FlocFloc, EPS and Membrane , EPS and Membrane FoulingFouling

DD. . JJ.. LeeLeeChemical EngineeringChemical Engineering DepartmentDepartmentNational Taiwan UniversityNational Taiwan UniversityTaipei 106, TaiwanTaipei 106, Taiwan

Disclaimer

EffluentBRPre-Stage Film

Two-phase flowO2 transfer

Adapting MOsMonitoring

etc

Fouling controlNew membrane

Monitoringetc

Pre-coagulationExtraction

PrevaporationPhase transfer

etc

MonitoringGene Chip

etc

Process Integration, backwashing sequence, risk assessment, etc

What occurs in MBRWhat occurs in MBR

Hygienic permeate

Bubbly shear flow

Adapting MicrobialCommunity

Fouling Layer

Membrane Ultrafiltration

RETENTATE

PERMEATE

PERMEATE

BOUNDARYLAYER

BOUNDARYLAYER

FEED

MEMBRANE

MEMBRANE

}

}

To reduce fouling:To reduce fouling:

1. Pretreatments of feed solution2. Modifying membrane properties3. Cleaning4. Positive control

- Assisted field (electric, vibrating, etc)- Flow manipulation

1. Turbulence promoters2. Secondary flow3. Pulsating flow4. Gas-liquid two-phase flow

0.0 40.0 80.0 120.0 160.0 200.0Time (min)

0.0

10.0

20.0

30.0

J v x 1

06 (m

3 /m2 -

s)

0.15um PMMA solutes VG= 5 l/min C = 3000 mg/l £K = 90¢X

-20 cmHg

-40 cmHg-60 cmHg

MWCO = 500 k

MWCO = 50 k

Flow Patterns in MBRFlow Patterns in MBRmembrane membrane

bubbly flow slug flow

bubble

Affects Floc Deposition & Detachment

Low Gas Flowrate & Low ∆P

High Gas Flowrate & Large ∆P

Effect of ∆P and attack angle (90o or 135o)

0.0 100.0 200.0 300.0Time (min)

0.0

20.0

40.0

60.0

J v x

106 (m

3 /m2 -s

)

0.8um PMMA solutes MWCO = 500 k C = 3000 mg/l £K= 90¢X

-20 cmHg

-40 cmHg-60 cmHg

-40 cmHg

-20 cmHg

VG= 2.5 l/min

VG= 1 l/min

VG= 0 l/min

300.0

g

0.0 100.0 200.0Time (min)

0.0

20.0

40.0

60.0

J v x

106 (m

3 /m2 -s

)

0.8um PMMA solutes MWCO = 500 k C = 3000 mg/l £K= 135¢X

VG= 2.5 l/min

VG= 1 l/min

-20 cmHg -40 cmHg -60 cmHg -40 cmHg -20 cmH

Cheng et al., 2004Cheng et al., 2004

Membrane fouls Membrane fouls ……

Interactions betweenInteractions betweenmicroorganismsmicroorganisms

and the membraneand the membrane

Medium fouling:Neutral polysaccharides: Kimura, Hane, Watanabe, 2003/NovNot carbohydrates or protein: Watanabe, 2004/Feb

Filtration resistance=Cake+medium+othersCake layer:Polysaccharides & protein: CH Lee, 2004/FebPermeate resistance and screener of fines

Goal:Fast rate & quality effluentLess irreversible cloggingGood cake slow rate & good screener??

Very confused termVery confused termChoiChoi/Fane (2002) EPS/Fane (2002) EPS contributed most to contributed most to

membrane foulingmembrane foulingLee/Hang/Shin (2003) Lee/Hang/Shin (2003) Flocs Flocs 70%, others 30%. 70%, others 30%.

No role of EPS.No role of EPS.Choi Choi et al. (2002) hydrophobic membrane fouls et al. (2002) hydrophobic membrane fouls

more severely than hydrophilic ones.more severely than hydrophilic ones.Ognier Ognier et al. (2002) Fouling is reversible if the et al. (2002) Fouling is reversible if the

TMPTMP--flux curve shows no flux curve shows no hyteresishyteresis..DefraneDefrane//Jaffrin Jaffrin (1999) if TMP does not increase (1999) if TMP does not increase

the fouling is reversible.the fouling is reversible.Many othersMany others……..

EPS: Glue together the EPS: Glue together the flocflocExtracellular Extracellular polymeric substances was polymeric substances was

produced by microorganisms to bind water produced by microorganisms to bind water and chemicals to form protective layer and and chemicals to form protective layer and storage room.storage room.

EPS is easily formed from soluble BOD by MO EPS is easily formed from soluble BOD by MO when Nwhen N-- or Por P-- is deficient. Suspended EPS is deficient. Suspended EPS increases with F/M ratio and shearing velocityincreases with F/M ratio and shearing velocity

Proposed to correspond to 5Proposed to correspond to 5--90% fouling90% foulingMainly comprised of carbohydrate and proteinMainly comprised of carbohydrate and protein

Role of EPS/soluble matters/colloidal particles Role of EPS/soluble matters/colloidal particles normally studied under normally studied under subcritical subcritical conditioncondition

NearNear--Membrane DynamicsMembrane Dynamics

precipitation

Fd

Fo

Fi

Surface Diffusion of adsorbed

membrane

FM

Interfacial properties

Two-phase flow

Fouling schematicsFouling schematics

bubbly flow

PoresFines

Mixed Liquor

Recoverable Clogging!

