water desalinationwwt.pacadengg.org/pdf/06 desalination iii.pdfminimum works of separation to...

WATER DESALINATIONWITH

REVERSE OSMOSIS

EFFICIENCY IMPROVEMENT

1

THE STRUCTURE

OF

WATER

2

The molecule is V-shaped. It is often shown

as orbut is better

represented as or even giving a more accurate idea of its rather

WATER MOLECULE

rotund shape and also indicating the charge (pink showing negatively charged surface and green

showing positively charged surface).

It is clear that life on Earth depends on the unusual structure and anomalous nature

of liquid water. 3

Water (H O) is the most remarkable substance.2

Water (H O) is the most common polyatomic molecule in the Universe and the most

Abundant substance on earth. 2

104.5º

o

WATER AVAILABILITY

4

Global Water Stress Intensifying

6

Water Availability In Decline

7

Salinity of water in Various Seas

Concentration

(ppm)

Baltic Sea

Black Sea

Adriatic Sea

Pacific Ocean

Indian Ocean

Atlantic Ocean

Mediterranean Sea

Arabian Gulf

Red Sea

7,000

13,000

25,000

33,000

33,800

36,000

39,400

43,000

43,000

Sea

8

Solubility of Scale – forming Chemicals in Pure Water

Temperature (°F)

Hemihydrate

CaSO4 1/2 H2O

Dihydrate

CaSO4 2H2OAnhydrite

CaSO4

CaCO3

Mg (OH)2

2500

2000

1500

1000

500

00 100 200 300 400

So

lub

ilit

y (

pp

m)

9

TYPICAL FEEDWATER ANALYSIS

Constituent

Water Supply

Brackish Well Seawater Open Intake

InorganicsA.

Calcium

Magnesium

Potassium

Sodium

Strontium

Iron

Bicarbonate

Chloride

Fluoride

Sulfate

Total Dissolved Solids

Silica

PhysicalB.pH

Temperature (°F)

53.6

87.0

30.3

546.2

9.1

0.5

44.5

1,026.5

0.5

212.4

2,000.6

11.1

7.2

77.0

400.0

1,272.0

380.0

10,556.0

13.0

0.0

140.0

18,980.0

1.3

2,649.0

34,391.3

2.0

8.2

77.0 10

WATER DESALINATION

Experts agree on one point: demand for water is soaring, and it will

only be met by broad, deep, and continuously improving desalination

efforts.

“We’ve been blessed and spoiled, I suppose, by copious qualities of very

low cost water,” says Furukawa (IDA PRESIDENT, 2004). That cost is going

up.”

11

The Rumaith:A Floating Desalination Plant Anchored at Sir Bani Yas Island,

Abu Dhabi.(August 1996) 12

CAPACITY 50,000 m³/d

MOBILE RO SYSTEM

Specifications

Membranes

Instrumentation

▪ Two pre- or post-treatment ASME code vessels.

▪ 200 GPM (45 m³/hr) @ 40° F (4.4°C) Reverse Osmosis System.

▪ Two × 100 GPM (23 m³/hr) arrays with stainless steel housings.

▪ Spiral wound cellulose acetate or polyamide thin film composite

▪ Flow indicator and totalizer

▪ System pressure gauges

▪ Conductivity or resistivity meter

▪ Feed pressure control system

▪ pH controller

▪ Acid, chlorine & inhibitor feed systems

▪ 5 micron cartridge prefilter

RO SYSTEM – ON BOARD

13

Compact Bicycle – Driven System for Seawater Desalination

14

CAPACITY 0.2L/min

INSTALLED CAPACITY

15

CAPACITY of all land-based desalting plants capable of producing

100 (m³/d)/UNIT or more of fresh water vs. REGION 16

PROPORTION of PROCESSES all land-based desalting plants capable of

producing 100(m³d)/UNIT or more of fresh water vs. CONTRACT YEAR

CONTRACT YEAR

PR

OP

OR

TIO

N

17

WORLDWIDE DISTRIBUTION OF

DESALINATION MARKET USERS

18

DESALINATION

PROCESS

(RO)

19

DESALINATION PRINCIPLES

PROCESSES INVOLVING A

PHASE – CHANGE OF WATER

EVAPORATION

PROCESSES

MULTI – STGE – FLASH

(MSF)

MULTIPLE – EFFECT

(ME)

VAPOR COMPRESSION

(VC)

CRYSTALLISATION

PROCESSES

VACUUM – FREEZING –

VAPOR – COMPRESSION

SECONDARY

REFRIGERANT

HYDRATE – FORMATION

PROCESSES WITHOUT A

PHASE – CHANGE OF WATER

MEMBRANE – PROCESSES

REVERSE OSMOSIS

ELECTRO – DIALYSIS

20

PROCESSES FOR SEPARATION, CLARIFICATION

& CONCENTRATION

Reverse Osmosis (RO) 30- 60 Bar Dewatering

Concentration

Nanofiltration (NF) 20- 40 Bar Demineralisation

Dewatering

Concentration

Ultrafiltration (UF) 5- 10 Bar Fractionation

Sugar removal

Concentration

Clarification

Microfiltration (MF) 1- 4 Bar Clarification

Pressure Applications

( 1 M Pa = 10 Bar ) 21

0.2 – 1.5 n m

0.8 – 10 n m

2 – 500 n m

100 – 2000 n m

Scale in metres

10 10 10 10 10 10

Reverse osmosis ULTRAFILTRATION Depth

Nanofiltration MICROFILTRATION filtration

(to > 1mm)

