The fouling of ultrafiltration membranes by natural organic matter after chemical coagulation treatment with different initial mixing conditions

2006 ◽  
Vol 6 (4) ◽  
pp. 117-124 ◽  
Author(s):  
H.C. Kim ◽  
J.H. Hong ◽  
S. Lee
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Mixing Conditions ◽  
Mechanical Mixing ◽  
Chemical Coagulation ◽  
Flux Decline ◽  
Hydrophobic Fraction ◽  
Hydrophilic Membranes

The flux decline in the UF membrane filtration of water pretreated by chemical coagulation using different initial mixing conditions were compared and the influence of natural organic matter (NOM) on the fouling of membranes was investigated. It was suggested that organic matter in the molecular weight ranges 300–2,000 and 20,000–40,000 Daltons were mainly responsible for the fouling. The fouling was greater for hydrophobic than hydrophilic membranes. ATR-FTIR analysis of the fouled hydrophobic membranes indicated that aliphatic amide and alcoholic compounds as well as polysaccharides contributed to significant membrane fouling. These adsorptive foulants are considered as neutral fractions present in hydrophobic and hydrophilic NOM components. In the case of similar hydrophilic fractions, water precoagulated with a high hydrophobic content resulted in greater flux decline, which was presumed to be due to the organic matter with neutral properties contained within the hydrophobic fraction. The relative concentrations of each NOM fraction in coagulated water are important. Mechanical mixing for chemical coagulation, with a backmixing-type, rather than pump diffusion mixing, with an in-line type, is likely to be more effective at reducing the fouling caused by NOM.

Coagulation/flocculation/ultrafiltration for natural organic matter removal in drinking water production

2004 ◽  
Vol 4 (5-6) ◽  
pp. 215-222 ◽  
Author(s):  
A.R. Costa ◽  
M.N. de Pinho
Keyword(s):  
Drinking Water ◽  
Organic Matter ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Water Production ◽  
Cellulose Acetate Membranes ◽  
Wide Range ◽  
Drinking Water Production

Membrane fouling by natural organic matter (NOM), namely by humic substances (HS), is a major problem in water treatment for drinking water production using membrane processes. Membrane fouling is dependent on membrane morphology like pore size and on water characteristics namely NOM nature. This work addresses the evaluation of the efficiency of ultrafiltration (UF) and Coagulation/Flocculation/UF performance in terms of permeation fluxes and HS removal, of the water from Tagus River (Valada). The operation of coagulation with chitosan was evaluated as a pretreatment for minimization of membrane fouling. UF experiments were carried out in flat cells of 13.2×10−4 m2 of membrane surface area and at transmembrane pressures from 1 to 4 bar. Five cellulose acetate membranes were laboratory made to cover a wide range of molecular weight cut-off (MWCO): 2,300, 11,000, 28,000, 60,000 and 75,000 Da. Severe fouling is observed for the membranes with the highest cut-off. In the permeation experiments of raw water, coagulation prior to membrane filtration led to a significant improvement of the permeation performance of the membranes with the highest MWCO due to the particles and colloidal matter removal.

Investigation of membrane fouling by synthetic and natural particles

2004 ◽  
Vol 50 (12) ◽  
pp. 279-285 ◽  
Author(s):  
J.H. Kweon ◽  
D.F. Lawler
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Research Articles ◽  
Clay Material ◽  
Dramatic Effect ◽  
Flux Decline ◽  
Scanning Electron

The biggest impediment for applying membrane processes is fouling that comes from mass flux (such as particle and organic matter) to the membrane surface and its pores. Numerous research articles have indicated that either particles or natural organic matter (NOM) has been the most detrimental foulant. Therefore, the role of particles in membrane fouling was investigated with two synthetic waters (having either particles alone or particles with simple organic matter) and a natural water. Membrane fouling was evaluated with flux decline behavior and direct images from scanning electron microscopy. The results showed that the combined fouling by kaolin and dextran (a simple organic compound selected as a surrogate for NOM) showed no difference from the fouling with only the organic matter. The similarity might stem from the fact that dextran (i.e., polysaccharide) has no ability to be adsorbed on the clay material, so that the polysaccharide behaves the same with respect to the membrane with or without clay material being present. In contrast to kaolin, the natural particles showed a dramatic effect on membrane fouling.

