View
44
Download
0
Category
Preview:
Citation preview
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
1/232
Copyright is owned by the Author of the thesis. Permission is given for
a copy to be downloaded by an individual for the purpose of research and
private study only. The thesis may not be reproduced elsewhere without
the permission of the Author.
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
2/232
Mebrane Fouling duringMicroltration of rotein
Soutions
Thesis submitted
for the degree of Doctor of Philosophy
at Massey University
New Zealand
by
Veera Venkata Satyanarayana Chiukuri
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
3/232
\
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
4/232
Abstract
Membrane ouling during croow microlraion (CFMF o proein i complex
depending upon eed properie operaing condi ion and membrane properie Four
dieren proein oluion (reconiued whey proein BSA lacoerrin and erriin
wih a range o phyicochemical properie were inveigaed a a varey o permeae
uxe under dieren oluion condiion o elucidae ouling mechanim durng
conan ux CFMF
MF ouling uually occur in hree age i adorpion ii pore ouling (pore plugging
or depoiion near he pore enrance and iii ormaion o a urace layer. The
imporance o ep (ii depend upon wheher a proein i compleely or pariallypermeable hrough he membrane.
BSA probably oued ineally r by pore plugging ollowed by ormaion o a
urace layer once all he pore were plugged. Prelraion and he preence o SDS
reduced ouling bu did no preven i uggeing ha aggregae preen in he iniial
eed a well a hoe ormed during MF conribue o pore plugging and o lead o
evere ouling.
Fouling reiance curve or lacoerrn indicae an iniial phae o low ouling by
plugging or depoiion o aggregae. Mahemaical modelling uggeed ha ouling
wa paricularly evere a he pore enrance. A ux wa increaed lacoerrin ormed a
concenraioninduced urace layer.
Ferriin ormed a concenraioninduced gel layer even a relaively low uxe (91
m.h) when he wall concenraion oproein reached he "gel concenraion. The gel
layer wa highly reverible o change in hydrodynamic condiion uch a croow
velociy and ranmembrane preure. Fouling wa more evere wih reconiued
whey han wih reh whey due o he preence o proein aggregae in he reconiued
whey.
The role o he phyicochemical properie o proein in aggregaion and probable
ouling mechanim during CFMF are dicued. Proeinproein ineracion under he
inuence o hear paricularly a higher uxe lead o aggregaion and ubequen
ouling.
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
5/232
11
Acknowledgemens
Fry I would ke o hank my che upervor Peer Munro or h encouragemen
gudance and hep all hrough h proec. My mmene graude o Alen Marhall
or h drecon eng me o hare h MF expere help n provdng me all he
acle durng my expermen n he plo pan parcuarly howng me how o
run MF rg h help durng preraon run. I am grael o Hander Sngh or
h proen chemry expere and upervon durng proen anay. I have
alway enoyed workng wh my PhD upervory eam.
I am hghy grael o New Zealand Vce-Chanceor Commee or awardng mecommonwealh cholarhp I hank Roya Socey o New Zealand or granng me a
ravel award o aend my r neaonal conerence n Sydney. The nanca
aance by New Zealand Dary Reearch Inue and Maey Unvery o aend
he conerence hghly apprecaed. The nancal aance by New Zeaand Dary
Board oward he preparaon o he he acknowledged
There are o many people who have helped encouraged movaed durng he
proec. I have ganed a new perpecve whch que deren rom wha I ea
durng my prevou undergraduae and pograduae ude. I hank New Zeaand
Dary Reearch Inue or gvng me he opporunty o conduc he expermen
ung conan ux MF rg n her plo plan. I alo hank Maey Unvery or
provdng me al he compung and laboraory acle I hank Taua Co-operave
Dary Company d and New Zealand Phanaceucal or gvng proen powderor he udy.
I am hankl o a o Proen Technology plo plan Mke Bruce Ian Bal
Gordon Alan Shane or her help and conderaon durng my expermen. I
exend my hank o Proen Technology a parcularly Mark Vay Ne Dedre
and Anne or reang me ncely. A Maey Unvery numerou people have
helped me Owen McCarhy Ovaldo Rod Benne Byron Mckllop June Mark
Dorey Seve Glagove and my ellow uden Taa Heavea Ram hank you a.
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
6/232
111
I wih to acknowledge ta at Indutrial Reearch Ltd, Max, John, Monwar, Andrew
Roberton, Zaid and many other or encouraging me to complete my thei. To all
thoe who have helped in the proect, Tim Winter Tatua, Loui Buchanan NZP
or their ource o inormation on protein literare, Andrew Fletcher NZDRI orhi help duing gain modication to permeate controller and Skelte Anema NZDRI
during ome paticle izing experiment thank you
I thank my riend and their amilie both in Palmerton North and Wellington,
Viay, Bolan, Satya Paumathy, PK Samal, Ranan, Pramod, Khannan Joghee, Raiv
Raman, Vihnu, Venkat Serie Karla, Ananthula, Cherukuri, Rameh and many
other My appreciation to tudent riend and variou inteational club preident
at Maey Univerity Student Aociation, cholarhip ocer, Mr Margaret ilbet
or all their help and riendhip I am gratel to my parent who nourihed me and
made me what I am today and alo relative and riend in ndia or encouraging me
to go overea to do a degree I highly appreciate moral uppot and encouragement
o ta at the college o Agricultural Engineering, ANR Agricultural Univerity,
India
Finally, would like to thank my wie Prauna, daughter Keethy and on Aun or
their patience, love, caring and upport during my tay in New Zealand
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
7/232
Tabe of Contents
Astract
Acnowledgements 1Tale of Contents
. ntroduction 1
2 Literature review: fouling y protens during microltration 4
2 Inducin 4
2 2 Pein adpin 10
2 3 Cncenain plaiain 1 2
24 Fain a dynamic membane/uace aye 14
2 5 Pe uing pein depiin 1 5
2 5 Fuing wihin he membane uctue 1 5
252 Fuing a he pe enance 1 5
26 Eec eed ppeie 6
26 1 Pein ize 6
262 Aggegain ae he pein 6
263 Secnday aggegain 1 7
264 pH and Inic engh 1 9
26 5 Cncenain 2
2 6 6 Peain 22
2.6 7 Peence mineal and uacan 2227 Eec membane ppeie 23
27 1 Pe ize 23
27 2 Pe mphgy 24
2. 7 3. Miccpy tudie n uing 26
2 Eec peaing vaiable 27
2. . Peeae ux/Tanmembane peue 27
2 2 Shea 302 3 Cw velciy 32
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
8/232
29. Foulng mechanim 33
2 0 Summary of lieraure review 4 1
2 . Need for rher ude 42
3 Theoretical and quantitative aspects of memrane processes 47
3 1 . nroducon 47
3 2 Polariaion in lraion 47
3 3 . CP model 49
3.4 Membrane foulng model 50
3 4 1 . Foulng reiance model 50
3 .4 2 Cake layer model 5 1
3 .4 3 Pore rericon model 52
344 Proein depoion model 52
35 Proein ranmion calculaion 53
3 .6 Pore blockng law 53
3 6. Pore narrowng model (andard blockng law 54
362 Pore plugging model (complee blockng law 54
3 .6 3 nermedae law 55
3 7. Micellaneou calculaon 55
4 Materials and methods 57
4 1 Membrane rg and preparaion 57
42 Feed preparaon 60
42 1 . Whey proen oluon60
422 Freh cheee whey 6
42 3 . Pure proein oluion 6
4 3 Plan operaion 62
43 Whey proen oluon and reh cheee whey 62
4 3. 2 Pure proein oluon 62
44. Meauremen and analy 63
v
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
9/232
5. Microltration fouling y reconstituted whey protein solutions 64
5 Introduction 5 2 Results 65
5 2 Overvew o experiments 6552.2. Eect othe permeate ux 65
5 2 3 Eect o onic strength 69
52.4 Naure o the eed material 7
5 2 5 Eect o the membrane pore size 72
526 Reversble versus irreversble ouling resistance 73
5 2 7 Relatonshp beween protein transmssion and 74
oulng resistance
5 3 Dscussion 75
5 3 Foulng on the 00 and 00 nm membranes 75
5 3 Inuence o permeate ux 75
5 3 2. Impact o onc strength 75
5 3 2. Probable oulng mechansms 77
5 3 2 Foulng on the 20 nm membrane 77
5 322 Foulng on the 00 nm membrane 7
5 3 2 3 Fouling on the 00 nm membrane 0
5 3 2 4 Comparson o ouling by resh whey
and reconstituted whey
5 3 2 5 Comparison o oulng behaviour on
00 and 00 membranes
5 4. Conclusions 2
. Microltration fouling y ovine serum alumin solutions 3
6. Inroduction 3
62 Results 4
62. Eect o the permeate ux 4
62 2 Eect o calcium addton 90
623 Eect opreltration and SDS additon 9262.4 Eect o sulphydryl b locking agent 9
6 2 5 Eect o cysteinyl blocked BSA 9
VI
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
10/232
62.6. Foulng reance veru proen ranmon 1 0
6 2 7. Effec o he membrane pore e 03
63 Dcuon 106
6 3 1 Effec of he permeae ux 06632 Role of calcum n proenproen neracon 07
6.3 3 Effec of hear and proenproen neracon 1 1 0
633 Dulde neracon 1 1
6332 Hydrophobc neracon 1 3
6.3.4 Propoed oulng mechanm 14
6.4 . Concluon 2 1
7 Microltration fouling by bovine lactoferrin solutions 123
7 1 Inroducon 123
72 Reul 123
7 2 1 Effec of he permeae ux 124
72. 2. Effec of calcum 127
72 3 . Effec of ux on rreverble and reverble 12
foulng reance
724. Effec o SDS on oulng 129
7.2 .5 Efec of foulng reance on proen 134
ranmon
726 Efec o he croow veocy 1 3 5
73 Dcuon 139
73 1 . Probable oulng mechanm 3973 . . Proen adorpon 39
732 Proen depoon 40
73 3 Marhall model 144
7314 Surace layer 45
732 Efec o permeae ux and concenraon 146
nduced foulng by aggregae
7 3 3 . SDSProen neracon 1477.3 4 . Summary of he propoed foulng mechanm 149
74 Concluon 150
v
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
11/232
8. Microltration fouling y ovine ferritin solutions
Inroducon
2 Reu
2 1 Effec of he permeae ux 22 Effec of SDS
2 3 Effec of cacum
24 Effec of foung reance on proen
ranmon
1 5
1 5
52
52155
5
60
2 5 Effec of permeae ux on he reverby 6
of foung reance
26 Effec of cro-ow veocy and ranmembrane 162preure on he reverby of he foung ayer
3 Dcuon
3 1 Probabe foung mechanm
3 1 Adorpon
3 1 2 Ge ayer formaon
3 2 Appcaon of ge mode o predc
permeae ux
167
67
167
6
169
3 3 Effec of ouon envronmen on 174
foung mechanm
34 Summary of foung behavour by ferrn 176
4 Concuon 76
MF Fouling y dierent protein solutions a general discussion 177
9 1 Inroducon 177
9 2 Comparave reu 79
93 Dcuon 6
93 1 Roe of phycochemca propere of proen 6
n aggregaon and foung
9 32 Foung behavour of BSA acoferrn ferrn 190
and whey proen ouon
V
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
12/232
93 3 Eec o ouling on eady ae proein
ranmiion
93.4 Comparaive ouling mechanim
93 5 Eec o oluion environmen on heouling behaviour o proein
9.4 Concluion
0 Recommendatons for further research
0 1 MF ouling by proein oluion
02 . General
Nomenclature
2 References
1 9 1
192
95
95
97
97
9
99
201
X
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
13/232
1. Introduction
Membrane eparaton procee have found a wde range of applcaton n the food
and botechnologcal ndutrie. Ultraltraton (U extenvely employed to
concentrate mlk whey proten clar uce wne and proce antbotc. Recent
progre n croow mcrolraton (CFMF ha opened up new poble
applcaton uch a eparaton of ndvdual proten caen tandardaton of
cheee mlk defattng and clarcaton of whey n the producton of hgh qualty
whey proten concentrate (WPC cell recovery from fermentaton broth and terle
ltraton of heat lable proten oluton etc.
