Y. Watanabe, DirectorCenter for Environmental Nano & Bio Engineering

Hokkaido University, Sapporo, JAPAN

Co-researchers:K. Kimura and H. Yamamura (Hokkaido Univ.)

H. Yonekawa (META Water corp.)T. Suzuki (Maezawa Kogyo corp.)

Mechanism and Control of Membrane Fouling in Water Purification

8th International Symposium on Water Supply Technology, 10-12, June 2009, Kobe

Am

ount

of w

ater

（m

3/d）

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

35,000,000

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

SWRONF+BWROLP+MF+UF

32,000,000 m3/d, 2006

（引用）膜分離技術振興協会: 浄水膜第2版（技報堂出版），p6, 2008.2

Global amount of water produced by membrane processesGlobal amount of water produced by membrane processes

Increase by 25 % each yearIncrease by 25 % each year

配水管内における微粒子の挙動

(Vreeburg, et.al, 2008)

Pipe cleaningSand filtration: Every 0.5 yearsMembrane filtration: Every 15 years

消毒のみ20.0%

緩速ろ過3.9% 膜ろ過

0.1%

急速ろ過76.0%

Disinfection

Slow Sand Filtration Membrane Filtration:

84 x 104 m3/day (1.2 %) in 2007

Rapid Sand Filtration

Total production of drinking water: 6900 x 104 m3/day

173,000 m3/d membrane filtration plant under construction in Yokohama city

101 x 104 m3/day (1.5%) in 2009

586 plants in 2006 623 plants in 2007

Water Purification Processes in Japan

In 1999

Renewal

New

Cross sectionLow foulinglayer

Supportlayer(high flux &high Strength)

Composite membrane

Line-up of PVDF hollow fiber membranes (Toray products)LineLine--up of PVDF hollow fiber membranes (Toray products)up of PVDF hollow fiber membranes (Toray products)

HFSPore sizeor MWCO 0.1 m

HFM HFU

150kDa0.02 m

Pretreatment None No Need or CoagulationCoagulation

Applicable ave.Feed turbidity ~ 0.05 NTU ~ 30 NTU ~ 50 NTU

Applicable Flux ~ 5.0 m/d(208 lmh)

~ 3.0 m/d(125 lmh)

~ 3.0 m/d(125 lmh)

Most Suitable membrane can be selected to meet the feed water quality.

Water source Ground water Surface water Surface water

Advance ｏｆ Monolith Ceramic Membrane

10

100

1000

5m3/m2/day2.5m3/m2/day1.8m3/m2/day1.5m3/m2/day

150m2 240m2/module73m213m28.9m2

Configuration unit Tube MonolithStage 1985 1988 1990 1994 2001 (2006)Length mm 1,000 1,500Diameter mm 10 30 180Channel Number － 1 19 37 61 2000Channel Diameter mm 7 4 3 2.5Membrane Area m2 0.02 0.24 0.35 0.48 15 24Packing Density m2/L 0.25 0.34 0.50 0.63 0.6 0.63Application － Industrial Use Water Purification

Modu

le C

apac

ity

(m3/da

y/m

odu

le)

8/26

Fe or Al micro-floc(5-10 µm)

Bacteria(1-2 µm)

Diatom(20 µm)

Clay particle(1-3 µm)

Cryptosporidium(7-12 µm)

Mechanism Size exclusion

Advantages • Strict removal of suspended and colloidal matters

• Easy operation without any special skill• Small footprint

Water

Membrane filtration

Conc.

mm

nm

μm

Å

suspendedmatters

colloidmatters

dissolvedmatters

Impu

rity

size

Impurities

siltsalgae

bacteriaprotein

oxidized substances (SiO2, Fe2O3, Al2O3, MnO2,etc.)humic acids

virus

taste and odor producinginorganic ions (Fe2+, Mn2+,

etc.)fulvic acids

Coagulation/Sedimentation＋MF・UF filtration

MF・UFfiltration

Adsorption,Ion exchange

+MF･UF

synthetic organic compounds (DDT,BHC, PCB,etc.)Inorganic compounds (Arsenic, Antimon, Selenium, etc.)

NF filtration

saccharoidOzonation, Activatedcarbon adsorption,Biological oxidation＋MF・UF filtration

protozoa (cryptosporidium , giardia , etc.)

organic･inorganic soil(clay, microorganisms, highmolecular weight humics, etc.)

