REVERSE OSMOSIS

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M

AHATMAAHATMA

G

ANDHIANDHI

M

ISSIONISSION

`

SS

College of Engineering &

College of Engineering & Technology

Technology

Kamothe, Navi Mumbai

SEMINAR

REPORT

ON

REVERSE OSMOSIS

Submitted By

Mr. Pandhare Baliram V.

Under the guidance of

Prof. Nishant Sawale

University of Mumbai

2011-2012

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MAHATMA GANDHI MISSION`S

COLLEGE OF ENGINEERING AND TECHNOLOGY

KAMOTHE NAVI MUMBAI KAMOTHE NAVI MUMBAI

Certificate

this is to certify that

mr.pandhare baliram v

has submitted the seminar report titledhas submitted the seminar report titled “

“

REVERSE

REVERSE OSMOSIS

OSMOSIS

””under the guidance of under the guidance of

prof. Nishant Sawale

for B.E(sem sem viii).for B.E(sem sem viii). this is the partial fulfillment of

this is the partial fulfillment of the requirements the requirements towards the award of degree of bachelortowards the award of degree of bachelor of engineering chemical of mumbai university.

of engineering chemical of mumbai university.

Prof.

Prof. NISHANT NISHANT SAWALE SAWALE Prof. Prof. C C K K MISTRYMISTRY Project Guide

Project Guide Department

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ACKNOWLEDGEMENT ACKNOWLEDGEMENT

When the compilation of the project comes to an end, the time comes to acknowledge all When the compilation of the project comes to an end, the time comes to acknowledge all persons who have made it a success. It gives me immense pleasure to express my persons who have made it a success. It gives me immense pleasure to express my gratitude to each individual associated directly or indirectly with the successful gratitude to each individual associated directly or indirectly with the successful completion of my seminar report. I would like to take this opportunity to especially thank completion of my seminar report. I would like to take this opportunity to especially thank my guide,

my guide, Prof. NISHANTSAWALEProf. NISHANTSAWALE of of Chemical Engineering Department, MGMChemical Engineering Department, MGM CET

CET for having trust in me and giving me such a challenging and demanding topic forfor having trust in me and giving me such a challenging and demanding topic for my seminar. I would also like to thank him for all the materials he has provided me which my seminar. I would also like to thank him for all the materials he has provided me which proved to be of great importance in understanding the topic and also providing me the lab proved to be of great importance in understanding the topic and also providing me the lab and internet facilities.

and internet facilities.

I would like to express my gratitude and appreciation to my friends and seniors for I would like to express my gratitude and appreciation to my friends and seniors for providing me with some valuable suggestions.

providing me with some valuable suggestions.

BALIRAM PANDHARE BALIRAM PANDHARE

BE CHEMICAL BE CHEMICAL

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ABSTRACT ABSTRACT

Earth is the only planet, which has water in abundant and in ready to use Earth is the only planet, which has water in abundant and in ready to use forms. So we have to consider only his water in our discussion. About 97% of water forms. So we have to consider only his water in our discussion. About 97% of water available on earth from the area under sea, remaining 3 % is found in continent and in available on earth from the area under sea, remaining 3 % is found in continent and in atmosphere. But more than 70% of this later portionis locked in glaciers and icecaps. atmosphere. But more than 70% of this later portionis locked in glaciers and icecaps.

The main reason for water shortage is uneven distribution of rain. Many The main reason for water shortage is uneven distribution of rain. Many other reasons are also there. Most of the water available is being polluted. So though other reasons are also there. Most of the water available is being polluted. So though there is water, we cannot use it as in the same form. For using the water we have to do there is water, we cannot use it as in the same form. For using the water we have to do some chemical and physical operation on this water. Bio-filtration is one of the some chemical and physical operation on this water. Bio-filtration is one of the operations for the purification of water. But we have large part of water by desalinizing operations for the purification of water. But we have large part of water by desalinizing the seawater. Seawater has salination value is 35000 ppm. But according to WHO for the seawater. Seawater has salination value is 35000 ppm. But according to WHO for human consumption salinity should be 500 ppm. In desalination process actual value is human consumption salinity should be 500 ppm. In desalination process actual value is brought to 500PPM.

brought to 500PPM.

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INDEX INDEX

S.NO.

S.NO. TOPIC TOPIC PAGE PAGE NO.NO.

1 INTRODUCTION



 WHAT IS OSMOSIS AND REVERSEWHAT IS OSMOSIS AND REVERSE OSMOSIS

OSMOSIS 

 PRINCIPLE OF REVERSE OSMOSISPRINCIPLE OF REVERSE OSMOSIS

6 6

2

2  OPERATION OPERATION 88

3

3 MEMBRANE MEMBRANE SELECTIONSELECTION 

 MEMBRANE MATERIALMEMBRANE MATERIAL 

 TYPES OF MAMBRANE MODULE.TYPES OF MAMBRANE MODULE.