Membrane foulng a maor problem retardng rher applcaton of CFMF.
Membrane foulng ha been extenvely uded. Mot of thee tude are pertnent
to foulng of polymerc and mcro ltraton (MF membrane n trreduntrredbatch cell ung contant preure operaton. In foulng occur predomnantlyon the membrane urface where the dynamc membrane control membrane
behavour. In MF evere pore pluggng by proten occur n pte of the pore beng
an order of magntude larger than the proten. In both the above procee foul ng
reult n a declne n ux wth tme and change n electvty of the membrane. The
ncreae n retenton an advantage n U applcaton but a dadvantage n ome
MF applcaton that requre hgh proten tranmon Croow devce are
generally preferred due to reducton n concentraton polaraton and urface foulng
compared to deadend devce
There growng nteret n the ue of ceramc membrane for MF There are three
maor advantage of ung ceramc membrane 1 they are retant to chemcal
cleanng 2 they can be team terlzed and backuhed and 3 they have long
membrane lfe. Wth the advent of ceramc membrane and ther applcaton n the
ndutry there a need to tudy mcroltraton foulng on ceramc membrane. A
membrane materal nuence the foulng proce t not reaonable to apply the
reult obtaned for polymerc membrane to ceramc membrane It uggeted nthe lterature that MF operaton at contant ux better than operaton at contant
preure becaue the former avod hgh permeate uxe n the rt few mnute.
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
14/232
2
Vey few sudies hae een conduced in cossow mode unde consan pemeae
u coniions usin ceamic memanes
Recen ndamena sudies indicaed ha foulin of MF memanes is inuenced y1 memane popeies 2 opeain condiions and 3 popeies of feed maeia
Seee memane fouin has een epoed in micoaion epeimens wih
oine seum aumin (BSA een when he poe size was much lae han he
poein (Bowen & Huhes 1990 Fanken et al., 1 990 Bowen & Gan 1 99 1 onssonet al 1992a Kelly et aI, 1993 Key & Zydney 1994 1995 acey & Dais 1994onsson et al. 1 996 Muee & Dais 1 996 Heeo et aI, 1 997 The eason fo he
seee fouin appeas o e he pesence of poein aeaes in he feed HoweeHaacek and Bouche (1993 showed ha peeed BSA soluions can si fou he
memane
Key and Zydney (1995 showed ha iniial fouin was caused y he conecie
deposiion of poein aeaes on o he memane suface onsson et al. (1996and Heeo et al (1997 hae poposed wo consequen seps in fouin sufacelockin and cake fomaion duin BSA laion In amos all hese cases foulin
occus pedominany on he memane suface y poein aeaes On he ohe
hand Fanken et al (1990 Bowen and Gan (1991 1992 and onsson et al (1992ahae suesed ha shea wihin he memane poes causes he poein o deposi
acey & Dais (1994 and Muelle & Dais (1996 duin foulin sudies usin
BSA on 02 m MF memane hypohesised ha poein molecues o aeaes
deposi a he poe walls o mouhs. Bowen and Gan ( 1 993 and Masha et al.(1997 hae suesed ha fouin duin MF of poein souions is mos ikey due
o he ineacion of poein wih he poe eomey a he poe enance Thee is
consideale deae whehe foulin is iniiaed on he memane suface o wihin
he poes o a he poe enance
Alhouh he aoe sudies ae some undesandin of he possile mechanisms of
poein foulin hee ae sill conicin iews aou he undeyin pinciples ha
oe poein fouin duin MF
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
15/232
3
he pesen sudy was undeaken as an eension of Masha (994 P hesis
wok which invesiaed wo aspecs of MF fouin, one in which he feed conained
poeins considealy lae han he memane poes (casein miceles) and he ohe,
in which he poein (lacoouin) was much smae han he poes wasdemonsaed ha a casein "e aye fomed on he memane suface caus
sevee fouin duin MF of skim mik on a 0 m poysufone memane (Mashal
et aI 1 996 Duin MF of -lacoouin on 50 and 00 nm ziconium oide
memanes a hih ues, poein-poein ineacions a o nea he poe led o poe
naowin and he evenual eenion of he poein y he memane (Masha et aI
1 997 he wok sessed he impoance of feed popeies on fouin and
ecommended he wok usin a ane of poeins of diffeen molecua weihs o
invesiae he effec of physicochemical popeies of poeins on foulin
mechanisms
he oecive of he pesen wok was o invesiae he fouin ehaviou of poein
soluions conainin whey poeins o ovine seum aumin o ovine lacofein o
ovine feiin on ceamic memanes duin CFMF unde consan pemeae u
condiions he effecs of poein size in soluion and peeamens such as
peion, aiion of calcium an addiion of a poein dissociain aen (sodium
doecyl su fae, SDS) on foulin mechanisms wee invesiaed In paicua he
effec of pemeae u and poein soluion envionmen on fouin ehaviou wee
invesiaed
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
16/232
2. Literature review: fouing by proteins during microtration
2 Introducton
Mcroltraton membrane foulng has been a maor problem n the process ndustry
Even though the pore szes n MF membranes are generaly over an order of
magntude larger than the characterstc sze of the proten there s consderable
expermental evdence that severe foulng occurs and protens play a crtcal roe n
MF foulng. A number of foung mechansms may arse dependng upon operatonal
varables, feed and membrane properes. embrane foulng n genera has been
extensvely studed and has been revewed by Fane and Fel (1987), Nlsson (990)
Marsha et (993) and Belfor et (1994). However there s currently ttle
nformaton avalable on the foulng behavour of protens on ceramc mcroltraton
membranes under constant ux and cross-ow condtons rotens are compex
molecules and a greater understandng of ther conformaton, stabty and nteractons
n dfferent membrane envronments and under condtons of shear s cruca to
understand and control foulng n these processes. The present lteraure revew
buds on the revew of arshal et (1993) and focuses on more recent work
manly related to membrane foulng durng F of proten soutons.
It s common to nd varous terms n the foulng lterature use erent authors
dependng on ther background, as there s no unversaly accepted termnology.
Foung s the deposton of solute partces both on the membrane surface and/or n
ts pores leadng to a change n the membrane performance (Gekas, 1988). For the
purpose of ths revew, a broad categorsaton s made under the terms adsorpton
deposton aggregaton and pore foulng (whch ncudes pore pluggng and pore
narrowng). The term adsorpton s rreversble atachment of a macromolecule due
to nterfaca forces an s lmted to a monoayer thckess Ths s dfferent from
deposton whch s aso rreversble but occurs by a varey of mechansms n
addton to adsorpton. Proten deposton ncludes the proten adsorbed under statc
condtons plus addtonal proten strongly assocated wth the membrane durng
ltraton Aggregaton s a term used to refer to a varety of protenproten
nteractons. The term pore puggng s the physca attachment of a macromoecue
at the pore openng or wthn the pore and s consdered synonymous wth pore
blockng /sealng /bndng /cloggng However the term pore brdgng means that
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
17/232
5
he pore is plugged by more hn one molecule by some sor of ggregion or
colescence of proein Pore nrrowing or pore consricion is process by which
inel pores of he membrne will hve reduced pore dimeer due o iniil
dsorpion nd subsequen deposiion of proein on he pore wll
Bowen nd Huges 1990) invesiged he deposiion of BSA on luminium oxide
MF membrnes They suggesed h deposiion occurred in wo phses The rs
phse of rpid deposiion ws he resul of monolyer dsorpion on o he membrne
surfce nd he BSA ws very srongly bound The second less rpid phse ws he
building up of relively wekly bound mulilyers of proein They concluded h
he level of proein deposied incresed if permee ux incresed possibly due o
incresed collisions wihin he pores resuling in greer inercion Clrk et l
1991) during consn pressure lrion of BSA on 100 nm lumin membrne
hypohesised h he fouling ws due o dsorpion reled pore plugging bu did no
differenie fouling by dsorpion nd pore plugging Proein deposis hve lso
been idenied wihin he mebrne srucure in MF Ai et l 1991 b) showed
h csein boh formed lyer on he surfce of he membrne nd penered he
membrne srucure o deposi wihin he pores during MF using 08 m membrnes
In mos MF processes rnspor of proein hrough he membrne is reuired Bowen
& n 1993) Inercions of proeins wih he inel pore srucure of he
membrne cn hve subsnil inuence on he effeciveness of such seprions
I hs been shown h effeciveness of selecive proein lrion cn be drmiclly
lered by ppropriely conrolling elecrosic inercions hrough chnges in pH
nd ionic srengh Sksen & Zydney 1994)
Belfor et l 1994) presened differen possibiliies of fouling mechnisms in MF
Fig 21) depending on he proein o pore size rio They dened pricle dimeer
d nd pore dimeer o illusre possible fouling mechnisms When d hepricles could ener os pores nd could conceivbly close smller pores hereby
reducing he open crosssecionl re for ow
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
18/232
FNG A
CSB: PORELUGGINGI
d-p
d CASC: GUAKE LAYERFMlO
d Dn =na
TBUON
.L.t.