Characteristic of algogenic organic matter and its effect on UF membrane fouling

2011 ◽  
Vol 64 (8) ◽  
pp. 1685-1691 ◽  
Author(s):  
T. Li ◽  
B. Z. Dong ◽  
Z. Liu ◽  
W. H. Chu
Keyword(s):  
Organic Matter ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Size Exclusion ◽  
Fluorescence Excitation ◽  
Membrane Pore ◽  
Blue Green Algae ◽  
Flux Decline ◽  
Exclusion Chromatography ◽  
Hydrophilic Compound

Algogenic organic matter (AOM) was extracted from blue-green algae (cyanobacteria) and its characteristic was determined by various methods including high-pressure size-exclusion chromatography (HP-SEC), hydrophobic and hydrophilic fractionation, molecular weight (MW) fractionation and fluorescence excitation emission matrix (EEM). The results revealed that AOM was hydrophilic fractionation predominantly, accounting for 78%. The specific ultraviolet absorbance of AOM was 1.1 L/(mg m) only. The analysis for MW distribution demonstrated that organic matter greater than 30,000 MW accounted for over 40% and was composed of mostly neutral hydrophilic compound. EEM analyses revealed that protein-like and humic-substances existed in AOM. A test for membrane filtration exhibited that AOM could make ultrafiltration membrane substantial flux decline, which can be attributed to membrane pore clog caused by neutral hydrophilic compound with larger MW.

Membrane fouling propensity after adsorption as pretreatment in rainwater: a detailed organic characterisation

2008 ◽  
Vol 58 (8) ◽  
pp. 1535-1539 ◽  
Author(s):  
L. Sabina ◽  
B. Kus ◽  
H.-K. Shon ◽  
J. Kandasamy
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Building Blocks ◽  
Fulvic Acids ◽  
Humic And Fulvic Acids ◽  
Removal Efficiencies ◽  
Hydrophilic Compounds ◽  
Hydrophobic Fraction

Organic characterisation in rainwater was investigated in terms of dissolved organic carbon (DOC) and molecular weight distribution (MWD) after powdered activated carbon (PAC) adsorption. PAC adsorption was used as pretreatment to membrane filtration to reduce membrane fouling. The MW of organic matter in rainwater used in this study was in the range of 43,000 Da to 30 Da. Each peak of organic matter consisted of biopolymers (polysaccharides and proteins), humic and fulvic acids, building blocks, low MW acids (hydrolysates of humic substances), low MW neutrals and amphiphilics. Rainwater contained the majority of hydrophilic compounds up to 72%. PAC adsorption removed 33% of total DOC. The removal efficiencies of the hydrophobic and hydrophilic fractions after PAC adsorption were 50% and 27%, respectively. PAC adsorption was found to preferentially remove the hydrophobic fraction. The majority of the smaller MW of 1,100 Da, 820 Da, 550 Da, 90 Da and 30 Da was removed after PAC adsorption. The MFI values decreased from 1,436 s/L2 to 147 s/L2 after PAC adsorption. It was concluded that PAC adsorption can be used as a pretreatment to membrane filtration with rainwater.