9 9

4

4  MAMBRANE SCALINGMAMBRANE SCALING 

 MAMBRANE FOULING MAMBRANE FOULING 1818 5

5  APPLICATION OF RO SYSTEM.APPLICATION OF RO SYSTEM.

20 20

6

6 ADVANTAGES ADVANTAGES AND AND DISADVANTAGES DISADVANTAGES 2323

7

7 CONCLUSICONCLUSION ON 2525

8

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INTRODUCTION INTRODUCTION

Reverse osmosis is a physical process by which the dissolved Material in the Reverse osmosis is a physical process by which the dissolved Material in the solvent may be separated from that solvent with the assistance Of a semi-permeable solvent may be separated from that solvent with the assistance Of a semi-permeable membrane. By application of pressure in excess of the natural osmotic pressure to the membrane. By application of pressure in excess of the natural osmotic pressure to the feed water the membrane will preferentially allow the solvent (i.e. water) molecules to feed water the membrane will preferentially allow the solvent (i.e. water) molecules to pass through and high percent of electrolytes and dissolved organic materials will be pass through and high percent of electrolytes and dissolved organic materials will be rejected. The raw water is pressure fed into a chamber containing semipermeable rejected. The raw water is pressure fed into a chamber containing semipermeable membrane. Only the pure water (known as permeate) can pass through the membrane, membrane. Only the pure water (known as permeate) can pass through the membrane, while the impurities are rejected and ruin to waste (known as concentrate). Reverse while the impurities are rejected and ruin to waste (known as concentrate). Reverse osmosis is operated as a continuous process.

osmosis is operated as a continuous process.

WHAT IS OSMOSIS AND REVERSE

WHAT IS OSMOSIS AND REVERSE OSMOSISOSMOSIS

It is the phenomenon of water flow through a semi-permeable membrane that blocks the It is the phenomenon of water flow through a semi-permeable membrane that blocks the transport of salt or other solutes through it. Osmosis is a fundamental effect in transport of salt or other solutes through it. Osmosis is a fundamental effect in all-biological system. Osmosis is applied to water purification and desalination, waste biological system. Osmosis is applied to water purification and desalination, waste material treatment and many other chemical and biochemical laboratory and industrial material treatment and many other chemical and biochemical laboratory and industrial process.

process.

Reverse Osmosis: Reverse Osmosis:

When two water or other solvent volumes are separated by a semi permeable membrane, When two water or other solvent volumes are separated by a semi permeable membrane, water will flow from the side of low solute concentration to side of high solute water will flow from the side of low solute concentration to side of high solute concentration. The flow may be stopped or even reversed, by applying external pressure concentration. The flow may be stopped or even reversed, by applying external pressure on the side of higher concentration. In such a case the phenomenon is called reverse on the side of higher concentration. In such a case the phenomenon is called reverse osmosis. RO is a-physical process.

osmosis. RO is a-physical process.

If there are solute molecules only in one side of the system, then the pressures that stop If there are solute molecules only in one side of the system, then the pressures that stop the flow is called osmotic pressure. By the application of pressure in excess of the natural the flow is called osmotic pressure. By the application of pressure in excess of the natural osmotic pressure to the feed water the membrane will preferentially allow the solvent osmotic pressure to the feed water the membrane will preferentially allow the solvent

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molecules to pass through and high percent of electrolytes and dissolved organic molecules to pass through and high percent of electrolytes and dissolved organic materials will be rejected.

materials will be rejected.

The raw water is pressure fed into a chamber containing semi permeable membrane. Only The raw water is pressure fed into a chamber containing semi permeable membrane. Only the pure water can pass through the semi permeable membrane, while the impurities are the pure water can pass through the semi permeable membrane, while the impurities are rejected and run to waste. Reverse osmosis is operated as a continuous process.

rejected and run to waste. Reverse osmosis is operated as a continuous process.

PRINCIPLE OF REVERSE OSMOSIS PRINCIPLE OF REVERSE OSMOSIS

Reverse osmosis is a membrane process that act as a molecular filter to remove 99% of Reverse osmosis is a membrane process that act as a molecular filter to remove 99% of all dissolved minerals, upto97% of most dissolved organic matter, more than 98% of all dissolved minerals, upto97% of most dissolved organic matter, more than 98% of biological and colloidal matter can be removed from water having concentration from 50 biological and colloidal matter can be removed from water having concentration from 50 ppm to 60,000 ppm. Reverse osmosis is a misnomer, since application of pressure lo ppm to 60,000 ppm. Reverse osmosis is a misnomer, since application of pressure lo overcome osmotic pressure reverses only the flow of solvent but not the direction of flow overcome osmotic pressure reverses only the flow of solvent but not the direction of flow of solute.

of solute.

As shown fig. (a), which depicts a semi permeable membrane separating pure water and a As shown fig. (a), which depicts a semi permeable membrane separating pure water and a salt solution is pure water passes in opposite direction in process called natural osmosis. salt solution is pure water passes in opposite direction in process called natural osmosis. The driving force for the two flows is the difference in chemical potential between the The driving force for the two flows is the difference in chemical potential between the two solutions. The water now continues until the pressure aerated by osmotic head two solutions. The water now continues until the pressure aerated by osmotic head equals-the osmotic pressure of salt solution in fig. (b). The two liquids are in equilibrium, equals-the osmotic pressure of salt solution in fig. (b). The two liquids are in equilibrium, by applying an external pressure; a salt solution in fig. (c) the flow of solvent may be by applying an external pressure; a salt solution in fig. (c) the flow of solvent may be revised. The reversal of flow has given the process the name REVERSE

revised. The reversal of flow has given the process the name REVERSE OSMOSIS.

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OPERATION OPERATION

By squeezing ordinary tap water (using your house water pressure) against a By squeezing ordinary tap water (using your house water pressure) against a special membrane, pure water molecules are separated from impurities. What's special membrane, pure water molecules are separated from impurities. What's even more impressive is that these rejected impurites are automatically rinsed even more impressive is that these rejected impurites are automatically rinsed down the drain leaving bottled quality water for you that's pure and delicious. down the drain leaving bottled quality water for you that's pure and delicious. We have combined this fantastic Eagle Reverse Osmosis process with other We have combined this fantastic Eagle Reverse Osmosis process with other quality components to create a compact drinking water appliance that fits neatly quality components to create a compact drinking water appliance that fits neatly under your kitchen sink. It provides you with an abundant supply of true bottled under your kitchen sink. It provides you with an abundant supply of true bottled quality water without the bottles from its own attractive spigot. We can even quality water without the bottles from its own attractive spigot. We can even hook up your

hook up your icemaker and refrigerator water dispenser!icemaker and refrigerator water dispenser!