Approximate Molecular weight in Daltons

Free

atoms

Small

Organic

Monomers

Sugars

Herbicides

pesticides

Colloids

Albumen protein

Colloidal silica

Viruses

(Bacteria to~40µm)

Crypto

sporidia

Red

blood

cells

Dissolved Endotoxins

salts pyrogens

Rejection Capability of the Different Membrane

Separation Process

200 20,000 500,000

22

-8-9-10 -7 -6 -5

Types of Membrane Filtration 23

Macromolecules and polymers

Proteins Viruses

Ultrafiltration Microfiltration Reverse Osmosis

Nanofiltration

Bacteria

Yeasts Algae

Ions

Typical flux

0.0001 µm

1 A

rate on pure

water (in l.hr .m .bar )

Coarse organic

molecules

0.002 µm 0.02 µm

200 – 500

200 A

20 - 4001 to 10

10 A 20 A

2 µm

oo o o

-1 -2 -1

Osmotic Pressure Of Various Solutions26

OSMOTIC PRESSURE OF BRINE WATER

27

THEORY

OF

REVERSE OSMOSIS

28

The Concept of Reverse Osmosis, in Which The Normal Osmotic Flow of

Water Across A Permselective Membrane is Reversed By Applied Pressure.

29

Schematic of Pressure - driven Membrane process

t g t m

Interface

Uc

J i

Jo

Cb

C wiU , J

p v

C w

Semi-permeable

retentive

C , JP p

C , J = 0P p

Membrane

Concentration

Polarization Layer

Effective gel layer

Effective adsorption layer

Effective fouling layer

Effective cake layer

30

Concentration of solute in

solvent

Maximum concentration of

solute within polarization zone

Minimum concentration of

Solution within the Gel layer

Concentration of solute in

product stream

Cross-Flow velocity of feed

stream

Velocity of product stream

Permeation of solvent into the

polarization layer

Permeation of solvent out of the

polarization layer back into

main feed stream

Permeation of solvent through

the membrane

Permeation of solute through

the membrane

Thickness of gel layer

Thickness of membrane

C

C

C

C

U

U

b

wi

w

p

c

p

J

J

J

J

t

t

i

o

v

p

g

m

31

Module Mass Balance

Permeate

Retentate

Feed

Vf, Cf

Vr, Cr

Vp, Cp

= Molar Concentration of the “key” Component

V = Volumetric Flow Rate

( The “key” component is the solute whose rejection by the

membrane is under study)

c

32

REVERSE OSMOSIS

PERMEATION OF WATER THROUGH THE MEMBRANE

Assumption : No gel layer

Therefore : C = C

Intrinsic salt rejection : <1

Where :

P = Specific water permeability

tm = Membrane thickness

ΔP = Applied transmembrane mechanical pressure

(at a specific point)

Δ = Actual osmotic pressure gradient based on C and C

(at a specific point)

v

w wi

w p

P= J

t m

vv

(ΔP - Δ)

P /t = Coefficient of water transport (determined experimentally)v m

33

NANOFILTRATION, ULTRAFILTRATION

AND MICROFILTRATION

Where:

P = Specific water permeability of clean membrane

tm = Membrane thickness

Pg = Specific permeability of the “g” layer

tg = thickness of effective gel/cake layer

µ = Shear viscosity of the fluid passing through the membrane

v

^

^

General form for water permeation :

J =v ΔP - Δ

t m

ˆP

+v

t

Pˆ

g

g

·µ[ ]

34

Further lumping of parameters :

J

Where :

R = Clean membrane resistance

R = Additional resistance from

gels, cakes and adsorption (fouling)

For microfiltration :

=ΔP - Δ

v

(R +R )m g

m

g

Δ & R length of module and timeg

Δ = negligible

35

PERMEABILITY PARAMETERS

OSMOTIC PRESSURE

Where :

n = Number of pores with

dia . “i” per unit area

d = dia . of pore “i”

i

i

P or P n dv

^ ^

8 i = o

4

i i

Thermodynamic property

For dilute, ideal solutions

= c R T — Van`t Hoff Eqn.

Where :

c = Ionic concentration

R = Gas constant

T = Temperature in K

= ac (n >1,~2)n

a = const.

( Linear form)

o

g

i

——

=

36

Intrinsic Rejection :

R

Δ = a (C – Cp)

OR Δ = a R C

USING VAPOUR PRESSURE DATA

v = R T lnsolvent

P solvent

P solution[ ]

v

v

Where :

v = Partial molar volume of the solvent

R = Gas constant

T = Solution Temperature, °K

Psolvent = Vapour pressure of solvent

Psolution = Vapour pressure of solution with

concentration “c”

v

v

=C – C w p

Cw

w

w

solvent

o

o

37

SUMMARY

The retentate concentration :

C=

(1 - )+ (1 – R ). exp (J / k)v

R + (1 – R ) exp (J / k ) v

f

The wall concentration :

C =w [ exp. (J /k)

R + (1-R ) exp (J / k )]v

The permeate concentration :

C =pC (1-R ) exp. (J / k )b v

v

R + (1-R ) exp (J / k )v

Estimate J for ROv

J =[vP

tv

m] (ΔP – a R C )w

Estimate “k” using boundary layer correlation

and physical dimensions of the system

1.