Identification and control of fouling of low-pressure (MF and UF) membranes by drinking-water natural organic matter

2003 ◽  
Vol 3 (5-6) ◽  
pp. 217-222 ◽  
Author(s):  
N. Lee ◽  
G. Amy ◽  
H. Habarou ◽  
J.C. Schrotter
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Membrane Filtration ◽  
Gel Formation ◽  
Flux Decline ◽  
Organic Fouling ◽  
Pore Blockage ◽  
Uf Membranes ◽  
And Control ◽  
Filtration Flux

Natural organic matter (NOM) is responsible for organic fouling during membrane filtration. Flux decline can be affected by the characteristics of the NOM and its interaction with membranes and their associated properties. The results showed that serious flux decline observed for MF membranes may be caused by pore blockage associated with large (macromolecular) hydrophilic molecules. In the case of UF membranes, flux decline may be caused by sequential or simultaneous processes such as cake/gel formation with large (macromolecular) molecules and pore blockage with relatively smaller molecules during filtration. The flux decline tests with representative macromolecules showed that fouling was affected more by the physical characteristics (e.g. size and structure (shape)) of foulants than the characteristics (e.g. hydrophilicity) of foulants.

Adsorptive fouling of a polypropylene microfiltration membrane with dissolved natural organic matter: do membranes possess an adsorption capacity?

2006 ◽  
Vol 6 (2) ◽  
pp. 25-30 ◽  
Author(s):  
M. Koh ◽  
M.M. Clark ◽  
K.P. Ishida
Keyword(s):  
Organic Matter ◽  
Adsorption Capacity ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Natural Waters ◽  
Uv Light ◽  
Attenuated Total Reflectance ◽  
Infrared Spectrometry ◽  
Flux Decline ◽  
Aromatic Ether

Rejection by membrane adsorption has been observed and widely reported. However, little is known about whether membranes possess an adsorption capacity. Experimental data showed that when a hydrophobic polypropylene (PP) microfilter was used to filter a large volume of particle-free surface water containing dissolved natural organic matter (NOM), later batches of microfiltration (MF) permeate caused more flux decline to a fresh 20K-Dalton polyethersulfone (PES) ultrafilter. This suggests that membranes can have an adsorption capacity for foulants. In this research, the gradual increase in absorbance of ultraviolet (UV) light by subsequent batches of MF permeate was observed, and supports the findings from previous studies, that only a small fraction of NOM causes membrane fouling. Attenuated total reflectance Fourier transform infrared spectrometry and energy dispersive spectroscopy of fouled PP and PES membranes suggests foulants containing amide, aromatic, ether, hydroxyl and silicate functional groups. Silicates appear to participate in membrane fouling, and its removal with the small fraction of fouling NOM can reduce the fouling potential of water. These data improve our understanding of membrane fouling by natural waters, and have implications for the design of membrane plants that filter natural waters.

scholarly journals Potential Pitfalls in Membrane Fouling Evaluation: Merits of Data Representation as Resistance Instead of Flux Decline in Membrane Filtration

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 460
Author(s):  
Bastiaan Blankert ◽  
Bart Van der Bruggen ◽  
Amy E. Childress ◽  
Noreddine Ghaffour ◽  
Johannes S. Vrouwenvelder
Keyword(s):  
Membrane Fouling ◽  
Membrane Filtration ◽  
Data Representation ◽  
Strong Impact ◽  
Experimental Conditions ◽  
Permeable Membrane ◽  
Dead End ◽  
Flux Decline ◽  
The Difference ◽  
Filtration Flux

The manner in which membrane-fouling experiments are conducted and how fouling performance data are represented have a strong impact on both how the data are interpreted and on the conclusions that may be drawn. We provide a couple of examples to prove that it is possible to obtain misleading conclusions from commonly used representations of fouling data. Although the illustrative example revolves around dead-end ultrafiltration, the underlying principles are applicable to a wider range of membrane processes. When choosing the experimental conditions and how to represent fouling data, there are three main factors that should be considered: (I) the foulant mass is principally related to the filtered volume; (II) the filtration flux can exacerbate fouling effects (e.g., concentration polarization and cake compression); and (III) the practice of normalization, as in dividing by an initial value, disregards the difference in driving force and divides the fouling effect by different numbers. Thus, a bias may occur that favors the experimental condition with the lower filtration flux and the less-permeable membrane. It is recommended to: (I) avoid relative fouling performance indicators, such as relative flux decline (J/J0); (II) use resistance vs. specific volume; and (III) use flux-controlled experiments for fouling performance evaluation.

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