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Influence of organic-salt interactions on membrane (UF) fouling potential and pre-treatment by coagulation
Desalination 200 (2006) 210–212
Influence of organic-salt interactions on membrane (UF) fouling potential and pre-treatment by coagulation Kumaravel Sundaramoorthya*, Andreas Loi-brueggerb, Stefan Panglischb, Rolf Gimbela,b a
Department of Mechanical Engineering, Institute for Energy- and Environmental Engineering (EUT), Faculty of Engineering, Water Technology Group, University of Duisburg-Essen, Bismarckstr. 90, 47048 Duisburg, Germany Fax +49 203379-3017; email: [email protected] b IWW, Rheinisch-Westfaelisches Institut fuer Wasserforschung GmbH Moritzstr. 26, 45476 Muelheim, Germany Received 26 October 2005; accepted 2 March 2006
Keywords: Water-fractionation; MF/UF pre-treatment; Seawater reverse osmosis (SWRO); Biological fouling
1. Introduction
2. Experiments, results and discussions
Seawater desalination using reverse osmosis (RO) membrane systems is being seen as an effective solution to the freshwater scarcity, as seawater is widely abundant. A big hindrance to operating RO systems is bio-fouling, and it largely depends on the seawater type and its organic contents. To study bio-fouling in a better way, one need to understand the salt-organic interactions that influence the membrane fouling potential of the organics in water, as well as the organic matrix of the seawater. The first part of this work investigates the salt-organic interactions and future work will look into organic size fractionation of SSW samples.
Frequently studied reservoir water from Roetgen, close to Aachen in Germany, is used as the mother water with its natural organic contents, and different salts that are usually present in seawaters are added according to a given recipe [2] to produce synthetic seawater (SSW). A number of SSW samples are produced by mixing different seawater salts in different combinations. These different SSW samples are then tested for their fouling potential on UF capillary submerged membranes without and with pre-coagulation. Later, only the most severely fouling SSW samples will be fractionised into different organic size fractions using ceramic membranes [1]. A 0.4 µm and 5 kD ceramic membrane modules (CMM) are used for fractionising water into particulates (P),
*Corresponding author.
Presented at EUROMEMBRANE 2006, 24–28 September 2006, Giardini Naxos, Italy. 0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2006.03.299
Normalised permeability (%)
K. Sundaramoorthy et al. / Desalination 200 (2006) 210–212
100
Raw water and the different SSW samples filtered on UF membranes without pre-coagulation
95 90 85 80 RW SSW-1 SSW-2
75 70 0
Fig. 1. Fractionation by 0.4 µm/5 kD CMM.
211
50
SSW-3 SSW-4 SSW-5
SSW-6 SSW-7 SSW-8
100 150 Time (min)
200
250
Fig. 2. Different SSW samples filtered on UF membranes without pre-coagulation.
colloids (C) and dissolved (D) fractions as shown in Fig. 1. Normal crossflow filtration and dia-filtration are the two techniques applied, and critical flow conditions are maintained to ensure sharp fractionation. The fractions will be tested for fouling potential on UF capillary membranes with/without prior coagulation. These experiments are expected to throw more light on the salt-organic interactions in seawater that tend to influence organic removal and fouling potential on MF/UF pre-treatment systems used prior to SWRO systems in order to minimise the danger of bio-fouling.
The different SSW samples prepared are listed in Table 1. The results of the fouling experiments (Fig. 2) on UF capillary submerged membranes, done using a single membrane capillary test unit, are plotted as normalised permeability (NP = permeability relative to that of pure water) against time (4 h). The fouling potential of the individual SSW samples are expressed using permeability decline coefficient (PDC) and CI-PDC [1].
Table 1 Description of the different SSW samples (salt conc. as in seawater [2]) SSW
NaCl
MgSO4
CaCl2
KCl
Na2SO4
MgCl2
Description
Salinity %
SSW-1 SSW-2
X
X X
X
X
X X
X
RoetW + all salts RoetW + only sulphate salts RoetW + only Ca RoetW + only monovalent Cl salts RoetW + without monovalent Cl salts RoetW + only Mg salts RoetW + only bivalent salts RoetW + only Cl salts
3.57 0.58
SSW-3 SSW-4
X X
X
SSW-5
X
SSW-6
X
SSW-7
X
SSW-8
X
X
X
X X
X X
X X
X
0.11 2.48 1.09 0.58 0.69 2.99
212
K. Sundaramoorthy et al. / Desalination 200 (2006) 210–212
References [1]
K. Sundaramoorthy and A. Loi-Bruegger, Fractionation of a surface water to study the fouling potential on two different MF membranes in coagulated and
[2]
non-coagulated conditions, Aachener Tagung — Membrantechnik, 6 (W14) (2005) 1–22. J. Lyman and R.H. Fleming, Composition of sea water, J. Marine Res., 3 (1940) 134–146.