2.

3.

4.

5.

C

C

r

r

o

oo

oo

o

o

o

38

Finally :

PERMEATE FLUX

J =P

tv

m

v [ ] [ΔP – a Rº{ C .exp (J / k )f

(-)Rº+(1-R).exp(J / k)}]v

v

— to be solved iteratively

For laminar flow in tubes :

2. U . D²[k = 1,295d.L

c ]1/3–

For laminar flow between parallel

plates spaced at 2h :

k =1.177 U .D²c[ h . L ]1/3–

Where :

U = average cross - flow

L = distance along the tube length

–c

39

Estimation of “k”

Reynolds No :

–R =

d.U .c ρ

e

µ

Schmidt No : µS =c

ρ.D

Where :

d = representative channel or tube

dimension for flow (i.e.diameter)

U = average cross-flow velocity

ρ = density

µ = Shear viscosity

D = Solute diffusivity

–

For turbulent flow:

k = U . 0.0791. R . S

R > 20,000 (in general)

R > 2,000 (in UF)

-1/4 -2/3

e cc

–

e

e

c

40

The Variation of The Upper and Lower Limits of Minimum

Work with The Salinity of Incoming Saline Water

Salinity, x (mole fraction)

W k

J/k

gm

in800

700

600

500

400

300

200

100

0

0.0 0.2 0.4 0.6 0.8 1.0

41

3.5 %4.50 %

2.00 %1.00 %

0.2

Minimum Works of Separation to Extract Pure Water From

4.5, 3.5, 2.0, 1.0, and 0.2% Salt Solutions at 15ºC

as a Function of Recovery Ratio

Recovery (%)

W

(kJ/k

g P

ure

Wate

r P

rod

uc

ed

)m

in

10

9

8

7

6

5

4

3

2

1

00 20 40 60 80 100

42

The theoretical minimum energy for desalting seawater as a function of freshwater

recovery. Calculation assumes infinite solubility of salt in water – precipitation of

NaCl salt begins at about 90% recovery.

43

DESIGN

CONSIDERATONS

44

The trade – off between capital costs and energy consumption

for practical desalination systems.

45

Key Factors for Consideration in

Technology Selection

Water production cost

Plant capital cost

Operating costs

Energy consumption

Cost of energy

Energy supply reliability

Feedwater / product ratio

Plant availability

Potential for & impact of

capacity expansion

Maintainability

Corrosion/erosion

Plant size/footprint

Plant life expectancy

Feedwater pre-treatment

Product post-treatment

Product water quality

Control/automation

Potential for technology

improvement

46

Economic Considerations

Characteristics MSF MED RO

Specific investment cost,

US$/m³/d of production capacity

Typical water production cost, US$/m³

Relative product water cost

Benefit from “economy of scale” for large plants

Flexibility to add capacity w/o adverse impact

1100 – 1600

>1.00

Highest

900 – 1250

0.55 – 0.90

Low

700 – 1000

0.45 – 0.75

Lowest

Medium/High

Low

Low/Medium

High

47

Comparison of Membrane Separations for

Municipal Water Treatment

Separation process

Rating,

pore size, or

molecular weight

cutoff

Operation

pressure range

(kPa)

Productivity

(L/cm³*day)

0.05 – 2.0 µm

0.001 – 0.1 µm

10 – 1000 Å,

MWCO*(Daltons):

1000 – 500,000

8 – 80 Å

MWCO (Daltons):

180 – 10,000

1 – 15 Å

Microfiltration

Ultrafiltration

Nanofiltration

Reverse Osmosis

140 – 5000

200 – 1000

550 – 1380

1380 – 6890

90 – 100% recovery

1 – 5

1 – 6

0.1 – 2. 3

* MWCO: Molecular Weight Cut Off is the molecular weight of species

rejected by the membrane. 48

Diagram of Flow Pattern In Spiral-Wound Membrane 49

Spiral Wound Module

1 – Water inlet.

2 – Concentrate outlet.

3 – Permeate outlet.

4 – Direction of flow of raw water.

5 – Direction of flow of permeate.

6 – Protective material.

7 – Seal between module and Shell.

8 – Holes collecting the permeate.

9 – Spacer.

10 – Membrane.

11 – Permeate collector.

12 – Sealed joint between the two membrane.

8

2

3

2

9

10

11

10

9

12

6

5

4

1

7

50

High Pressure Module by Toray

Structure of RO element Structure of Brine Conversion

Seawater RO Membrane

Product

Water

Feed Water

Brine Seal

Center Tube

Permeate

Brine

Water

Feed Water Spacer

Feed WaterRO Membrane

Permeate Permeate Spacer

Seawater

Ultra – thin Salt Rejection Layer

crosslinked fully aromatic polyamide

0.3 µm

Supporting Layer

polysulfone

45 µm

Base Fabric

Unwoven polyester

100 µm

51

1 - Raw water inlet

2 - Permeate outlet

3 - Concentrate outlet.

