AMTA/AWWA © 1

Ceramic Membranes for ReuseHolly Shorney-Darby, J. Zheng, G. Galjaard

PWN Technologies, the Netherlands

AMTA/AWWA © 2

acknowledgements

• Clement, Tian, and Tan (2009)

• Dow, Murphy, Clement, and Duke; Water, (2013)

• Zheng, Shorney-Darby, and Galjaard (2015)

• Metawater

AMTA/AWWA © 3

objectives

• evaluate pre-treatment to optimize the performance

of ceramic membranes for reuse applications

– coagulation

– oxidation

– performance parameters:

• flux

• cleaning protocols

• treated water quality

• suitability for downstream RO

• identify benefits of ceramic membranes in reuse

applications

AMTA/AWWA © 4

background

Location Membrane Pre-treatment

Bedok, Singapore intermediate Pre-coag, pre-ozone

Asian client 4.3 sqft (0.4 m2) Pre-coag, pre-chlorination and

pre-ozone

Australia 269 sqft (25 m2) Pre-coag, pre-ozone

Current Australia pilot 269 sqft (25 m2) Pre-coag, pre-ozone

Medemblik, NL 4.3 sqft (0.4 m2) Pre-coag, pre-ozone

Metawater Reuse Plant 269 sqft (25 m2) Pre-coag, pre-ozone

AMTA/AWWA © 5

ceramic microfiltration

• Metawater ceramic microfiltration module

• total membrane filtration area 25 m2 (269 ft2)

• pore size of 0.1 μm

• 2000 filtration channels

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coagulation and ozone pre-treatment

(Bedok, Singapore)

• 12 month pilot

• two intermediate sized membranes in parallel

• TOC = 6 to 7 mg/L

• turbidity = 5 to 6 NTU

• temperature = 29 oC

• initial testing showed PACl better than ferric coagulant

• ozone dosed directly upstream of membrane

contact time unknown

Clement, Tian, and Tan (2009)

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coagulation and ozone pre-treatment

(Bedok, Singapore)

PACl Flux Ozone Fouling Rate

(mg/L) (gfd) (lmh) (mg/L) (psi/day) (kPa/day)

2 119 200 0 2.5 – 5.1 17 - 35

Clement, Tian, and Tan (2009)

0

20

40

60

80

100

120

140

160

1 2 3 4 5 6 7

TM

P(K

pa

/da

y)

Days

FeCl3

PACL

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coagulation and ozone pre-treatment

(Bedok, Singapore)

PACl Flux Ozone Fouling Rate

(mg/L) (gfd) (lmh) (mg/L) (psi/day) (kPa/day)

2 119 200 0 2.5 – 5.1 17 - 35

2 - 6 119 200 2 - 6 0.07 - 0.1 0.5 - 0.7

Clement, Tian, and Tan (2009)

0

20

40

60

80

100

120

140

160

1 2 3 4 5 6 7

TM

P(K

pa

/da

y)

Days

FeCl3

PACL

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Ozone Dose (mg/L)

TM

P I

ncre

ase (

kp

a/d

ay)

0 2 4 6

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Australian pilot - Melbourne

• secondary effluent

• target ozone residual > 0.8 mg/L

• contact time not stated, few seconds

• DOC = 10 to 15 mg/L

• 90 day CIP target

• PACl coagulant (3 mg as Al3+/L)

Dow, Murphy, Clement, and Duke; Water, (2013)

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TMP curves at different flux for coagulation with

ozone pretreatment at Australian pilot

Dow, Murphy, Clement, and Duke; Water, (2013)

108 gfd (182 lmh)

100 gfd (169 lmh)

87 gfd (147 lmh)

higher flux not possible due to equipment size limitations

TMP

(bar)(psi)

44

36

22

15

7

0

29

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Ozone and coagulation pre-treatment

at Australian pilot

Flux = 96 gfd (162 lmh)

PACl = 3 mg/L as Al3+

Ozone = 0.5 mg/L

Dow, Murphy, Clement, and Duke; Water, (2013)

TMP

(bar)(psi)

36

22

15

7

0

29

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Asian client

• pilot with small membrane –

4.3 sqft (0.4 m2)

