The significance of interactions between organic compounds on low pressure membrane fouling

2011 ◽  
Vol 64 (3) ◽  
pp. 632-639 ◽  
Author(s):  
S. R. Gray ◽  
N. Dow ◽  
J. D. Orbell ◽  
T. Tran ◽  
B. A. Bolto
Keyword(s):  
Organic Compounds ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Alginic Acid ◽  
Hollow Fibre ◽  
Acid Solutions ◽  
Small Molecular Weight ◽  
Filtration Apparatus ◽  
Hydrophilic Membranes ◽  
Hydrophilic Membrane

Fouling of hollow fibre microfiltration and ultrafiltration membranes by solutions of pure organic compounds and mixtures of these compounds was studied with a backwashable membrane filtration apparatus. Small molecular weight compounds resulted in little fouling, while their polymeric analogues resulted in more severe fouling. Neutrally charged dextran resulted in minor, irreversible fouling, that was considered to be associated with blocking of small pores. Cationically charged chitosan produced gross fouling for which the extent of reversibility increased with salt addition. Anionically charged alginic acid resulted in gross irreversible fouling, except when being filtered by a hydrophilic membrane in the absence of calcium where a high degree of flux recovery was observed. Calcium addition to the alginic acid solutions resulted in gross fouling of all membranes and calcium bridging was considered to be responsible for this behaviour. Greater fouling occurred on the hydrophilic membrane compared to the hydrophobic membranes for bovine serum albumin (BSA) solutions, and this was considered to be due to physical blocking of pores, because addition of calcium resulted in lower flux declines. Addition of BSA and calcium to alginic acid solutions resulted in lower flux recoveries for the alginic acid system, consistent with the proposition that interactions between polysaccharide and other compounds are required for irreversible fouling on hydrophilic membranes.

Investigation of membrane fouling in ultrafiltration using model organic compounds

2005 ◽  
Vol 51 (6-7) ◽  
pp. 101-106 ◽  
Author(s):  
J.H. Kweon ◽  
D.F. Lawler
Keyword(s):  
Organic Compounds ◽  
Membrane Fouling ◽  
Alginic Acid ◽  
Membrane Surface ◽  
Sem Images ◽  
Membrane Processes ◽  
Xps Spectra ◽  
Relative Composition ◽  
Flux Decline ◽  
The City

Natural organic matter (NOM) is known to be the worst foulant in the membrane processes, but the complexities of NOM make it difficult to determine its effects on membrane fouling. Therefore, simple organic compounds (surrogates for NOM) were used in this research to investigate the fouling mechanisms in ultrafiltration. Previous research on NOM components in membrane processes indicated that polysaccharides formed an important part of the fouling cake. Three polysaccharides (dextran, alginic acid, and polygalacturonic acid) and a smaller carbohydrate (tannic acid) were evaluated for their removal in softening (the treatment process in the City of Austin). Two polysaccharides (dextran and alginic acid) were selected and further investigated for their effects on membrane fouling. The two raw organic waters (4 mg/L C) showed quite different patterns of flux decline indicating different fouling mechanisms. Softening pretreatment was effective to reduce flux decline of both waters. The SEM images of the fouled membrane clearly showed the shapes of deposited foulants. The high resolution results of the XPS spectra showed substantially different spectra of carbon, C(1s), in the membrane fouled by two raw organic waters. The XPS was beneficial in determining the relative composition of each fouling material on the membrane surface.

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.

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.

scholarly journals Characterization of secondary treated effluents for tertiary membrane filtration and water recycling

2012 ◽  
Vol 2 (2) ◽  
pp. 74-83 ◽  
Author(s):  
C. Ayache ◽  
M. Pidou ◽  
W. Gernjak ◽  
Y. Poussade ◽  
J.-P. Croué ◽  
...  
Keyword(s):  
Water Quality ◽  
Organic Matter ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Low Pressure ◽  
Hollow Fibre ◽  
Feed Water ◽  
Chemical Cleaning ◽  
Characterization Methods ◽  
Secondary Effluents

This study evaluates the impacts of water quality from three different secondary effluents on low pressure membrane fouling. Effluent organic matter (EfOM) has been reported by previous studies as responsible for membrane fouling. However, the contribution of the different components of EfOM to membrane fouling is still not well understood. In order to improve and optimize treatment processes, characterization and quantification of the organic matter are important. The characterization methods used in this study are liquid chromatography coupled with an organic detector (LC-OCD) and excitation emission matrix fluorescence spectroscopy (EEM). A bench-scale hollow fibre membrane system was used to identify the type of fouling depending on the feed water quality. Results showed no measurable dissolved organic carbon removal by the membranes for the three secondary effluents. Biopolymers and humic-like substances found in different proportions in the three effluents were partially retained by the membranes and were identified to contribute significantly to the flux decline of the low pressure membranes. The observed fouling was determined to be reversible by hydraulic backwashing for two effluents and only by chemical cleaning for the third effluent.

scholarly journals Filtration Performances of Different Polysaccharides in Microfiltration Process