4 - Potting resin

5 - Hollow fibres

6 - Shell

Hollow Fibre Module with Internal skin: straight bundle

52

Photomicrograph of Hollow-Fiber 53

SALT REJECTING

LAYER

Porous Support

Layer

Electron Micrograph Showing The Structure of The Loeb – Sourirajan Reverse

Osmosis Membrane. Note The “skin” Region That is Responsible For The

Membrane’s Permselective Qualities.

54

TYPICAL MEMBRANE REJECTIONS/ PASSAGES

CATIONS

Sodium

Calcium

Magnesium

Potassium

Iron

Manganese

Aluminum

Ammonium

Copper

Nickel

Zinc

Strontium

Hardness

Cadmium

Silver

Mercury

SALTS

94.96

96.98

96.98

94.96

98.99

98.99

99+

88.95

98.99

98.99

98.99

96.99

96.98

96.98

94.96

96.98

5

3

3

5

2

2

1

8

1

1

1

3

3

3

5

3

5 - 10

-

-

5 - 10

-

-

10-20

3-8

10-20

10-20

10-20

-

-

10-20

-

-

SymbolsPercent

Rejection

Percent

Passage

(Average)

Maximum

Concentration

Percent

ANIONSChloride

Bicarbonate

Sulfate

Nitrate

Fluoride

Silicate

Phosphate

Bromide

Borate

Chromate

Cyanide

Sulfite

Thiosulfate

Ferrocyanide

Name

94.95

95.96

99+

85-95

94-96

80-85

99+

94.96

35.70

90-98

90-95

98-99

99¹

99¹

5

4

1

10

5

10

1

5

—

6

—

1

1

1

5-8

5-10

5-15

3-6

5-8

—

10-20

5-8

—

8-12

4-12

5-15

10-20

10-20

Na¹

Ca

Mg

K

Fe

Mn

Al

NH4

Cu

Ni

Zn

Sr

Ca and Mg

Cd

Ad

Hg

+ ²

+ ²

+ ¹

Cl

HCO3

SO4

NO3

F

SiO2

PO4

Br

B4O7

CrO4

CN

SO3

S2O3

Fe(CN)6

+ ²

+ ²

+ ³

+ ¹

+ ²

+ ²+ ²

+ ²

+ ²

+ ¹+ ²

-¹

-¹

-²

-¹

-¹

-²

-³

-¹

-²

-²

-¹

-²

-²

³

Must watch for precipitation, other ion controls maximum concentration.

Extremely dependant on pH; tends to be an exception to the rule. 55

ORGANICS

Sucrose sugar

Lactose sugar

Protein

Glucose

Phenol

Acetic acid

Formaldehyde

Dyes

Biochemical Oxygen

Demand

Chemical Oxygen

Demand

Urea

Bacteria & virus 500,000-50,000

Pyrogen 1000-5000

Molecular Weight

342

360

10,000 Up

180

94

60

30

400 to 900

(BOD)

(COD)

60

Percent

Rejection

99.9

99.9

99.9+

99

•••

•••

•••

99.9

90-99.9

99.9

40-60

99.9+

99.9+

Maximum

Concentration

Percent

30-35

30-35

50-80

15-20

—

—

—

—

—

—

Reats similar

to a sall

—

—

Permeate is enriched in material passage through the membrane

BACTERIA & VIRUSES

56

RO MODULE EFFICIENCY – SEAWATER

HOLLOW FIBER TYPICAL SINGLE DOUBLE SPIRAL

BUNDLE BUNDLE WOUND

Flux

gal/day~ft² membrane

L/day/m², membrane

Membrane Area

Per Pressure Vessel,

ft²

m²

Volume of

Pressure Vessel,

ft³

liters

Flow Per

Pressure Vessels,

gpd

cumd

Efficiency Per

Pressure Vessel,

gpd/ft³

cumd/m³

0.8-1.4

33-57

4000-5000

370-465

1-2

28-56

3K–7K

12-27

3200-3500

435-480

0.8-1.4

33-57

8500-10,000

790-930

2-3

56-85

7K–14K

26-53

3400-4650

474-625

6.5-9

265-365

2000*

185*

7.5*

210

13K–18K*

49-68*

1725-2400*

235-320*

* Six 8-inch diameter cartridges/pressure vessel 57

Characteristics of New SW Desalination

Membrane Elements

Product name Active area

ft²(m²)

Flow rate

gpd(m³/d)

NaCl rejection

%

Boron rejection

%

Maximum pressure

psi (bar)

FILMTEC

SW30HR LE-400

FILMTEC

SW30XLE-400

FILMTEC

SW30HR-320

400

(35.3)

400

(37.2)

320

(29.7)

7500

(28.4)

9000

(34.1)

6000

(22.7)

Typical 99.75

Minimum 99.60

Typical 99.70

Minimum 99.55

Typical 99.75

Minimum 99.60

91.0

88.0

91.0

1200

(83)

1200

(83)

1200

(83)

Standard test condition: NaCl feed of 32,000 mg/L, recovery of 8%, 25° C, 55 bar, pH 8

58

HYDRAULIC OPTIMISATION OF NANOFILTRATION

59

High Pressure Common Brine Line

High Pressure Common Brine Line

Low Pressure Common Brine Line

En

erg

y R

ec

ove

ry C

en

ter

Brine

Product

Pumping

Center

Product

Feed

High Pressure Common Feed Line

The Three – Center SWRO System Allows Plant Operations

To Vary Flows, Which Reduces Production Costs.