Coagulation＋MF・UF

Design Matrix of MF/UF Membrane SystemDesign Matrix of MF/UF Membrane System

Monolith Ceramic Ｍｅｍｂｒａｎｅ ( META Water Product)

5

Magnification

Profile of G and GCt Value in Monolith Channel with low κ

100

G value 20sec-1

40

60

80

2.5mmChannel diameter

Flux

2 m2 m33/m/m22/day/dayC

han

nel Len

gth

1.00

0 1.

000

㎜㎜

Recovery

90 90 ％％

Let’s consider

“flocculation condition in channel”

Especially, near the membrane surface

GG value

20-100sec-1 : desirable value for flocculation

Contact TTime

Enough. : Laminar velocity is very low.

CConcentration.

Highly concentrated : accompanied by filtration

19

Floc Re-aggregation in Monolith Channel

IWA NANO & PARTICLES (Sep. 23, 2003)

)r/(duv opoL232 32Lateral migration

Shear-induced Diffusion )r/(du.v opoS 22 4050

(b) aggregation

Shear induced lift force

(c) lifting from membrane

Ceramic membrane surface

Disaggregated floc particles

ｕ(membrane flux)

Ceramic membrane surface

(a)carrying near the membraneaccompanied with filtration

P

Coagulant (PACl) Small membrane

Filtrate

MM

0

4

8

12

16

20

1 10 100

Particle Size [ m]

Freq

uenc

y (V

olum

e ba

sed)

[%]

SP1

SP1

SP2

SP2

SP3

SP3

SP4

SP4

Particle Size in pre-coagulated Monolith Membrane System

18

0

2

4

6

8

10

0 2 4 6

Log

viru

s re

mov

al (l

og (C

/C0)

)

Operating time, h

1.62 mg Al/L

1.08 mg Al/L

0.54 mg Al/L

CoagulantDosage: varying

CT:2.4 s

Pore:0.1 m

Matsushita, T., Matsui, Y., Shirasaki, N. and Kato, Y., Effect of membrane pore size, coagulation time, and coagulant dose on virus removal by a coagulation-ceramic microfiltration hybrid system, Proceedings of EDS 6th International Conference on Membranes in Drinking and Industrial Water Production, L'aquila, Italy, 15-17 November 2004 (Keynote Speech), selected for publication in Desalination, 178 (1-3), 21-26, 2005.

Virus Removal by Coagulation-MF

PACl doseFlux=1.5 m/dayChannel length=10 cm

Conc.

mm

nm

μm

Å

suspendedmatters

colloidmatters

dissolvedmatters

Impu

rity

size

Impurities

siltsalgae

bacteriaprotein

oxidized substances (SiO2, Fe2O3, Al2O3, MnO2,etc.)humic acids

virus

taste and odor producinginorganic ions (Fe2+, Mn2+,

etc.)fulvic acids

Coagulation/Sedimentation＋MF・UF filtration

MF・UFfiltration

Adsorption,Ion exchange

+MF･UF

synthetic organic compounds (DDT,BHC, PCB,etc.)Inorganic compounds (Arsenic, Antimon, Selenium, etc.)

NF filtration

saccharoidOzonation, Activatedcarbon adsorption,Biological oxidation＋MF・UF filtration

protozoa (cryptosporidium , giardia , etc.)

organic･inorganic soil(clay, microorganisms, highmolecular weight humics, etc.)

Coagulation＋MF・UF

Design Matrix of MF/UF Membrane SystemDesign Matrix of MF/UF Membrane System

原水

粉末活性炭

浸漬型膜装置

処理水槽

塩素PACl凝集剤

P

P

B膜透過水

ｴｱｰｽｸﾗﾋﾞﾝｸﾞ用空気

処理水ポンプ

逆洗ポンプ

ﾌﾞﾛﾜｰ

P

循環ポンプ

循環水

Hybrid Submerged MF membrane system including coagulation, carbon adsorptionand biological oxidation

PAC

Raw water

Submerged MF membranes

Cl2

0

0.2

0.4

0.6

0.8

Membrane Flux

m/day

0

5

10

15

20

25

30

Water

temperature ℃

Flux

Water Temperature

0102030405060708090

100

3-Jun

3-Jul

2-Aug

1-Sep

1-Oct

31-Oct

30-Nov

TMP kPa

2002

0 30 60 90 120 150

Operating days

Change in Flux and TMP: symmetrical PTFETMP increase for symmetric PTFE MF membrane ( pore size=0.1μm)