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 897
Author(s):  
Shujuan Meng ◽  
Hongju Liu ◽  
Qian Zhao ◽  
Nan Shen ◽  
Minmin Zhang
Keyword(s):  
Membrane Fouling ◽  
Xanthan Gum ◽  
Membrane Filtration ◽  
Extracellular Polymeric Substances ◽  
Molecular Structures ◽  
Feed Water ◽  
Permeate Flux ◽  
Small Molecular Weight ◽  
Membrane Pores ◽  
Flux Decline

Membrane technology has been widely applied for water treatment, while membrane fouling still remains a big challenge. The polysaccharides in extracellular polymeric substances (EPS) have been known as a significant type of foulant due to their high fouling propensity. However, polysaccharides have many varieties which definitely behave differently in membrane filtration. Therefore, in this study, different polysaccharides alginate sodium and xanthan gum were chosen to study their effects on membrane fouling in a wide concentration range. The results demonstrated that the filtration behaviors of alginate sodium and xanthan gum were completely different, which was due to their different molecular structures. Alginate had a small molecular weight and it was easy for alginate to penetrate membrane pores resulting in pore blocking. A series of concentrations of alginate including 5 mg/L, 10 mg/L, 20 mg/L, 30 mg/L, 40 mg/L, and 50 mg/L were examined and it was found that the permeate flux decline highly depended on the level of alginate in the feed water. While for the filtration of xanthan gum, the same concentration of xanthan gum led to more serious fouling than that observed in alginate, which might be due to its large molecule. In addition, calcium chloride was added in the solutions of both alginate and xanthan gum to examine the influence of a divalent cation on polysaccharide fouling. A “unimodal” peak can be observed in the fouling propensity caused by Ca2+ and alginate with increasing the concentration of alginate. Such a phenomenon was not found in the fouling of xanthan gum and Ca2+ led to more serious fouling for all concentrations of xanthan gum. In light of this, this study gave new insights into the fouling propensities of different polysaccharides.

scholarly journals Catalytic Ozonation and Membrane Contactors—A Review Concerning Fouling Occurrence and Pollutant Removal

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2964
Author(s):  
Savvina Psaltou ◽  
Anastasios Zouboulis
Keyword(s):  
Metal Oxides ◽  
Organic Compounds ◽  
Hydroxyl Radicals ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Advanced Oxidation ◽  
Polymeric Materials ◽  
Catalytic Ozonation ◽  
Pollutant Removal ◽  
Solid Catalyst

Membrane filtration has been widely used in water and wastewater treatment. However, this process is not very effective for the removal of refractory organic compounds (e.g., of pharmaceutical origin). Coupling membrane filtration with ozonation (or other Advanced Oxidation Methods) can enhance the degradation of these compounds and, subsequently, the incidence of membrane fouling (i.e., the major problem of membrane uses) would be also limited. Ozonation is an efficient oxidative process, although ozone is considered to be a rather selective oxidant agent and sometimes it presents quite low mineralization rates. An improvement of this advanced oxidation process is catalytic ozonation, which can decrease the by-product formation via the acceleration of hydroxyl radicals production. The hydroxyl radicals are unselective oxidative species, presenting high reaction constants with organic compounds. An efficient way to couple membrane filtration with catalytic ozonation is the deposition of an appropriate solid catalyst onto the membrane surface. However, it must be noted that only metal oxides have been used as catalysts in this process, while the membrane material can be of either polymeric or ceramic origin. The relevant studies regarding the application of polymeric membranes are rather scarce, because only a few polymeric materials can be ozone-resistant and the deposition of metal oxides on their surface presents several difficulties (e.g., affinity etc.). The respective literature about catalytic membrane ozonation is quite limited; however, some studies have been performed concerning membrane fouling and the degradation of micropollutants, which will be presented in this review. From the relevant results it seems that this hybrid process can be an efficient technology both for the reduction of fouling occurrence as well as of enhancement of micropollutant removal, when compared to the application of single filtration or ozonation.

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.

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.

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.

scholarly journals Effect of Pre-Oxidation on Coagulation/Ceramic Membrane Treatment of Yangtze River Water

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 369
Author(s):  
Shengji Xia ◽  
Xinran Zhang ◽  
Yuanchen Zhao ◽  
Fibor J. Tan ◽  
Pan Li ◽  
...  
Keyword(s):  
Water Treatment ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Ceramic Membrane ◽  
Membrane Separation ◽  
Membrane System ◽  
Coagulation System ◽  
Fouling Control ◽  
Filtration System ◽  
Membrane Treatment

The membrane separation process is being widely used in water treatment. It is very important to control membrane fouling in the process of water treatment. This study was conducted to evaluate the efficiency of a pre-oxidation-coagulation flat ceramic membrane filtration process using different oxidant types and dosages in water treatment and membrane fouling control. The results showed that under suitable concentration conditions, the effect on membrane fouling control of a NaClO pre-oxidation combined with a coagulation/ceramic membrane system was better than that of an O3 system. The oxidation process changed the structure of pollutants, reduced the pollution load and enhanced the coagulation process in a pre-oxidation-coagulation system as well. The influence of the oxidant on the filtration system was related to its oxidizability and other characteristics. NaClO and O3 performed more efficiently than KMnO4. NaClO was more conducive to the removal of DOC, and O3 was more conducive to the removal of UV254.

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