Influence of organic-salt interactions on membrane (UF) fouling potential and pre-treatment by coagulation Kumaravel Sundaramoorthya*, Andreas Loi-brueggerb, Stefan Panglischb, Rolf Gimbela,b a
Department of Mechanical Engineering, Institute for Energy- and Environmental Engineering (EUT), Faculty of Engineering, Water Technology Group, University of Duisburg-Essen, Bismarckstr. 90, 47048 Duisburg, Germany Fax +49 203379-3017; email: [email protected] b IWW, Rheinisch-Westfaelisches Institut fuer Wasserforschung GmbH Moritzstr. 26, 45476 Muelheim, Germany Received 26 October 2005; accepted 2 March 2006
Keywords: Water-fractionation; MF/UF pre-treatment; Seawater reverse osmosis (SWRO); Biological fouling
1. Introduction
2. Experiments, results and discussions
Seawater desalination using reverse osmosis (RO) membrane systems is being seen as an effective solution to the freshwater scarcity, as seawater is widely abundant. A big hindrance to operating RO systems is bio-fouling, and it largely depends on the seawater type and its organic contents. To study bio-fouling in a better way, one need to understand the salt-organic interactions that influence the membrane fouling potential of the organics in water, as well as the organic matrix of the seawater. The first part of this work investigates the salt-organic interactions and future work will look into organic size fractionation of SSW samples.
Frequently studied reservoir water from Roetgen, close to Aachen in Germany, is used as the mother water with its natural organic contents, and different salts that are usually present in seawaters are added according to a given recipe [2] to produce synthetic seawater (SSW). A number of SSW samples are produced by mixing different seawater salts in different combinations. These different SSW samples are then tested for their fouling potential on UF capillary submerged membranes without and with pre-coagulation. Later, only the most severely fouling SSW samples will be fractionised into different organic size fractions using ceramic membranes [1]. A 0.4 µm and 5 kD ceramic membrane modules (CMM) are used for fractionising water into particulates (P),
*Corresponding author.
Presented at EUROMEMBRANE 2006, 24–28 September 2006, Giardini Naxos, Italy. 0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2006.03.299
Normalised permeability (%)
K. Sundaramoorthy et al. / Desalination 200 (2006) 210–212
100
Raw water and the different SSW samples filtered on UF membranes without pre-coagulation
95 90 85 80 RW SSW-1 SSW-2
75 70 0
Fig. 1. Fractionation by 0.4 µm/5 kD CMM.
211
50
SSW-3 SSW-4 SSW-5
SSW-6 SSW-7 SSW-8
100 150 Time (min)
200
250
Fig. 2. Different SSW samples filtered on UF membranes without pre-coagulation.
colloids (C) and dissolved (D) fractions as shown in Fig. 1. Normal crossflow filtration and dia-filtration are the two techniques applied, and critical flow conditions are maintained to ensure sharp fractionation. The fractions will be tested for fouling potential on UF capillary membranes with/without prior coagulation. These experiments are expected to throw more light on the salt-organic interactions in seawater that tend to influence organic removal and fouling potential on MF/UF pre-treatment systems used prior to SWRO systems in order to minimise the danger of bio-fouling.
The different SSW samples prepared are listed in Table 1. The results of the fouling experiments (Fig. 2) on UF capillary submerged membranes, done using a single membrane capillary test unit, are plotted as normalised permeability (NP = permeability relative to that of pure water) against time (4 h). The fouling potential of the individual SSW samples are expressed using permeability decline coefficient (PDC) and CI-PDC [1].
Table 1 Description of the different SSW samples (salt conc. as in seawater [2]) SSW
NaCl
MgSO4
CaCl2
KCl
Na2SO4
MgCl2
Description
Salinity %
SSW-1 SSW-2
X
X X
X
X
X X
X
RoetW + all salts RoetW + only sulphate salts RoetW + only Ca RoetW + only monovalent Cl salts RoetW + without monovalent Cl salts RoetW + only Mg salts RoetW + only bivalent salts RoetW + only Cl salts
3.57 0.58
SSW-3 SSW-4
X X
X
SSW-5
X
SSW-6
X
SSW-7
X
SSW-8
X
X
X
X X
X X
X X
X
0.11 2.48 1.09 0.58 0.69 2.99
212
K. Sundaramoorthy et al. / Desalination 200 (2006) 210–212
References [1]
K. Sundaramoorthy and A. Loi-Bruegger, Fractionation of a surface water to study the fouling potential on two different MF membranes in coagulated and
[2]
non-coagulated conditions, Aachener Tagung — Membrantechnik, 6 (W14) (2005) 1–22. J. Lyman and R.H. Fleming, Composition of sea water, J. Marine Res., 3 (1940) 134–146.