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Affordable Desalination Collaboration Findings Related to Regulatory Criteria, Process and Costs for
Seawater Desalination
Tom Seacord, P.E.ADC – Chairman of the Board of Directors
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Goals of the ADC
1. Demonstrate affordable desalination using innovative technologies & processes
2. Create a body of data that can guide & benefit future designs
3. Educate the public to show that desalination is an affordable, viable source of fresh water
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Current and past members of the ADC have included agencies, consultants, and leading manufacturers
West Basin municipal water district
Zenon
AMIAD
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ADC’s work has included three different phases
1. ADC 1: Demonstrating actual SWRO energy using conventional pretreatment and full-scale commercial technology (May 2005 - April 2006)
– Funded by ADC members
2. ADC 2: Further demonstration using alternate pretreatment and RO membranes (Jan - Nov 2009)
– Funded by Prop 50 and ADC members
3. ADC 3: Brackish RO concepts– Collier County, FL (June – Dec 2006)– Funded by TWDB and ADC members (Feb - Dec 2010)
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ADC has proven that SWRO’s efficiency has improved significantly using off-the-shelf technology
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1970 1980 1990 2000 ADC 2006
Sp
ec
ific
Po
we
r (k
W-h
r/A
F)
18.4
24.6
30.7
36.8
43.0
49.1
0
4.9
6.5
8.1
9.7
11.4
13.0
12.33.2
6.11.6
0
18.4
24.6
30.7
36.8
43.0
49.1
0
4.9
6.5
8.1
9.7
11.4
13.0
12.33.2
6.11.6
Sp
ecifi
c P
ow
er
(kW -
hr/
kg
al )
Sp
ecifi
c P
ow
er
(kW -
hr/
m3)
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ADC’s work has been widely referenced when defending desalination as a water supply alternative in California
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State Project Water Colorado Aqueduct Water SWRO
Sp
ec
ific
Po
we
r (k
W-h
r/A
F)
0
12.3
18.4
26.4
0
3.2
4.9
6.5
6.11.6
Sp
ecifi
c P
ow
er
(kW -
hr/
kg
al )
Sp
ecifi
c P
ow
er
(kW -
hr/
m3)
General Perception
Expert's Perception
ADC 2006
ADC 2006SWRO Process
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BackgroundCalifornia Water Supply & Treatment Costs
ADC 2006
Expert Perception
PublicPerception
$0
$200
$400
$600
$800
$1,000
$1,200
State
Pro
ject
Wat
er
Colora
do Aqued
uct W
ater
Met
ropolit
an W
ater
Dis
trict
Recyc
led R
O
Seawat
er R
O
Su
pp
ly &
Tre
atm
ent
Co
st (
$/A
F)
Prod. &Dist. Cost
BrineDisposalFromInlandEmpireArea
$0
$0.6
$1.2
$1.8
$2.4
$3.0
$3.6
$0
$0.6
$1.2
$1.8
$2.4
$3.0
$3.6
$0
$0.1
$0.3
$0.4
$0.6
$0.8
$0.9
$0
$0.1
$0.3
$0.4
$0.6
$0.8
$0.9
Su
pp
ly &
Tre
atm
en
t C
ost
($/
kg
al )
Su
pp
ly &
Tre
atm
en
t C
ost
($/m3
)
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ADC 1 & ADC 2US Navy Test Facility - Port Heuneme, CA
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ADC’s SWRO Demonstration Plant
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ADC SWRO Plant Schematic
HP Pump
PX BoostPump
PX
3 x 7 element 8” RO vessels
Multi-MediaFilter
Supply Pump
Micron Filter
Seawater
1.8 kWh/m36.8 kWh/kgal
SeawaterReturn
40 Foot Containerized 200-350 m3/day SWRO Pilot40 Foot Containerized 200-350 m3/day SWRO Pilot
A B
C D
EF
G
H
Stream A B C D E F G H
