved for gaseous materials.

Particles above 0.01 micron, however, are usually considered to be filterable.


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Mechanism Operation

Difference between Pore flow,Diffusion and Sieve


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Molecular diffusion often called simply diffusion is a net transport

of molecules from a region of higher concentration to one of lower

concentration by random molecular motion.

Example :

Diffusion of Cigarette smokeDiffusion of a Drop of an ink in water

Diffusion of water is classified as osmosis.

Diffusion


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Haynie, Donald T. (2001 (, Biological Thermodynamics ,Cambridge: Cambridge University Press,

pp. 130136 (pt 1, 2, 3)

Osmosis is the diffusion of water through a semi-permeable membrane ,

from a low concentrate solution (high water potential) to a highly

concentrated solution (low water potential).

The simplest definition is that it is diffusion of water across a

semipermeable membrane.

It is a physical process in which a solvent moves, without input of energy,

across a semi-permeable membrane (permeable to the solvent, but not the

solute) separating two solutions of different concentrations.

The semi permeable membrane is selectively permeable, so only

necessary materials are let into the cell and waste left out.

Maton, Anthea; Jean Hopkins, Susan Johnson, David LaHart, Maryanna Quon Warner, Jill

D. Wright (1997 (. Cells Building Blocks of Life .Upper Saddle River, New Jersey: Prentice

Hall. pp. 6667 . (pt. 4)

http://www.answers.com/topic/osmosis?method=8


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Natural Examples

Osmosis can also be seen when potato slices are added to a high

concentration of salt solution. The water from inside the potato moves tothe salt solution, causing the potato to shrink and to lose its 'turgor

pressure'. The more concentrated the salt solution, the bigger the

difference in size and weight of the potato slice.

Soaking effect in dry fruit when put in water.


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Keep the concentrations of various ions and other important substances constant.

Keep the volume of water in your body constant.

Remove wastes from your body (urea, ammonia, drugs, toxic substances).

Keep the acid/base concentration of your blood constant

Function of a Kidney


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Cells in the human body and in the bodies of all living things behave

like microscopic bags of solution housed in a semipermeable

membrane. The health and indeed the very survival of a person, animal,

or plant depends on the ability of the cells to maintain their

concentration of solutes.

Two illustrations involving salt water demonstrate how osmosis can

produce disastrous effects in living things .

Biological Example of osmosis process


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If you put a carrot in salty water, the salt water will "draw" the water

from inside the carrotwhich, like the human body and most other

forms of life, is mostly made up of water. Within a few hours, the

carrot will be limp ,its cells shriveled .

Worse still is the process that occurs when a person drinks salt

water. The body can handle a little bit, but if you were to

consume nothing but salt water for a period of a few days, as in

the case of desert island, the osmotic pressure would begin drawing

water from other parts of your body. Since a human body ranges from

60% water (in an adult male) to 85% in a baby, there would be a great

deal of water availablebut just as clearly, water is the essentialingredient in the human body. If you continued to ingest salt water, you

would eventually experience dehydration and die.



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How, then, do fish and other forms of marine life survive in a salt-

water environment? In most cases, a creature whose natural habitat is

the ocean has a much higher solute concentration in its cells than

does a land animal. Hence, for them, salt water is one that has the same

concentration of solute and hence the same osmotic pressure as in theirown cells.



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One vital process closely linked to osmosis is dialysis, which is critical tothe survival of many victims of kidney diseases. Dialysis is the process by

which an artificial kidney machine removes waste products from a

patients' bloodperforming the role of a healthy, normally functioning

kidney. The openings in the dialyzing membrane are such that not only

water, but salts and other waste dissolved in the blood, pass through to a

surrounding tank ofdistilled water.The red blood cells, on the other hand,are too large to enter the dialyzing membrane, so they return to the

patient's body.



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Osmosis in Plants

Plants depend on osmosis to move water from their roots to their

leaves. The further toward the edge or the top of the plant, the

greater the solute concentration, which creates a difference in

osmotic pressure. This is known as osmotic potential, which

draws water upward. In addition, osmosis protects leaves against

losing water through evaporation.

Francis, Frederick J., editor-in-chief .Encyclopedia of FoodScience and Technology .New York: Wiley, 2000.Gardner, Robert .Science Project Ideas About KitchenChemistry .Berkeley, N.J.: Enslow Publishers, 2002.

http://members.tripod.com/~urila


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Osmotic Pressure

Net movement of solvent is from the less-concentrated to the

more-concentrated solution, which tends to reduce the difference

in concentrations, untill equiblirium in solution is achieved.

The osmotic pressure is defined to be the pressure required to

maintain an equilibrium, with no net movement of solvent.


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FeedWater / Feed Stream

Input stream to the membrane

Permeate

The portion of the feed stream that passes through the membrane thatcontain lower TDS than the feed stream.

Concentrate/ Retentate/ Reject

The portion of the feed stream that does not pass through the membrane that

contains higher TDS than the feed stream


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Fouling

Deposition of existing solid material in the element on the feed stream of the

membrane.Fouling Causes resistance to flow of feed stream:

Three major mechanisms of resistance flow:

Pore narrowing

Pore plugging

Gel/cake formation


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Module

A complete unit comprised of the membranes, the feed inlet and outlet permeate

and retentate ports, and an overall support structure.