Courtesy of IDE Technologies

60

SIMPLE SCHEMATIC OF CLASS I ENERGY

RECOVERY DEVICE

61

SIMPLE SCHEMATIC OF CLASS II ENERGY

RECOVERY DEVICE

62

SIMPLE SCHEMATIC OF CLASS III ENERGY

RECOVERY DEVICE

63

EFFECT OF CMF PRETREATMENT

64

HETE Vs SYSTEMS CAPACITY

65

SPECIFIC POWER CONSUMPTION

VS SYSTEM CAPACITY

66

SPECIFIC POWER CONSUMPTION VS RECOVERY

AT CONSTANT GFD

67

Process Chart of Typical Seawater RO Desalination Plant

Intake/pretreatment process

1 RO desalination process2Post-treatment

process3RO membrane module

Reducing agentMineralizing agent

Sterilizing agent

Product

water

Product water tank

Backwash tank

Backwash

pump

Check filterFilter

Filtrate tank

Pump Intake pump

Washing waste water Raw

seawater

Sterilizing agent

coagulant

Pressure pump

(with energy-recovery system)

68

Simplified Process Flow Diagram 69

DEGASSIFIER & SUMPDRAW

BACK

TANK

SODA ASH

PRODUCT TO

STORAGE

PRODUCT TRANSFER

PUMPS

PERMEATOR

RACKS

WELL

PUMPS

ACID

CARTRIDGE

FILTERS

CONCENTRATE RETURN

TO SEA

MOTOR

ENERGY RECOVERY TURBINE

HIGH PRESSURE RO PUMP

13.5 L/m2-hr

R=45%

15.5 L/m2-hr

R=50%

18.0 L/m2-hr

R=50%

SW

RO

Perm

eate

Sali

nit

y, (m

g/L

TD

S)

15 20 25 30

260

240

220

200

180

160

140

120

100

80

SWRO Permeate Salinity v/s Seawater Temperature ( °C )

and RO Membrane Flux

Temperature (ºC) 70

Factors in Performance Decline in RO Desalination Plants

Factors Occurrence (%)

Mechanical damage (water hammer, telescoping etc)

Mechanical degradation (oxidation and/or hydrolysis)

Membrane fouling

Inorganic colloids

Absorbed organics

Coagulants

Biofouling

Silica scale or silica fouling

Other inorganic scale and fouling with waste water

4.1

18.2

13.8

11.4

4.0

33.5

10.0

5.0

71

Beginnings of A Biofilms. Bacteria Are Seen In The Atomic Force Microscope

Attached To The Surface Of A reverse Osmosis Membrane.

Courtesy of Jana Safarik, Orange Country Water District72

An Early Reverse Osmosis Membrane Biofilm of

Rod – Shaped Bacteria.

73

ENERGY RECOVERY DEVICES

F - Hydraulic turbocharger by Fluid Equipment Development Co.

(FEDCO), Monroc Michigan

FT - Francis turbine as symbolized in the Water Service Corporation

Plants, Malta

PW - Impulse turbine (Pelton Wheel) by Calder Pressure Systems,

Worcester England and Seon Switzerland

PX - Pressure exchanged by Energy Recovery, Inc.(ERI),

San Leandro California

T - Hydraulic turbocharger by Pump Engineering Inc. (PEI),

Monroc Michigan

DWEER - Work exchanger by DesalCO Ltd., Bermuda 74

Pelton Wheel Energy Recovery System

Motor

Pelton

wheel

turbine

Feed

water

HP

pump

RO elements

Permeate

Brine

to disposalBy – pass Valve – 2

Valve – 1

75

Feed

solution

Booster

pump

HP

pumpRO elements

PE

Permeate

water

Brine

high

pressure

Brine

low

pressure

Pressure Exchange Energy Recovery System

76

HOW THE PX WORKS

77

Pt Hueneme Recovery vs. Energy Consumption

@ Constant 7.2 GFD

System Recovery (%)

kW

h/m

³

6.2

5.6

5.0

4.4

3.8

3.2

2.6

2.0

1.426% 29% 31% 33% 35% 37% 40% 45%

78

SWRO Desalination Plant – 90,000 m³/day, 30 M m³/year – CONVENTIONAL

Pretreatment – Principle Flow Diagram

79

WATER

TREATMENT COSTS

80

WATER TREATMENT COSTS

Treatment cost for water from current generation advanced desalination and

water purification facilities is between $ 1 and $ 3 per thousand gallons

(or up to 5-6 times more than ‘conventionally treated’ fresh water). The cost

of producing water from these advanced desalination and water purification

technologies has declined over time, albeit at a rate of only approximately

4% per year

This improvement may be viewed in terms of the thermodynamic minimum

of salt removal from seawater. For a solution of 3.5% sodium chloride, the

minimum energy used due to osmotic pressure is 3 kJ/kg of water. This may

be expressed in terms of electrical energy 3.1 kWh per 1000 gal or

approximately $0.30 per 1000 gal. This energy use will never be achieved but

is presented to illustrate that substantial improvement is possible.

