Ceramic microfiltration – influence of pretreatment on operational performance

A sustainable membrane operation often requires pretreatment of the feed liquor to improve its technical and economic feasibility. This paper reports the impact of pretreatment on the performance of ceramic microfiltration for several pilot studies at different locations. Four different pretreatment processes were investigated: (1) in-line coagulation (to remove high molecular weight, HMW, dissolved organic carbon, DOC); (2) ion exchange (to remove low molecular weight, LMW, DOC); (3) ozone (for disinfection, taste and odor control, and modifying the character of DOC) (4) ion exchange followed by in-line coagulation (for almost complete removal of DOC). Pretreatment in all cases was needed to control membrane fouling, to establish a technically and economically feasible process. These studies seem to show that the DOC's HMW (which includes biopolymers) and LMW fractions (the latter includes humics/acids), are primarily responsible for the TMP increase after filtration followed by backwashing (irreversible fouling). Removing one of these organic fractions often results in more stable operation. Ozonation in all cases led to better operation, but is not always economically feasible. The feasibility of ozone as pre-treatment depends largely on the initial ozone demand, and whether or not there are secondary treatment targets (e.g., higher virus removal, taste, and/or odor).

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Biologically active ion exchange (BIEX) for NOM removal and membrane fouling prevention

Water Science & Technology Water Supply ◽

10.2166/ws.2017.016 ◽

2017 ◽

Vol 17 (4) ◽

pp. 1178-1184 ◽

Cited By ~ 3

Author(s):

M. Schulz ◽

J. Winter ◽

H. Wray ◽

B. Barbeau ◽

P. Bérubé

Keyword(s):

Molecular Weight ◽

Biological Activity ◽

Ion Exchange ◽

Membrane Fouling ◽

Building Blocks ◽

Biologically Active ◽

Low Molecular Weight ◽

Effective Removal ◽

Pre Treatment ◽

The Impact

The natural organic matter (NOM) removal efficiency and regeneration behavior of ion-exchange filters with promoted biological activity (BIEX) was compared to operation where biological activity was suppressed (i.e. abiotic conditions). The impact of BIEX pre-treatment on fouling in subsequent ultrafiltration was also investigated. Biological operation enhanced NOM removal by approximately 50% due to an additional degradation of smaller humic substances, building blocks and low molecular weight acids. Promotion of biological activity significantly increased the time to breakthrough of the filters and, therefore, is expected to lower the regeneration frequency as well as the amount of regenerate of which to dispose. Pre-treatment using BIEX filters resulted in a significant decrease in total and irreversible fouling during subsequent ultrafiltration. The decrease was attributed to the effective removal of medium and low molecular weight NOM fractions. The results indicate that BIEX filtration is a robust, affordable and easy-to-operate pre-treatment approach to minimize fouling in ultrafiltration systems and enhance the quality of the produced permeate.

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In-line coagulation assessment for ultrafiltration fouling reduction to treat secondary effluent for water reuse

Water Science & Technology ◽

10.2166/wst.2020.571 ◽

2020 ◽

Author(s):

Samia A. Aly ◽

William B. Anderson ◽

Peter M. Huck

Keyword(s):

Membrane Fouling ◽

Water Reuse ◽

Hollow Fiber Membrane ◽

Secondary Effluent ◽

Membrane Performance ◽

Coagulant Dosage ◽

Pre Treatment ◽

Uf Membranes ◽

Fouling Reduction ◽

The Impact

Abstract Low pressure membranes are attracting attention for their potential to improve secondary effluent quality, but membrane fouling can limit their widespread applicability. In this study, in-line coagulation as pre-treatment to ultrafiltration (UF) was investigated using a bench-scale hollow fiber membrane at a constant flux of 33 L/m2 h. Membrane fouling was monitored by observing change in trans-membrane pressure when the membrane was fed with secondary effluent and in-line coagulated secondary effluent over a 24-h period. The impact of four coagulants at different dosages on reversible and irreversible membrane fouling and permeate quality was studied. It was found that in-line coagulation improved UF performance to varying degrees depending on coagulant type and dosage. Generally, higher reduction of fouling was achieved by increasing coagulant dosage within the 0.5–5.0 mg/L range investigated. Ferric-based coagulants were better than aluminum-based coagulants with respect to improving membrane performance for the secondary effluent investigated, even at low dosages (0.5 mg/L). Further investigations are required to determine how in-line coagulation affects removal of organic compounds through UF membranes.

