Presantation on Reverse Osmosis

WATER

WATER

The earth is so blessed with water resources that it is

The earth is so blessed with water resources that it is called thecalled the

`WATER PLANET’. But a mere 2.5% of the earth`s water is fresh

`WATER PLANET’. But a mere 2.5% of the earth`s water is fresh

Water usable by human beings; the remaining 97.5% is Sea water.

Water usable by human beings; the remaining 97.5% is Sea water.

 Now a days due to increase in population & industries, demand of 

 Now a days due to increase in population & industries, demand of 

Water has been increased rapidly.

Water has been increased rapidly.

Pollution is also increases. Due to lack of water resource, Human

Pollution is also increases. Due to lack of water resource, Human

Beings find new technology, called ` Reverse Osmosis’

Reverse

Reverse

Osmosis

Technical

Technical

Presentation

Presentation

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q

Reverse Osmosis Terminology

Reverse Osmosis Terminology

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Principles of Reverse Osmosis

Principles of Reverse Osmosis

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Types of R O Membranes

Types of R O Membranes

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Typical Applications

Typical Applications

of

of

Reverse Osmosis

Reverse Osmosis

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q

Industrial process water

Industrial process water

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Production of potable

Production of potable

water

water

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Food processing

Food processing

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Principles of

Principles of

Reverse

Reverse

Osmosis

Osmosis

Osmosi

Osmosi

s

s

The spontaneous flow of water from a dilute

The spontaneous flow of water from a dilute

solution to a concentrated solution, when the two

solution to a concentrated solution, when the two

solutions are separated by a semipermeable

solutions are separated by a semipermeable

membrane.

membrane.

Dilute Dilute Solution Solution semi-permeable semi-permeable membrane membrane Concentrated Concentrated Solution Solution

Osmotic

Osmotic

Pressure

Pressure

The pressure that must be applied to

The pressure that must be applied to

a concentrated solution to prevent

a concentrated solution to prevent

osmosis.

osmosis.

P = P = P P Dilute Dilute Solution Solution Concentrated Concentrated Solution Solution

Reverse

Reverse

Osmosis

Osmosis

P P >>

Reversing osmotic flow by

Reversing osmotic flow by

applying a pressure in excess of the

applying a pressure in excess of the

osmotic pressure

osmotic pressure

Dilute Dilute Solution Solution Concentrated Concentrated Solution Solution

Three Cases of

Three Cases of

Osmosis

Osmosis

osmosis

osmosis

e

eq

qu

ui

il

li

ib

br

ri

iu

um

m

re

r

ev

ve

er

rs

se

e

o

os

sm

mo

os

si

is

s

π

π

22

P

P

π

π

1 1

π

π

22

P =

P =

∆∆

π

π

_{P >}

_{P >}

∆∆

π

π

π

π

1 1 <<

π

π

22

Factors Influencing Permeation Rates

Factors Influencing Permeation Rates

of Dissolved Materials

of Dissolved Materials

Greatest Influence:

Greatest Influence:

Electrical Charge

Electrical Charge

Moderate Influence:

Moderate Influence:

Molecular Weight

Molecular Weight

Slight Influence:

FEED WATER LIMITING

FEED WATER LIMITING

CONDITIONS

CONDITIONS





_{Oxidizing Agents like chlorine - Nil}

_{Oxidizing Agents like chlorine - Nil}





_{COD & BOD with in limit.}

_{COD & BOD with in limit.}





_{OIL & GREACE NIL}

_{OIL & GREACE NIL}





_{SDI LESS THAN 5.}

_{SDI LESS THAN 5.}





_{pH range 3 to 11}

_{pH range 3 to 11}



Permeation Rates of Other

Permeation Rates of Other

Dissolved Species

Dissolved Species

•

•

Dissolved Gases pass freely through the

Dissolved Gases pass freely through the

membrane.

membrane.

•

•

Many

Many Dissolved

Dissolved Organics

Organics are

are weak

weak acids.

acids.

Their 

Their 

rate of permeation will depend not only on their 

rate of permeation will depend not only on their 

molecular weight and structure but on their degree

molecular weight and structure but on their degree

of ionization.

of ionization.

HX

-Permeation Rates

Permeation Rates

of

of

Weak Acids

Weak Acids

Weak acids are those acids that do

Weak acids are those acids that do

not become

not become

completely

completely ionized

ionized in

in water.

water.

Included

Included

in

in this

this

group of acids are chromic, boric and many

group of acids are chromic, boric and many

organic acids.

organic acids.