Irreversible Clogging

Membrane

Permeate

CellsLee, 2002

Irreversible cloggingIrreversible cloggingMechanism I:Mechanism I:

The fines pass through and precipitate inside The fines pass through and precipitate inside the membrane pores.the membrane pores.

Mechanism II:Mechanism II:Cell deposits at the membrane surface first, Cell deposits at the membrane surface first, and then yields and then yields ECPsECPs to clog the pores.to clog the pores.

Ways to block out Mech. I or II are different!!

EPS: abundant in EPS: abundant in flocfloc, rarely in solution, rarely in solution

(40X)

(100X)

AlcianAlcian Blue & Blue & indian indian ink stainingink staining

(40X) (1000X)

Perimeter

Centre

EPS: not in a uniform state (Li XY, 2004): LB (exchangeable) & TB　EPS

Centri. 6,000 g, 10 minSonicated 2 mins in0.85% NaCl solu

Shaken 10 mins, sonicated 2 mins,centri. 8,000 g 10 min

Liquid LB EPS

Solids

Sonicated 2 mins in 0.85% NaCl soluHeated at 80oC for 10-45 minscentri. 12,000 g 30 min

TB EPS

ResidueSolids

Liquid

pH0 2 4 6 8 10

ζ-po

tent

ial,

mV

-16

-14

-12

-10

-8

-6

-4

-2

0

2

4

LB EPSTB EPS

500 nm

size (nm)

1e-1 1e+0 1e+1 1e+2 1e+3 1e+4 1e+5

Inte

nsity

(%)

0

20

40

60

80

100

120

S1

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.050.0

52

54

56

58

60

62

64

66

68

70

72

74

76

78

80.3

cm-1

%T

3546.21

3473.38

3411.76

2924.36

1619.58

1639.16

1381.811121.67

872.72

604.19 475.52

LBEPSLBEPS

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.064.0

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79.1

cm-1

%T

3434.17

2929.97

1633.56

1381.81

1244.75

1076.921110.48

1406.99

TBEPSTBEPS

Clean membrane Fouled membrane

0

100

200

300

400

500

600

700

800

900

0 10 20 30 40 50 60 70

Time (min)

Flux

(l/h

.m2)

Sludge

LBEPS

TBEPS

Low MLSS

Cleaned membraneFouled membrane

0

50

100

150

200

250

300

350

400

0 20 40 60 80 100 120 140 160

Time

Flux

Fouled

Cleaned

IrreversibleClogging

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 700.0cm-1

%T

refenece

fouled

1540 cm-1

Protein is a player

FTIR-Microscope Perkin Elmer spectrum 1Measured down to 10 x 10 µm.

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 700.078.2

80

82

84

86

88

90

92

94

96

98

100

102

104

106

108

110

112

114.7

cm-1

%T

ref

flbeps

93

94

95

96

97

98

99

100

101

101.9

%T

ref

ftbeps

Aliphatic Amide

LBEPS fouledLBEPS fouled

&&

TBEPS fouledTBEPS fouled

membranesmembranes

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 700.084.8

86

87

88

89

90

91

92

cm-1

Probably greaseAs well!

PCAl, mg/L as Al0 2 4 6 8 10 12

ζ-po

tent

ial,

mV

-30

-20

-10

0

10

LB EPSTB EPSPACl coagulation is

not efficient to remove EPS

PCAl, mg/L as Al0 2 4 6 8 10 12

Tur

bidi

ty, N

TU

0

1

2

3

4

5

LB EPSTB EPS

flocStick

floc Stick

Clean membrane Membrane to foul

FlocFloc on membraneon membrane

Scanned

Fouled and Clean Membranes Fouled and Clean Membranes

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 700.0cm-1

%T

ref

fouled

3274.02

2925.04

2351.98 2326.86

1740.46

1627.43

1539.00

1384.02

1052.60

820.50Aliphaticcarbon Amide

Fouled membrane with TBEPS

Layer under attached floc

Fouled TipFouled Tip

force constant =0.2 N/mLength = 450 µmWidth = 50 µmThickness = 2 µmTip height is 10-15 µm

Inorganic deposition on membrane

NanoNano CaCOCaCO33 particlesparticles

4-5nm

NearNear--Membrane DynamicsMembrane Dynamics

precipitation

Fd

Fo

Fi

Surface Diffusion of SMA

membrane

FM

Interfacial properties

Two-phase flow

500 nm

0

100

200

300

400

500

600

700

800

900

0 10 20 30 40 50 60 70

Time (min)

Flux

(l/h

.m2)

Sludge

LBEPS

TBEPS

Layer under attached floc

Proposal:

To clearly identify the terms usedInterpret data in a unified wayProvide fundamental information

In order to provide comprehensive data baseFor better design/control of MBR.

黃帝曰：

﹁彼無為謂真是也，狂屈似

之，我與汝終不近也。

夫知

者不言，言者不知，故聖

人行不言之教。道不可致，

德不可至。

仁可為也，義可

虧也，禮相

偽也。故曰：

﹃失道而後德，失德而後仁，

失仁而後義，失義而後禮。﹄

︽莊子．外

篇．知北游第二十二︾

Thank you O!

NITROCELLULOSE/MCE MEMBRANE; CELLULOSE NITRATE MEMBRANE; MIXED CELLULOSE ESTER (MCE) MEMBRANE; MIXED CELLULOSE ESTER MEMBRANE FILTER; MIXED CELLULOSE ESTER (MCE); MIXED ESTERS OF CELLULOSE MEMBRANE; NITROCELLULOSE MEMBRANE; PURE NITROCELLULOSE MEMBRANE

CAS NUMBER: 9004-70-0EC NUMBER