New Composite PTFE membrane with a skin layer of 15μmand porosity of about 80 %

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Mem

bran

e　

Flu

x　m

/da

y

0

10

20

30

40

50

Wat

er　

Tem

pera

ture

　℃

Flux

Water　Temperature

TemperaturFkux

Average membrane Flux:: 1.2m/day

:

0

10

20

30

40

50

60

70

80

90

100

4-D

ec

3-Jan

2-Feb

3-M

ar

2-A

pr

2-M

ay

1-Jun

1-Jul

31-Jul

30-A

ug

TM

P　

ｋＰ

ａ

Chemical

　Washing

0 30 60 90 120 150 180 210 240 270

Operating　days

2 .4 32 .2 9

1 .1 7

0

0 .5

1

1 .5

2

2 .5

3

3 .5

4

T O C

mg/

l

r a w w a t e r

r a w w a t e r (s o lu b le )

m e m b r a n e f ilt r a t e 0 .0 9 9

0 .0 8 6

0 .0 1 7

0 .0 3 1

0

0 .0 2

0 .0 4

0 .0 6

0 .0 8

0 .1

0 .1 2

E 2 6 0 T H M F P

1/cm

m

g/l

2 0 0 3 / 9 / 1 ～ 2 0 0 4 8 / 3 1

Permeate Quality of Hybrid PTFE MF membrane systemRemoval Efficiency of TOC, E260, THMFPin Hybrid System

0.1

05

0.1

5

0.0

90

0.0

16

0.0

1

0

0.05

0.1

0.15

0.2

0.25

0.3

Manganese Ammonia nitrogen

mg/

l

raw water

raw water (soluble)

membrane filtrate

2003/6/25～11/13

without pre-chlorination

(biological oxidation)

0.1

00

0.2

3

0.0

79

0.0

02

0.0

1

0

0.05

0.1

0.15

0.2

0.25

0.3

Manganese Ammonia nitrogen

mg/

l

raw water raw water (soluble)

membrane filtrate

2003/11/13～2004/8/31

with pre-chlorination

(chemical oxidation)

Removal Efficiency of Mn and NH4-N in Hybrid System

21/26Drawback of membrane filtration

Membrane fouling

Physically reversible fouling Physically irreversible fouling

which can be canceledby physical cleaning

which is difficult to be canceled by physical cleaning

(Canceled by chemical cleaning)

Chemical cleaning will cause significant problemsDamage of membrane materialDisposal of chemical reagents…

Control of physically irreversible fouling is important

Pre-coagulation for monolith ceramic MF Membrane

Hybrid system

22/26

Lake Inbanuma

Yodo RW

Toyohira RW

Kushiro RWVery clean river water

River water containinglarge amount of HA

Eutrophic lake water

River water containinglarge amount of EfOM

NOM samples used for fractionation

Removal of divalent ions with cation exchange

resins

Concentration of NOM with RO membrane

Removal of particleswith cartridge filter

Four different natural water samples (400L) were used for fractionation

TOC=2.5 mg/L

TOC= 2.8 mg/L

TOC = 5.7 mg/L

TOC = 2.6 mg/L

23/26

Tran

s-m

embr

ane

pres

sure

(kPa

)

HPI fraction of NOM contributed to the physically irreversible fouling regardless of the types of NOM sources

Fraction contributing to membrane foulingTr

ans-

mem

bran

e pr

essu

re (k

Pa)

Toyohira RW (HPI) Lake Inbanuma (HPI) Kushiro RW (HPI) Yodo RW (HPI)

Toyohira RW (HPO) Lake Inbanuma (HPO) Kushiro RW (HPO) Yodo RW (HPO)

24/62

Change in TMP difference during pilot run.Rate of accumulation of physically irreversible fouling

was fairly different depending on membrane materialsRate of accumulation of physically irreversible fouling

was fairly different depending on membrane materials

Tans

-mem

bran

e pr

essu

re (k

Pa)

Operation time (days)

Variation of TMP in two membranes in pilot plant

Additional physical cleaning

Development of physically irreversible fouling

Raw water = Chitose River water

25/62

Carbohydrate

Chemical shift (ppm)

NMR spectra of extracted foulant by NaOH solution.