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Reducing Magnesium within Seawater Used in Mineral Processing to Improve Water Recovery and Rheological Properties When Dewatering Clay-Based Tailings

Polymers ◽

10.3390/polym14020339 ◽

2022 ◽

Vol 14 (2) ◽

pp. 339

Author(s):

Matías Jeldres ◽

Norman Toro ◽

Sandra Gallegos ◽

Pedro Robles ◽

Iván Salazar ◽

...

Keyword(s):

Yield Stress ◽

Aggregate Size ◽

Complete Removal ◽

Mineral Processing ◽

Water Recovery ◽

Concentrated Suspensions ◽

Reflectance Measurement ◽

Pre Treatment ◽

A Minor ◽

The Impact

In areas where access to water for mineral processing is limited, the direct use of seawater in processing has been considered as an alternative to the expense of its desalination. However, efficient flotation of copper sulfides from non-valuable phases is best achieved at a pH > 10.5, and raising the pH of seawater leads to magnesium precipitates that adversely affect subsequent tailings dewatering. Seawater pre-treatment with lime can precipitate the majority of magnesium present, with these solids then being removed by filtration. To understand how such treatment may aid tailings dewatering, treated seawater (TSw) was mixed with raw seawater (Rsw) at different ratios, analyzing the impact on the flocculated settling rate, aggregate size as measured by focused beam reflectance measurement (FBRM), and vane yield stress for two synthetic clay-based tailings. A higher proportion of Tsw (10 mg/L Mg2+) led to larger aggregates and higher settling rates at a fixed dosage, with FBRM suggesting that higher calcium concentrations in Tsw may also favor fines coagulation. The yield stress of concentrated suspensions formed after flocculation decreased with higher proportions of Tsw, a consequence of lower flocculant demand and the reduced presence of precipitates; while the latter is a minor phase by mass, their high impact on rheology reflects a small particle size. Reducing magnesium concentrations in seawater in advance of use in processing offers advantages in the water return from thickening and subsequent underflow transport. However, this may not require complete removal, with blending Tsw and Rsw an option to obtain acceptable industrial performance.

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Advances in Antifouling Strategies in Membrane Ultrafiltration: A Brief Review

Journal of Advanced Research in Materials Science ◽

10.37934/arms.76.1.1016 ◽

2021 ◽

Vol 76 (1) ◽

pp. 10-16

Author(s):

Amina Tahreen ◽

Mohammed Saedi Jami

Keyword(s):

Membrane Fouling ◽

Separation Efficiency ◽

Membrane Integrity ◽

Graphene Oxide Nanosheets ◽

Membrane Pore ◽

Pore Blockage ◽

As Adsorption ◽

Pre Treatment ◽

The Impact

This study briefly reviews the recent advances in membrane and separation technology for antifouling strategies for membrane ultrafiltration. Membrane fouling is inevitable in ultrafiltration due to the eventual membrane pore blockage with foulants. Consequently, flux declines and affects the membrane integrity over time along with elevation in processing time and thereby complicating the overall membrane maintenance. To combat this issue, several studies had been undertaken such as grafting of TiO2 nanotubes (TNTs), graphene oxide nanosheets, zwitterions or polymers in the membrane and also by applying direct current. Moreover, many researchers emphasized on the integration of an enhanced pre-treatment process such as adsorption, coagulation, electrocoagulation and so on. By critically analysing and comparing the existing studies, the impact, suitability, efficiency and sustainability of the antifouling strategies will be discussed in this review. This refined approach of observing the progress in membrane technology will enable the determination of the existing gaps in the studies and will help to expand and propel the field further in separation efficiency.

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Removal of algogenic organic matter by magnetic ion exchange resin pre-treatment and its effect on fouling in ultrafiltration

Water Science & Technology Water Supply ◽

10.2166/ws.2011.003 ◽

2011 ◽

Vol 11 (1) ◽

pp. 15-22 ◽

Cited By ~ 3

Author(s):

C. Liu ◽

W. Chen ◽

V. M. Robert ◽

Z. G. Han

Keyword(s):