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Typical RO System in Collier County, FloridaTypical RO System in Collier County, Florida


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RO System in Yuma


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Ultrafiltration System


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Flux

Flux is a term which describes the rate of flow of liquid through a given

area of membrane surface.

Permeate flux is usually stated in gallons passed trough an area of

membrane surface during some unit of time.

Flux is monitored at start up.

While a membrane is in use in-order to determine its efficiency.

Flux is the best overall indicator of system efficiency within the

acceptable range of operating pressures.


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Membrane Material

Biological: Animal or Plant origin

Synthetic: Organic (polymeric) and Inorganic (ceramics)membranes

(Example of organic membrane: cellulose acetate, cellulose esters,

polypropylene polyamides, polysulfones, etc.); organic- cheaper.

Also Ceramic: Alumina, Titania, and Zirconia: high thermal/chemicalresistant


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Material ApplicationMicrofiltration Ultrafiltration Reverse

Osmosis

Cellulose Acetate X X X

Cellulose triacetate X X X

Cellulose nitrate XX

Polyacrylonitrila (PAN) XX

Polyvinyl chloride (PVC) X X X

Polyvinylchloride copolymer X X X

Polyamide X X X

Polysulfone (PS) X X

Polytetrafluoroethylene (PTFE) X

Polyvinylideneflouoride (VF) X X

MEMBRANE MATERIAL AND THEIR APPLICATION


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MembraneMembrane

ProcessProcess

MembraneMembrane

driving foredriving fore

TypicalTypical

separationseparation

mech

anismmech

anism

Pore sizePore size TypicalTypical

OperatingOperating

range, mrange, m

PermeatePermeate

descriptiondescription

TypicalTypical

constituentsconstituents

removedremovedMicrofiltrationMicrofiltration HydrostaticHydrostatic

pressurepressure

differencedifference

SieveSieve MacroporesMacropores

(>50nm)(>50nm)

0.080.08--2.02.0 Water +Water +

DissolvedDissolved

solutessolutes

TSS, turbidity,TSS, turbidity,

protozoanprotozoan

oocysts andoocysts and

cysts, somecysts, some

bacteria andbacteria and

virusesviruses

UltrafiltrationUltrafiltration HydrostaticHydrostatic

pressurepressuredifferencedifference

SieveSieve MacroporesMacropores

(2(2--50nm)50nm)

0.0050.005--0.20.2 Water + smallWater + small

moleculesmolecules

MacromoleculMacromolecul

es, colloids,es, colloids,most bacteria,most bacteria,

some viruses,some viruses,

proteinsproteins

NanofiltrationNanofiltration HydrostaticHydrostatic

pressurepressuredifferencedifference

DiffusionDiffusion MacroporesMacropores

(


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MEMBRANE MODULE

Tubular Module

Membrane is cast inside the support tube

Tubular membranes have a diameter of 5 - 15 mm

Mainly MF and UF

Low packing density, high prices per module


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FeedRetentate

Permeate (flows radially)

Tubular Module


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MEMBRANE MODULE

Hollow Fiber

The hollow fiber membrane module consists of a bundle of hundreds tothousand of fibers.

The feed can be applied to the inside of the fiber (inside out flow) or the

outside of the fiber (outside in flow).


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Hollow FiberHollow Fiber


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Hollow FiberHollow Fiber


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MEMBRANE MODULE

Spiral Wound

Rolled arrangement of the membrane

Flexible permeate spacer is provided between two flat sheet membranes

Membrane: sealed three side and open side is attached to perforated pipe

Flow is in a spiral pattern.

Filtrate is collected within the envelop and piped out

RO and NF


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SpiralWoundSpiralWound


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MICROFILTRATION

Micro : Denoting a factor of one millionth (10-6)

Comes from Greek word mikro [source oxford dictionary]

Sieving phenomena

Pore size = 0.08 m - 2 m

(P = 7 to 100 kPa

Most effectively remove particles and microorganisms (bacteria)

High flux


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ULTRAFILTRATION

Ultra means extreme (adjective) [source: oxford dictionary]

Sieving Phenomena

Pore size = 0.005 m - 0.2 m

(P = 70 to 700 KPa

Moderate pressure

Remove particles and microorganisms and Viruses


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NANOFILTRATION

Nano denoting a factor of 10-9

Dwarf in Greek (Oxford dictionary)

Diffusion phenomena

Pore size = 0.001 micron range.

(P = 500 to 1000 kPa.

NF is essentially a lower-pressure version of reverse osmosis.

NF performance characteristics between reverse osmosis and

ultrafiltration.

Water softening, removal of organic matter, desalting of organic

reaction products.


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REVERSE OSMOSIS

Diffusion Phenomena

Operating Pressure: 850 - 7000 kPa

RO has the separation range of 0.0001 to 0.001Qm

Color removal from textile effluents, production of high purity water

(boiler feed, electronics, medical, pharmaceutical).


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Thanks to ..Thanks to ..

The Seniors of EEDThe Seniors of EED

. For making me preparing presentation on this topic.. For making me preparing presentation on this topic.

The AudienceThe Audience. For being patient with me during presentation.. For being patient with me during presentation.

presentation 1 28th may

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