GPM 93 51 43 51 93 42 51 51
PSI 35 20 20 737 763 5 747 10
TDS 34k 34k 34k 35k 35k 103 66k 65k
ROSA6.0 Projections SW30XLE-400, 7.2 gfd, 45% recovery, 60°F, 34,432 TDS feed, 0.85 Fouling
Typical ADC Operating Conditions
HoldingTank
Intake pier
Product
Reject
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Testing Protocol
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Test Parameters & Data Collection
• Variables– Flux rates: 6, 7.5, 9 gfd– Recovery: 35, 42.5, 50%– Membrane Rejection: 99.5%-99.8%– Plant size: 10, 50 MGD
• Data analysis– Power consumption– Feed pressure and membrane DP– ASTM normalized data– Feed quality– Permeate quality and Boron– NPV of capital costs vs. O&M (energy costs)
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Cost Estimating Procedures
• Net Present Value Analysis– Amortized capital costs
• Project Life 30 years, 5% interest • Co-location
– 10 MGD: Co-located with WWTP outfall, new open intake
– 50 MGD: Co-located intake/outfall with power plant
– Annual O&M• Power $0.08/kW-hr• Replacement of Membranes (CARR)
– To maintain performance (energy & permeate quality)
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50-MGD Conceptual Study
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50-MGD Conceptual Study
Pressure Center• Pump Center• Energy Recovery Center
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10-MGD Conceptual Study
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10-MGD Conceptual Study
Dedicated Pumps/ERDs• Feed pump for every train• Energy recovery for every train
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Test Results
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0.01
0.1
1
10
0 200 400 600 800 1000 1200 1400 1600
Run Time (hours)
Turb
idit
y (
NT
U)
0
1
2
3
4
5
6
Sil
t D
en
sit
y I
nd
ex
Raw Turb
RO Feed Turb
SDI
Pretreatment
• Initial Filtration Problems – Red tide
• SDI < 5 – Not exceeded 86%
• Turbidity < 0.1 – Not exceeded 88%
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0
2
4
6
8
10
12
0 2 4 6 8 10
Train Size (MGD)
Sp
ecif
ic P
ow
er (
kW-h
r/kg
al)
SW30HR-380, 6 GFD @ 50%
SW30XLE-400i, 9 GFD @ 50%
SW30HR LE-400i, 6 GFD @ 50%
Sp
ecif
ic P
ow
er (
kW-h
r/m
3)
0
1.8
2.0
2.3
2.5
2.0
2.3
Impact of Feed Pump - Scalability
• PD Pump Selected for ADC– High efficiency– Pulsating flow
• Centrifugal Pumps Used for Larger Trains– Low efficiency for small
pumps– Smooth flow
• Pressure Center Design– May reduce power @ low flow
rates
• 50 MGD Case Study– 5.9 to 8.9 kWh/kgal
• 10 MGD Case Study– 6.6 to 9.8 kWh/kgal
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0.3
0.5
0.8
1.0
1.3
1.5
1.8
2.0
35% 43% 50%
Recovery
SW
30X
LE
-400
i Per
mea
te B
oro
n (
mg
/L) 6 GFD
7.5 GFD
9 GFD
Boron < 1.45 mg/L to comply with California standard
Permeate Quality - Boron
• Flux = Boron • Recovery = Boron • Low energy membrane
produced marginally acceptable boron– SW30HR-380
• 0.45 to 0.85 mg/L
– SW30XLE-400i• 1.05 to 1.44 mg/L
– SW30HR LE-400i• 0.45 to 0.85 mg/L
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Permeate Quality - Boron
0.0
0.3
0.5
0.8
1.0
1.3
1.5
1.8
2.0
35% 43% 50%Recovery
SW
30
HR
-38
0 P
erm
eate
Boro
n (
mg
/L) 6 GFD
7.5 GFD9 GFD
Boron < 1.45 mg/L to comply with California standard
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50
100
150
200
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300