81

Development of water costs 82

Cost Structure For Reverse – Osmosis

Desalination Of Seawater

Electric Power – 44%

Fixed Charges –37%

Membrane Replacement – 5%

Labour – 4%

Maintenance % Parts –7%

Consumables –3%

83

Seawater Desalination Cost Structure

(General)

Thermal SWRO

Capex

Intake and outfall structures

Contribution from steam generating plant

Desalination process equipment

Civil works

Opex

Electrical consumption and heat input

Maintenance and overhaul

Chemicals

Personnel costs

Capex

Intake and outfall structures

Pre-treatment including civil works

Equipment

Membrane

Civil

Opex

Electrical consumption

Maintenance and overhaul

Chemicals

Personnel costs

%

10-15

5-15

70-72

5

%

60-80

10-15

8

10

%

5-20

5-10

40-50

25-35

5

%

50-60

20-26

10

12

84

BREAKDOWN OF TOTAL COST

OF DESALINATION WATER

85

Energy and Capital Costs for a 6 mgd (22,710 m³/d) Caribbean

SWRO Plant Utilizing The Advanced Membrane

Development Plus Turbo For Booster Pressure

86

gd

Breakdown of Capital and O&M Costs for 185-mgd

Permeate Flow RO Plant, USA

Parameter Value ($M)8”×40”RO plant 8”×60”RO plant 16”×60”RO plant

Capital Costs

Membrane cost

Pressure vessels

Skid piping

Support frame

Membrane feed pumps

Other installed membrane train

equipment

Additional process items

Buildings

Site development

Electrical

Plant controls

Other facilities

Construction contingency

Overall project contingency

Total capital

Total capital costs/y

Operation and maintenance costs

Energy ($/y)

Labor ($/y)

Chemicals ($/y)

Membrane replacement ($/y)

Miscellaneous ($/year)

Total O$M costs/y

Total cost/y

Total cost/1,000 gal permeate

20.6

8.2

11.1

3.5

5.0

17.8

11.3

14.7

0.6

7.0

7.0

3.5

28.4

28.6

$167.3

$14.6

7.44

1.68

3.98

4.13

2.48

$19.7

$34.3

$0.508

18.3

8.2

11.1

3.5

5.0

17.8

11.3

14.7

0.6

7.0

7.0

3.5

28.4

28.6

$165.0

$14.4

7.44

1.68

3.98

3.67

2.48

$19.3

$33.7

$0.499

17.6

7.4

2.1

0.7

5.0

12.2

11.3

11.1

0.6

4.5

4.5

3.5

20.0

20.2

$120.7

$10.5

7.41

1.68

3.98

3.52

2.48

$19.1

$29.6

$0.43887

ASHKELON DESALINATION PLANT, ISRAEL

The new Ashkelon seawater reverse osmosis (SWRO) plant – the largest

desalination plant of its kind in the world – commenced initial production

in August 2005, less than 30 months after construction began. Initially running

at around 30% to 40% capacity, it will ultimately provide an annual 100

million m³ of water, roughly 5% to 6% of Israel`s total water needs or around

15% of the country`s domestic consumer demand.

In total, the project cost approximately $250 million and was funded by a

mixture of equity (24%) and debt (77%). The over all revenue over the period

of the contract will be in the region of $825 million.

88

The Ashkelon Plant’s Average Base Total Water Price

Capacity : 100 Mm³/y (60 mgd)

Cost item NIS/m³ US¢/m³ * % of TWP Linkages

Based fixed price

Based variable price

Energy

Membranes

Filters

Chemicals

Post-treatment

Others

Subtotal

Base total water price (TWP)

1.315

0.565

0.120

0.020

0.090

0.040

0.070

0.905

2.220

31.1

13.4

2.8

0.5

2.1

0.9

1.7

21.4

52.5

59.2

25.4

5.4

0.9

4.1

1.8

3.2

40.8

100.0

CPI

Electricity price**

CPI & USD/NIS

exchange rate

”

”

”

”

* At the relevant base exchange-rate of 4.23 NIS/USD

** The “required revenue per kWh” as published by the Israel Public Utility Authority - Electricity

89

PERTH SEAWATER DESALINATION PLANT

Water Corporation of Western Australia (WORLD`S LARGEST PLANT USING RENEWABLE ENERGY)

Peak Capacity

Cost

Perth`s Water

Needs

Wind Farm

(Associated)

Energy Recovery

144,000 m³/d

US $ 290 million

17 %

82 MW

Isobaric

(PX) – ERI

90

Specific Energy Consumption for SWRO Plants

(GREECE)

Location Production, Power of the Energy Energy Specific energy Recovered energy

(m³) HP pump recovery consumption consumption consumption

(kW) system (kWh) (kWh/m³) (kWh/m³)

Oia

Oia

Oia

Ios

Ithaki

Syros

Mykonos

12,000

5,400

9,000

14,880

9,275

17,856

15,000

110

75

75

75

200

110

160

Pelton wheel

Turbo charger

Pelton wheel,

Grundfos

PX-60

Pelton wheel

Pelton wheel

Pelton wheel

55,200

25,110

47,563

45,073

87,000

109,992

125,350

4.60

4.65

5.28

3.02

9.38

6.10

8.36

13.93

11.62

18.85

7.55

37.12

16.21

36.33

91

Total Cost of Water, All Processes

Plant Capacity(mgd)

Co

st

of

Wate

r ($

/kg

al)

0 2 4 6 8 10 12 14 16

12.00

10.00

8.00

6.00

4.00

2.00

0.00

MSF PR=12 lbs/kBtu MED PR=12 lbs/kBtu MVC PR=12 lbs/kBtu SWRO BWRO

92

ACTUAL COSTS OF DESALINATED WATER

2000 PROJECTS COST (US $/m³)

1. Ashkelon, Israel

2. Singapore

3. Palmachim, Israel

0.50 – 0.53

0.50

0.53

2008 PROJECT

Tempa Bay,

USA0.49

CAPITAL COSTS

Brackish Water1.

