Contribution of biofouling to permeation flux decline and membrane resistance changes during whey ultrafiltration

Membrane separation technology represents an alternative way to achieve biomass retention in anaerobic bioreactors for wastewater treatment. Due to high biomass concentrations of anaerobic reactors, cake formation is likely to represent a major cause of flux decline. In the presented research, experiments are performed on the effect of biomass concentration and level of gas sparging on the hydraulic capacity of a submerged anaerobic membrane bioreactor. Both parameters significantly affected the hydraulic capacity, with biomass exerting the most pronounced effect. After 50 days of continuous operation the critical flux remained virtually unchanged, despite an increase in membrane resistance, suggesting that biomass characteristics and hydraulic conditions determine the bio-layer formation rather than the membrane's fouling level. The concept of bio-layer management is introduced to describe the programmed combination of actions performed in order to control the formation of biomass layer over membranes.

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Prediction of permeation flux decline during MF of oily wastewater using genetic programming

Chemical Engineering Research and Design ◽

10.1016/j.cherd.2011.10.002 ◽

2012 ◽

Vol 90 (6) ◽

pp. 846-853 ◽

Cited By ~ 36

Author(s):

H. Shokrkar ◽

A. Salahi ◽

N. Kasiri ◽

T. Mohammadi

Keyword(s):

Genetic Programming ◽

Permeation Flux ◽

Oily Wastewater ◽

Flux Decline

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Predictability of fouling-potential of raw water for ultrafiltration membranes

Water Science & Technology Water Supply ◽

10.2166/ws.2011.078 ◽

2011 ◽

Vol 11 (4) ◽

pp. 481-489

Author(s):

S. Krause ◽

A. Obermayer

Keyword(s):

Water Quality ◽

Membrane Fouling ◽

Large Scale ◽

High Capacity ◽

Raw Water ◽

Ultrafiltration Membranes ◽

Small Water ◽

Lab Experiments ◽

Flux Decline ◽

Public Drinking Water

The public drinking water supply of southern Germany is characterized by a rather decentralized network. Due to the hydrogeological setting in these parts of Germany many of the small water works with an average capacity of 50 m3/h have to treat raw water extracted from karstic or cliffy aquifers. These raw waters tend to be contaminated with particles and pathogens acquired during snowmelt or after strong rainfalls. In the last decade ultrafiltration has become the technology of choice for the removal of the aforementioned contaminants. Flux decline caused by unanticipated membrane fouling is the main limitation for the application of ultrafiltration membranes. This paper describes how membrane fouling phenomena can be predicted by using a statistical approach based on data from large scale filtration systems in combination with field and lab experiments on raw water quality and membrane performance. The data defines water quality and respective fouling phenomena both in technical scale filtration plants and in lab experiments of eleven different raw waters. The method described here is more economically feasible for small water works when compared to typical pilot experiments that are used for high capacity water works.

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Ultrafiltration of silica sols

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19890091 ◽

1989 ◽

Vol 54 (1) ◽

pp. 91-101 ◽

Cited By ~ 5

Author(s):

Milan Stakić ◽

Slobodan Milonjić ◽

Vladeta Pavasović ◽

Zoja Ilić

Keyword(s):

Particle Size ◽

Silica Particle ◽

Specific Resistance ◽

Membrane Surface ◽

Membrane Resistance ◽

Experimental Conditions ◽

Surface Unit ◽

Silica Sols ◽

Filtration Flux ◽

Batch Cell

Ultrafiltration of three laboratory made silica and two commercial silica sols was studied using Amicon YC membrane in a 200 ml capacity batch-cell. The effect of silica particle size, stirring conditions, pressure, pH and silica contents on ultrafiltration was investigated. The results obtained indicate that the smaller particles have, disregarding the stirring conditions, lower filtration flux. The differences observed in filtration flux are more pronounced in the conditions without stirring. The obtained value of the membrane resistance is independent of the conditions investigated (stirring, pressure, pH, silica contents and particle size). The values of the resistance of polarized solids, specific resistance, and the mass of gel per membrane surface unit were calculated for all experimental conditions.