1.

1. Sediment filterSediment filter_{: sand, sediment, silt}_{: sand, sediment, silt} 2.

2. Pre-carbon filterPre-carbon filter_{: insecticides, pesticides, herbicides, chlorine}_{: insecticides, pesticides, herbicides, chlorine} 3.

3. Pre. 5-micron filterPre. 5-micron filter_{:dirt, rust, turbidity}_{:dirt, rust, turbidity} 4.

4. RO membraneRO membrane_{: inorganic minerals, nitrates, arsenic, barium,}_{: inorganic minerals, nitrates, arsenic, barium, copper}_copper 5.

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MEMBRANE MEMBRANE

Definition : Definition :

Membrane can be defined as essentially as a barrier; which separates two phases and Membrane can be defined as essentially as a barrier; which separates two phases and restricts transport of various chemicals in a selective manner. Membrane is a heart of restricts transport of various chemicals in a selective manner. Membrane is a heart of every membrane process. The membrane can be made of an inorganic or organic, every membrane process. The membrane can be made of an inorganic or organic, synthetic or biological product. Membrane of reverse osmosis system permeable for synthetic or biological product. Membrane of reverse osmosis system permeable for solvent and impermeable for solute.

solvent and impermeable for solute.

Material used for membranes in RO Material used for membranes in RO

Membranes are prepared from almost every available material. In large-scale production Membranes are prepared from almost every available material. In large-scale production commercial thermoplastic and cellulosics are primarily used.

commercial thermoplastic and cellulosics are primarily used. 1. Cellulose acetate. 1. Cellulose acetate. 2. Aromatic polyamide 2. Aromatic polyamide 3. Polyamide 3. Polyamide 4. Polyphyenylene oxides 4. Polyphyenylene oxides

MODULES TYPES FOR REVERSE

MODULES TYPES FOR REVERSE OSMOSIS SYSTEMOSMOSIS SYSTEM The several forms of Reverse Osmosis membranes are sold The several forms of Reverse Osmosis membranes are sold

packaged in devices to contain the steam pressure and to separate the feed and packaged in devices to contain the steam pressure and to separate the feed and reject stream from the permeate streams. The device; usually called a module, reject stream from the permeate streams. The device; usually called a module, is designed to control the feed stream-velocity and turbulence in order to reduce is designed to control the feed stream-velocity and turbulence in order to reduce concentration polarization.

concentration polarization. There are four

There are four types of modules related to types of modules related to the types of membranethe types of membrane a) Spiral wound

a) Spiral wound b) Tubular b) Tubular

c) Plate and frame c) Plate and frame

d)hollow module membrane d)hollow module membrane

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1)Spiral wound module 1)Spiral wound module

A variation of the basic plate-and-frame concept is the spiral-wound module, which is A variation of the basic plate-and-frame concept is the spiral-wound module, which is widely used today in reverse osmosis, ultrafiltration, and gas separation. Its basic design widely used today in reverse osmosis, ultrafiltration, and gas separation. Its basic design is illustrated in Figure 1.

is illustrated in Figure 1.

Fig.

Fig. 1 1 Schematic drawing Schematic drawing of of a a spiral-wound membrane spiral-wound membrane modulemodule

The feed flow

The feed flow channel spacer, the membrane, and channel spacer, the membrane, and the porous membrane the porous membrane support support form anform an envelope which is rolled around a perforated central collection tube and inserted into an envelope which is rolled around a perforated central collection tube and inserted into an outer tubular pressure shell. The feed solution passes in axial direction through the feed outer tubular pressure shell. The feed solution passes in axial direction through the feed channel across the membrane surface. The filtrate is moves along the permeate channel channel across the membrane surface. The filtrate is moves along the permeate channel and is collected in a perforated tube in the center of the roll. Small spiral wound units and is collected in a perforated tube in the center of the roll. Small spiral wound units consist of just one envelope which limits the total membrane area that can be installed in consist of just one envelope which limits the total membrane area that can be installed in one unit to about 1 to 2 m

one unit to about 1 to 2 m22. The main reason for the limitation of the surface area which. The main reason for the limitation of the surface area which can be installed in a module containing one single envelope is the pressure drop can be installed in a module containing one single envelope is the pressure drop encountered by the permeate moving down the permeate channel to the central collection encountered by the permeate moving down the permeate channel to the central collection tube. Because the channel in a practical unit is very narrow its length is limited to 2 to 5 tube. Because the channel in a practical unit is very narrow its length is limited to 2 to 5 m. A significantly longer path would resultr in an unacceptable pressure drop in the m. A significantly longer path would resultr in an unacceptable pressure drop in the permeate channel. To install larger membrane surfaces in a spiral wound module a permeate channel. To install larger membrane surfaces in a spiral wound module a multi-leaf arrangement in used as indicated in the Figure 1b.

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Fig. 1b Schematic drawing illustrating the construction of a multi-leaf spiralwound Fig. 1b Schematic drawing illustrating the construction of a multi-leaf spiralwound module

module

Commercial spiral wound modules are about 1 meter long and have a diameter of 10 to Commercial spiral wound modules are about 1 meter long and have a diameter of 10 to 60 cm. The membrane area in a spiral-wound element is 3 and 60 m

60 cm. The membrane area in a spiral-wound element is 3 and 60 m 22. Generally, 2 to 6. Generally, 2 to 6 elements are placed in series in a pressure vessel.

elements are placed in series in a pressure vessel.