s r pvw i r A
(,) :"') Vw "0. :
POz Sf
6
Figure 21 . Possible fouling mechanisms during membrane ltration Belfort
. 1994)
This is shown schemticlly s oss of poes om the poe size distibution nd
decese in the slope of the ux. A simi effect occus when d nd some poese ost becuse of poe plugging. Fo the cse when d the ptices e unbeto ente most poes nd hence deposit on the fce of the membne esuting in
cke/ge build up Assuming the poe size distibution of the membne emins the
sme s fo clen membne the shpe of the poe size distbution of the ge/ckewil most likely chnge with time nd tnsmembne pessue (TMP Compction,
engement nd deposition of smle pticles in the poes of the gel/cke coud
expin this In this cse, the slope of the ux vesus TMP cuve will decese with
incesing pessue. This is oen obseved expeimentlly nd hs been ttibuted to
incesed deposit thickness (Btt et a 1970 nd o osmotic effects (Jonsson
984.
Muele nd Dvis (1996 pesented dt tht showed occuence of inte nd
exte fouing duing MF of BSA unde constnt pessue conditions (Fig 2.2
They epesented fouing by totl esistnce which they clcuted using R
P/.J The slope of the esistnce cuves ws used to intepet whethe fouling ws
intel o extel.
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
19/232
501
WZ 30+12
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
20/232
z
>
0
08
0
0.4
02
05
Prateln
o BA
e Obi 6 aobin
P e 6-ln
Fro Tm ()
90 12
Figure 23. Permeae ux loss (o anel) and rae of ux decline (boom anel)during MF of BSA, ovalbumin and lacoglobulin hrough 0.22 m PFmembrane a a consan ressure o 14 Pa and 00 rm. Solid lines are modellines (Key & ydney 7
Ty prpsd a mdl a nsidrd surfa arg inrains and drag fr du
nviv ux In is as fuling urs prdminanly in frm f a surfa
layr
Rnly Marsall et a (199) av usd rlainsip bwn fuling rsisan
and prin ransmissin luida fuling baviur f laglbulin (Fig 24)
Ty pld fuling rsisan daa frm all xprimns prfrmd a diffrn
nsan prma uxs agains rrspnding prin ransmissin valus Ty all
fall ls a singl urv a rprsns a dras in prin ransmissin
ninuusly wi an inras in fuling rsisan Ty dvlpd a mamaial
mdl wi swd a prin dpsiin urs prdminanly nar pr
nran
8
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
21/232
9
8
\+
6 + D.
.
,
.
40 60 70 O 0 100F U x )
Figure 2.4. Proein ransmission versus fouling resisance for a 0 nmmembrane during MF of acoglobulin. The line is a model redicion, deailsof which are given in he ex (Marsh all . 997
Fouling whih esults in deline in peete ux nd poo seletivity is due to
viety o mehnisms The ux deline is used by sevel phenomen in o ne
the membne In genel, the ux deline is used by deesed diving oe
n/o n inesed esistne. The esistne duing lttion poess n be
gouped into , R p R nd the esistne o the membne itsel Fig 25)Poes n beome plugged by the solute Rp nd dsoption o the solute on to the
wlls o the poes nd o the membne sue ) p is used by phenomenon
known s 'onenttion polistionP) whih is umultion o etined
moleules ne the membne sue Thee hs been howeve onsideble
debte ove how P edues the peete ux One gument is tht the
onentted lye ne the membne oes esistne to peete ow nd the
othe gument is tht the osmoti pessue II) indued by the umultion o
momoleul solutes t the membne sue eetively deeses the
tnsmembne pessue nd hene the peete ux
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
22/232
R
R R
m
R
0
0 0 T
R
R : 0
: aza
igure 2 Possible resistnces to permete ux in membrne ltrtion nden Berg, 988
Wen te concentraton at te membrane nterface reaces a certan eve dependng
on te tpe of feed te concentrated soton ma cange nto a ge aer" wt a
resstance R n ts revew epermenta evdence on eac penomenon casng
decne w be presented separate and ten te most mportant factors tat
nence MF fong b protens w be dscssed
. Proten dsorton
Adsorpton s a termodnamca spontaneos process and s probab te rst step
n te fong process t s we known tat protens adsorb at qdsod nterfaces
and te amont of proten adsorbed depends on te membrane srface caracterstcs
(dropobc dropc and srface carge) te proten tpe and te soton
propertes (pH onc strengt and concentraton) n statc stdes Mattasson
(1983) on pomerc membranes and Cark et (199) on an amna membrane
ave fond tat BSA adsorpton ncrease to a satraton vae wt ncreasng
soton concentraton and te adsorpton was mc greater near te proten
soeectrc pont of pH 49. Bowen and Gan (991) drng MF of BSA sng 0 m
capar pore amnm ode membranes fond tat proten adsorpton
corresponded to appromate a monoaer However te oss of permeabt de
to adsorpton was sbstanta ess tan te decrease n te rate of permeaton drng
te traton of proten soton Bowen and Gan (1993) sng posfone MF
membranes nder dnamc condtons fond tat te membranes adsorbed on 3/4
0
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
23/232
11
of a monoayer of he enzyme yeas alohol dehydrogenase YADH) The obsered
derease in permeaion rae was de neiher o onentraion polarisaion nor o
proein adsorpion alone. Howeer i was anied sing he sandard bloking
raion law whih desribes a derease in pore ome de o deposiion of proein
in he inerior srre of he membrane Persson et al. 993a) sing laogobin
on for differen poymer MF membranes also fond ha proein adsorpion
orresponded o a monoayer on and in he pores of he membrane.
Proein adsorpion was fond o be sighly reded on hydrophili membranes sing
BSA (Bowen & Gan, 1991) and laoglobin Persson et al 1993a) Akhar et al(1995) reaed PVDF and CA membranes wih a srfae graing of
meharyoyoxyehyl phosphoryholine They showed ha membranes wih his
oaing ha inhibied proein binding improed he iniia x in boh he membranes
inesigaed, b proed o be more effeie for PVDF membranes in reding an
86% x deine o 10% han for he CA membrane in reding a 48% x deine o
17% dring MF of BSA. This improemen in membrane performane was
onomian wih a redion in proein foing on he srfae and wihin he marixof he oaed membranes as assessed by ransmission eeron mirosopy For a
typial MF membrane (wih a pore diameer of 0.2.0 m), he x redion ased
by monoayer adsorpion of a proein sh as BSA is ony 212 % Befor et al
1994) Howeer, a larger peren redion in x wod be expeed o or pon
adsorpion of ery arge maromoeles or aggregaes
A eas in MF, de o reaiey larger pores, x deine de o foing an be
aribed in a smal par o proein adsorpion of a monolayer, b he major
onribion is from proein deposiion nder dynami ondiions. Howeer
adsorpion of proeins on he membrane pays an imporan par in he iniia sages of
foling pariarly in he ase of inea foling whih is a more dominan form of
foling wih MF membranes.
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
24/232
To coclude pote adsopto at the pote-membae teface s almost
evtable ad s ueced by a umbe of paametes. oweve t ca be mmsed
by sutable membae suface modcato techques o choosg membaes that
ae vey low adsobes-maly used pocessg of hgh value potes. At least MF though adsopto aloe may ot affect ux substatally but t ca play a
mpotat ole the subsequet foulg.
2.3. Concentrtion olristion
2
The covectve taspot of solute towads a membae U ad evese osmoss
(RO) causes t to accumulate at the membae suface a cocetated boudaylaye leadg to a loweg of ux elatve to that of pue solvet U & R,
cocetato polasato bulds up quckly (Chudacek & Fae, 984 Fae 986;
Ama et a 99) ad s a cto of the hydodyamcs the membae system.
t s depedet of the popetes of the membae f eteto s 00%. t s
mpotat to dstgush betwee cocetato polasato ad foulg Foulg s
the couplg of deposted mateal to the membae though the temedate step of
C whch st causes a accumulato o cease cocetato o the membaesuface (Mashall et a 993). The loss of ux due to C s evesble i.e. upo
ushg of the membae wth wate the poto of the ux loss ue to C s estoed
ad whee foulg s sgcat the ux etus to ts ogal value (Mashall &
Dau 995) O the othe had loss of ux due to foulg s geeally evesble
i e upo ushg wth wate the poto of ux loss due to foulg s ot estoed
utl afte the membae has bee chemcally cleaed
The cotbuto of C to foulg s domat UF wheeas ts effect s elatvely
less MF stuatos whee thee s eteto of macomolecules ethe tally o
late the pocess due to poe foulg C ca play a mpotat ole eve MF,
cotollg ux ad pote tasmsso.
