2011 Salinity Summit

Contributions to Permeation Resistance in a VSEP RO System Treating Brackish Water or Brine

Mark Benjamin and Wei Shi

Department of Civil and Environmental Engineering, University of Washington, Seattle, WA 98195

Reverse Osmosis (RO) Reverse Osmosis (RO):

Increasingly used in treatment of brackish water and brine for potable water

Fouling: Production

Time

Pressure

Time

Constant Pressure Constant Production

VSEP Vibratory Shear Enhanced

Processing

Source: New Logic Research Inc. Emeryville, CA

Shear

VSEP Applications

Landfill Leachate Manure Management Mining Petroleum Processing Pulp and Paper Desalination

VSEP Operation

ConcentrateFeed

Pump

Feed tank

Amplitude: 13°Frequency: 55HzTMP: 140 psi

RO Feed Composition

Brackish water*

Brine: 10 times as concentrated

pH 8.0 Cl 175Ca 275 as CaCO3 Ba 25Mg 100 as CaCO3 Si 5SO4 350 Fe 0.5Na 175 Alk 150 as CaCO3

TDS 1050* All units in mg/L, except for pH

Permeate FluxBrackish solution

0

10

20

30

40

50

0.0 0.2 0.4 0.6 0.8 1.0Recovery

Flux

(L/m

2 -h)

w/ vibrationw/o vibration

Permeate FluxBrine

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0

5

10

15

20

25w/o vibrationw/ vibration

Recovery

Flux

(L/m

2-h)

Resistance Breakdown

Rm

RTOT

Rπ

RFRF

= RTOT –Rm –RCP–Rπ

RCP

Contributions to Resistance

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0

10000000000000

20000000000000

30000000000000

40000000000000

50000000000000MembraneOsmotic PFoulingCPTotal

Recovery

Res

ista

nce

(m-1

)

w/ w/o vibrationBrackish solution

inlet outlet

S1S2S3S4

w/o Vibration

w/ Vibration

Higher Shear

Painted Membrane Tests

Shaded Area

Ring for permeation

5.0

5.1

2,

22Re2

F

RAr

hr

ravg(Jaffrin et al. 2002)

r

A

0 100 200 300 400 5000.0

0.2

0.4

0.6

0.8

1.0

5, 0.6410, 0.32 5, 1.2710, 0.6413, 0.9510, 1.2710, 1.5913, 1.27

Specific Volume (L/m2)

Rel

ativ

e Fl

ux (J

/J0)

R, A

Painted Membrane Tests

Painted Membrane Tests

9.0 9.4 9.8 10.2 10.6 11.0-1.0

-0.8

-0.6

-0.4

-0.2

0.0

f(x) = 0.378849919316468 x − 4.28982761861908R² = 0.96729281987083

ln(γ)

ln(J

/J0)

0.380/ 0.137 WJ J

Mechanisms to Generate Shear

Membrane Rotation

Ultrasound

Longitudinal Vibration

Shear- fouling relationship

Torsional Vibration

Conclusions Membrane vibration

Increases permeate flux Reduces the contribution of fouling

to the total resistance Changes scale morphology into

more porous structures Shear Rate

Governs fouling of RO membranes

Facilitate the design of similar systems for fouling prevention/reduction

Acknowledgements This work was supported by the Water

Research Foundation (WRF) *. The authors thank New Logic Research,

Inc., for providing the test unit. Yujung Chang and Pierre Kwan of HDR,

Inc., and Sommer Carter of NLR provided valuable technical assistance during the project.

*The views expressed are those of the authors and do not necessarily reflect those of WRF.

RO Membranes

inlet outlet

0.9 cm10.0 cm

10.24 cm

Membrane BW-30 FEMWCO (da) 50 30

Material Polyamide

Polyamide

pH 1-12 2-11Tmax (oC) 70 60

Cl2 Tolerance (mg/L) <0.1 <0.1Flux*

(L/m2‑h) 71 90Vendor Filmtec Saehan

*At a TMP of 2068 kPa

Solute Rejections

Brackish solution

Brine

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0

200

400

600

800

1000

0

2000

4000

6000

8000

10000Permeate, w/o vibrationPermeate, w/ vibrationFeed, w/o vibrationFeed, w/ vibration

Recovery

Con

duct

ivity

(uS/

cm)

Con

duct

ivity

(uS)

Mg Ca Na Si Cl SO450

60

70

80

90

100 w/o vibrationw/ vibration

Rej

ectio

n (%

)

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0

600

1200

1800

2400

3000

0

20000

40000

60000

80000Permeate, w/o vibraitonPermeate, w/ vibrationFeed, w/o vibrationFeed, w/ vibration

Recovery

Con

duct

ivity

(uS/

cm)

Con

duct

ivity

(uS)

Mg Ca Na Si Cl SO450

60

70

80

90

100 w/o vibrationw/ vibration

Rej

ectio

n (%

)

Solid Precipitation EDAX spectrum of scales on the membrane surface

Gypsum

Aragonite

Solid Precipitation - XRD XRD spectrum of precipitates in the feed solution