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1. Compare the effect of coagulation conditions (e.g. dose, pH) for

conventional coagulation (coagulation/ flocculation/ sedimentation/

filtration) on RO feed water quality in terms of TEP and biopolymers

removal and RO fouling potential (MFI-UF) reduction.

2. Understand and propose mechanisms for the interaction between TEPs,

biopolymers and coagulant using analytical techniques such as FTIR,

Laser Raman Microscopy, etc.

3. Simulate the fouling rate and CIP frequency in SWRO using a model

equation in combination with MFI-UF values obtained from different

coagulation conditions.

KEMIRA Project

Objective 1

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Research Approach

2

Compare effect of coagulation conditions on RO feed quality

Understand mechanisms

between coagulant and TEPs

Simulate CIP frequency in RO

membranes

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Experimental Conditions

3

Compare effect of coagulation conditions on RO feed quality

PIX-111

FeCl3Cellulose acetate

0.45m

Coagulation Conditions Filtration Conditions

RM G = 1,100s-1

RM t = 20s

Settling t = 20min

Flocculation G = 45s-1

Flocculation t = 15min

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Experimental Matrix

4

pH Coagulant dose (mgFe/L)

80 0.5 1 5 10 20

5

Settled Filtered

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Analytical Parameters

5

Settled Filtered

Biopolymers

MFI-UF10kDa

TEP10kDa

TEP0.4

Fe

UV254

Turbidity

-

x

x

x

x

-

x

x

x

x

x

x

x

x

Volume [mL]

40

60

1000

100

100

100

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Sample Preparation

Maximum volume that can be withdrawn from each jar = 500mL Volume required per experimental condition (dose, pH) = 1.5L, hence 3

jars are coagulated per experiment

6

Jar 3TEP0.4 Filtered

Jar 2TEP0.4

Settled

Jar 1 Settled/Filtered

LC-OCD (biopolymers)

Fe, UV254, Turbidity

TEP10kDaMFI-UF10kDa

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Biopolymers Conc.

2.3mgC/L

Chaetoceros affinis (marine diatom)

0.0

0.5

1.0

1.5

2.0

0 20 40 60 80 100

rel.SignalResponse

Time [min]

20kDa < Biopolymers < 2m

7

LC-OCD Analysis (harvest day 15)

Feed Water

Feed solution concentration for experiments = 0.5mgC/L as biopolymers

Total feed water volume required for all experiments = 36L Ideally all experiments within this matrix should be done with the same

batch of TEP

Experiments were performed with 2 distinct batches of TEP

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Results

8

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Effect of Coagulation on MFI-UF10kDa

MFI-UF10kDa decreases consistently with increase in coagulant dose for settled and filtered water samples at pH 8

At pH 5, MFI-UF10kDa values do not decrease significantly for settled samples for coagulant dose > 5mgFe/L

Filtration through 0.45m significantly reduces MFI-UF10kDa for both pH values

9

bdl0

5000

10000

15000

20000

25000

30000

SSW Feed 0 0.5 1 5 10 20

MFI-UF10kDa

[s/L2]

Coagulant Dose [mg Fe/L]

Settled (pH=8) Filtered (pH=8)

0

5000

10000

15000

20000

25000

30000

SSW Feed 0 0.5 1 5 10 20

MFI-UF10kDa

[s/

L2]

Coagulant Dose [mg Fe/L]

Settled (pH=5) Filtered (pH=5)

MFI-UF10kDa measurements performed with 10kDa regenerated cellulose (RC) filters at 60L/m2h

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Normalized MFI-UF10kDa

10

bdl0%

20%

40%

60%

80%

100%

120%

SSW Feed 0 0.5 1 5 10 20

NormalizedMFI-UF10kDa

Coagulant dose (mg Fe/L)

Settled (pH=8) Settled (pH=5) Filtered (pH=8) Filtered (pH=5)

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Fe Residual

Settled supernatant exceeds RO manufacturers recommendation for RO feed; 0.05mgFe/L

At pH 5, filtration through 0.45m does not reduce iron residual below guideline value