• approx 8 weeks testing

• TOC = 14 mg/L

• turbidity = 3 NTU

• ozone contactor = 1 minute

• coagulation = 2 minutes

• total ozone contact time = 3 minutes

AMTA/AWWA © 13

in-line coagulation pretreatment

Asian client (from Zheng, Shorney-Darby, and Galjaard, 2015)

Coagulant Flux Ozone Fouling Rate

(mg/L as Al3+) (gfd) (lmh) (mg/L) (psi/day) (kPa/day)

Up to 7 59 100 0 0.07 0.5

Up to 7 119 200 0 1.3 9.3

TMP (10 °C)

(kPa)(psi)

36

29

22

15

7

0

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Asian client

(pilot results for pre-coagulation)

Parameter Units Value

Flux (maximum instantaneous) lmh189

BW interval min 32

EBW frequency days 1 per day

Coagulant dose mg/L 6 mg/L Al3+

Coagulant mixing min 2.9

CIP target invertavl days >30

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TMP under different pre-treatment conditions

Asian client (from internal PWNT report)

• 59 gfd (100 lmh) for direct

filtration

• 119 gfd (200 lmh) for In-

line coagulation and pre-

ozone alone

• 178 gfd (300 lmh) for

combined pre-ozone and

coagulation pretreatment

>10mg/L applied ozone

dose

TMP (10 °C)

(kPa)(psi)

36

29

22

15

7

0

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SDI of membrane permeate

Asian client (Zheng, Shorney-Darby, and Galjaard (2015))

chlorinated feed unchlorinated feed

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DOC fractions

0

1

2

3

4

5

6

7

8

0 20 40 60 80 100

OC

D s

ignal (a

.u.)

retention time (minute)

Humic substances

Biopolymers

Building blocks

Low MW acids

Low MW neutrals

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NOM change and removal with pre-ozone and coagulation

Asian client (Zheng, Shorney-Darby, and Galjaard (2015))

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TOC concentration Sachtocklar PACl (6 mg/L Al3+)

flux of 112 gfd (189 lmh) with chlorinated feed water

Asian client (PWNT, internal report, 2014)

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Ozone Influence on Membrane Performance

Current Pilot, Australia

-17.8 kPa/day 65.3 kPa/day 21.3 kPa/day

Fouling Rate: Fouling Rate:

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Medemblik, NL Pilot

• starting up now

• coagulation and ozone pre-treatment

– measure ozone demand and decay

• systematic water quality evaluation

– organic characterization LC-OCD

– metals

– general water quality

– biological quality

• bench-scale ion exchange pre-treatment

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full-scale treatment

• Metawater research – similar findings

– residual ozone control

– coagulant dose optimization

– residual ozone concentration

• full-scale system in Japan

– comparable flux

– CIP interval > year

– optimized coagulant dose and BW interval

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conclusions

Site Achieved flux Pre-treatment Other highlights

Bedok, Singapore 119 gfd (200 lmh) PACl + ozone Ozone greatly reduced fouling rate

Australian Pilot108 gfd (182 lmh)[higher flux possible]

PACl + ozone

Ozone > 0.8 mg/L residual on

membrane (>>90 day CIP interval);

PACl dose at 3 mg/L Al3+

ACC 178 gfd (300 lmh) PACl + ozoneLow SDI, but high ozone dose

needed (e.g., ~ 10 mg/L)

ACC 112 gfd (189 lmh) PAClOptimized dose at approx. 2 to 6

mg/L as Al3+

Medemblik, NL To be determined Coagulant, ion exchange, ozone Broader water quality evaluation

• Optimized pre-treatment, with coagulation and sometimes oxidation, can

yield sustainable and high flux with ceramic membranes

• More research needed on treated water quality

AMTA/AWWA © 24

conclusions

• ceramic membranes can perform well for secondary

effluent reuse applications

• coagulation necessary for fouling control

• PACl often used

• ozone can:

– increase sustainable flux

– reduce CIP frequency

– lower operating TMP

– provide disinfection and oxidation

– (but ozone demand is often high)

AMTA/AWWA © 25

questions