H

H

₂₂

CrO

CrO

₄₄

H

H

++

_{+ HCrO}

_{+ HCrO}

4 4

-HCrO

HCrO

₄₄-

-H

H

++

_{+ CrO}

_{+ CrO}

4 4

-H

H

₃₃

BO

BO

₃₃

H

H

++

₊

₊

_H

_H

2 2

BO

BO

33

-Reverse

Reverse

Osmosis

Osmosis

Terminology

Terminology

PRODUCT

PRODUCT _FEEDFEED

REJECT

REJECT

RECOVERY = PRODUCT FLOW / FEED FLOW RECOVERY = PRODUCT FLOW / FEED FLOW SALT PASSAGE = PRODUCT TDS / FEED TDS SALT PASSAGE = PRODUCT TDS / FEED TDS SALT REJE

Reverse

Reverse

Osmosis

Osmosis

Terminology

Terminology

PRODUCT PRODUCT FEED FEED PRESSURE PRESSURE REJECT PRESSURE REJECT PRESSURE

P = FEED PRESSURE – REJCT PRESSURE P = FEED PRESSURE – REJCT PRESSURE

REVERSE OSMOSIS

REVERSE OSMOSIS

System has divided into three parts.

System has divided into three parts.

•

•

_{PRE-TREATMENT}

_{PRE-TREATMENT}

•

•

_{R.O. SYSTEM}

_{R.O. SYSTEM}

•

Reverse osmosis system

Reverse osmosis system

Pretreatment Pretreatment RO hydra RO hydra block block Cleaning Cleaning system system Clarification Clarification Coagulation Coagulation Filteration Filteration De-chlorination De-chlorination Dosing system Dosing system Cartridge filter Cartridge filter Membrances Membrances Pressure tubes Pressure tubes HP pumps HP pumps Control pannel Control pannel Cleaning tank Cleaning tank Pump (SS) Pump (SS) Cartridge filter Cartridge filter DM plant DM plant pH adjustment pH adjustment Degassification Degassification Post Post treanment treanment

Coagulation, Coagulation, sedimentation, sedimentation, Chlorination Chlorination Sand Sand filter filter Activated Activated carbon filter carbon filter Dechlori Dechlori nation.

nation. AntiAnti_scalescale

High pressure High pressure pump pump DESALATION DESALATION SECTION SECTION Membrane modules Membrane modules Product Product water water  Waste  Waste brine brine Cartridge Cartridge filter filter

Schematic diagram of RO unit for waste water

Block Diagram of RO

Block Diagram of RO

(PERMEATE ) (PERMEATE ) PRODUCT PRODUCT WATER WATER REJECT REJECT WATER WATER (CONCENTRATE) (CONCENTRATE) M   M  _E  E   M   M  _B B  R  R _A A  N   N  _E  E   HIGH HIGH PRESSURE PRESSURE PUMP PUMP SALT SALT WATER WATER

The basic expanded design of a single system The basic expanded design of a single system includes the following:

includes the following:

q

qRaw water feed pump to supply water to the preRaw water feed pump to supply water to the pre

treatment treatment

q

qPre treatment system for Pre treatment system for Turbidity,TSS,ColloidalTurbidity,TSS,Colloidal

particles & Organic matter. particles & Organic matter.

q

qCartridge filter to remove micron size particle toCartridge filter to remove micron size particle to

control the SDI( Silt density index) of feed water control the SDI( Silt density index) of feed water

q

qAnti scalant dosing system.Anti scalant dosing system. q

qHigh pressure pump&feed control valve toHigh pressure pump&feed control valve to

pressurize the feed water. pressurize the feed water.

q

qMembranes housed in Pressure tubes.Membranes housed in Pressure tubes.

RO System components

q

q_{A reject control valve to A reject control valve to control the recovery of thecontrol the recovery of the}

RO system. RO system.

q

q_{A skid to mount to all mechanical equipment .A skid to mount to all mechanical equipment .}

q

q_{Flow indicators to measure permeate and reject flowFlow indicators to measure permeate and reject flow}

rates. rates.

q

q_{Pressure gauges for monitoring the differentialPressure gauges for monitoring the differential}

pressures across the RO feed, reject and intermediate pressures across the RO feed, reject and intermediate stages.

stages.

q

q_{Conductivity & pH meter for measuring the qualiConductivity & pH meter for measuring the quality ofty of}

the permeate water. the permeate water.

q

q_{And other necessary instruments for monitoring easyAnd other necessary instruments for monitoring easy}

operation and critical parameters. operation and critical parameters.

q

q_{A cleaning A cleaning system csystem consisting onsisting of Tof Tank,CF,Pump ank,CF,Pump andand}

necessary instruments. necessary instruments.

