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.

Effect of Aggregated Floc Circulation on Membrane Fouling in Contact Circulated Coagulation-Membrane Filtration Hybrid Process for Treatment of Surface Water

2013 ◽  
Vol 864-867 ◽  
pp. 1226-1232
Author(s):  
Xue Hui Zhao ◽  
Hong Wei Zhang ◽  
Jie Wang
Keyword(s):  
Surface Water ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Hollow Fibre ◽  
Hybrid Process ◽  
Effluent Quality ◽  
Dead End ◽  
Flux Decline ◽  
Coagulation Tests ◽  
Floc Characteristics

The effect of aggregated floc circulation on membrane fouling in contact circulated coagulation-membrane filtration hybrid process for treatment of surface water was investigated in this study. In order to understand the floc characteristics, the floc formation, breakage and re-growth were monitored by Mastersizer 2000 under the coagulation dosage of 5, 10, 15 and 20mg/l. A contact circulated coagulation tests were carried out and the effluent was filtered by a dead-end micro-filtration with the hollow fibre membrane. The coagulation effluent quality and the relative permeability J/J0 of membrane was determined at the circulated floc dosage of 22, 44 and 66mg/l. The experiment results indicated that the addition of circulated floc obviously improved the flux decline and the degree of improvement was closely related to the dosage of circulated floc. Compared to traditional coagulation, the contact circulated coagulation was an economic and efficient method to retard the membrane fouling.

Membrane filtration of wastewater effluents for reuse: effluent organic matter rejection and fouling

2001 ◽  
Vol 43 (10) ◽  
pp. 225-232 ◽  
Author(s):  
C. Jarusutthirak ◽  
G. Amy
Keyword(s):  
Organic Matter ◽  
Membrane Filtration ◽  
Treated Wastewater ◽  
High Concentration ◽  
Effluent Organic Matter ◽  
Dead End ◽  
Flux Decline ◽  
Uf Membranes ◽  
Stirred Cell ◽  
Filtration Unit

The reuse of treated wastewater to augment natural drinking water supplies is receiving serious consideration. Treatment of secondary and tertiary effluent by membrane filtration was investigated by assessing nanofiltration (NF) membrane and ultrafiltration (UF) membranes in bench-scale experiments. It was found that secondary and tertiary effluent contained high concentration of effluent organic matter (EfOM), contributing EfOM-related fouling. Flux decline and EfOM rejection tests were evaluated, using a dead-end stirred cell filtration unit. Surface charge and molecular weight cut-off (MWCO) of membranes were significant factors in membrane performance including permeability and EfOM-rejection.

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.

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.

A Combination of an Anaerobic Baffled Reactor with Membrane Filtration for Decentralised Wastewater Treatment

2010 ◽  
Vol 5 (4) ◽  
Author(s):  
S. Pillay ◽  
S. Pollet ◽  
K.M. Foxon ◽  
C.A. Buckley
Keyword(s):  
Membrane Fouling ◽  
Membrane Filtration ◽  
Tap Water ◽  
Pressure Head ◽  
Hollow Fibre ◽  
Anaerobic Baffled Reactor ◽  
Flat Sheet ◽  
Stabilisation Period ◽  
The Difference ◽  
Low Pressures

This paper presents the performance of a laboratory-scale anaerobic baffled reactor (ABR) with a combined membrane filtration polishing step. The plant treated a synthetic blackwater comprised of a faecal and urine slurry obtained from ventilated improved pit latrine (VIP) toilets. Feed to the system was kept constant at 2 000 mg COD/L with COD, TS and VS removal efficiencies of 81, 24 and 20% obtained through the ABR. Two effluent polishing systems were investigated: a hollow-fibre system that housed Polymem modules and a flat-sheet system that housed Kubota and locally-produced fabric modules. Membranes were operated in the dead-end mode under ultra-low pressures using a hydrostatic pressure head (less than a metre). Fouling behaviour differed with the type of filtration process despite the same feed characteristics. Effluent filtration with the Polymem module showed that the flux did not reach a stabilisation period with severe fouling occurring after 8 d. Membrane fouling was largely reversible with the fouling layer easily removed by a simple tap water wash. In contrast, effluent filtration with Kubota and fabric membranes resulted in a period of low stabilised flux (˜0.5 L/m2.h) at ultra-low pressures with flux independent on the TMP used. Kubota modules exhibited a similar performance to fabric ones but were able to produce slighter higher fluxes after prolonged filtration. Membrane fouling in both flat-sheet module types was irreversible with a gel-like layer forming during filtration. The difference in hollow-fibre and flat-sheet modules may be due to a number of factors, such as pore size and the manufacturing process used to prepare membranes. Through deductive investigations, it was concluded that the fouling constituents in the effluent may be colloidal and/or soluble in nature.