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
25/232
13
Bot of tese effects sould be eggble fo te ltato of pote soutos
toug te cea M membaes sce tese age poe membaes ae essetay
o etete to most potes Howee tese peomea ca be mpotat fo
fouled membaes due to pote deposts (pog & Zydey 99; Moczuk &Zydey 992) smotc pessue may become mpotat fo a foued membae
ee M
Te accumulato of soute ea te membae suface s geeally descbed by te
m model Te lm model assumes tat te cocetato bouday laye esdes
wt a t lama lm at te membae suface ad tat all mass tasfe takes
pace by cka dfso pepedcula to te membae Te m s dyamc
atue Some estgatos (fo eg Nakao et al 979 saacso et al 980
Josso 984) ae used te osmotc mode to expla te ux decle Te osmotc
model assumes tat esstace to ow esdes wt te solute accumulated ad s
caused by osmotc pessue Ufotuately tese models we apped to M of
collod patcles udepedct te ux obseed Te easo fo ts ux paadox"
(Romeo & Das 988 990) at least fo collods appeas to be due to ceased
back-taspot caused by ydodyamc effects ke ) sea duced dfso ad 2)
lateal mgato due to etal l (See efeeces Belfot et al (994) fo moe
detas) addto to dfso Alteate models suc as sea duced dfso
ad ateal mgato models ae bee poposed to descbe te taspot of patces
away fom te membae Romeo ad Das (988 990) cosde ts ssue
moe detal Romao & Das (988) ad Lojke et a! (992) eewed te aous
modes tat ae bee poposed to expla ts beaou Recety a ued model
combg gel ad osmotc models as bee poposed to pedct ux (Battacaee et al 996). Howee appcato of tese modes to
macomoecula solutos s questoabe as ux decle M s pedomaty due
to tea foulg
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
26/232
24. ormtion of dynmic membrne/surfce lyer
Several researchers have reported foation of a dynmic layer by proteins dring
R and UF Lim et al. 971; Glover & Brooker, 974; Lee & Merson, 975, 976a;
Kim et al 1992; Marshall et aI 1996). This is generally expected as the protein sieis larger than the pore sie of the membranes sed in their stdies Srprisingly, a
dynamic layer was reported even dring MF for example, sing skim milk on a 02
m membrane Attia et al 991a) Casein micelles foed a srface layer as they
are of similar sie to the membrane pores. Srface layer foation was observed
even dring MF of proteins which are mch smaller than the pore sie mainly dring
the later stages of the processing de to complete loss of inteal pore area Jonsson et
aI 996; Marshall et aI 1997). Generally in MF once a srface layer has foned, it
redces the protein transmissions to a level that wold be deteined by the porosity
of the deposited srface layer.
Interestingly in some cases sing nonprotein feed streams, a dynamic membrane had
a positive inence on the membrane perfoance, for example, Cakl and Miklek
1995) dring MF of latex particles of broad sie distribtion sing almina
membranes showed that an adeqate secondary membrane can improve x by
rotectin the membrane from ore lgging and therefore contribtes to a higher and
more stable x also see section 2.9). AMalack and Anderson 1996) showed that
the dynamic membrane foed on the rimary membrane can be sed as an anti
foling techniqe They foed a dynamic membrane sing potassim peanganate
KMn) with particle sies less than the pore sie of the primary membrane. Pore
narrowing pore bridging by the particle and precipitation on the membrane srce
were reported to be the mechanisms of dynamic membrane foation. Improved x
and trbidity were obsered with increased concentration of KMn when this
dynamic membrane was sed to treat a secondary eent from waste water.
Kberkar and Davis 1998) reported that a secondary membrane foed by yeast and
BSA mixtre improved BSA transmission compared to when BSA alone was
microltered on a 0.07 m celllose acetate membrane
4
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
27/232
25 Pore ouling or protein deposition
25 ouling within the membrne structure
usch and Wach 982) showed eecton micoaphs of the top suface of a 3 m
Nucepoe memane ae ltation of atexstyene paticles Even thouh the
paticles wee ony onetenth of the poe diamete, they inteacted with the poe wals
of the memane, thus fomin aomeates that nally locked the poes. A
nume of investiatos have found potein adsoption within the memane poes
(Nakao et al 1988 Dejmek & Nisson 989 Hanemaaije et al 1989 Bowen &
Gan, 99) Matsumoto et al 988) compaed esistance due to inteal and suface
laye fouin with ovalumin 44 kDa) on ceamic memanes With low veocities
(amina) and with the 02 m and to a lesse extent the 08 m memane, suface
aye fouin dominated With lae poe sizes 5 3 m) poe pluin appeaed
to e the pedominant foulin mechanism With hih velocities, fo al fou
memanes, poe pluin was pedominant Bowen and Gan 993) used a thin m
composite polysulfone memane duin MF of YADH. hey suested that
deposition of macomolecules inside the poe stuctue was an impotant mechanism
fo ux oss. To conclude, thee is expeimental evidence that potein deposits withinthe memane poes as well as on the suface
252 oul ing t the pore entrnce
Visvanathan and Ben Am 989) suested that in the ealy staes of tation,
cooids can deposit on the memane suface in etween the poes and thus
accumuate ate, aeates of cooids can fom ides ove the poe openins,
esultin in patial lockin of the poes A smae poe stuctue is then availae
fo susequent cooids to deposit This idin of aeated colloids leads to the
eventual fomation of a lm of colloids on the memane suface Bowen and Gan
199) poposed that potein deposition occus in the immediate vicinity of the poe
entance due to the hih shea caused y the local pemeate ows. Tacey and Davis
1994) duin MF of BA solutions usin tacketched poycaonate memanes
found that the poe adii deceased on the feed side ut not on the pemeate side,
indicatin that the foulin laye is not evenly distiuted thouhout the poes, ut
instead concentated nea the poe entances. Masha et al 1997) duin MF of
lactoloulin showed that fouin occued ove a smal pat of the memane
15
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
28/232
6
pobably at the poe entance Km et al 1997) have also epoted BSA oulng data
that suppots poten deposton at the poe entance also see secton 27.3)
To summase, a numbe o studes have hypothessed that poten deposton occus
nea the entance o the membane poe
2.6. Effect of feed properties
2.6. . Protein sie
Pdanos et al 996) lteed 5 deent potens pepsn, BSA, lpase, globuln
and nvetase) wth molecula weghts o 36, 67, 80, 150 and 270 kDa on 002 m
patally etentve Anopoe membanes They ound that as the molecula weght
nceased, thee was a declne n u. Howeve, nvetase showed a stange
behavou; t was the bggest poten, but ts u declne cuve was between those o
lpase 80 kDa) and BSA 67 kDa) Ths behavou was attbuted to the ato o
molecula and mean poe szes whch s >1 o nvetase and also t s the only poten
studed that s totally etaned by the membane wheeas othes gave etentons below
70% Unde the same condtons o ltaton, nvetase appeaed to have blockedvey ew poes educng the u only a small amount wheeas lpase and -globuln
could block a lot moe poes and conseuenty educe the pemeate u substantally
Gell and Davs 996) ound that BSA and lysozyme dsplayed only nteal
membane oulng on 0.2 m PS and PC membanes wheeas ovalbumn hghe
molecula weght) ehbted an ntal phase n whch nteal oulng domnated
ollowed by a suace laye on the same membanes ndcatng the eect o poten
sze on oulng behavou
2.6 .2. Aggregtion or stte of the protein
Poulot et al 1994) dung MF o whey potens usng alumna membanes ound
that oulng was stongly dependent upon the state o the potens n the eed They
concluded that pH and onc stength ae the mpotant soluton popetes that
nuence aggegaton o the poten theeby aectng poten oulng Bowen and
Hall 1995) obseed that the ate o taton and tansmsson o YADH though an
MF membane depend on the molecula state degee o aggegaton o the enzyme n
soluton) Kelly et al 1993) showed that BSA oulng was assocated wth the
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
29/232
7
deposton of trae quanttes of aggregated anor denatured BSA wt tese foulng
spees servng as ntaton stes for foulng durng strred ell traton troug 0
m membranes e foulng tendeny of dfferent BSA preparatons was gly
orrelated wt te onentraton of BSA dmers and oter g moleular wegt
spees present n tese BSA solutons Gsan et al 993 found tat durng MF of
pretreated wey usng arbosep M4 membranes protens and alum pospate
aggregates were responsble for foulng w nreased aordng to te omplete
blokng" ltraton law Maa and Hsu 99a reported tat wen zn ons were
added to ndue aggregates te foulng tendeny of reombnant uman growt
ormone rGH solutons nreased wt nreasng amount and sze of te
aggregates ndatng tat te aggregates present before ltraton mgt be
responsble for membrane foulng n summary tere s onsderable expermental
evdene tat proten aggregates are responsble for severe foulng durng MF
2.6.3. Secondry ggregton
Suk et al 984 ypotessed tat aggregaton of proten BSA s possble at g
MP due to onvetve ow leadng to supersaturaton of membrane surfae wtproten ey proposed tat aumulaton of solute provdes a reseror of moleules
on te membrae tu raall x ro moue due to aeaton and
oulaton on te memrane surfae Later Suk et al 98 attempted to model
UF foulng by assumng tat proten aggregated n te onentrated laer next to te
membrane based on oulaton teory Usng data avalable for BSA te ux was
alulated as te aggregated layers bult up Inreased ux delne at ger feed
onentratons was predted by te model However te model does ot allow for
dfferenes n te membrane propertes
Mereles et al 990 usng lgt satterng analyss and turbdty measuremets
sowed tat BSA fomed aggregates of large sze durng UF at 22 ey sowed
tat at a temperature of 1 te ger te gear pump speed te eaver te
deaturaton w tey nterpreted usg trbdty measurements In a later
publaton Mereles et al 99a reported tat te rate of proten denaturaton
nreased wt temperature rossow veloty FV and tme of proessng ey
suggested tat under g onentraton polarsaton denaturaton an our n te
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
30/232
odary layer if the wa cocetratio exceeds 40% hey attrited BSA foig
to partial deatratio eadig to aggregatio XJiag et al (1995) drig dead ed
MF sig two eraes i series hypothesised that at roo teperatre (22C) ad
with a pisto pp givig high shear coditios, BSA is ssceptie to deatratio
casig a rapid rise i pressre drop drig costat rate ltratio. hey attrited
the pressre drop to adsorptio aloe eglectig pressre drop de to pore plggig
y aggregates. Blapai et al (1993) drig MF of eer reported foratio of loca
aggregates of acro sotes over the pore opeigs eadig to foig
Ki et al (1992) coclded that aggregate foratio drig is exacerated ycoditios like erae srface roghess ad high covective ows cose to the
erae srface hey fod foratio of aggregates with higher iitial x eraes, t ot o the ower x eraes. hey attrited aggregatio to
coforatioa chages i the BSA olecles associated with the high shear rates
that exist ear the erae srface. hey hypothesised that these cofoatioal
chages exposed hydrophoic regios o the BSA oeces which the iteracted to
for arge protei aggregates at the erae srface.