Recovery Rate

Recovery Rate

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q

Ratio of permeate flow to feed flow

Ratio of permeate flow to feed flow

q

q

Expressed as %

Expressed as %

q

q

Recovery = (permeate flow/feed flow)

Recovery = (permeate flow/feed flow)

* 100

* 100

Role of Pretreatment in RO

Role of Pretreatment in RO

q

q _{To reduce particulates & iTo reduce particulates & improve SDI.mprove SDI.}  – 

 –  _{Clarification / Filtration.Clarification / Filtration.}

 – 

 –  _{Polymer/coagulant addition.Polymer/coagulant addition.}

 – 

 –  _{Micro-filtration.Micro-filtration.}

q

q _{Minimize Scaling &fouling.Minimize Scaling &fouling.}  – 

 –  _{Softening.Softening.}

 – 

 –  _{Acid & anti scalant addition.Acid & anti scalant addition.}

 – 

 –  _{Anti scalant addition.Anti scalant addition.}

q

q _{Chlorine Removal.Chlorine Removal.}  – 

 –  _{Carbon Filtration.Carbon Filtration.}

 – 

Role of Pretreatment in RO

Role of Pretreatment in RO

q

q _{Minimize Silica Scaling.Minimize Silica Scaling.}

 – 

 –  _{Antiscalant addition.Antiscalant addition.}

 – 

 –  _{Softening & pH control.Softening & pH control.}

 – 

 –  _{Turbocirculator.Turbocirculator.} q

q _{Controlling Organic.Controlling Organic.}

 – 

 –  _{Dissolved Organic.Dissolved Organic.}

 – 

Role of Pretreatment in RO

Role of Pretreatment in RO

q

q

_Si

_Si

_lt

_lt

_De

_De

_ns

_ns

_it

_it

_y

_y

_In

_In

_de

_de

_x

_x

_:

_:

_It

_It

_is

_is

_th

_th

_e

_e

_se

_se

_co

_co

_nd

_nd

parameter used to determine colloidal

parameter used to determine colloidal

quantity of the RO Feed water. A test is run

quantity of the RO Feed water. A test is run

to determine the rate of the pluggage of a

to determine the rate of the pluggage of a

0.45 micron filter at 30 psig for 15 minutes.

0.45 micron filter at 30 psig for 15 minutes.

This test consists of determining amount of

This test consists of determining amount of

time it takes to collect a 500 ml sample at the

time it takes to collect a 500 ml sample at the

start of the 15 minutes test and comparing 

start of the 15 minutes test and comparing 

this time to the amount of time it takes to

this time to the amount of time it takes to

collect a 500 ml sample at the end of the 15

collect a 500 ml sample at the end of the 15

minutes.

Cross section of

Cross section of

Spiral Wound Membrane

Spiral Wound Membrane

Mesh Spacer  Mesh Spacer  Permeate Carrier  Permeate Carrier  Membrane Membrane “O” Ring “O” Ring Permeate Tube Permeate Tube Membrane Backing Membrane Backing Outer Cover  Outer Cover 

Membrane Assembly

Reverse Osmosis

Reverse Osmosis

Membranes

Membranes

-Types

Types

q

q

_{Cellulose Acetate}

_{Cellulose Acetate}

q

q

_{Thin Film Composite}

_{Thin Film Composite}

q

Thin Film Composite

Thin Film Composite

Membrane Characteristics

Membrane Characteristics

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q

Lower Operating

Lower Operating

Pressure

Pressure

q

q

High Salt Rejection

High Salt Rejection

q

q

Available for Sea

Available for Sea

Water

Water

q

q

Stable to pH 11

Stable to pH 11

q

Operating Parameters

Operating Parameters

F

Fe

ee

ed

d

P

Pr

re

es

ss

su

ur

re

e

Concentration

Concentration

 pH

 pH

Temperature

Temperature

P

Pe

er

rm

me

ea

at

te

e

C

Co

on

nc

ce

en

nt

tr

ra

at

ti

io

on

n

Flow

Flow

Pressure

Pressure

C

Co

on

nc

ce

en

nt

tr

ra

at

te

e

F

Fl

lo

ow

w

Pressure

Pressure

Concentration

Concentration

INSTRUMENTATION

INSTRUMENTATION



 _{Instruments used in RO SystemInstruments used in RO System}

• •PPHH ** OORRPP • •CCoonndduuccttiivviitty y MMeetteerr * * LLeevveel l SSwwiittcchheess • •RRoottaammeetteerr * * PPrreessssuurre e SSwwiittcchheess • •PPrreessssuurre e GGaauuggeess * * EElleeccttrriiccaal l CCoonnttrrooll

Fouling

Fouling

There are Six main causes of membrane

There are Six main causes of membrane

Fouling.

Fouling.

•

•

_{Scaling by hardness salts.}

_{Scaling by hardness salts.}

•

•

_{Scaling by Silica.}

_{Scaling by Silica.}

•

•

_{Fouling by Metal Oxides.}

_{Fouling by Metal Oxides.}

•

•

_{Plugging by suspended solids.}

_{Plugging by suspended solids.}

•

Scaling

Scaling

The deposition of sparingly soluble salts onto

The deposition of sparingly soluble salts onto

the

the

membrane surface and/or the feed channel

membrane surface and/or the feed channel

material.

material.

 – 

 – 

Scaling occurs primarily in the

Scaling occurs primarily in the

downstream elements because of the

downstream elements because of the

higher concentrations existing in this

higher concentrations existing in this

portion of the RO system.

portion of the RO system.

 – 

 – 

Common scalants include calcium sulfate,

Common scalants include calcium sulfate,

silica and calcium carbonate.