By: John Kiernan, Senior Business Developer

Electrochemical Desalination

Water Technologies

Slide 2 Water Technologies

The Challenge

In August, 2007, the Singapore Environment & Water Industry Development Council (EWI) offered a Challenge

They sought ideas to produce drinking water from seawater at an energy value of 1.5 kWh/m3 or less

Siemens Water Technologies R&D was announced the sole winner in June, 2008 from 35 proposal submissions

The Siemens Project officially commenced on 01 October 2008

The project is to culminate with 50 m3/d Demonstration Plant in Singapore, treating actual seawater, by October, 2011 2010

Slide 3 Water Technologies

The Pursuit of 1.5 kWh/m3

Minimum energy to desalt 35,000 ppm Total Dissolved Solids (TDS) to drinking water standards is ~ 1.0 kWh/m3 This value assumes 35%

recovery at 25 degrees Celsius The working range to optimize

inefficiencies is, therefore, only 0.5 kWh/m3

The challenge of achieving an energy value target of 1.5 kWh/m3 is enormous

Recovery Rate

0%

4.8

0

kWh/m3

20% 40% 60%

3.4

1.5

0.8

Best Av ailable Technology

Target

Thermodynamic Minimum

Slide 4 Water Technologies

Process Schematic

Value Proposition Low pressure pumps, piping, valves, fittings, etc. Low vibration, low noise levels Less Pretreatment, Less Post-treatment Less corrosion concerns with non-metal piping Chlorine tolerant components Improved finished water quality Improved safety (elimination of high pressure)

SeawaterPost

Treatment

Drinking Water

Pumping Pretreatment Electrodialysis(ED)

Continuous Electrodeionization

(CEDI)

Slide 5 Water Technologies

What does this mean for the customers?

New desal technology will be “best available”

Siemens Value Proposition

Lower Maintenance

Lower Civil Costs

Higher Quality

Easier Operation

Energy Savings

Improv ed Safety

• Lowest total cost of ownership • Ability to desalinate under residential

water pressures (40 psi)• Reduction in maintenance, • Lower construction and civil. • Improvement in Health & Safety work

conditions

• Energy costs have only been the “tip of the iceburg“ of conditions limiting desalination

• Customers also have signifincant concerns on operating costs, consistency of performance and high water pressure work environment.

The Customer’s Challenges of Desalination

Slide 6 Water Technologies

Electrochemical DesalinationThe Technology: ED, CEDI

Cathode (-)

Anode (+)

Cation Exchange Membrane

Anion Exchange Membrane

Product

Brine

Na+

Na+

Cl-Na+

Na+

Cl-Cl

Na+ Na+

Cl-Cl-

Cl-Cl-

Na+

Na+

Cl-Na+

Na+Na+

Na+

Cl-Cl-

- - - - -

Cl-

+ + + + +

Na+ Na+Na+

Cation Exchange Membrane

Seawater

Slide 7 Water Technologies

ED Testing Results; Predictive Model

Fractions of Ions Remaining vs. TDS in ED ProductStandard Membranes

Synthetic Seawater as Feed

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 5000 10000 15000 20000 25000 30000 35000

TDS (ppm)

% Remaining

SO4-2

Mg+2

Ca+2

Na+1

Slide 8 Water Technologies

Advanced computer modeling (gPROMS) to simulate mass transfer

Investigating potential gradient at electrolyte-membrane interface

Expand to multi-component mixtures

Allow modeling of mixed-salt solutions

Mass Transfer, Boundary Layer Simulations (RWTH Aachen University, Prof. W. Marquardt)

Slide 9 Water Technologies

Prototype Testing

Initial lab tests confirmed feasibility of achieving 1.5 kWh/m3

Lab tests recycled water until 500 ppm TDS was achieved; voltage drops per cell pair were totaled

Prototype modules produced drinking water quality in a single pass

A prototype system yielded deionization energy of 1.7 kWh/m3; this value excluded pumping energy

Slide 10 Water Technologies

Membrane Development

Available membranes were characterized for resistance, permselectivity, strength, dimensional swelling, & others Available membranes used for industrial electrodialysis, diffusion dialysis,

and fuel cells are not conducive to seawater desalting & are very expensive Internal development has progressed well, including a trial run

Slide 11 Water Technologies

Transport Inefficiencies (Water Loss)

Other membrane properties were discovered which adversely affect deionization efficiency, including: Hydraulic Water Permeation

due to pressure gradient Osmotic Water Permeation due

to concentration gradient Electro-osmotic Water

Permeation due to ion hydration

Product TDS, ppm

0

10.0%

0%

Water Loss

10k 20k 30k

7.5%

5.0%

2.5%

40k

Electro-osmotic

Osmotic

Slide 12 Water Technologies

Module & Spacer Development

Module & Spacer designs seek to: Maximize deionization efficiency Minimize pumpage energy Minimize energy penalties due

to cross leakage, current leakage Minimize Donnan Potential,

Concentration Polarization Minimize electrode voltage,

scaling potentialy = 0.0184xR2 = 0.9853

y = 0.0171x2 + 0.2241xR 2 = 1

0.0

0.2

0.4

0.6

0.8

0.0 0.5 1.0 1.5 2.0 2.5

Flow velocity (cm/sec)

Pressure drop (psi)

0.00

0.02

0.04

0.06

0.08

Pressure gradient (psi/cm)

Pressuredrop in ports

Pressuregradient inchannel

Slide 13 Water Technologies

Power Contributing Processes

UF Pretreatment Pre-chlorination feed pump ED 1, 2, 3 Desalting energy (applied DC Current) ED 1, 2,3 conc, dilute pumping energy CEDI 1, 2, 3 Desalting energy (applied DC Current) CEDI 1, 2, 3 conc, dilute pumping energy ED, CEDI DC power supply efficiency factor ED, CEDI electrode solution pumps Boron Removal IEX column pumping energy

Slide 14 Water Technologies

EWI Project Deliverable

50 m3/d demonstration unit

Location: PUB Variable Salinity Plant, Pasir Ris, Singapore

Seawater storage tanks

Feed pumps & screens

UF pretreatment Desal ED + CEDI

Slide 15 Water Technologies

Demo Trailer – ED, CEDI

Slide 16 Water Technologies

Steps Towards Commercialization

A balance is needed, optimizing the combination of applied current & membrane area, e.g. Energy costs vs. Capital costs Alternate module

configurations are being explored The objective is to provide

Siemens customers with the lowest total cost of ownership The goal remains to transform

seawater to drinking water economically across the globeCurrent Density, A/m2

kWh/m3 m2/(m3/h)

Membrane Area Required

Energy Consumption

Slide 17 Water Technologies

Thank You