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Electrochemical Properties of Lipid Membranes Self-Assembled from Bicelles

Membranes ◽

10.3390/membranes11010011 ◽

2020 ◽

Vol 11 (1) ◽

pp. 11

Author(s):

Damian Dziubak ◽

Kamil Strzelak ◽

Slawomir Sek

Keyword(s):

Electrochemical Properties ◽

Self Assembly ◽

Lipid Membranes ◽

Lipid Membrane ◽

Membrane Resistance ◽

Electrochemical Characteristics ◽

Freeze Thaw ◽

Lipid Films ◽

Supported Lipid Membranes

Supported lipid membranes are widely used platforms which serve as simplified models of cell membranes. Among numerous methods used for preparation of planar lipid films, self-assembly of bicelles appears to be promising strategy. Therefore, in this paper we have examined the mechanism of formation and the electrochemical properties of lipid films deposited onto thioglucose-modified gold electrodes from bicellar mixtures. It was found that adsorption of the bicelles occurs by replacement of interfacial water and it leads to formation of a double bilayer structure on the electrode surface. The resulting lipid assembly contains numerous defects and pinholes which affect the permeability of the membrane for ions and water. Significant improvement in morphology and electrochemical characteristics is achieved upon freeze–thaw treatment of the deposited membrane. The lipid assembly is rearranged to single bilayer configuration with locally occurring patches of the second bilayer, and the number of pinholes is substantially decreased. Electrochemical characterization of the lipid membrane after freeze–thaw treatment demonstrated that its permeability for ions and water is significantly reduced, which was manifested by the relatively high value of the membrane resistance.

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

Membranes ◽

10.3390/membranes11070460 ◽

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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Effect of Leukoreduction on Hematobiochemical Parameters and Storage Hemolysis in Canine Whole Blood Units

Animals ◽

10.3390/ani11040925 ◽

2021 ◽

Vol 11 (4) ◽

pp. 925

Author(s):

Maria Teresa Antognoni ◽

Maria Luisa Marenzoni ◽

Ambra Lisa Misia ◽

Luca Avellini ◽

Elisabetta Chiaradia ◽

...

Keyword(s):

Whole Blood ◽

Complete Blood Count ◽

Membrane Resistance ◽

Progressive Increase ◽

Rbc Membrane ◽

Morphological Index ◽

The Difference ◽

Hematobiochemical Parameters ◽

And Storage ◽

Individual Donor

Storage lesions (SLs) occur when the red blood cell quality is altered during the preservation of blood units. Pre-storage leukoreduction would limit the number of SLs. The aims of this study were to evaluate the effectiveness of a leukoreduction filter for human use and the effect of pre-storage leukoreduction on some ematobiochemical parameters in stored canine whole blood. Seven canine blood units were tested. Each one was divided into two units—one leukoreduced (LRWB) and one non-leukoreduced (nLRWB). On each unit, we determined the complete blood count (CBC), lactate-dehydrogenase (LDH), electrolytes (Na+, K+, Cl−), morphological index (MI) and hemolysis, on storage days 0, 7, 14, 21, 28, 35, and 42. Leukoreduction allowed a 98.30% recovery of the RBC count, retaining 99.69% and 94.91% of WBCs and PLTs, respectively. We detected a significant increase of LDH and MI with strongly higher values in nLRWB compared to LRWB. A progressive increase in electrolytes and LDH concentrations was observed as indices of stored hemolysis. LDH showed significantly lower values in LRWB units compared to nLRWB, suggesting its release from leukocytes. In the majority of units, hemolysis reached 1% on the 42nd day of storage. We assert the human leukoreduction filter effectiveness on canine whole blood, and we recommend using nLRWB before day 14, especially for critically ill patients. The difference of the basal hemolysis (day 0) percentages observed between subjects suggests that more studies should be performed to confirm a possible inter-individual donor biological variability of RBC membrane resistance, as happens in humans.