The spiral-wound module provides a relatively large membrane area per unit volume. The spiral-wound module provides a relatively large membrane area per unit volume. The large scale production is quite cost effective and module costs per membrane area The large scale production is quite cost effective and module costs per membrane area quite low. The major application of the spiral-wound module is in reverse osmosis sea quite low. The major application of the spiral-wound module is in reverse osmosis sea

membrane membrane

ff eed eed solution solution spacerspacer

membrane membrane permeate spacer permeate spacer permeate outlet permeate outlet ff eeeed d ff llowow concentrate concentrate permeate flow permeate flow

porous centre tube porous centre tube

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2)

2)The plate-and-frame membrane moduleThe plate-and-frame membrane module

Another module type used on an industrial scale for various membrane separation Another module type used on an industrial scale for various membrane separation processes including ultrafiltration, reverse osmosis, and gas separation is the processes including ultrafiltration, reverse osmosis, and gas separation is the plate-and-frame module. Its design has its origin in the conventional filter press-concept. The frame module. Its design has its origin in the conventional filter press-concept. The membranes, porous membrane support plates, and spacers forming the feed flow channel membranes, porous membrane support plates, and spacers forming the feed flow channel are clamped together and stacked between two endplates and placed in a housing as are clamped together and stacked between two endplates and placed in a housing as indicated in the schematic diagram of Figures 2a and 2b.

indicated in the schematic diagram of Figures 2a and 2b.

Fig.

Fig. 2a 2a Schematic Schematic drawing drawing illustrating the illustrating the concept concept of of a a plate-and-frame membraneplate-and-frame membrane module

module

The feed

The feed solution solution is pressurized in is pressurized in the housing and the housing and forced across the forced across the surface of surface of thethe membrane. The permeate is leaving the module through the permeate channel to a membrane. The permeate is leaving the module through the permeate channel to a permeate collection manifold which in

permeate collection manifold which in circular devices is circular devices is central tube as central tube as indicated in theindicated in the Figure b. Often the device contains one or more baffels to extend the path-length of the Figure b. Often the device contains one or more baffels to extend the path-length of the feed solution in the device.

feed solution in the device.

permeate permeate

feed solution

feed solution retentateretentate

permeate permeate

feed channelspacer feed channelspacer permeate channel

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Fig. 2b

Fig. 2b Circular plate-and-frame filter device with one Circular plate-and-frame filter device with one baffel to extend baffel to extend the feed the feed flowflow path length

path length

There are various types of plate-and-frame modules on the market which offer, however, There are various types of plate-and-frame modules on the market which offer, however,

feed s

feed solol utionution

permeate permeate

retentate retentate

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membranes is labor intensive. Therefore, the plate-and-frame module is quite expensive. membranes is labor intensive. Therefore, the plate-and-frame module is quite expensive.

3 )The tubular membrane module 3 )The tubular membrane module

While the previously described some membrane module types required flat sheet While the previously described some membrane module types required flat sheet membrane material for their preparation, special membrane configurations are needed for membrane material for their preparation, special membrane configurations are needed for the preparation of the tubular, capillary, and hollow fiber modules.

the preparation of the tubular, capillary, and hollow fiber modules.

The tubular membrane module consists of membrane tubes placed into porous stainless The tubular membrane module consists of membrane tubes placed into porous stainless steel of fiber glass

steel of fiber glass reinforced plastic pipes. The pressurized reinforced plastic pipes. The pressurized feed solution flows down thefeed solution flows down the tube bore and the permeate is collected on the outer side of the porous support pipe, as tube bore and the permeate is collected on the outer side of the porous support pipe, as indicated in Figure 3. The diameters of tubular membranes are typically between 1-2.5 indicated in Figure 3. The diameters of tubular membranes are typically between 1-2.5 cm. In some modules, the membranes are cast directly on the porous pipes and in others cm. In some modules, the membranes are cast directly on the porous pipes and in others they are prepared separately as tubes and then installed into the support pipes. Today, they are prepared separately as tubes and then installed into the support pipes. Today, tubular modules are used in ultrafiltration at low hydrostatic pressures. This allows the tubular modules are used in ultrafiltration at low hydrostatic pressures. This allows the membrane tubes to be made by a welding or glueing procedure of flat sheet membranes membrane tubes to be made by a welding or glueing procedure of flat sheet membranes that are cast on a relatively thick and mechanacilly strong porous polyester support that are cast on a relatively thick and mechanacilly strong porous polyester support material. These tubes which have a diameter of 0.5 to 1 cm do not need additional material. These tubes which have a diameter of 0.5 to 1 cm do not need additional support when operated at hydrostatic pressures of less than 2 to 4 bars.

support when operated at hydrostatic pressures of less than 2 to 4 bars.