2. Sea Water

130

795

RAW WATER SOURCE COST (US $/m³)

WATER PRODUCTION

93

Tampa

Trinidad Larnaca

Average Life – cycle Water Costs as Function of Lifetime,

Normalized for Electricity Rates of $0.04/kWh A

vera

ge w

ate

r co

st(

$/m

³)

0 10 20 30

0.8

0.7

0.6

0.5

0.4

0.3

0.2

Life – cycle

94

BREAKDOWN OF DESALINATION PLANT

CAPITAL COSTS

95

TYPICAL OPERATION AND MAINTENANCE COSTS FOR

BRACKISH AND SEAWATER DESALINATION PLANTS

96

SEAWATER ELEMENT PRICE REDUCTION

97

COST REDUCTION IN MEMBRANE DESALINATION

98

A Modern Thin – Film Composite Membrane With A Modified Surface To

Retard Biofueling, As Seen in The Atomic Force Microscope.

Image Courtesy of Jana Safarik, Orange County Water District. 99

“Intelligent” Water Purification Membranes Of The Future

Will Resemble Biological Systems.

100

RENEWABLE ENERGY

DRIVEN

DESALINATION PLANTS

101

Reverse Osmosis Plants Driven by Photovoltaic Cells

Jeddah, Saudi Arabia

Conception Oro, Mexico

North of Jawa

Red Sea, Egypt

Hassi-Khebi, Argelir

Cituis West, Jawa,

Perth, Australia

Wanoo Roadhouse, Australia

Vancouver, Canada

Doha, Qatar

Thar desert, India

North west of Sicily, Italy

St. Lucie Inlet State Park, FL, USA

Lipari Island, Italy

Lampedusa Island, Italy

University of Almeria, Spain

42800 ppm

Brackish water

Brackish water

Brackish water

(4.4 g/L)

Brackish water

(3.2 g/L)

Brackish water

Brackish water

Brackish water

Seawater

Seawater

Brackish water

Seawater

Seawater

Seawater

Seawater

Brackish water

3.2 m³/d

1.5 m³/d

12 m3/d

50 m³/d

0.95 m³/h

1.5 m³/h

0.5-0.1 m³/h

—

0.5-1 m³/d

5.7 m³/d

1 m³/d

—

2×0.3 m³/d

2 m³/h

3+2 m³/h

2.5 m³/h

8 kW peak

2.5 kW peak

25.5 kW peak

19.84 kW peak (pump), 0.64 kW

peak (control equipment)

2.59 kWp

25 kWp

1.2 kWp

6 kWp

4.8 kWp

11.2 kWp

0.45 kWp

9.8 kWp + 30 kW Diesel

Generator

2.7 kWp + Diesel Generator

63 kWp

100 kWp

23.5 kWp

Plant

Location Salt

Concentration

Plant

CapacityPhotovoltaic

system

102

Cost of Unit Volume of Product Water

Using RES

System Water production, (m³/y) Cost of water production, (€/m³)

100% PV 3096 6.64

60% PV + 4 kW wind turbines 3096 5.58

40% PV + two 4 kW wind turbines 3096 5.21

35% PV + 10 kW wind turbine 3096 5.36

103

FUTURE SWRO DESALINATION ADVANCES

❖ Development of membranes of higher salt and pathogen rejection, and productivity;

and reduced trans – membrane pressure, and fouling potential;

❖ Improvement of membrane resistance to oxidants, elevated temperature and compaction;

❖ Extension of membrane usefull life beyond 10 years;

❖ Integration of membrane pretreatment, advanced energy recovery and SWRO systems;

❖ Integration of brackish and seawater desalination systems;

❖ Development of new generation of high – efficiency pumps and energy recovery systems

for SWRO applications;

❖ Replacement of key stainless steel desalination plant components with plastic components

to increase plant longevity and decrease overall cost of water production.

❖ Reduction of membrane element costs by complete automation of the entire production

and testing process;

❖ Development of methods for low – cost continuous membrane cleaning that reduce

downtime and chemical cleaning costs;

❖ Development of methods for low – cost membrane concentrate treatment, in – plant

and off – site reuse, and disposal. 104

T A R G E T S

Next Five

years

2020

20% 50%Cost Reduction of

Desalinated Water

105

ENERGY RECOVERY

SYSTEM

ERI106

Seal Zone

PX High Pressure Outlet

PX Low Pressure inlet

Seal Zone

Start

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump0 flow

0 bar

0 flow

0 bar

0 flow

0 bar

0 flow

2 bar

0 flow

0 bar 0 flow

0 bar

0 flow

Permeate

0 flow

PX High Pressure Inlet

PX Low pressure Outlet

V

F

D

FM

FM

PX Rotor

Step 1: Start seawater supply or fresh water flush.