Maa ad Hs (1996a) sggested that folig was ore attrited to the aggregatio
takig place i the lter pores drig ltratio (secodary aggregatio) tha to the
aggregates preset efore tratio. Foratio of BSA aggegates drig acta
stirred cell ltratio was hypothesised y Kelly ad Zydey (1995). Josso et al
(1996) hypothesised isitu geeratio of BSA aggregates drig ppig. It wassggested that high deatratio de to ppig eads to foratio of aggregates that
caot peetrate ito pores t for a cake
he effect of operatig coditios o protei aggregatio drig UF was ivestigated
y Ki et al (1993a) They hypothesised that high shear rate coied with high
protei cocetratio ehaced protei aggregatio. Havacek ad Bochet (1993)
deostrated that protei sotios iitially free of aggregates ca ipair a MF
process, if deatratio ad aggegatio coditios are preset i the syste. Protei
aggregates ca for y a variety of echaiss. Persso ad Gekas (1994) i their
18
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
31/232
reew, sggested that aggregation of macromoleces IS de to their exible
secondary and tertiary strctre
In concsion, protein aggregates in the feed or those generated dring processing
appear to pay an important role in the severe foling observed with MF membranes
264 pH nd ionic strength
he inence of p and ionic strength on protein foing in UF was reported by Fane
et al. 983) and Ski et al. 984) hey showed that deposition was highest at theisoeectric p IEP) of the protein BSA and reatively low at p away from the IEP
Addition of sat NaC) generally increased deposition he expanation given is as
follows: BSA molecles at the IEP no sat) are in their most compact state and carry
no net charge giving the least permeabe deposit layers Away om the IEP and in
the absence of salt, the molecles expand and have sigicant net charge giving
relatively permeabe layers Addition of salt at these p extremes will shied charges
casing moleclar contraction At the IEP, the effect wold be different since the
addition of salt cases anion binding, enlargement of the molecle and acqisition of
char with an xpected increas in permeability
einemann et al. 988) stdied the effect of salt on foing and protein transmissiondring MF of whey protein soltion throgh a 02 m hydrophiic membrane hey
fond that addition of 00 mM NaC decreased x of protein sotions, the x
decrease being independent of p owever steady state protein transmission was
30-35% higher and the degree of loss of transmission was less at p vales away
from the IEP Protein transmission of the sat-free soltion was at a maximm arond
the IEP, whereas in the presence of salt, the steady state transmission was at a
minimm hey considered interaction of charged moeces with the charges on the
membrane srface to expain the reslts Addition of sat seems to have redced
eectrokinetic interaction between protein and membrane leading to a compressed
dobe ayer, less interaction and increased protein transmission owever redced
size of the protein apparenty cased pore pgging and denser deposits redcing x
hey proposed that at the IEP, in the presence of sat, the salting ot" effect
9
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
32/232
20
enhances aggregaon an he bul up of enser eposs resung n reuce ux
an proen ransmsson
Palecek et al 993) nvesgae he effec of onc envronmen on he hyrauc
permeably of he eposs urng F of BSA usng a 0 6 m Poyehersufone
PES) membrane They foun ha permeabl of epose ayers of BSA was a
mnmum a he proen soelecrc pH an ecrease wh ncreasng souon onc
srengh IS) a pH boh above an beow he IEP They aso foun ha ux was a
ncon of he eecrole composon wh he ux for BSA n NaC approxmaey
40% greaer han ha for BSA n a CaC soluon of he same IS Ths epenency
on IS an on vaency was arbue o porosy n he epos whch was eermne
prmary by he baance beween he compressve pressure assocae wh he rae
ux an he elecrosac repuson beween he charge proens whn he epos.
Palecek an Zyney (1994a) foun ha seaysae permeably for albumn,
lysoyme rbonucease A haemogobn an mmunoglobun eposs was a
mnmum a he proen soelecrc pH an ecrease wh ncreasng saconcenraon a pH values boh above an beow he IEP In a aer pubcaon
Paecek an Zyney (1994b) suggese ha ux eclne urng proen lraon
hrough even large pore F embranes s ue o he formaon of a proen epos
on he membrane wh he epose proen layer provng a arge aona
hyrauc ressance o he lrae ow The seay sae ux hrough he fferen
proen eposs was a mnmum a he proen soelecrc pon an appeare o
ncrease amos lnearly wh he proen surface charge ensy. Poulo et al (994)
have aso foun sgncany hgher foung a he proen IEP ue o ncrease
eposon an hyraulc ressance.
Baakrshnan an Agarwal 1996) use a vorex ow er o suy ux an
ransmsson behavour of ysoyme (14 kD, pI 106) ovalbumn (44 kD, pI: 46)
an myogobn 17 pI 68) usng a 100 kD cuoff hyrophc polyacronre
membrane For a hese proens he ux ncrease nearly wh ncreasng TP up
o 30 kPa an rher ncrease n TP resue n a margnal nonlnear ncrease n
ux The foung was mnmal for ovalbun bu ysoyme an myogobn showe a
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
33/232
2
sall reducon (7 & 35%) n ux durng proen raon. The ranssson
however vared arkedly for hese hree proens Whe ovabun and yogobn
exhbed proen ransssons n he range of 25-50 & 75-95% respecvey
lysozye exhbed an unexpecedy hgh ranssson up o 20% pyng
concenraon of proen n he pereae srea They arbued hs o he presence
of aracve proen-ebrane elecrosac neracons under he condons used
The dfference n proen ranssson was arbued o he pH condons of he
soluons The experens were conduced a pH 68 whch was below he pI of
ysozye Consequenly lysozye was posvely charged a hs pH and
experenced overall aracon owards he hydrophc ebrane apparenly leadng
o a hgh proen ranssson of abou 20% On he oher hand ovalbun (I 6)
whch s negavely charged a hs pH was repelled by he ebrane surface and
dspayed ranssson arkedly below 00% (25-55%) Mygobn whch s a
zweron a pH 68 foowed a prole sar o ha of ovalbun bu wh uch
hgher ransssons (75-95%) Ths was appareny because onc neracons
beween he neura yogobn olecules and he ebrane surface were na
causng he yoglobn ranspor o occur any by olecuar sevng
o suars foun s svere a proen I and becoes ess severe boh above
and below I Addon of sa generally ncreases severy of foulng a pH away
fro I however a I decreases foulng
2.6.5. Concntrton
Concenraon of he feed sees o deerne he ype of foulng echans Tracey
and Davs (199) found ha foung by 00% BSA soluons was ore severe han
wh 0% soluons on 02 poycarbonae ebranes I was hypohessed ha
proen aggregaes ha fored a 01 % concenraon are larger han aggregaes
fored a 00 % causng exeal foung leadng o foraon of a porous cake
whereas saer aggregaes a low concenraon are sucen o ener he pores and
cause nea foung reducng proen ranssson below ha obaned wh
exea foung On he oher hand Ge and Davs (996) usng a 02
ebrane repored ha ovabun aggregaes ha fored a hgh concenraon
ncreased ux declne by pore puggng Bowen and Ha (995) usng e anayss of
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
34/232
22
ltration data obtained fro MF of YADH showed that the fouing echanis
changed o inpore deposition to surface deposition as concentration was increased
In suary concentration of protein which is inked to aggregate foration can
affect fouing by plugging the pores or foring a surface layer depending upon
aggregate size The porosity of the deposited layer of aggregates affects the ux and
protein transission
266 Preltrton
Kelly et al (993) deonstrated that preltration of BSA solutions prior to MF
substantially reduced their fouling tendency with the degree of iproveent
increasing as the preltration was perfored through saler olecuar weight cut
off ebranes Maa and Hsu (996a) also observed reduction in fouing when
recobinant huan growth horone (rhGH) was pretered On the other hand
Hlavacek and Bouchet (993) found that preltered BSA solutions sti fouled during
MF Jonsson et al (996) observed a signicant deay in cake foration when BSA
was preltered In suary pretration sees to reduce the severity of fouling butdoes not eliinate it copletely especially when secondary aggregation occurs
267 Presence of mnerls nd surfctnts
Vetier et al (988) during MF of ik on auina ebranes found that caciu and
phosphorous sats increased fouing probably by aowing better adsorption of casein
icees on the aluina and by acting as inteicear bonds in the deposit. The
seru ilk proteins were retained by the porous icear deposit under both static
and dynaic conditions resulting in progressive fouing of the dynaic icear
ebrane enabing ilk to be processed with a inera MF ebrane Scanning
electron icroscopy (SEM) studies revealed that fouing occurred in dynaic
ltration which was siiar to that described for static conditions except that the layer
was uch thinner with a iniu of 5 (thicknesses 50 ties greater were
observed in static experients) The ost iportant role of the caciu and
phosphorous sats present in the soluble phase of ilk is to act as a ceent between
icelles and aluina in fouling and between the iceles theselves It was
suggested that fouing was initiated by adsorption of a thin of casein and sats on
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
35/232
23
whch wee then deposted othe mcelles whch may be connected by phosphocalcc
bonds
Maa and Hs (1996b obseved mpoved taton by the addton o sodm dodecyl
sate (SDS a sactant Ezo et al (1996 ond that the pesence o tton
a nononc sactant cased weake adheson oces between glass patcles and a
model membane consstng o a ceose dacetate m They ond easy emoval
o patces om the sace de to the pesence o sactant The edcton n
adheson enegy de to the pesence o sctant s expaned by a nmbe o actos
The hydophobc tas o the tton ae adsobed on patcle saces and the
membane sace s ths exposed to the hydophlc head gop o the sactant
The pesence o tton ndced stec eects between saces and a sbstanta
decease n adheson between patces and the membane sace was obseved
2.7 Effect f membrne prperties
27 Pre size
Hghe pemeate xes ae expected wth MF becase o the elatvey lage poesze Bt Atta et al (1991 b whe pocessng skm mlk on almnm oxde MF
memaes on e emeate xes wth a 02 m membae than a 08 m
membane Spsngy seveal nvestgatos have shown that thogh xes
nceased wth nceasng poe sze x declne was geate as the poe sze
nceased Pot et al (1984 consdeed the peomance o Nclepoe membanes
(001 003 005 008 01 m wth cheese whey n an Amcon Ce Fxes
nceased ntl the 008 m membanes ae whch the x declned In addton
they ond that etenton was owest o the 005 m membane nceasng as the
poe sze both deceased and nceased Meeles et al ( 1991 b) consdeed the
peomance o a ange o poyslone membanes wth BSA ovalbmn and
lactabmn Ae 1 mnte the poten etentons o BSA wee 100 85 and 20% o
10 40 and 100 MWCO membanes espectvely Howeve poten etentons o
the thee membanes at steady state wee 100 100 and 98% Changes n poten
etenton by olng ae moe sevee as the membane poe sze nceases n a
nmbe o cases an optmm poe sze wth espect to pemeate x has been
dented below whch the esstance o the membane tsel and the omaton o a
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
36/232
24
surface fouling layer reduce the permeate ux and above which the increased rate of
membrane fouling due to deposition within the pores causes ower long te uxes.