Organic Matter ◽

Ion Exchange ◽

Membrane Fouling ◽

Exchange Resin ◽

Ion Exchange Resin ◽

Major Barrier ◽

Treated Water ◽

Fouling Control ◽

Pre Treatment ◽

Magnetic Ion

Natural organic matter (NOM) fouling continues to be the major barrier to efficient application of ultrafiltration (UF) in drinking water treatment. Algogenic organic matter (AOM), the main contributor to total NOM levels in raw waters characterised by elevated algae levels, is currently the subject of much investigation. In this study, the effect of AOM on fouling of ultrafiltration and the effectiveness of magnetic ion exchange resin (MIEX®) pre-treatment for AOM removal and membrane fouling control was evaluated. The results showed that, the main species of algae in raw water were Chlorella vulgaris, which accounted for 80% of total algae. AOM was predominantly hydrophilic (50% or more) with a low SUVA (1.7 Lm−1 mg−1). Coagulation alone could not remove AOM effectively (less than 20%), however, when combined with magnetic ion exchange resin pre-treatment, more than 60% of AOM was be removed; pre-treatment followed by coagulation was observed to be very effective in controlling membrane fouling by AOM. The application of magnetic ion exchange resin technology at a bed volume treatment rate (BVTR) of 800 was observed to effectively eliminate fouling of UF membrane. Careful analyses of the molecular weight (MW) distribution of AOM and UV absorbance of treated water revealed that the effectiveness in membrane fouling control was the result of the changes in AOM molecular characteristics in treated water, namely a change in MW due to the preferential removal of high molecular proteins by coagulation and magnetic ion exchange resin pre-treatment. The results demonstrate that magnetic ion exchange resin followed by coagulation might be a new membrane pre-treatment option for UF membrane fouling control.

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Effect of anionic fluidized ion exchange (FIX) pre-treatment on nanofiltration (NF) membrane fouling

Water Research ◽

10.1016/j.watres.2010.03.007 ◽

2010 ◽

Vol 44 (10) ◽

pp. 3283-3293 ◽

Cited By ~ 37

Author(s):

E.R. Cornelissen ◽

D. Chasseriaud ◽

W.G. Siegers ◽

E.F. Beerendonk ◽

D. van der Kooij

Keyword(s):

Ion Exchange ◽

Membrane Fouling ◽

Pre Treatment

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Assessment of the Performance of Electrodialysis in the Removal of the Most Potent Odor-Active Compounds of Herring Milt Hydrolysate: Focus on Ion-Exchange Membrane Fouling and Water Dissociation as Limiting Process Conditions

Membranes ◽

10.3390/membranes10060127 ◽

2020 ◽

Vol 10 (6) ◽

pp. 127 ◽

Cited By ~ 1

Author(s):

Sarah Todeschini ◽

Véronique Perreault ◽

Charles Goulet ◽

Mélanie Bouchard ◽

Pascal Dubé ◽

...

Keyword(s):

Ion Exchange ◽

Volatile Compounds ◽

Membrane Fouling ◽

Hydrophobic Interactions ◽

Limiting Current ◽

Water Dissociation ◽

Process Conditions ◽

Off Flavors ◽

Huge Impact ◽

The Impact

Herring milt hydrolysate (HMH), like many fish products, presents the drawback to be associated with off-flavors. As odor is an important criterion, an effective deodorization method targeting the volatile compounds responsible for off-flavors needs to be developed. The potential of electrodialysis (ED) to remove the 15 volatile compounds identified, in the first part of this work, for their main contribution to the odor of HMH, as well as trimethylamine, dimethylamine and trimethylamine oxide, was assessed by testing the impact of both hydrolysate pH (4 and 7) and current conditions (no current vs. current applied). The ED performance was compared with that of a deaerator by assessing three hydrolysate pH values (4, 7 and 10). The initial pH of HMH had a huge impact on the targeted compounds, while ED had no effect. The fouling formation, resulting from electrostatic and hydrophobic interactions between HMH constituents and ion-exchange membranes (IEM); the occurrence of water dissociation on IEM interfaces, due to the reaching of the limiting current density; and the presence of water dissociation catalyzers were considered as the major limiting process conditions. The deaerator treatment on hydrolysate at pH 7 and its alkalization until pH 10 led to the best removal of odorant compounds.

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Assessment of water treatment processes: detailed organic matter characterisation and membrane fouling indices at the Loddon Water Treatment Plant, Victoria, Australia

Water Science & Technology Water Supply ◽

10.2166/ws.2011.040 ◽

2011 ◽

Vol 11 (3) ◽

pp. 274-280 ◽

Cited By ~ 1

Author(s):

C. Khorshed ◽

S. Vigneswaran ◽

J. Kandasamy ◽

R. Aryal ◽

D. Dharmapalan

Keyword(s):