11

0.0

0.4

0.8

1.2

1.6

2.0

2.4

Feed 0 0.5 1 5 10 20

FeResidual[mgFe/L]

Coagulant Dose [mg Fe/L]

Settled (pH 5) Filtered (pH 5)

bdlbdl bdl0.0

0.4

0.8

1.2

1.6

2.0

2.4

SSW Feed 0 0.5 1 5 10 20

FeResidual[mgFe/L]

Coagulant dose [mg Fe/L]

Settled (pH 8) Filtered (pH 8)

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Effect of Coagulation on UV254 Absorbance

UV254 absorbance increases with the presence of dissolved iron at pH 5

UV254absorbance is reduced for coagulant dose 5mgFe/L at pH 8

12

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

SSW Feed 0 0.5 1 5 10 20

UV254

[abs/cm]

Coagulant Dose [mg Fe/L]

Filtered (pH=8) Filtered (pH=5)

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Effect of Coagulation on Turbidity

For settled water, turbidity decreases with increase in coagulant dose at pH 8. This trend is not observed

at pH 5

Filtration reduces turbidity well below the RO feed recommended turbidity of1.0 NTU for both pH values

13

0.0

0.4

0.8

1.2

1.6

2.0

2.4

SSW Feed 0 0.5 1 5 10 20

Turbidity[NTU]

Coagulant dose [mg Fe/L]

Settled (pH 8) Filtered (pH 8)

0.0

0.4

0.8

1.2

1.6

2.0

2.4

SSW Feed 0 0.5 1 5 10 20

Turbidity[NTU]

Coagulant dose [mg Fe/L]

Settled (pH 5) Filtered (pH 5)

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Biopolymers Concentration (LC-OCD)

Biopolymer reduction is relatively higher for pH 8 than pH 5

Maximum biopolymers removal is approximately 70% at 20mgFe/L and pH 8

14

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0

100

200

300

400

500

600

700

SSW Feed 0 0.5 1 5 10 20

Nor

alized

Re

oval

BiopolymerConcentration[g/L]

Coagulant dose [mg Fe/L]

BP (pH 8) BP (pH 5) Removal (pH 8) Removal (pH 5)

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F-EEM Settled Samples at pH 8

Protein-like peak observed for feed water, that decreases in intensity with increase in

coagulant dose

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SSW Blank Feed 0mgFe/L 0.5mgFe/L

1mgFe/L 5mgFe/L 10mgFe/L 20mgFe/L

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F-EEM Filtered Samples at pH 8

Filtration almost completely eliminates the protein-like peak

Increase in coagulant dose does not significantly affect the intensities of the peaks

16

Feed 0mgFe/L 0.5mgFe/L 1mgFe/L

5mgFe/L 10mgFe/L 20mgFe/L

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F-EEM Settled Samples at pH 5

17

SSW Blank Feed 0mgFe/L 0.5mgFe/L

1mgFe/L 5mgFe/L 10mgFe/L 20mgFe/L

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F-EEM Filtered Samples at pH 5

18Feed, Filtered

SSW Blank Feed 0mgFe/L 0.5mgFe/L

5mgFe/L 10mgFe/L 20mgFe/L

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Effect of Coagulation on TEP0.4

19

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

Feed 0 0.5 1 5 10 20

TEP0.4um(

mgXeq/L)

Settled pH 8 Filtered pH 8

LOD

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Effect of Coagulation on TEP10kDa

20

0

1

2

3

4

5

6

7

8

SSW Feed 0 0.5 1 5 10 20

TEP10kDA[mgX

eq/L]

Coagulant dose (mg Fe/L)

Settled (pH=8) Filtered (pH=8)

0

1

2

3

4

5

6

7

Feed 0 0.5 1 5 10 20

TEP10kDa(mg

Xeq/L)

Coagulant Dose [mgFe/L]

Settled (pH 5) Filtered (pH 5)

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Summary of Findings

MFI-UF10kDa is significantly lowered for coagulant doses>10mgFe/L and filtration through 0.45m

Turbidity residual is strongly enhanced (to

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Plan of Experiments

Complete TEP0.4 measurements for settled andfiltered samples at pH 5

22

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Thank You!

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