Jonsson et al (996 studied the effect of pore size on fouing. t was observed that
surface bocking rate decreased with an increase in mean pore radii and a decrease in
porosity whereas the cake formation step decreased with an increase in mean pore
radii. Kim et a. (992 comparing the different membranes used in their studyfound that there is a general relationship for the membranes between the amountof protein deposited and the ux decine This observation was ess apparent with the
Nucepore and Anopore MF membranes Whist the Anopore membrane had a lower
ux decline in spite of its greater protein deposition the Nuclepore membrane
showed a tremendous ux oss (>90% for a relativey sma amount of protein
deposition The explanation advanced was the lower porosity of the Nuclepore
membrane (0% compared to the Anopore membrane (50%) Comparing 02 m
and 005 m polycarbonate membranes during ltration of BSA solutions Tracey &
Davis (994 hypothesised that the 02 m membrane initiay fouls inteally as no
signicant protein reection is occurring and yet the resistance is increasing; once the
pores are constrcted fouling becomes exteal. However on the 005 m membranecake ayer build up occurs immediately on the surface of the membrane
2.7.2. Pore morpholo
Use of membranes with the matrix side facing the feed soution (YADH gave much
slower decreases in ltration ux showing the importance of pore morphology in the
optimisation of ltration rates (Bowen & an 993 However the resut was not
repeated when ltering industrial ferentation broth. The results were attributed to
pressureinduced pore broadening of the polymeric membrane whereas with
fermentation broth the high suspended solids present blocked the exposed matrix
Persson et al (993b used liquid displacement porosity (DP to characterse four
polymeric MF membranes. DP showed a clear pore size distribution for al
membranes analysed with 0% of the pores having at east 90% of the permeabiity
Mueller and Davis (996 investigated effects of varying membrane morphoogy and
surface chemistry on protein fouling mechanisms of MF membranes. A 02 m
tracketched polycarbonate (PC membrane foued inteally with exteal fouing
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
37/232
25
becomin the dominant means of foulin only at later times. A 02 m cellulose
acetate CA) membrane showed only inteal foulin, while 0.2 m polysulfone PS)
and polyvinylidene uoride PVDF) membranes showed only exteal foulin It is
hypothesised that the low surface porosities and lare thickness of the PS and PVDF
membranes reduced permeate ux and allowed protein areates to uickly plu the
few pores, leadin to almost immediate exteal foulin surface layer), while the
hiher surface porosities and small thickness of the PC and CA membranes yielded
hiher uxes and caused extensive inteal foulin before exteal foulin took over
They reported sinicant loss of protein transmission durin exteal foulin In part
11 of the study, on the effects of various surface modications, results show thatsurfacemodied polyethlene and polypropylene membranes have lower initial
uxes than the unmodied membranes However, the hydrophilic modied
membranes demonstrated comparable nal uxes and lower percent ux declines
than the unmodied membranes The azlactone modied membranes showed very
low lon-term uxes and lare decreases in permeate protein concentration due to
ecient protein bindin Aain, protein transmission remained constant or only
slihtlydecreased durin inteal foulin, while a sinicant loss of protein
transmission was observed durin exteal foulin J onsson et al (99) suested
that membrane morholo rather than surface chemistr is more important in MF
foulin as the primary cause of the ux decline is the deposition of protein areates
affected by morpholoy) rather than adsorption of protein molecules affected by
surface chemisr) Gell and Davis ( 996) found that lower surface porosity
membranes exhibited more rapid exteal foulin probably due to pluin of the few
pores that contrbute to the larer permeate ows
In summar, pore foulin appears to have a sinicant inuence on subseuent MF
foulin Membranes with lare inteal area may have increased interactions between
proteins and membranes These interactions sometimes lead to formation of protein
areates and pluin of lare pores resultin in dramatically lower uxes even
thouh initial uxes are hih
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
38/232
26
27.3. Microscopy studies on ouling
Drec observaton of foed membranes sng SEM Atomc Force Mcroscopy
(AFM) and Fed Emsson Scannng Eecron Mcroscopy (FESEM) ave been
performed by severa nvesgators o ecdate te fong mecansms Km et al(1992) sng FESEM observed srface deposon even on membranes ta pass
sbstana amons of proens. Tere was no FESEM observabe proen wn te
pores. Two dfferen ypes of foant deposs were observed on te membrane
srface fong by mayer (cake) coang and fong by aggregaes of proens.
Tey sowed at proen aggregaes were formed on a poysfone membrane
mmedatey ( 1 mn) . Grow of aggregaed proen wt tme drng UF of 0 1%
BSA on poysfone membranes was demonstrated Havacek and Bocet ( 1 993)
sng SEM sowed at e fong drng consant x MF of BSA on a 02 m
M pore membrane s mosty a srface depos made p of proten aggregaes. Key
and Zydney (199 ave aso sowed a fong was predomnany by aggregates
on te srface ayer. Tracey and Davs ( 1 99) sng SEM reveaed a pore rad and
pore densy bo decreased w raon me Bowen and Ha ( 1 995) sng AFM
fond arge amons of Y ADH deposed on a Cycopore membrane srface w onya few pores vsbe ncovered by deposs. Maa and Hs ( 1 996a) sng SEM anayss
sowed a .2 m membranes wen sed o er rGH sotons nder 035 bar
TM were pgged o a grea exen.
Km et al (1997 measred sreamng poentas of vrgn and foed membranes to
sdy fong. Tey sed sets of poycarbonate rack etced membranes of two pore
sze ranges smaer pore sze (001 0.03 .05 m) and arger pore sze (0.1 and 0.2
m) o er BSA. Comparson of apparen zea poentas (cacaed based on
sreamng potena measrements of vrgn and foed membranes sggesed tat te
measred poenas are deermned by e proen propertes. I appears at te
proen adsorpon compeey moded e srface carge of e orgna membranes
Tey sed forer ransform nfrared (FTIR) specroscopy o ook a e exen of
proten deposton F or e membranes w sma pores e B SA peak dd notappear n e specra b te BSA peaks were seen ceary w bgger pore sze
membranes Te amon of proen adsorbed on te smaer pore sze membrane may
be nder te deecon m of te nsrmen de to er ow porosty and sma pore
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
39/232
27
ze Fo the membanes with lage poes howeve, the BSA peaks inceased with
inceasing poe size due to the geate volume of BSA solution passed Analysis of
the FTIR specta of the potein fouled 02 m membane pefomed on both sides of
the membane indicated that the feed side gave moe intense BSA peaks than the
pemeate side suggesting that the adsoption is pedominantly on the feed suce
The depthpoling of the fouled membane also suggests that potein adsoption was
mainly on the suface o nea the poe enties athe than thoughout the membane
poe Suface poperties ofthe fouled membanes mio popeties of the deposited
potein. Thee is a lack of poe size effect on the zeta potentials of the potein fouled
membane suggesting again pedominantly suface laye, which was conmed by
Electron micoscopy To simulate BSA fouling they lteed silve colloids of size 8
nm using a 02 m membane. FESEM pictues showed gadual poe bidging and
evenual coveage by the silve colloids They poposed that a simila mechanism is
expected with BSA even though BSA molecules ae quite diffeent fom silve
colloids.
To summaise, all the above diect observations of MF membanes obtained aepotein ltation indicate that fouling did not occu thoughout the membane
strucue but pedominantly on the suface o nea the poe entrance
2.8 . Effect of operating variables
2.8.1 . Permeate uxTransmembrane pressure (TMP)
Piot et al. (1986) obtained esults when pocessing whole milk on a 8 m ceamic
membane The ate of ux decline deceased and the aveage pemeate ates
inceased as the TMP was educed fom 1 0 to 0.8 to 065 ba These esults show that
thee is possibly an optimum TMP at which ux ate is a maximumfo the given poe
size . Optimum TMP deceased as the poe size inceased Inceasing the TMP also
esulted in lowe wate ux ecovey ae wate ushing suggesting that moe sevee
fouling had occurred (Pesson et al., 1 993a) Van de Host and Piesma ( 988)
duing CFMF of skim milk found that fo both 04 and 07 m membanes the ux
deceased with inceasing TMP and deceasing coss-ow velocity Bowen and Gan
( 1 99 ) when pocessing BSA with 02 m Anopoe capil lay membanes found that
inceasing the TMP (0 14 , 034, 0 .69 and 1 .3 8 ba) inceased the initial pemeate ux
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
40/232
28
b also increased e rae of x declne Te nal permeae xes were fairly
simlar Tey sggesed a e reason for connos declne in x was sear
ndced deposon of proen molecles Jonsson et al 992b) obseved x decline
dng MF of BSA solions Tey sggesed a e x declne cold be relaed odenaraion of e BSA molecles a e pore enries becase of e ig sear
forces Bowen and Gan 992) fond a x declne was more severe wen
operaed a ger TM Tey demonsraed a decreased aciviy of YADH was
becase of enzyme ineracons resling om a sear indced deformaion of e
enzyme srcre Dan and Merin 1995) repored qoing io et al 986) and
Malmberg and Holm 988) work a e TM s a mos crcal parameer
nencing x decline in MF of milk I was sown a increasing TM by 0 1 5
bar dobled e x b wen TM exceeded 0 bar or 065 bar foling occrred
mc faser Frenander and Jnsson 1996) glged a crical TM o minimse
foling dring consan x operaon
Te imporance of consan x operaon as been sressed o redce foling in MF
Seean et al 988) sed permeae ow conrol n preference o permeae pressreconrol and e average x was fond o ncrease by a facor of 25 dring e
recover of an exracel llar baceral proease Te repored a n order o redce
e folng rae i s imporan o keep TM as low as possble wle mainainng
recrclaion rae as g as possible Marsall et al 996) dring MF of skim mlk
sng 0 1 m polyslfone membrane demonsraed a severe foling cold be
prevened by carel sar p procedres and b conrol of permeae x However i
was fond a ere was no bene of sng consan x operaon drng UF vanRes et al 997) wile separang IgGBSA and BSA monomerolgomer mxres
sggesed a operaion n e pressre dependen regme of e lrae x cve
and carel conrol of id damc sar p condiions will minmse foling and
increase selecivy
Meller and Davis 1996) sowed a increased ransmembrane pressre resled nmore severe folng of e polyslfone and VDF membranes erssonet a 993a)
sing for dfferen polmeric MF membranes fond a increased TM resled in
an ncreased foling layer for e wey proein Irreversible foling increased wi
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
41/232
29
ncreasng TMP leadng to poor x recovery Tey sggested tat ncreased folng
was a combnaton of pore narrowng pore pggng and cake layer bd p
coverng a te possbe optons).