350
400
35% 43% 50%
Recovery
SW
30X
LE
-400
i P
erm
eate
TD
S (
mg
/L)
6 GFD
7.5 GFD
9 GFD
Permeate Quality - TDS
• Flux = TDS • Recovery = TDS • Low energy membrane
produced highest TDS– SW30HR-380
• 80 to 175 mg/L
– SW30XLE-400i• 190 to 350 mg/L
– SW30HR LE-400i• 95 to 295 mg/L
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Permeate Quality - TDS
0
50
100
150
200
250
300
350
400
35% 43% 50%Recovery
SW
30H
R L
E-4
00i P
erm
eate
TD
S (
mg
/L)
6 GFD
7.5 GFD
9 GFD
0
50
100
150
200
250
300
350
400
35% 43% 50%
Recovery
SW
30H
R-3
80 P
erm
eate
TD
S (
mg
/L)
6 GFD
7.5 GFD
9 GFD
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Treatment CostsEstimated Costs for 50-MGD SWRO WTP (SW30HR-380)
30% 35% 40% 45% 50% 55%$0.0
$1.0
$2.0
$3.0
$4.0
$5.0
$6.0
$7.0
$8.0
$0
$1
$2
$3
$4
$5
$6
$7
$86 GFD O&M 7.5 GFD O&M9 GFD O&M 6 GFD Total Water7.5 GFD Total Water 9 GFD Total Water6 GFD Capital 7.5 GFD Capital9 GFD Capital
O&
M &
To
tal
Co
sts
($
/kg
al)
Ca
pit
al
Co
st
($/g
pd
)
O&
M &
To
tal
Co
sts
($
/Ac
re F
oo
t)
$2,607
$1,955
$1,303
$652
$-
$325
$1,629
$978
$2,280
Capital Cost
Total Cost
O&M Cost
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Treatment CostsEstimated Costs for 10-MGD SWRO WTP (SW30HR-380)
30% 35% 40% 45% 50% 55%$0.0
$1.0
$2.0
$3.0
$4.0
$5.0
$6.0
$7.0
$8.0
$0
$2
$4
$6
$8
$10
$12
$14
$16
$18
6 GFD O&M 7.5 GFD O&M9 GFD O&M 6 GFD Total Water7.5 GFD Total Water 9 GFD Total Water6 GFD Capital 7.5 GFD Capital9 GFD Capital
O&
M &
To
tal
Co
sts
($
/kg
al)
Ca
pit
al
Co
st
($/g
pd
)
O&
M &
To
tal
Co
sts
($
/Ac
re F
oo
t)
$2,607
$1,955
$1,303
$652
$-
$325
$1,629
$978
$2,280Capital Cost
Total Cost
O&M Cost
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Summary
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Conclusions
• Flux & recovery impact permeate quality• Low energy SWRO membrane has lowest cost, but
poorest permeate quality• Due to size and type of pump, 10 MGD plant less
efficient– 10 MGD – 6.6 to 9.8 kWh/kgal– 50 MGD – 5.9 to 8.9 kWh/kgal
• ADC’s design power by – 10 MGD – approx. 30% over industry perception– 50 MGD – approx. 40% over industry perception – Low = 5.98 kW-hr/kgal
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Conclusions (cont.)
• Recovery of 50% resulted in lowest NPV • Improving boron/TDS rejection results in higher energy
use & treatment cost• SWRO is competitive with other supply options in
California– 10 MGD
• $1,552 to $1,820/AF
– 50 MGD• $794 to $966/AF
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Recommendations
• Data must be taken in context of raw water quality (i.e., temperature)
• Designers must consider public values when establishing design water quality (i.e., boron)
• Future Work– Pretreatment– Higher Recovery– Long Term Testing– Economy of Scale – Large Diameter Elements
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ADC’s Publications & Outreach
1. Seacord, et al. 2006. Affordable Desalination Collaboration 2005 Results. Desalination & Water Reuse Quarterly. Vol. 16:2.
2. Seacord, et al. 2007. ADC 10 MGD Case Study. Proc. 2007 AMTA Annual Conf.
3. MacHarg, et al. 2008. ADC Baselines SWRO Performance. Desalination & Water Reuse Quarterly. Vol. 18:2.
4. Dundorf, et al. 2009. Optimizing Lower Energy Seawater Desalination. Proc. 2009 IDA World Congress.
5. AMTA Preconference Workshops– 2008, 2009, 2011