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Evaluating Fertilizer-Drawn Forward Osmosis Performance in Treating Anaerobic Palm Oil Mill Effluent

Membranes ◽

10.3390/membranes11080566 ◽

2021 ◽

Vol 11 (8) ◽

pp. 566

Author(s):

Ruwaida Abdul Wahid ◽

Wei Lun Ang ◽

Abdul Wahab Mohammad ◽

Daniel James Johnson ◽

Nidal Hilal

Keyword(s):

Palm Oil ◽

Pure Water ◽

Water Flux ◽

Forward Osmosis ◽

Salt Flux ◽

Palm Oil Mill Effluent ◽

Performance Ratio ◽

Water Recovery ◽

Flux Decline ◽

Palm Oil Mill

Fertilizer-drawn forward osmosis (FDFO) is a potential alternative to recover and reuse water and nutrients from agricultural wastewater, such as palm oil mill effluent that consists of 95% water and is rich in nutrients. This study investigated the potential of commercial fertilizers as draw solution (DS) in FDFO to treat anaerobic palm oil mill effluent (An-POME). The process parameters affecting FO were studied and optimized, which were then applied to fertilizer selection based on FO performance and fouling propensity. Six commonly used fertilizers were screened and assessed in terms of pure water flux (Jw) and reverse salt flux (JS). Ammonium sulfate ((NH4)2SO4), mono-ammonium phosphate (MAP), and potassium chloride (KCl) were further evaluated with An-POME. MAP showed the best performance against An-POME, with a high average water flux, low flux decline, the highest performance ratio (PR), and highest water recovery of 5.9% for a 4-h operation. In a 24-h fouling run, the average flux decline and water recovered were 84% and 15%, respectively. Both hydraulic flushing and osmotic backwashing cleaning were able to effectively restore the water flux. The results demonstrated that FDFO using commercial fertilizers has the potential for the treatment of An-POME for water recovery. Nevertheless, further investigation is needed to address challenges such as JS and the dilution factor of DS for direct use of fertigation.

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Pyrite (FeS2)-supported ultrafiltration system for removal of mercury (II) from water

Emergent Materials ◽

10.1007/s42247-021-00282-7 ◽

2021 ◽

Author(s):

Dong Suk Han ◽

Kawsher M. D. Solayman ◽

Ho Kyong Shon ◽

Ahmed Abdel-Wahab

Keyword(s):

Membrane Filter ◽

Pyrite Surface ◽

Ph Change ◽

Filtration Process ◽

Sem Images ◽

Flux Decline ◽

Cake Layer ◽

Water Effects ◽

Almost All ◽

Over Time

AbstractThis study investigated the Hg(II) removal efficiencies of the reactive adsorbent membrane (RAM) hybrid filtration process, a removal process that produces stable final residuals. The reaction mechanism between Hg(II) and pyrite and the rejection of the solids over time were characterized with respect to flux decline, pH change, and Hg and Fe concentration in permeate water. Effects of the presence of anions (Cl−, SO42−, NO3−) or humic acid (HA) on the rejection of the Hg(II)-contacted pyrite were studied. The presence of both HA and Hg(II) increased the rate of flux decline due to the formation of irreversible gel-like compact cake layers as shown in the experimental data and modeling related to the flux decline and the SEM images. Stability experiments of the final residuals retained on the membrane using a thiosulfate solution (Na2S2O3) show that the Hg(II)-laden solids were very stable due to little or no detection of Hg(II) in the permeate water. Experiment on the possibility of continuously removing Hg(II) by reusing the Hg/pyrite-laden membrane shows that almost all Hg(II) was adsorbed onto the pyrite surface regardless of the presence of salts or HA, and the Hg(II)-contacted pyrite residuals were completely rejected by the DE/UF system. Therefore, a membrane filter containing pyrite-Hg(II) could provide another reactive cake layer capable of further removal of Hg(II) without post-chemical treatment for reuse.

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