SW Pump

Start

Flush

End View

Seal zone

107

Seal Zone



PX Rotor Rotation

Seal Zone

Seawater Pump

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor

Step 2: Set PX LP flow rate and start PX booster pump.

58.8 flow

Start

Booster

End View

Seal zone

LPLP

LP

LPLP

LP

108

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor

Seawater Pump

58.8 flow

Start

Booster


End View

Seal zone

LPLP

LP

LPLP

LP

109

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor

Seawater Pump

58.8 flow

Start

Booster


Seal zone

End View

LP

LPLP

LP

LPLP

110

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor

Seawater Pump

58.8 flow

Start

Booster

Stop

SW Pump


End View

Seal zone

LPLP

LP

LPLP

LP

111

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor

Seawater Pump

58.8 flow

Start

Booster

Stop

SW Pump


End View

Seal zone

LPLP

LP

LPLP

LP

112

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor

Seawater Pump

58.8 flow

Start

Booster

Stop

SW Pump


Seal zone

End View

LP

LPLP

LP

LPLP

113

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump58.8 flow

2 bar

58.8 flow

1 bar

58.8 flow

0 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor

Step 3: Set PX booster flow rate and start main HP pump.

Seawater Pump

58.8 flow

Stop

Booster

Start

HP Pump

End View

Seal zone

LPLP

LP

LPLP

LP

114

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

58.8 flow

2 bar

58.8 flow

1 bar

58.8 flow

0 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor

Main High Pressure

Pump

Seawater Pump

58.8 flow

Stop

Booster

Start

HP Pump


End View

Seal zone

LPLP

LP

LPLP

LP

115

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

58.8 flow

2 bar

58.8 flow

1 bar

58.8 flow

0 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor

Main High Pressure

Pump

Seawater Pump

58.8 flow

Stop

Booster

Start

HP Pump


Seal zone

End View

LP

LPLP

LP

LPLP

116

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

100 flow

69 bar

60 flow

67 bar41.2 flow

2 bar

58.8 flow

2 bar

Permeate

40 flow



Shutdown Sequence: Stop main HP pump, stop PX booster, stop seawater pump.

PX Booster

Pump

FM58.8 flow

66 bar

PX Rotor

FM

60 flow

1 bar

Low Pressure

Brine

V

F

D

Main High Pressure

Pump

Seawater Pump

100 flow

Stop

HP Pump

End View

Seal zone

HPHP

HP

LPLP

LP

117

Seal Zone


PX Rotor Rotation

Seal Zone

PX Rotor Rotation

100 flow

69 bar

60 flow

67 bar

58.8 flow

2 bar

Permeate

40 flow



PX Booster

Pump

FM58.8 flow

66 bar

PX Rotor

41.2 flow

2 bar

FM


60 flow

1 bar

Low Pressure

Brine

V

F

D

Main High Pressure

Pump

Seawater Pump

100 flow

Stop

HP Pump


End View

Seal zone

HPHP

HP

LPLP

LP

118

Seal Zone


PX Rotor Rotation

Seal Zone

PX Rotor Rotation

PX Booster

Pump

100 flow

69 bar

60 flow

67 bar

58.8 flow

66 bar

58.8 flow

2 bar

Permeate

40 flow



FM

PX Rotor

41.2 flow

2 bar

FM


60 flow

1 bar

Low Pressure

Brine

V

F

D

Main High Pressure

Pump

Seawater Pump

100 flow

Stop

HP Pump


Seal zone

End View

HP

HPHP

LP

LPLP

119

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor

FWF Step 2: Start PX booster pump.

58.8 flow

Start

Booster

FWF Pump

End View

Seal zone

LPLP

LP

LPLP

LP

120

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor


58.8 flow

Start

Booster

FWF Pump

End View

Seal zone

LPLP

LP

LPLP

LP

121

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor


FWF Pump

58.8 flow

Start

Booster

Seal zone

End View

LP

LPLP

LP

LPLP

122

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump58.8 flow

2 bar

58.8 flow

1 bar

58.8 flow

0 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor

FWF Shutdown: Stop pumps and secure system.

Stop

Flush

58.8 flow

End View

Seal zone

LPLP

LP

LPLP

LP

123

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump58.8 flow

2 bar

58.8 flow

1 bar

58.8 flow

0 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor


Stop

Flush

58.8 flow

End View

Seal zone

LPLP

LP

LPLP

LP

124

Seal Zone



PX Rotor Rotation

Seal Zone

PX Rotor Rotation

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump58.8 flow

2 bar

58.8 flow

1 bar

58.8 flow

0 bar

0 flow

2 bar

58.8 flow

2 bar 58.8 flow

1 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor


Stop

Flush

58.8 flow

Seal zone

End View

LP

LPLP

LP

LPLP

125

Seal Zone



Seal Zone

Low Pressure

Brine

PX Booster

Pump

Main High Pressure

Pump0 flow

0 bar

0 flow

0 bar

0 flow

0 bar

0 flow

0 bar

0 flow

0 bar 0 flow

0 bar

Permeate

0 flow



V

F

D

FM

FM

PX Rotor

Seal zone

End View

Step 1: Start seawater supply pump.

Start

0 flow

SW Pump

Seawater Pump

126

water desalinationwwt.pacadengg.org/pdf/06 desalination iii.pdfminimum works of separation to...

Documents