Blanpan et al 1 993 ) ave reported ncrease n adsorpton at ger TMPs Increase
n TMP seems to ncrease drvng force to te membrane enancng proten
concentraton at te srface of te membrane and ts ncreasng te adsorpton
Marsa et al 1 997) ave reported severe folng at ger permeate xes Tey
proposed tat as te x s ncreased te sear sress n te pore s ncreased casng
an ncrease n te proten nfoldng deposton and fong drng MF of
lactoglobln
Boyaval et al. 1 996) sded te effect of TMP on permeate x drng MF of actc
acd bactera on a 02 m membrane In ts case te ce s were totay rejected by
te membrane de to ter sze compared to te argest pores of te membrane
Folng was predomnanty de to te formaton of a reversble cake of mcroba
partces on te srface. At ower pressres an ncrease n TMP from 0 1 to 03 bar)ndced a sarp ncrease of x wc reaced 120 Lm for a TMP of 03 bar At
TMP above ts vale x reaced almost a stable vale At constant TMP beow
ts vale x was constant wt tme Ts beavor s smlar to te cassca
pressre verss x relatonsp observed n UF Ts ype of beavor s generay
observed wen tere s predomnantly a srface layer on te MF membrane Tey
also stded te effect of transent operaton condtons on fong Tey fond tat
fast ncrease of TMP 5 mn) reslted n severe folng compared to ncrease of TMP
over a perod of 30 mn Tey sggested tat n a fast transent regme te
convectve forces are stronger and partces ave less tme and space to organse Te
depost composed of a ess dense strcre wod ten be capabe of entrapment of
medm molecles wereas te slow transent regme ndced a more organsed
depost
A dfferent observaton was made by Cakl and Mkek 1995) we terng PVC
latex Tey sowed tat ncreasng TMP dd not aways ncrease te x Tey
reported tat TMP ncreased x nearly f te partcles were bgger tan te pores
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
42/232
30
I was fond a e x nceased lneay w TM a ow vaes p o a cca
vae en e ae of ncease deceased and nay x become neay ndependen
of TM a g vales. I seems ee s an opmm TM below wc e dvng
foce s oo ow and above wc nceased fong cases a edcon n x Ts sabed o e fomaon of a le cake w ge essance once e deposed
pacles ndego compacon nde ge TMs
Mc Donog et al 1995) sed a ado soope ecnqe and eecon dode aay
mcoscope EDAM) o sdy C dng UF and MF of BSA and dexan ble 2000
) solons on 001 m poe polysfone and 05 and 08 m poe ceose
aceae membanes. Te aon cel was paced beween e wo enses of e
EDAM sc a e egon exendng om e membane sface no e ow
cannel was vewed paalel o e membane sface and pependca o e
decon of coss-ow. Tey sowed a ncease n TM nceased e soe
concenaon nea e membane and also nceased e exen o sze of e
polased aye e egon wee e concenaon s ge an e blk Te nea
wall concenaon of dexan meased a a dsance of 20 m fom e membanewa de o e eqpmen consan) nceased fom abo 20 gl fo e case of 05
ba o 1 1 5 g / a 1 ba and o 1 0 g/ a 1 .5 ba.
In smmay appeas a opeaon on e low TM sde of e maxmm n e
pesse dependen egon s bee fo edcng fong emeae xes ae
genealy obseved o s ncease w nceasng TM and afe a cean cca
vae ey wold decease w e ncease n TM. TM s vey cca o
peven sevee folng n MF pocesses. Te TM wee e maxmm x occs
seems o decease as e membane poe sze nceases fo e gven ype of feed
Low and nfom TM appeas o be ccal o mnmse folng dng MF.
2..2. Sher
Nelson and Gaz 1985) epoed a nde d sea condons aggegaonnvoves e followng seps. Inay aggegaon occs by coll sons ndced by
e Bownan moon of e poens. Ts esls n e fomaon of pmay
aggegaes . Aggegaon connes by s mecansm nl e aggegaes become
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
43/232
3
large enog for id moion o promoe collisions a wic poin rer
aggregaion is goveed by sear indced coll isions Aggregaion does no conine
indeniely insead as e aggregaes ge bigger eir growt rae decreases and
evenally ey reac a limiing size wic depends on e inensity of e sear eldJonsson et al 996) aribed foling of membranes o a slig denaraion of
proeins de o e ig sear sresses presen inside e pmp Comparaive foling
sdies by em wi and wio pmping indicaed less severe foling in e no
pmping case sggesing no aggregae formaion in e absence of pmping. Maa
and Hs 996b) repored some canges in proein conformaion wen recombinan
man growt ormone rGH) was sbeced o ig sear raes (> 0 ) in a
omogeniser. Maiorella et al 99 ) repored a sear damages nearly 30 of
animal cells by a lobe pmp a a ow velocity of 3 5 m/s. Tog ere is no direc
experimenal evidence of proein denaraion by sear i is ypoesised a sear
a e membrane pore cases aggregaion of proein leading o sbseqen foling in
MF Candavarkar 990 Meireles et al 99 a) On e oer and a os of oer
invesigaors Franen et a 990 Bowen & Gan 99 992 993 Jonsson et al
992a Marsall et a 997) ypoesised a sear a e membrane pore enrance
cased proeins o deposi dring MF. One ing is clear in MF as e ineal
membrane area is signicanly larger an a of membranes ineracion ofproein wi e membrane geomery can play an imporan role especially nder ig
sear given a proein and membrane are bo srface acive
Hig sear sress a e membrane wall is generally elpl in sweeping away any
deposis on e membrane srface. A criical raio of x and sear sress J/) adeermines e balance beween convecive ow owards e membrane e
angenial erosion Aber et al 993) and sear indced difsion Davis &
Leigon 987 Belfor et a, 99) was proposed o minimise foling in siaions
were foling is predominanly by formaion of a srface layer or cake Boyaval et
al 996) dring MF of lacic acid baceria fond a foling was faser and more
severe wen J was greaer an a criical vale of 5 m a Le Berre andDan 994) previosly repoed a similar concep and presened a criical vale of
L ma for MF of skim milk and prereaed wey Gsan et al 995) is
no known wy e vale is so close wi ese wo feeds esed.
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
44/232
32
To smmaise shea can case poein o deposi a he poe enance o enhance
aggegaion of poein leading o sevee foling in mos cases
2.83. Crossow veloci
Sheehan et al (1988) obseved ha inceasing eciclaion ae om 60 o 00
liesmine (coesponding o linea velociies of 06 o 10 ms ) podced a
oghly 50 incease in x pefomance fo he same TM pole ding cell
sepaaion Howeve Meieles et al ( 1 990) epoed ha incease in eenae velociy
inceased poein aggegaion and sbseqen foling ding BSA laion on
polymeic membanes Bowen and Gan ( 99 ) sdied he effec of siing ding
U and MF of BSA solions They sowed ha siing (500 pm) had lile effecon pemeae x when leing sing a 02 m Anopoe membane wheeas sing a
UF membane (MW c-off of 10 kDa) in he same cell nde compaable condiions
siing gave a dobling in he pemeaion ae In he case of he UF membane bo
C and deposiion on he on face of he membane appeaed o be impoan
Siing had lile effec in MF as ee is no appaen accmlaion of poein
deposis on he fon face of he membane. On he ohe hand Cakl and Mklek(995) ding laion of acylic copolyme laex paicles on a 0 m membane
showed a inceasing CFV did no always incease he x In is case he
membane foled ineally Tey fond a powe law elaionship beween x and
feed velociy in he case of VC laex paicles on a 02 m membane In his case
foling was in he fom of a cake Mackley and Sheman ( 993) ding laion of a
polyehylene sspension fond ha inceased CFV deceased lae x Inceased
CFV appaenly fomed an ecienly packed le cake leading o low poosiy
Taleon and Wakeman (993) ciing Fische et al (986) leing calcim cabonae
slies epoed ha e size of he paicles in he cake laye deceased as he CFV
inceased leading o a edcion of he pemeae x even hogh he cake hickness
was deceased. Li et al ( 996) epoed MF ofEColi sing a ceamic membane E
Coli fomed a sface cake as i is signicanly lage han e membane poe size
(02 m) Inceasing CFV inceased pemeae x
In conclsion CFV appeas o affec foling in siaions whee sface laye
fomaion is he dominan mechanism of foling Howeve is effec was minimal
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
45/232
33
wen foung was predomnanly by an nea pore foulng mecansm excep n
cases were ncreased CFV reduced parce se ncreasng e possby of
puggng
2.9. ouling mechnisms
Te mecansms by wc foung may occur are several Tese depend on: )
weer e gven proen s smaller or arger an e average pore se of e
membrane; 2) e ype of proenproen neracons; and 3) e proen-membrane
neracons nvolved A sngle ype of mecansm appears o be rare as ere s
usualy a se dsrbuon n bo e membrane pores and e macromoecueslered. Smuaneous occurrence of more an one mecansm s mos kely
dcang ux and seecvy n MF. As a resul e use of exsng foulng modes s
med o e analyss of expermenal daa w quanave predcons of ux under
specc condons raer an provdng an undersandng of e foulng
penomenon A beer undersandng of e foung mecansms s essena f CFMF
s o be exploed fuy by mnmsng foulng.