PVDF

PE

Carbohydrate-like substances mainly contributed to the physically irreversible fouling

Carbohydrate-like substances mainly contributed to the physically irreversible fouling

NMR results - Organic matters extracted by NaOH

26/26

Electrostatic

1. Electrostatic repulsion2. Van der Waals interaction3. Hydrogen bond

-4mV -4mV

-126mV-130mV

Carboxyl-group(COOH)

Hydroxyl-group(OH)

Forces exerted on particles

Van der Waals interaction

Hydrogen bond

Adh

esio

n fo

rce

(nN

)

Adh

esio

n fo

rce

(nN

)

Hydroxyl-microsphere(carbohydrate)

Carboxyl-microsphere(humic acid)

Membrane material vs. adhesion force of foulants

BSA-microsphere(protein)

Adh

esio

n fo

rce

(nN

)

28/62

1. Degree of physically irreversible fouling was different(PVDF membrane > PE membrane)

2. Carbohydrate-like substances mainly contributed to the development of physically irreversible fouling for both membranes

3. HPI fraction of NOM contributed to the physically irreversible fouling regardless of the types of NOM sources

Summary 1 ( Continuous Experiments)

29/62

1. Hydroxyl groups showed much higher adhesion force than carboxyl groups possibly because the generation of hydrogen bond

2. Affinity of hydroxyl group was much higher for PVDF membrane than for PE membrane, possibly due to the high electronegative nature of PVDF

3. Significant adhesion force of hydroxyl group was seen even when the membrane was fouled to a large extent

Summary 2 (Fouling mechanisms)

There is a possibility to prevent fouling by using membrane that has low affinity for hydroxyl group

(1) Pre-ozonation + PVDF membrane

(2) Monolith ceramic membrane with chemically enhanced backwashing

Membrane filtration systems with high flux operation

Pre-Ozonation- PVDF MF Membrane System PrePre--OzonationOzonation-- PVDF MF Membrane System PVDF MF Membrane System

オゾン反応塔 滞留塔

千歳川表流水

滞留塔オゾン反応塔 空気曝気塔

オゾン注入 空気注入

P

膜透過水

水逆洗

エア

P

膜透過水

膜モジュール

水逆洗

エア

オゾン注入

P

膜透過水

水逆洗

エア

膜モジュール

膜モジュール

Ｏｚｏｎａｔｉｏｎ－ＭｅｍｂｒａｎｅResidual O3

Run－4.1、4.2Run－5.1、5.2

Ｏｚｏｎａｔｉｏｎ－ＭｅｍｂｒａｎｅResidual O3

Run－4.1、4.2Run－5.1、5.2

Ozonation－Membrane

No residual o3Run－4.3Run－5.3

Ozonation－Membrane

No residual o3Run－4.3Run－5.3

MembraneRun－4.4Run－5.4

MembraneRun－4.4Run－5.4

Pressurized membrane⇒Pore size:0.1μm(MF)⇒ PVDF(polyvinylidenefluoride)

Pressurized membrane⇒Pore size:0.1μm(MF)⇒ PVDF(polyvinylidenefluoride)

O3

Chitose R.water

O2

Permeate

O3

PVDF membrane

Fig.6 High Flux experiment using acid CEB.

40 30 20 10 0

40 30 20 10 0

14 24 13. 03/ Feb. 23 04/ Jan. 14 24 13. 03/ Feb. 23 04/ Jan. Date

Ceramic MembraneCeramic MembraneCoagulation Mn oxidization

CEB(Acid) Experimental Flow

TMP

(kPa

) 10 m3/m2/day

8 m3/m2/day

6 m3/m2/day 4 m3/m2/day, without CEB with CEB

Fig.6 High Flux experiment using acid CEB.

40 30 20 10 0

40 30 20 10 0

14 24 13. 03/ Feb. 23 04/ Jan. 14 24 13. 03/ Feb. 23 04/ Jan. Date

Ceramic MembraneCeramic MembraneCoagulation Mn oxidization

CEB(Acid) Experimental Flow

TMP

(kPa

) 10 m3/m2/day

8 m3/m2/day

6 m3/m2/day 4 m3/m2/day, without CEB4 m3/m2/day, without CEB with CEB

High Flux Experiment of Monolith Ceramic Membrane Using Acid CEHigh Flux Experiment of Monolith Ceramic Membrane Using Acid CEBB

Conclusions

1: Characteristics of components causing physically irreversible fouling

2: Affinity of carbohydrate-like substances to membrane surface

3: High flux membrane filtration system with pre-Ozonation or CEB

To gain the knowledge about the constituents and mechanisms related to physically irreversible fouling

To gain the knowledge about the constituents and mechanisms related to physically irreversible fouling