Usually, 10 to 30 individual tubes are installed in a larger tube and potted at the end of Usually, 10 to 30 individual tubes are installed in a larger tube and potted at the end of the tube.

the tube. The feed The feed solution is fed solution is fed in in parallel through the tubular parallel through the tubular bundel while thebundel while the permeate of the individual tubes is collected in the outer shell tube as indicated in the permeate of the individual tubes is collected in the outer shell tube as indicated in the schematic drawing of Figure 4b. The main advantage of the tubular module is that schematic drawing of Figure 4b. The main advantage of the tubular module is that concentration polarization effects and membrane fouling can be easily controlled, and concentration polarization effects and membrane fouling can be easily controlled, and plugging of the membrane module is avoided even with feed solutions that have very plugging of the membrane module is avoided even with feed solutions that have very high concentration of solid matter and thus high viscosity. The disadvantage of the high concentration of solid matter and thus high viscosity. The disadvantage of the tubular module design is the low surface area, that can be installed in a given unit tubular module design is the low surface area, that can be installed in a given unit volume, and the very high costs. Therefore, tubular membrane modules are generally volume, and the very high costs. Therefore, tubular membrane modules are generally only applied in applications where feed solutions with high solid content, and high only applied in applications where feed solutions with high solid content, and high viscosity have to be treated and other module concepts fail due to membrane fouling and viscosity have to be treated and other module concepts fail due to membrane fouling and module plugging. This is the case in certain applications in the food and pharma industry module plugging. This is the case in certain applications in the food and pharma industry and in the treatment of certain industrial effluents.

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Fig. 3a Schematic drawing illustrating the tubular membrane module Fig. 3a Schematic drawing illustrating the tubular membrane module

permeate permeate ff eeeedd concentrate concentrate porous tube porous tube membrane membrane permeate permeate ff eed eed solutionsolution

retentate retentate

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.. 4

4 The hollow fiber membrane moduleThe hollow fiber membrane module

The same basic spinning process is used for the preparation of hollow fiber membranes, The same basic spinning process is used for the preparation of hollow fiber membranes, which have an outer diamter of 50 to 100 µm. In hollow fiber membranes, the selective which have an outer diamter of 50 to 100 µm. In hollow fiber membranes, the selective layer is on the outside of the fibers, which are installed as a bundle of several thousand layer is on the outside of the fibers, which are installed as a bundle of several thousand fibers in a half loop with the free ends potted with an epoxy resin in a pressure tube as fibers in a half loop with the free ends potted with an epoxy resin in a pressure tube as indicated in Figure 4. The filtrate passes through the fiber walls and flows up the bore to indicated in Figure 4. The filtrate passes through the fiber walls and flows up the bore to the open end of the fibers at the epoxy head.

the open end of the fibers at the epoxy head.

Fig. 4

Fig. 4 Schematic drawing illustrating the construction of Schematic drawing illustrating the construction of a hollow fiber a hollow fiber modulemodule

The hollow fiber membrane module has the highest packing density of all module types The hollow fiber membrane module has the highest packing density of all module types available on the market today. Its production is very cost effective and hollow fiber available on the market today. Its production is very cost effective and hollow fiber membrane modules can be operated at pressures in excess of 100 bars. The main membrane modules can be operated at pressures in excess of 100 bars. The main disadvantage of the hollow fiber membrane module is the difficult control of disadvantage of the hollow fiber membrane module is the difficult control of concentration polarization and membrane fouling. When operated with liquid solutions concentration polarization and membrane fouling. When operated with liquid solutions the modules do not tolerate any particals, macromolecules or other materials that may the modules do not tolerate any particals, macromolecules or other materials that may

epoxy resin epoxy resin hollow

hollow fifiberber permeate permeate feed solution feed solution concentrate concentrate shell tube shell tube

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easily precipitated at the membrane surface. Therefore, an extensive pretreatment is easily precipitated at the membrane surface. Therefore, an extensive pretreatment is required when hollow fiber membranes are used for the treatment of liquid mixtures. The required when hollow fiber membranes are used for the treatment of liquid mixtures. The main application of the hollow fiber module is today in reverse osmosis desalination of main application of the hollow fiber module is today in reverse osmosis desalination of sea water and in gas separation. Both application require high operating pressures and sea water and in gas separation. Both application require high operating pressures and low cost membranes which have a long useful life. In reverse osmosis, of sea water an low cost membranes which have a long useful life. In reverse osmosis, of sea water an extensive pretreatment of the sea water is required.

extensive pretreatment of the sea water is required.

Tab. I Commercially available membrane modules, there costs and major applications Tab. I Commercially available membrane modules, there costs and major applications Membrane Membrane Module Module Membrane area Membrane area per unit volume per unit volume (m (m22mm-3-3)) Membrane Membrane costs costs Control of Control of concentration concentration polarization polarization Application Application Spiral-wound Spiral-wound Module Module 800

800

_–

1200 1200 Low Low good good UF, UF, RO, RO, GSGS Plate-and-frame

Plate-and-frame Module

Module

400

_–

800 800 Medium Medium good good MF, MF, UF, UF, RO,RO, D,

D, ED ED Tubular

Tubular module module 2020

_–

100 100 very high very high very very good good MF, MF, UF, UF, RORO Hollow fiber

Hollow fiber Module Module

2000

_–

5000 5000 very very low low very very poor poor RO, RO, GSGS

MF = microfiltration MF = microfiltration UF = ultrafiltration UF = ultrafiltration RO = reverse osmosis RO = reverse osmosis ED = electrodialysiS ED = electrodialysiS GS = gas separation GS = gas separation

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FOULING FOULING Membrane fouling is

Membrane fouling is one of one of the most the most serious problems in serious problems in case of case of Reverse Reverse OsmosisOsmosis system. This affects directly on the performance of the reverse osmosis system. It may system. This affects directly on the performance of the reverse osmosis system. It may cause permanent damage to membrane. The main reasons of fouling are:

cause permanent damage to membrane. The main reasons of fouling are: 1. Membrane scaling 1. Membrane scaling 2. Metal oxide ppt. 2. Metal oxide ppt. 3. Device plugging 3. Device plugging

