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
5
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
24
25
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 High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
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 High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
V
F
D
FM
FM
PX Rotor
Seawater Pump
58.8 flow
Start
Booster
Step 2: Set PX LP flow rate and start PX booster pump.
End View
Seal zone
LPLP
LP
LPLP
LP
109
Seal Zone
PX High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
V
F
D
FM
FM
PX Rotor
Seawater Pump
58.8 flow
Start
Booster
Step 2: Set PX LP flow rate and start PX booster pump.
Seal zone
End View
LP
LPLP
LP
LPLP
110
Seal Zone
PX High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
V
F
D
FM
FM
PX Rotor
Seawater Pump
58.8 flow
Start
Booster
Stop
SW Pump
Step 2: Set PX LP flow rate and start PX booster pump.
End View
Seal zone
LPLP
LP
LPLP
LP
111
Seal Zone
PX High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
V
F
D
FM
FM
PX Rotor
Seawater Pump
58.8 flow
Start
Booster
Stop
SW Pump
Step 2: Set PX LP flow rate and start PX booster pump.
End View
Seal zone
LPLP
LP
LPLP
LP
112
Seal Zone
PX High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
V
F
D
FM
FM
PX Rotor
Seawater Pump
58.8 flow
Start
Booster
Stop
SW Pump
Step 2: Set PX LP flow rate and start PX booster pump.
Seal zone
End View
LP
LPLP
LP
LPLP
113
Seal Zone
PX High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
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 High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
V
F
D
FM
FM
PX Rotor
Main High Pressure
Pump
Seawater Pump
58.8 flow
Stop
Booster
Start
HP Pump
Step 3: Set PX booster flow rate and start main HP pump.
End View
Seal zone
LPLP
LP
LPLP
LP
115
Seal Zone
PX High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
V
F
D
FM
FM
PX Rotor
Main High Pressure
Pump
Seawater Pump
58.8 flow
Stop
Booster
Start
HP Pump
Step 3: Set PX booster flow rate and start main HP pump.
Seal zone
End View
LP
LPLP
LP
LPLP
116
Seal Zone
PX High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
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 High Pressure Outlet
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 High Pressure Inlet
PX Low pressure Outlet
PX Booster
Pump
FM58.8 flow
66 bar
PX Rotor
41.2 flow
2 bar
FM
PX Low Pressure inlet
60 flow
1 bar
Low Pressure
Brine
V
F
D
Main High Pressure
Pump
Seawater Pump
100 flow
Stop
HP Pump
Shutdown Sequence: Stop main HP pump, stop PX booster, stop seawater pump.
End View
Seal zone
HPHP
HP
LPLP
LP
118
Seal Zone
PX High Pressure Outlet
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
PX High Pressure Inlet
PX Low pressure Outlet
FM
PX Rotor
41.2 flow
2 bar
FM
PX Low Pressure inlet
60 flow
1 bar
Low Pressure
Brine
V
F
D
Main High Pressure
Pump
Seawater Pump
100 flow
Stop
HP Pump
Shutdown Sequence: Stop main HP pump, stop PX booster, stop seawater pump.
Seal zone
End View
HP
HPHP
LP
LPLP
119
Seal Zone
PX High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
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 High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
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
121
Seal Zone
PX High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
V
F
D
FM
FM
PX Rotor
FWF Step 2: Start PX booster pump.
FWF Pump
58.8 flow
Start
Booster
Seal zone
End View
LP
LPLP
LP
LPLP
122
Seal Zone
PX High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
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 High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
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
124
Seal Zone
PX High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
V
F
D
FM
FM
PX Rotor
FWF Shutdown: Stop pumps and secure system.
Stop
Flush
58.8 flow
Seal zone
End View
LP
LPLP
LP
LPLP
125
Seal Zone
PX High Pressure Outlet
PX Low Pressure inlet
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
PX High Pressure Inlet
PX Low pressure Outlet
V
F
D
FM
FM
PX Rotor
Seal zone
End View
Step 1: Start seawater supply pump.
Start
0 flow
SW Pump
Seawater Pump
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