Characterisation of Fouling of Nanofiltration Membranes used to Treat Surface Waters

Baker, John S.; Stephenson, Tom; Dard, Stephan; Côté, Pierre

doi:10.1080/09593331608616335

Cited by 59 publications

(21 citation statements)

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“…The concentration of ions, such as calcium, particularly relevant to such processes, which are designed to retain salts. Of these salts, calcium 51 was shown to be the principal element in fouling layers from surface water, as demonstrated in 52 an earlier study (Baker et al 1995). This unfortunately can lead to inorganic fouling due to scale 53 formation of sparingly soluble inorganic salts, which occurs whenever the ionic salt 54 concentration stream exceeds the equilibrium solubility.…”

mentioning

confidence: 91%

The significance of calcium ions onPseudomonas fluorescensbiofilms – a structural and mechanical study

Safari

Habimana

Allen³

et al. 2014

Biofouling

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mentioning

confidence: 91%

The significance of calcium ions onPseudomonas fluorescensbiofilms – a structural and mechanical study

Safari

Habimana

Allen³

et al. 2014

Biofouling

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“…solutes unable to pass through the membrane pores) and precipitation or gelation of inorganic and organic particulates at the membrane surface as a result of the localised high concentrations that occur at the membrane-solution interface. While interactions between solutes and the membranes are poorly understood, it is thought that effects like charge interactions, bridging, and hydrophobic interactions may play an important role in fouling [6].…”

Section: Introductionmentioning

confidence: 99%

Fouling effects on rejection in the membrane filtration of natural waters

Schäfer¹,

2000

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Membrane processes in drinking water applications are micro-(MF), ultra-(UF), and nanofiltration (NF). These processes remove turbidity and bacteria (MF), viruses and macromolecules (UF) and small molecules and hardness (NF). Of particular concern in water treatment is the removal of natural organic matter (NOM) which contains potential disinfection by-product precursors. The presence of colloids, multivalent ions and organics in surface waters may cause substantial fouling of membranes.A study was carried out which looked at the rejection abilities of a range of membranes targeting hematite colloids (40-500nm), NOM and cations, fouling conditions and cost of treatment of these processes with consideration of chemical pretreatment with ferric chloride [1]. In this paper the effect of membrane fouling on rejection is presented.The study was based on experiments with two MF membranes (GVWP, GVHP, 0.22 µm, Millipore), six UF membranes (1, 3, 5, 10, 30, 100 kDa, regenerated cellulose, Millipore), and four organic nanofiltration (NF) membranes (TFC-SR, TFC-S, TFC-ULP, CA-UF, Fluid Systems, U.S.).Three different types of organics (IHSS humic acid, IHSS fulvic acid and an Australian concentrated NOM) in a carbonate buffer containing calcium chloride and a background electrolyte were used. Experiments were carried out in perspex (MF, UF) and stainless steel (NF) stirred cells of a volume of 110-185 mL and a membrane area of 15.2 -21.2*10 -4 m 2 at transmembrane pressures of 1, 3, and 5 bar for MF, UF, and NF, respectively.UF removes 10 -95% of NOM depending on the molecular weight cut-off (MWCO) of the membrane. Pore sizes of < 6 nm are required to remove about 80% of NOM, where a 6 nm pore size corresponds to a MWCO of about 10 kDa. Colloids are fully rejected.NF removes NOM effectively (70 -95% as dissolved organic carbon (DOC) and 85 -98% as UV absorbance). Cation rejection is very membrane dependent and varies for the investigated membrane types between 13 and 96% for calcium and 10 to 87% for sodium. 1Fouling was also dependent on pore size and was caused by large colloids (250 nm) or coagulant flocs in MF, small colloids, organic-calcium flocs and aggregates with a dense structure (formed slowly) in UF, and by a calcium-organic precipitate in NF. The fouling influenced the rejection of colloids in MF and that of NOM in UF and NF. If a highly charged layer was deposited on the NF membranes, cation rejection was also influenced. The characterisation of permeate organics revealed that low molecular weight acids passed through the NF membranes and that the rejection of these acids was also dependent on the deposit on the membrane.The mechanisms which can explain such an increase in rejection are different for the three membrane processes. In MF, pore plugging and cake formation was found responsible for fouling. This reduces the pore size and increases rejection. In UF, internal pore adsorption of calcium-organic flocs reduces the internal pore diameter and subsequently increases rejection. In NF, the key fact...

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“…Feed spacers have been shown to play an important part in fouling [27][28][29][30][31]. In the present study, the effect of spacer presence on transmembrane hydraulic biofilm resistance was evaluated.…”

Section: Biofilm Resistance With and Without Feed Spacermentioning

confidence: 99%

Development and testing of a transparent membrane biofouling monitor

Dreszer

Flemming

Wexler³

et al. 2014

Desalination and Water Treatment

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A modified version of the membrane fouling simulator (MFS) was developed for assessment of (i) hydraulic biofilm resistance, (ii) performance parameters feed-channel pressure drop and transmembrane pressure drop, and (iii) in situ spatial visual and optical observations of the biofilm in the transparent monitor, e.g. using optical coherence tomography. The flow channel height equals the feed spacer thickness enabling operation with and without feed spacer. The effective membrane surface area was enlarged from 80 to 200 cm 2 by increasing the monitor width compared to the standard MFS, resulting in larger biomass amounts for analysis. By use of a microfiltration membrane (pore size 0.05 μm) in the monitor salt concentration polarization is avoided, allowing operation at low pressures enabling accurate measurement of the intrinsic hydraulic biofilm resistance. Validation tests on e.g. hydrodynamic behavior, flow field distribution, and reproducibility showed that the small-sized monitor was a representative tool for membranes used in practice under the same operating conditions, such as spiral-wound nanofiltration and reverse osmosis membranes. Monitor studies with and without feed spacer use at a flux of 20 L m −2 h −1 and a cross-flow velocity of 0.1 m s −1 clearly showed the suitability of the monitor to determine hydraulic biofilm resistance and for controlled biofouling studies.

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Characterisation of Fouling of Nanofiltration Membranes used to Treat Surface Waters

Cited by 59 publications

References 0 publications

The significance of calcium ions onPseudomonas fluorescensbiofilms – a structural and mechanical study

The significance of calcium ions onPseudomonas fluorescensbiofilms – a structural and mechanical study

Fouling effects on rejection in the membrane filtration of natural waters

Development and testing of a transparent membrane biofouling monitor

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