4. Biological growth inside device. 4. Biological growth inside device. 5. Colloidal fouling.

5. Colloidal fouling. Membranes scaling : Membranes scaling :

Membrane scaling is caused by ppt of the salts dissolved in feed water. The salts in feed Membrane scaling is caused by ppt of the salts dissolved in feed water. The salts in feed water are usually concentrated by a factor of two to ten in RO process, their solubility water are usually concentrated by a factor of two to ten in RO process, their solubility limits can be exceeded thus ppt can occur. The most common scales encountered in water limits can be exceeded thus ppt can occur. The most common scales encountered in water treatment application are calcium carbonate and calcium sulfate. But ether compounds treatment application are calcium carbonate and calcium sulfate. But ether compounds such as silicate, strontium sulfate, beryllium sill late and calcium fluoride also can such as silicate, strontium sulfate, beryllium sill late and calcium fluoride also can scaling.

scaling.

Metal Oxide Precipitation :

Metal Oxide Precipitation : Soluble species in feed water can be oxidized in the reverseSoluble species in feed water can be oxidized in the reverse osmosis system ahead of the permiator or in the permiator itself, to form insoluble osmosis system ahead of the permiator or in the permiator itself, to form insoluble species, which can deposit into permiator. Both manganese and iron can cause fouling by species, which can deposit into permiator. Both manganese and iron can cause fouling by this mechanism, but iron fouling is most prevalent.

this mechanism, but iron fouling is most prevalent. Device plugging :

Device plugging :

Plugging is caused by mechanical filtration in which particles too large to pass through Plugging is caused by mechanical filtration in which particles too large to pass through the feed brine passage are trapped in device. Device plugging problem.

the feed brine passage are trapped in device. Device plugging problem. Biological fouling :

Biological fouling :

Biological fouling occurs mainly due to growth of micro-organism in RO device. Biological fouling occurs mainly due to growth of micro-organism in RO device. Micro-organisms may itself grow in membrane and when feed water is filtered these bacteria's organisms may itself grow in membrane and when feed water is filtered these bacteria's may enter in product water.

may enter in product water. Colloidal fouling :

Colloidal fouling :

Colloidal fouling is caused by entrapment of colloids on membrane surface in RO. Colloidal fouling is caused by entrapment of colloids on membrane surface in RO. Colloidal fouling is also caused by coagulation of colloids during RO process.

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NEW DEVELOPMENT NEW DEVELOPMENT

Prefiltration of high fouling waters with another, larger-pore membrane with less Prefiltration of high fouling waters with another, larger-pore membrane with less hydraulic energy requirement, has been evaluated and sometimes used, since the 1970s. hydraulic energy requirement, has been evaluated and sometimes used, since the 1970s. However, this means the water passes through two membranes and is often repressurized, However, this means the water passes through two membranes and is often repressurized, requiring more energy input in the system, increasing the cost. Other recent development requiring more energy input in the system, increasing the cost. Other recent development work has focused on integrating RO with

work has focused on integrating RO with electrodialysiselectrodialysis to improve recovery of valuableto improve recovery of valuable deionized products or minimizing concentrate volume requiring discharge or disposal deionized products or minimizing concentrate volume requiring discharge or disposal

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APPLICATION OF REVERSE OSMOSIS APPLICATION OF REVERSE OSMOSIS

TECHNIQUE TECHNIQUE

Reverse osmosis system or technique has a many application over other conventional Reverse osmosis system or technique has a many application over other conventional techniques; so in industry it is most widely used technique. Some of them are as follows. techniques; so in industry it is most widely used technique. Some of them are as follows. a. The most wide use of RO is in the desalination of sea water.

a. The most wide use of RO is in the desalination of sea water.

b. RO is also used in sewage water treatment plants for the removal of nitrates phosphates b. RO is also used in sewage water treatment plants for the removal of nitrates phosphates or the non-biodegradable surfractants.

or the non-biodegradable surfractants.

c. RO is used in the treatment of hard water. c. RO is used in the treatment of hard water.

d. Paper and pulp industry also use this technique for the treatment of waste water. d. Paper and pulp industry also use this technique for the treatment of waste water. e. Electroplating and electro painting industries also needs RO.

e. Electroplating and electro painting industries also needs RO.

f. RO is used in the removal of common water pollutants like nitrates, borate, fluorides, f. RO is used in the removal of common water pollutants like nitrates, borate, fluorides, phosphates, alkyl benzene sulphonate.

phosphates, alkyl benzene sulphonate.

g. RO is used in pharmaceutical and electronic industries. g. RO is used in pharmaceutical and electronic industries. Water and wastewater purification

Water and wastewater purification

Rain water collected from storm drains is purified with reverse osmosis water processors Rain water collected from storm drains is purified with reverse osmosis water processors and used for landscape irrigation and industrial cooling in Los Angeles and other cities, and used for landscape irrigation and industrial cooling in Los Angeles and other cities, as a solution to the problem of water shortages. In industry, reverse osmosis removes as a solution to the problem of water shortages. In industry, reverse osmosis removes minerals from boiler water at

