The Opportunities and Limitations of

Electromagnetic Field (EMF) for Scaling

Control

Pei Xu, Wenbin Jiang, Xuesong Xu, Juliano Aleida, Lu

Lin, Huiyao Wang, Randy Shaw

MSSC Summit, February 27, 2020

Scaling in Water Systems

Scaling in Water Systems

➢ Loss in performance and economics

➢ Chemical treatment

➢ Addition of scale inhibitors

➢ Chemical softening

➢ Ion-exchange

➢ Chemical cleaning

➢ Handling, storage, and management of chemicals

➢ Environmental and health impacts

Non-chemical Scaling Control –

Electromagnetic Field (EMF)

(a) Permanent magnets (b) Solenoid coil

(c) Schematic representations of wavesforms

Pilot Testing of EMF on RO Scaling Control during

Brackish Groundwater Desalination at BGNDRF

◼ Two types of EMF devices tested

HydroFLOW: induce an electric signal of ±150 kHz in the liquid

inside of a pipe on which they are installed. A specialized

transducer connected to a ring of ferrites performs the electric

induction

Pilot Testing of EMF on RO Scaling Control during

Brackish Groundwater Desalination at BGNDRF

◼ Two types of EMF devices

tested

HydroFLOW: HS48 was

installed in the metal pipeline

before the cartridge filter and

S38 was installed in the inlet

of the RO vessel.

Pilot Testing of EMF on RO Scaling Control during

Brackish Groundwater Desalination at BGNDRF

◼ Two types of EMF devices tested

Eco1st Separation Enhancer: an inline fluid ionization system

using electrochemical ionization principles. It induces EMF into the

flowing fluid and discharges electrons from the molecules exist in

the water. The free electrons will then be routed and drawn to a

dedicated earth ground.

Pilot Testing of EMF on RO Scaling Control during

Brackish Groundwater Desalination at BGNDRF

◼ Two types of EMF devices tested

Eco1st Separation Enhancer: installed before the cartridge filter of

a 2-stage RO system.

Feed Water Quality

◼ Two types of groundwater used

Water quality parameter Unit Well 1 Well 2

Temperature ℃ 21.3 27.0

pH pH unit 7.74 7.17

Electrical conductivity µmhos/cm 1840 6440

Total dissolved solids mg/L 1260 5850

Langelier Saturation Index SI 0.44 0.55

Total alkalinity (as CaCO3) mg/L 147 244

Chloride mg/L 36 521

Sulfate mg/L 723 3200

Total hardness (as CaCO3) mg/L 233 2550

Calcium mg/L 66 501

Magnesium mg/L 16 316

Potassium mg/L 4.7 2.1

Silicon dioxide mg/L 21.5 20.8

Sodium mg/L 305 650

Strontium mg/L 1.9 8.1

RO Scaling Simulation

◼ Scaling indices for the RO system based on the ROSA

modeling: Well 2 water at 50% water recovery

Parameter Feed Water Concentrate

Langelier Saturation Index 1.07 1.80

Stiff & Davis Stability Index 0.69 1.16

Ionic Strength (Molar) 0.14 0.29

CaSO4 (%Saturation) 105 238

BaSO4 (%Saturation) 174 352

SrSO4 (%Saturation) 71 150

Pilot Testing Results - HydroFLOW

◼ Membrane flux decline during 150 hr desalination of Well

2 water at 50% water recovery without antiscalant

0

10

20

30

40

70 90 110 130 150

Wate

r perm

eabili

ty d

eclin

e r

ate

(%

)

Operating time (h)

Phase 1 without EMF

Phase 2 with EMF 35%

Pilot Testing Results - HydroFLOW

◼ EMF + Hydraulic flushing partially restore membrane

performance

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0

10

20

30

40

50

60

70

80

90

100

0 100 200 300 400 500 600 700 800 900

Sp

ecific

w

ate

r flu

x a

t 2

5 o

C (

gfd

/psi)

Wa

ter

reco

ve

ry (%

)

Operating time (hours)

Phase 2 Water recovery

Phase 2 Specific water flux

Hydraulic flush

Pilot Testing Results - HydroFLOW

◼ Product Water Quality

60%

80%

100%

Na+ K+ Mg2+ Ca2+ Cl- SO42- Conductivity

Ions r

em

ove

al

No EMF With EMF

Pilot Testing Results - HydroFLOW

0

2000

4000

6000

0 1 2 3 4 5 6 7

Co

un

ts

Kev

P1E1-DI

C

N

O

Si

Al

FMg

S

NaK Ca Fe

(a)

0

4000

8000

12000

16000

0 1 2 3 4 5 6 7

Cou

nts

Kev

C

N

O SiAl

P1E3-DI

S Ca

(b)

0

4000

8000

12000

0 1 2 3 4 5 6 7

Cou

nts

Kev

P2E3-DIC

N

OSi

AlF

SMgNa Ca

(d)

0

4000

8000

12000

0 1 2 3 4 5 6 7

Cou

nts

Kev

P2E1-DIC

N

O Si

AlF

S

MgNa FeCaK

(c)

No EMF Lead

No EMF End

With EMF End

With EMF Lead

No EMF

With EMF

Pilot Testing Results

◼ Clean up the scales in the water pipelines

Bench-Scale Testing

➢ Impact of EMF on RO membrane fouling and

scaling during treatment of secondary effluent and

brackish water

Schematic Diagram

Bench Testing – Secondary Effluent

➢ EMF + hydraulic flushing can control membrane fouling

0

5

10

15

20

0 10 20

Flu

x d

eclin

e, %

Time, h

EMF + HD

Bench Testing – Secondary Effluent

➢ EMF + hydraulic flushing can control membrane fouling

0

5

10

15

20

0 10 20

Flu

x d

eclin

e, %

Time, h

Hydraulic clean EMF + HD

Factors Affecting EMF Effectiveness

Summary

➢ EMF requires no or low energy.

➢ EMF pretreatment can significantly reduce chemical costs,

energy, and negative environmental impacts of chemical

treatment.

➢ Reduce initial membrane scaling and fouling by 30-40%.

➢ Periodic hydraulic flushing + EMF can recover RO

membrane performance by removing the foulants loosely

accumulated on membrane surface and flow channels.

➢ Work at moderate water recovery.

➢ Promote bulk precipitation, spacer design is critical.

Future work

➢ Evaluate the combination of EMF with 3D printed

open flow channel RO membranes to achieve

high recovery

Future work

➢ Molecular dynamics simulations to gain insights

into how the applied electromagnetic fields effect

the motions of ions in the fluid. Develop methods

to compute polarizabilities, net atomic charges,

and force-field simulations on molecular

interactions between ions and membranes.

➢ Sensors to monitor the induction time and particle

motions.

Acknowledgements

➢ Bureau of Reclamation

➢BGNDRF

➢DWPR funding

➢ El Paso Water

➢ AquaMembranes

➢ HydroFLOW

➢ Eco1st

Pei Xu: pxu@nmsu.edu