Organic Matter ◽

Water Treatment ◽

Ion Exchange ◽

Membrane Fouling ◽

Treatment Plant ◽

Water Treatment Plant ◽

Treatment Methods ◽

Wide Range ◽

Exchange Adsorption ◽

Pre Treatment

Recent advances in membrane technology have led to its broad application, and reverse osmosis (RO) systems now represent the fastest growing segment of the desalination market. Its performance is hindered by membrane fouling. In this study pre-treatment methods to reduce RO fouling were investigated including flocculation, adsorption and ion exchange. Detailed organic characterisations were made in terms of florescence spectroscopy excitation emission matrix (EEM), UV254 absorbance and liquid chromatography-organic carbon detection (LCOCD). The different pre-treatment methods were assessed in terms of the fouling potential. This was quantified in terms of the modified fouling index measured using a dead-end cell micro-filtration (MF) unit. The existing pre-treatment of granular activated carbon (GAC) filter led to a good organic removal. Among the pre-treatment methods tested in the laboratory, purolite ion exchange/adsorption was found to be better than FeCl3 flocculation in terms of the amount as well as the wide range of organics removal. A pre-treatment of flocculation with Poly-ferric-silicate (PFSi) as flocculent gave a higher removal of organic matter compared to other pre-treatments tested. DOC was reduced from 11.5 to 4.25 mg/L, and it removed mostly the humic type substances.

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Understanding of Adsorption and Desorption Mechanisms of Anthocyanins and Proanthocyanidins on Heterogeneous and Homogeneous Cation-Exchange Membranes

Membranes ◽

10.3390/membranes11020136 ◽

2021 ◽

Vol 11 (2) ◽

pp. 136

Author(s):

Véronique Perreault ◽

Veronika Sarapulova ◽

Ksenia Tsygurina ◽

Natalia Pismenskaya ◽

Laurent Bazinet

Keyword(s):

Ion Exchange ◽

Cation Exchange ◽

Membrane Fouling ◽

Electrostatic Interactions ◽

Exchange Capacity ◽

Type Ii ◽

Cranberry Juice ◽

Membrane Processes ◽

Adsorption And Desorption ◽

The Impact

The presence of membrane fouling is the main drawback in membrane processes, and it is related to the premature use and high cost for the replacement of membranes. Polyphenols in cranberry juice are associated with ion-exchange membrane fouling, and it results in a loss of these beneficial compounds in the juice when treated by membrane processes such as electrodialysis. In the present work, four heterogeneous or pseudohomogeneous cation-exchange membranes (CSE-fg, MK-40, CEM Type-II, and CJMC-5), different in terms of the polymer matrix (aromatic, aliphatic), exchange capacity, size, and location of meso and macropores, were studied to understand the impact of the membrane structure and physico-chemical properties on adsorption and desorption of phenolic compounds (anthocyanins and proanthocyanidins) from cranberry juice. It appeared from these results that MK-40, CEM Type-II, and CSE-fg were more prone to fouling due to their high ion-exchange capacity, their thickness, and the presence of meso and macropores in their structure. Indeed, electrostatic interactions occurred between fixed groups of membranes and polyphenolic ions. Desorption of the entire membrane and cryogenic grinding with pH adjusted to 10 allowed a better recovery of anthocyanins and proanthocyanidins (PACs), respectively, since hydroxide ions competed with polyphenols and membrane that induced desorption of polyphenols. In the future, this new knowledge will become the basis for a more sensible choice of membranes and for the development of protocols for extending their life cycle.

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Effect of pre-coagulation on mitigating irreversible fouling during ultrafiltration of a surface water

Water Science & Technology ◽

10.2166/wst.2005.0626 ◽

2005 ◽

Vol 51 (6-7) ◽

pp. 93-100 ◽

Cited By ~ 21

Author(s):

K. Kimura ◽

Y. Hane ◽

Y. Watanabe

Keyword(s):

Molecular Weight ◽

Surface Water ◽

Water Purification ◽

Membrane Fouling ◽

Pilot Scale ◽

Organic Substances ◽

Chemical Cleaning ◽

Membrane Unit ◽

Pre Treatment ◽

Purification Plant

Membrane fouling can be divided into two types: reversible fouling and irreversible fouling. The former can be easily canceled by physical cleaning (e.g., backwashing) while the latter needs chemical cleaning to be mitigated. For more efficient use of membranes, the control of irreversible membrane fouling is of importance. In this study, the effectiveness of pre-coagulation/sedimentation on irreversible membrane fouling was investigated, based on the pilot-scale operation of the membrane unit installed at an existing water purification plant. The membrane employed was a low-pressure ultrafiltration (UF) membrane made of polysulfone and having a molecular weight cut-off of 750,000 daltons. Although pre-coagulation/sedimentation significantly mitigated membrane fouling mainly through the reduction of reversible membrane fouling, the degree of irreversible fouling was not reduced by the pre-treatment. This was because the irreversible fouling observed during this study was mainly attributed to polysaccharides/protein like fractions of organic substances that cannot be efficiently removed by coagulation/sedimentation. Aluminium used as coagulant was thought to cause irreversible fouling to some extent but did not in the pilot operation, which could probable be explained by the fact that coagulation was conducted at relatively high pH (7.0) in this study.

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