minerals from boiler water at power plantspower plants. The water is boiled and condensed. The water is boiled and condensed repeatedly. It must be as pure as possible so that it does not leave deposits on the repeatedly. It must be as pure as possible so that it does not leave deposits on the machinery or cause corrosion. The deposits inside or outside the boiler tubes may result machinery or cause corrosion. The deposits inside or outside the boiler tubes may result in under-performance of the boiler, bringing down its efficiency and resulting in poor in under-performance of the boiler, bringing down its efficiency and resulting in poor steam production, hence poor power production at turbine. It is also used to clean effluent steam production, hence poor power production at turbine. It is also used to clean effluent and brackish groundwater. The effluent in larger volumes (more than 500 cu. meter per and brackish groundwater. The effluent in larger volumes (more than 500 cu. meter per day) should be treated in an effluent treatment plant first, and then the clear effluent is day) should be treated in an effluent treatment plant first, and then the clear effluent is subjected to reverse osmosis system. Treatment cost is reduced significantly and subjected to reverse osmosis system. Treatment cost is reduced significantly and membrane life of the RO system is increased. The process of reverse osmosis can be used membrane life of the RO system is increased. The process of reverse osmosis can be used for the production of

for the production of deionized waterdeionized water . RO process for water purification does not require. RO process for water purification does not require thermal energy. Flow through RO system can be regulated by high pressure pump. The thermal energy. Flow through RO system can be regulated by high pressure pump. The recovery of purified water depends upon various factors including membrane sizes, recovery of purified water depends upon various factors including membrane sizes, membrane pore size, temperature, operating pressure and membrane surface area. In membrane pore size, temperature, operating pressure and membrane surface area. In 2002,

2002, SingaporeSingapore announced that a process namedannounced that a process named NEWaterNEWaterwould be a significant part of would be a significant part of its future water plans. It involves using reverse osmosis to treat domestic wastewater its future water plans. It involves using reverse osmosis to treat domestic wastewater before discharging the NEWater back into the reservoirs.

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Food industry Food industry

In addition to desalination, reverse osmosis is a more economical operation for In addition to desalination, reverse osmosis is a more economical operation for concentrating food liquids (such as fruit juices) than conventional heat-treatment concentrating food liquids (such as fruit juices) than conventional heat-treatment processes. Research has been done on concentration of orange juice and tomato juice. Its processes. Research has been done on concentration of orange juice and tomato juice. Its advantages include a lower operating cost and the ability to avoid heat-treatment advantages include a lower operating cost and the ability to avoid heat-treatment processes, which makes it suitable for heat-sensitive substances like the

processes, which makes it suitable for heat-sensitive substances like the proteinprotein andand enzymes

enzymes found in most food products. Reverse osmosis is extensively used in the dairyfound in most food products. Reverse osmosis is extensively used in the dairy industry for the production of whey protein powders and for the concentration of milk to industry for the production of whey protein powders and for the concentration of milk to reduce shipping costs. In whey applications, the whey (liquid remaining after cheese reduce shipping costs. In whey applications, the whey (liquid remaining after cheese manufacture) is concentrated with RO from 6% total solids to 10

manufacture) is concentrated with RO from 6% total solids to 10

_–

20% total solids before20% total solids before UF (ultrafiltration) processing. The UF retentate can then be used to make various whey UF (ultrafiltration) processing. The UF retentate can then be used to make various whey powders, including

powders, including whey protein isolatewhey protein isolate used in bodybuilding formulations. Additionally,used in bodybuilding formulations. Additionally, the UF permeate, which contains lactose, is concentrated by RO from 5% total solids to the UF permeate, which contains lactose, is concentrated by RO from 5% total solids to 18

18

–

22% total solids to reduce crystallization and drying costs of the lactose powder.22% total solids to reduce crystallization and drying costs of the lactose powder.

Car washing Car washing

Because of its lower mineral content, reverse osmosis water is often used in car washes Because of its lower mineral content, reverse osmosis water is often used in car washes during the final vehicle rinse to prevent water spotting on the vehicle. Reverse osmosis is during the final vehicle rinse to prevent water spotting on the vehicle. Reverse osmosis is often used to conserve and recycle water within the wash/pre-rinse cycles, especially in often used to conserve and recycle water within the wash/pre-rinse cycles, especially in drought stricken areas where water conservation is important. Reverse osmosis water also drought stricken areas where water conservation is important. Reverse osmosis water also enables the car wash operators to reduce the demands on the vehicle drying equipment, enables the car wash operators to reduce the demands on the vehicle drying equipment, such as air blowers.

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Future Advancements Future Advancements

Improvements will be necessary as RO is used to treat the ever greater expanding Improvements will be necessary as RO is used to treat the ever greater expanding candidate feed waters, including municipal and industrial wastewater effluents, and other candidate feed waters, including municipal and industrial wastewater effluents, and other source waters that are less than optimal for conventional RO membranes (e.g., source waters that are less than optimal for conventional RO membranes (e.g., wastewaters containing high concentrations of biological chemical demand (BOD), wastewaters containing high concentrations of biological chemical demand (BOD), chemical oxygen demand (COD), TOC, silica, and suspended solids, such as chemical oxygen demand (COD), TOC, silica, and suspended solids, such as food-processing condensates and cooling tower blowdown). Membranes will need to be processing condensates and cooling tower blowdown). Membranes will need to be developed that are tolerant of chlorine for microbial growth control, and resist to fouling developed that are tolerant of chlorine for microbial growth control, and resist to fouling with suspended solids and organics. Other membrane technologies, such as with suspended solids and organics. Other membrane technologies, such as microfiltration and ultrafiltration, are finding fresh application in pre-treating RO

microfiltration and ultrafiltration, are finding fresh application in pre-treating RO

systems operating on these challenging water sources. There is also continuing research systems operating on these challenging water sources. There is also continuing research into higher-performance (high flux and high rejection) membranes to further reduce the into higher-performance (high flux and high rejection) membranes to further reduce the size and cost of RO systems. Nanotechnology shows promise for having a role in the size and cost of RO systems. Nanotechnology shows promise for having a role in the development of these high-performance membranes. Improvements will be required in development of these high-performance membranes. Improvements will be required in the chemistries used to treat RO. These chemistries include antiscalants, which will be the chemistries used to treat RO. These chemistries include antiscalants, which will be needed to address higher concentrations of scale formers such as silica, and membrane needed to address higher concentrations of scale formers such as silica, and membrane cleaners, which will have to address microbes, biofilms, and organics.

