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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
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