Modeling NOM fouling of low pressure membranes: impact of membrane properties and NOM characteristics

2008 ◽  
Vol 8 (1) ◽  
pp. 75-83
Author(s):  
NoHwa Lee ◽  
John Pellegrino ◽  
Gary Amy
Keyword(s):  
Membrane Fouling ◽  
Membrane Filtration ◽  
Principal Component ◽  
Low Pressure ◽  
Time Frame ◽  
Membrane Properties ◽  
Flux Decline ◽  
Cake Layer ◽  
Highly Correlated ◽  
Significant Flux

This research attempted to identify characteristic coordinates responsible for significant flux decline in low pressure membrane filtration, and to explain relationships among those coordinates with a modeling approach. A Pearson's correlation matrix supported that significant flux decline over a short time frame (low delivered DOC) is highly correlated with high molecular weight (MW) components of NOM. Simulations of flux decline by model equations were close to the experimental results revealing that low pressure membrane fouling is dominantly affected by NOM characteristics and membrane properties. One source water, exhibiting the highest flux decline, showed mostly cake formation as a fouling mechanism. The results indicate that significant flux decline is caused by high MW components leading to formation of a cake layer. Principal component analysis (PCA) revealed that high MW polysaccharides are the most important NOM component affecting significant membrane fouling.

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.

Effect of coagulation mechanisms on the fouling and ultrasonic cleaning of PTFE membrane

2012 ◽  
Vol 66 (11) ◽  
pp. 2291-2298 ◽  
Author(s):  
Meng-Wei Wan ◽  
Cybelle Morales Futalan ◽  
Cheng-Hung Chang ◽  
Chi-Chuah Kan
Keyword(s):  
Membrane Fouling ◽  
Permeate Flux ◽  
Cleaning Efficiency ◽  
Ultrasonic Cleaning ◽  
Ptfe Membrane ◽  
Pore Blocking ◽  
Dead End ◽  
Flux Decline ◽  
Cake Formation ◽  
Scanning Electron

In this study, the effect of coagulation pretreatment on membrane fouling and ultrasonic cleaning efficiency was investigated using a dead-end polytetrafluoroethylene (PTFE) microfiltration system. The extent of membrane fouling was examined under different coagulation mechanisms such as charge neutralization (CN), electrostatic patch effect (EPE) and sweep flocculation (SW). Fouling through EPE mechanism provided the greatest flux decline and least permeate flux recovery over CN and SW. EPE produces more stable, smaller and more compact flocs while CN and SW have large, easily degraded and highly-branched structured flocs. The predominant fouling mechanism of EPE, CN and SW is pore blocking, a combination of pore blocking and cake formation, and cake formation, respectively. Better permeate flux recovery is observed with SW over CN and EPE, which implies formation of less dense and more porous cake deposits. The morphology of fouled membranes was examined using scanning electron microscopy (SEM).

Response of zeta potential to different types of local membrane fouling in dead-end membrane filtration with yeast suspension

RSC Advances ◽  
2015 ◽  
Vol 5 (96) ◽  
pp. 78738-78744 ◽  
Author(s):  
Hui Jia ◽  
Hongmei Zhang ◽  
Jie Wang ◽  
Hongwei Zhang ◽  
Xinbo Zhang
Keyword(s):  
Zeta Potential ◽  
Membrane Fouling ◽  
Fiber Length ◽  
Membrane Filtration ◽  
Yeast Suspension ◽  
Zeta Potentials ◽  
Dead End ◽  
Different Types

The zeta potentials that responded to different types of local membrane fouling with yeast suspension were investigated by monitoring both local flux and local zeta potential, and the effect of fiber length on local fouling behavior was also studied.

Fouling of a polyethersulfone ultrafiltration membrane by natural organic matter

2004 ◽  
Vol 4 (4) ◽  
pp. 205-212 ◽  
Author(s):  
G. Makdissy ◽  
J.-P. Croué ◽  
G. Amy ◽  
H. Buisson
Keyword(s):  
Natural Organic Matter ◽  
Surface Waters ◽  
Membrane Fouling ◽  
Adsorption Mechanism ◽  
Transmembrane Pressure ◽  
Membrane Flux ◽  
Dead End ◽  
Flux Decline ◽  
Hydrophilic Fraction ◽  
Significant Flux

This research focused on membrane flux decline trends observed during ultrafiltration (UF) of solutions of NOM fractions isolated from surface waters. All filtration experiments were performed with a non-stirred dead-end cell unit equipped with flat sheet polyethersulfone PES UF membrane coupons under a constant transmembrane pressure of 1 bar. Results showed that the most significant flux decline was due to the organic colloid fraction, a hydrophilic fraction consisting mostly of bacterial cell wall residues. This research demonstrated that these colloids which incorporate 2/3 of dissolved organic structures (<0.45 μm) and 1/3 of particulate organics exert strong fouling properties due to both rejection phenomena and the adsorption mechanism. The fouling contribution by humic-like materials depends on their origin and nature. Aromaticity appears to be a secondary parameter which influences membrane fouling. Polysaccharides, proteins and amino sugars also largely present in humic-like structures (supramolecular structure) play an important role in UF membrane fouling. The perspective of NOM as a biopolymer mixture can contribute to an understanding of membrane fouling.

Sign in / Sign up

Export Citation Format

Share Document