Electrodialysis: an overview on some industrial applications · Electrodialysis: an overview on some industrial applications PCCell GmbH Lebacher Str. 60 66265 Heusweiler, Germany

Electrodialysis: an overview on some industrial applications

PCCell GmbH Lebacher Str. 60 66265 Heusweiler, GermanyPhone +49 6806 603730Fax +49 6806 603731 [email protected]

Patrick Altmeier, Henning Bolz

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Electrodialysis: an overview on some industrial applications2

Electrodialysis vs. Reverse Osmosis

● ions move, solution stay

● concentrate „pure“

● uncharged material in diluate

● concentration electrically driven

Diluate

Ions

ED-Cell

DiluateConcen-trate

Water

RO-UnitPressureConcen-

trate

● water moves, ions stay

● diluate is „pure“

● undesired material in retentate

● concentration by pressure difference

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Case 1: MgSO4 Spa Water

Management● No effluent draining off possible● MgSO4 loss in spa need to be reduced● RO not capable to achieve sufficient

concentration level

Solution● Feed circles between ED (high concentrate

production) and RO (pure water production)

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How ions move in ED stack(and how water accompany ions)

A K A K AK

Konzentrat

Diluat

AK A K

A-A-

A-A-

M+

M+

M+

M+

O2 H2

A-

A-

M+

M+

A-

A-

M+

M+

A-

M+

A-

M+

K Cation Exchange Membrane blocks anions lets cations throughA Anion Exchange Membrane blocks cations lets anions throughIons move through membrane – with hydrate shell – with additional water

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Electroosmotic flow of water with chloride and sodium ions

PC

40

0D

PC

20

0D

PC

SA

PC

Aci

d1

00

PE

EK

PC

Aci

d6

0

PC

FE

L

AM

V

3 4 5 6 7 8 94

5

6

7

8

9

EO

F /

mo

l/F

AEM (vs. CMV)Result:

● Ionic transfer coupled with water transfer.

● Maximum concentration obtainable depends on membrane (in MgSO

4-case concentrations range from 14-20%)

Standard

High crosslinked (acidblocker)

Open membranes (for large ions)

Cation membrane:contributes with approx. 3 water/F

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Salt removal during batch desalinationi = const = 0,4 kA/m²

00:00 00:30 01:00 01:30 02:00 02:30 03:00 03:30 04:00 04:300

10

20

30

40

50

60

70

80

90

100

110

120

130

140 Diluat Konzentration

c(M

gS

O4

) /

g/l

Zeit

00:00 00:30 01:00 01:30 02:00 02:30 03:00 03:30 04:00 04:300

200

400

600

800

1000

1200

1400

1600

1800

n Mg Dil

n(M

gS

O4

) /

mm

ol

Zeit

● constant current transfer constant amount of MgSO

4.

● The water co-transfer reduces diluate volume → concentration drops down faster and faster.

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● Water reuse / disposal criteria: < 1 g/ L Cl- ● Iron salts need to be removed because of

chloride criteria

Solution● electrodialysis with multivalent ion permeation

and acidblocker anion exchange membranes● Excess acid reconcentration with monovalent

selective membranes

Case 2: Fe/HCl Scrubber Rinse Water Recycling

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EvaporatorConcd.

acid solution

feed solution

HCl / FeCl2

concd HCl/FeCl

2

45 l/m2h13,8 kWh/t

ion depleted waste stream

20 m³ / dca 4 g/L FeCl

2

ca 6 g/L HCl

19 m³ / dCa 0.8 g/L FeCl

2

Ca 0.3 g/L HCl

ca 1 m³ / dca 110 g/L FeCl

2

ca 120 g/L HCl

ED5 m² + 15 m²

PCCell ED 1000H

Solid Iron Oxide

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HCl removal from FeCl2/HCl mixture

00:30 00:45 01:00 01:15 01:30 01:45

0

100

200

300

400

500

600

700

Cond. Diluate out Cond. Diluate in Cond. Concentrate

Co

nd

uct

ivity

/ m

S/c

m

t / hh:mm Diluatetank (feed)

Pure acid removal with monovalent selective membranes:Conductivity in diluate and concentrate over time ina bach run with

Feed compositionCa 0.8 g/L FeCl

2

Ca 0.3 g/L HCl

Concentrate shape if multivalent selective membranes are used

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● Concentrate volume reduction to 300 L/h for evaporator

● Hardness in concentrate critical, CaCO3

transfer into concentrate to be minimised

Solution● electrodialysis with monovalent ion permeation● Pre-concentration with RO

Case 3: CIP Water Handling

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CIP waste rinsing water handling(high HCO

3--containing water)

Feed solutionNa2SO4/

NaCl

EDPCCell ED

1000H

Concd.salt

solution

Evaporator

ROCIP

permeate

RORetentat

e

Permeate

water

6000 L/h2800 ppm salt100 ppm CaCO3

(ca 60% Mg)

Distillate

Desal. solution

Salt waste





UF

CIP rinse feed

116 m² membrane area

4 Stacks with 29 m² each

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Example of a batch electrodialysis desalination kinetic

PC C e ll E D 6 4 0 02

PC C e ll B -ED 1 -2

Ex ter n al l iq u id t an k s

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Conductivity during a batch desalination

00:02 00:04 00:06 00:08 00:10 00:12 00:14 00:16 00:18 00:20 00:220,0

0,2

0,4

0,6

0,8

2468

10121416182022

Drinking water quality

LF Conc LF Dil

Co

nd

uct

ivity

/ m

S c

m

Time / h

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00:02 00:04 00:06 00:08 00:10 00:12 00:14 00:16 00:18 00:20 00:22

0

4

8

12

16

20

24 U

Vo

ltag

e /

V

Time / h

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

Cu

rre

nt

/ A

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Comparision of the conductivity at inlet and outlet of the cell

00:00 00:15 00:30 00:45 01:00 01:15 01:30 01:450

5

10

15

20

25

30

35

40

45

50

55

Ausschaltstufe: 0,58 mS/cm

Diffusionskoeffizient: 23,8 mS/cm/h/m2*L

ED288h, Standard SpacerED200, 20 ZellpaareUmax = 1V/ZPT = 21,8 - 27,3 °CDurchflüsse: DIL: 69,5 L/h KONZ: 177 L/hLF Konz max: 109,4 mS/cmLF Konz end: 108,4 mS/cm

Le

itfä

hig

keit

/ m

S/c

m

Zeit / h

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Thank you very much for your attention.

Any questions?

Documents

Electrodialysis: an overview on some industrial applications · Electrodialysis: an overview on some industrial applications PCCell GmbH Lebacher Str. 60 66265 Heusweiler, Germany