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ADVANTAGES AND DISADVANTAGES ADVANTAGES AND DISADVANTAGES Advantages of reverse osmosis

Advantages of reverse osmosis

1. Thermal damage of product is eliminated 1. Thermal damage of product is eliminated

2. Retention of original aroma and taste is retained 2. Retention of original aroma and taste is retained 3. Reduction is energy consumption

3. Reduction is energy consumption 4. Easy in operation 4. Easy in operation 5. Compact size 5. Compact size 6. Low maintenance. 6. Low maintenance. Disadvantages ; Disadvantages ; 1 High Cost 1 High Cost

2 Less membrane life 2 Less membrane life

Factors Influencing Reverse Osmosis Performance Factors Influencing Reverse Osmosis Performance

Permeate Flux and Salt Rejection are the key performance parameters of a Permeate Flux and Salt Rejection are the key performance parameters of a reverseosmosis process. They are mainly influenced by variable parameters which are as reverseosmosis process. They are mainly influenced by variable parameters which are as follows: follows: 1)Pressure 1)Pressure 2)Temperature 2)Temperature 3)Recovery 3)Recovery

4)Feed water salt concentration 4)Feed water salt concentration ..

Pressure Pressure

With increasing effective feed pressure, the permeate TDS will decrease while the With increasing effective feed pressure, the permeate TDS will decrease while the permeate flux will increase.

permeate flux will increase. Temperature

Temperature

If the temperature increases and all other parameters are kept constant, the permeate flux If the temperature increases and all other parameters are kept constant, the permeate flux and the salt passage will increase.

and the salt passage will increase. Recovery

Recovery

The recovery is the ratio of permeate flow to feed flow. In the case of increasing The recovery is the ratio of permeate flow to feed flow. In the case of increasing

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RO product water cost calculations: RO product water cost calculations:

The most critical parameters in cost evaluation are the fixed charges and the energy cost The most critical parameters in cost evaluation are the fixed charges and the energy cost for the production of desalinated water. Other parameters that may have lower effect on for the production of desalinated water. Other parameters that may have lower effect on the unit product cost include the cost of chemicals and labor.

the unit product cost include the cost of chemicals and labor.

The following method of calculation may be used for knowing the cost of water The following method of calculation may be used for knowing the cost of water desalinated by Reverse Osmosis technology. The calculations proceed as follows: desalinated by Reverse Osmosis technology. The calculations proceed as follows: - Calculate the amortization factor

- Calculate the amortization factor a = i(1+i)n(up)

a = i(1+i)n(up) (1+i)n -1

(1+i)n -1

- Calculate the annual fixed charges - Calculate the annual fixed charges A1 = (a) (DC)

A1 = (a) (DC)

- Calculate the annual electric power cost - Calculate the annual electric power cost A2 = (c) (w) (f) (m) (365)

A2 = (c) (w) (f) (m) (365)

- Calculate the annual chemical cost - Calculate the annual chemical cost A3 = (k) (f) (m) (365)

A3 = (k) (f) (m) (365)

- Calculate the annual membrane replacement cost - Calculate the annual membrane replacement cost A4 = 10% of membrane purchase cost

A4 = 10% of membrane purchase cost - Calculate total annual labor cost - Calculate total annual labor cost A5 = (l) (f) (m)

A5 = (l) (f) (m)

- Calculate total annual cost - Calculate total annual cost At = A1 + A2 + A3 + A4 + At = A1 + A2 + A3 + A4 + A5A5 - Calculate unit product cost (m3) - Calculate unit product cost (m3) As = At/ ((f) (m) (365))

As = At/ ((f) (m) (365))

- Calculate unit product cost (m3/d) - Calculate unit product cost (m3/d) As = At / ((f) (m) (365)

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CONCLUSION CONCLUSION

Today's day water is basic need and the availability of pure water is little quantity Today's day water is basic need and the availability of pure water is little quantity on earth. So desalination is necessary for today's world and selecting Reverse Osmosis on earth. So desalination is necessary for today's world and selecting Reverse Osmosis process we can solved water problem to some extend to use of membrane technology. process we can solved water problem to some extend to use of membrane technology. 1. Reverse osmosis is most efficient and convenient hyper filtration process

1. Reverse osmosis is most efficient and convenient hyper filtration process of water purification.

of water purification.

2. Reverse osmosis process gives more promising result. 2. Reverse osmosis process gives more promising result.

3. Reverse osmosis is simple and effective method than any other 3. Reverse osmosis is simple and effective method than any other purification method.

purification method.

4. Organic matter removal and particle colloidal reduction are effectively 4. Organic matter removal and particle colloidal reduction are effectively controlled by RO.

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REFERENCES &INTERNET SITES REFERENCES &INTERNET SITES

1)

1) Technical Management of RO System, S.El-Manharawy, A.Hafez/329-344Technical Management of RO System, S.El-Manharawy, A.Hafez/329-344 2)

2) Desalination Plant Seawater Reverse Osmosis (SWRO) Plant.Desalination Plant Seawater Reverse Osmosis (SWRO) Plant. Water- Water-technology.net

technology.net 3)

3) www.scribd.comwww.scribd.com 4)

4) Reverse osmosis industrial application and processes by Jane kuceraReverse osmosis industrial application and processes by Jane kucera 5)