Frs foung mecansms durng lraon of non-proen feeds are consdered
followed by foulng mecansms nvolvng proens. Ten e reevance of non
proen foulng o proen foulng wll be dscussed
ore brdgng by collods was repored by Vsvanaan and Ben Am (989) we
erng coods of average dameer 12 nm roug a 200 nm pore se membrane
Tey found a foulng a ow appled pressure was manly due o a combnaon of
e brdgng of coods over e pore openngs and a concenraon poarsaon ayer
wc ed o exeal membrane foulng wereas neal foulng of e membrane
played a reavely nsgncan role Te brdgng was presumaby by collodal
aggregaes a were formed on e membrane surface appareny due o deposon
and cuserng. roens n smar suaons woud probaby gve more severe
foulng as proen-membrane and proenproen neracons are expeced o be far
more sgncan
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
46/232
34
Tarleton and Wakeman 1993) sggested tat folng by partclates appears to be
cased by two ndependent mecansms wc occr smltaneosly Te rst
acconts for ntal sarp declne n permeate x and s rreversble for all practcal
prposes and s de to te rapd deposton and captre of ner parcles omsspenson and ter sbseqent penetraton nto te pores of te membrane Te
second mecansm s largely reversble and cases rter partclate layers) to form
above te membrane srface n te form of a cake
Km et al 1 993b) sded te effect of collod sze on te membrane pore sze drng
ltraton of dlte slver collods of sze 8326 nm sng 30 1 00 300 k and 022
m membranes Slver partcles formed a cake on te small pore sze 30 k
membrane Wt te 00 and 300 k membranes wose pore sze was larger tan te
sze of te folant severe folng occrred de to folng wtn te membrane pores
However wt te 022 m membrane te retenton of slver collods was low and
te small ncrease n resstance was peraps de to te deposton of slver partcles
on te pore walls
Cakl and Mklek 1995) dented two pases of x declne drng constant
pressre MF of syntetc collods Acrylc copolymer AC) latex & poly vnyl
clorde VC) latex partcles of average szes 0 1 m and 1 0 m respectvely were
processed on 0. 1 and 02 m almna based ceramc membranes respectvely Frst
reversble concentraton polarsaton blt p wtn te rst mnte Ten x
contned to declne for p to several ors de to polymer collod deposton on te
front srface of te membrane or wtn te membrane pores Tey conclded tat
cake formaton prevals f te parcles are larger tan te pores VC latex)
Increasng feed velocty generally ncreased permeate x A dfferent folng
beavor occrred f te actve layer pore sze was very close to te dameter of te
partcles ltered AC latex parcles). Increasng te feed velocty ad a lmted
effect If te parcles are sfcently exble tey can enter te pores and reman
nsde probably de to some nteracton wt te membrane materal Wen te feedvelocty was scently low s) te perod of pore l lng was sor Te pores
may be only slgtly entered by partcles wc ten begn nstantly to brdge over te
pore and form a very tn l ter cake Ts depost can be taken as a secondary
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
47/232
35
membrane wc proecs e MF membrane agans pggng by parcles and
erefore conbes o a ger and more sabe x A ger veoces (> s)
smaler parces can block e pores redcng x
Boyaval et al ( 996) drng MF ofactobacillus helveticus (rods of -5m n eng
and 05 1 m n dameer) sng 02 m almna membranes fond a fong was
de o a reasonably consan rreversble ayer formaon and o a domnan reversbe
ce cake nder varos permeae xes nvesgaed Domnan reversble cake was
de o e oal rejecon of e ce s by e membrane Ts work sggess a wen
mcrobal ces of sze mc bgger an e membrane pore sze are ered a
consan amon of rreversble folng predomnanly by adsorpon and a domnan
reversble srface ayer or cake occrs
Te effec of pore sze on e ype of fong mecansm was repored by Da-Cn et
al ( 996) Tey fond a membrane folng was e res of varyng combnaons
of adsorpon pore pggng and concenraon polarsaon or gel ayer formaon
drng UF of a plp m een conanng parces of a broad sze range 0 o 37m sng membranes of molecar weg coff (MWCO) range 300 Da o >500
kDa. Tey ypoessed a srace asorpon was key for ower MWCO
membranes and a e adsorbed layer was conrong membrane performance
wereas adsorpon seemed o ave cased pore narrowng w ger MWCO
membranes
To smmarse fong by non proen maerals folng wn e membrane or as a
cake layer occrs dependng pon weer e parce sze s larger or smaer an
e pore sze Cooda aggregaes may form brdges over pore openngs eadng o
pore consrcon and formaon of a cake In some cases formaon of a srface ayer
(secondary membrane) can proec agans pore plggng W sver collods e
fong mecansm canges from deposon wn e membrane pores o foaon
of a cake as e pore sze s decreased I appears a fong by less neracve nonproen feeds s domnaed by deposon and cake formaon wereas w proens
addona facors ke er neracons w e membrane and emseves pay a
major roe A leas n eory more severe folng s expeced w proens
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
48/232
36
compared o ess ineracive non-proein eeds Nevereess knowedge o non
proein oing cod o a basis or ndersanding proein oing Te aggegaion
endency o proeins is an imporan aspec a ms be considered wi proein
oing
Meireles et al 1 990) sggesed a in genera membrane oing by proeins can be
de o a combinaion o naive proein adsorpion and o aggregae deposiion, e
aer being sensiive o operaing condiions e ormer dependen on e
concenraion o e proein.
Adsorpion and pore plgging played a signican roe on 35 and 100 nm pore size
almina membranes o orm a gel layer ding raion o BSA nder consan
pressre condiions Cark et a 1991) Tey aibed gel ayer omaion o
proeinproein ineracions van Reis et al 1991) wile separaing proeins om
mammalian cels sing a 0.2 m polypropylene membrane ypoesised e
olowing x decine mecanisms: 1) adsorpion 2) denaraion de o proein
membrane ineracion or e generaion o airiqid inerces; and 3) reenion bymoeclar sieving de o aggregaes in e eed or aggregaes prodced dring
lraion isel
Severe oing by BSA on a range o membranes o varios pore sizes was repoed
by onsson et al 992a). Adsorpion o BSA ad a major role on a 20 k
polyslone membrane However wi 02 and 1 m pore size membranes wen
exposed o BSA nder saic condiions adsorpion alone cased a vey sma drop in
x However nder low pressre lraion 0 1 05 bar) very severe oing
occrred sowing a pore pgging dominaed oing wi ese membranes
Using SEM ey ave demonsraed a oing occred on e ron ace o e
membrane. I is ineresing o noe is beavior wi BSA as severe oing as
been obseved wi a range o pore sizes. Is oing beavior nder consan
pressre operaion as been repoed as a wo sep process onsson et a 1996) Ioled ineally rs and laer a srace ayer omed Tey sggesed a BSA
ineracs wi e membrane srcre and nally orms a srace layer I is no cear
weer is beavior is specic o BSA Is oling beavior nder consan x
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
49/232
37
condons w be ineresng o invesgae as ow inia TMs mg avoid TM
nduced proen-membrane neracons and subsequen fouing
Larger aggregaes can actuay reduce e foung effec f ey are bigger an epore sze as repored by Tracey and Davis ( 994) . Tey used e umped erms
"exea fouing and "nea foing drng MF Exea fouing refers o
foung due o e accmuaon of proein aggregaes a do no ener e pores
wereas inea fouing refers o foing wiin e inea pore srcure of e
membrane de o adsorpion and deposiion Tey ypoessed a drng MF of
very diue BSA soions (001 using a 02 m poycarbonae membrane fouing
occurred a e mous of e pores, sowy cosng off pore entrance we aowng
compee ransmission of proen for a period of me. Evenuay, e pores became
so constrced a proen ransmssion decreased and a ayer of rejeced proen
formed on e exea membrane surface However w 0 souons of BSA on
e same membrane, foing aowed for neary compee ransmssion of proens for
e enre eng of e expermens I was ypoessed a proein aggregaes a
form a 0 1 concenraion are arger an aggregaes formed a 0.0 concentraionTe arger aggregaes did no pass roug e membrane and so e foung was
exea Te rejeced ayer of arger proein aggregaes was appareny packed
oosey enoug o aow proein monomers o pass roug For due proen
souons i s proposed a aggregaes are sufceny sma o ener e pore mou
and cause inea fouing evenuay pugging e pores redcing proein
ransmission.
Simiar resus sowng a arger aggregaes can mnmize foung nder certain
condiions were aso repored by Gsan et al ( 995) Tey demonsraed e benes
of a modied prereamen meod o mnmse fouing for carng wey by MF
Longer MF operaion and better wey carcaon due o arger cacum pospae
parices and ower cacim and pospae conen in e aqueous pase were
aceved as a res of modied prereamen Loosey srcured deposis caused by
arger compex-pd-cacum pospae parices on e membrane srface, ncreased
e permeaon rae of deposs enancing MF uxes
5/21/2018 Hien Tuong Fouling Trong Dd Co Protein
50/232
38
Initiation o f fouling by aggregates present i n the feed seems to be the key factor in
determining the fouing mecanism (Kely & Zydney, 99 , 997) Te fouling
behaviour of BSA, cysteinyated BSA, ovabumin, ysoyme, pepsin, myglobin,
actalbumin & actoglobuin on a 022 m pore sie PVDF membrane under
constant pressure conditions was studied (Kelly & Zydney, 997) Fouing was
severe wit -actogobulin and ovalbumin and ighter with lysoyme while other
proteins behaved in the intermediate range Lysoyme was smallest of a in
moecular weigt They reported two distinct mechanisms ) deposition of arge
protein aggregates and 2) chemical attachment of native proteins to the growing
deposit The chemica attacment was found to occur via the formation of
intermoecuar disulde inkages invoving a ee suphydryl group in the native
protein Among the proteins investigated, actogobuin fouled severely athoug it
has ony one ee suphydry group They aributed the fouing to the reactivity of
the sulphydry groups rather than the number of groups Ovabumin aso foued
severely even though it does not have any free sulphydr group They attributed the
fouling behaviour of ovalbumin to aggregation by other mechanisms such as
hydropobic interactions
Daun and erin ( ) atriuted ouing during o pretreated whe at constant
ux to pore blocking This phenomenon exhibited itsef as a slow increase of fouling
resistance (R) with time, in which pores were progressively blocked until a point
when the remaining active ltering layer must compensate for bocked pores by
tering larger volumes The inevitable consequence was a fast fouing which was
expressed in a sharp increase of R unti l the limiting value As a consequence, a fast
decrease in protein transmission was also observed The fouing mechanism
Recommended