Special Issue "Fouling and Cleaning in Membrane Processes"

A special issue of Membranes (ISSN 2077-0375). This special issue belongs to the section "Membrane Applications in Industry and Chemical Analysis".

Deadline for manuscript submissions: closed (31 March 2019)

Special Issue Editor

Guest Editor
Prof. Dr. Frank Lipnizki

Department of Chemical Engineering, Lund University, Box 124, 221 00 Lund, Sweden
Website | E-Mail
Interests: membrane separation processes; integration of membrane processes; fouling and cleaning; membrane applications in food, biotech and chemical industry; water and wastewater treatment

Special Issue Information

Dear Colleagues,

Membrane technology is one of the fastest growing separation technologies for a wide range of applications, ranging from seawater desalination and medical applications to applications in the food, biotech and process industry, as well as water preparation and wastewater treatment. One challenging aspect in most membrane applications is membrane fouling with reduces the filtration capacity of membranes due to deposition of dissolved and suspended materials on and/or in the membrane. In order to regenerate the membrane performance mechanical and chemical cleaning is often required. Thus, fouling and cleaning have a significant impact on membrane plant capital and operating expenditures and, thus, the sustainability of membrane processes. Despite significant progress in the field of fouling and cleaning of membranes there are still many challenges ahead.

This Special Issue aims, therefore, to provide the latest advances in membrane fouling and cleaning including scaling with focus on industrial and water/wastewater applications. Thus, the scope of this issue covers, but is not limited to, approaches to monitor and model fouling and cleaning, modified low-fouling membranes and membrane materials, mechanical cleaning methods such as back-flushing and pulsing, chemical cleaning methods and protocols, case studies including environmental and economical evaluations.

Authors are welcome to submit original research papers, communications, and review articles. Looking forward to your outstanding contribution for this Special Issue.

Prof. Frank Lipnizki
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Membranes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • fouling
  • cleaning
  • scaling
  • monitoring
  • modelling
  • membrane processes
  • low-fouling membranes
  • case studies

Published Papers (4 papers)

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Research

Open AccessArticle Membrane Fouling Due to Protein—Polysaccharide Mixtures in Dead-End Ultrafiltration; the Effect of Permeation Flux on Fouling Resistance
Received: 28 November 2018 / Revised: 14 January 2019 / Accepted: 16 January 2019 / Published: 1 February 2019
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Abstract
Significant gaps exist in our knowledge of ultrafiltration (UF) membrane fouling, due to mixtures of poly-saccharides and proteins, despite a fair amount of related research. To get new insights into fouling layer characteristics, experiments were performed under constant-flux, within the range of practical [...] Read more.
Significant gaps exist in our knowledge of ultrafiltration (UF) membrane fouling, due to mixtures of poly-saccharides and proteins, despite a fair amount of related research. To get new insights into fouling layer characteristics, experiments were performed under constant-flux, within the range of practical interest (15–90 L/m2h), with typical polysaccharides (sodium alginate, SA), proteins (bovine serum albumin, BSA) as well as their mixtures in various proportions (1:3, 1:1, 3:1), and total organic matter concentration of 30 mg/L. The feed-water salinity and calcium ion concentration were 2000 mg/L NaCl and 2 mM, respectively. The temporal evolution of such fouling layers on flat-sheet membranes was monitored by recording the trans-membrane pressure variation. The results show that the specific fouling resistance α is strongly affected by flux, and the fouling propensity of polysaccharide-protein mixtures is significantly enhanced compared to single foulants, i.e., when BSA and SA are alone. The fouling layers are compressible and their resistance α tends to increase with the mass ratio of alginate in the mixture, particularly at high fluxes. To quantify these effects, correlations are presented of the initial fouling resistance αi with permeate flux J and of the evolution of α. R&D priorities are suggested on this topic of mixed foulants. Full article
(This article belongs to the Special Issue Fouling and Cleaning in Membrane Processes)
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Open AccessArticle Investigations of Alkaline and Enzymatic Membrane Cleaning of Ultrafiltration Membranes Fouled by Thermomechanical Pulping Process Water
Received: 10 September 2018 / Revised: 2 October 2018 / Accepted: 8 October 2018 / Published: 10 October 2018
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Abstract
The pulp and paper industry is one of the most important industrial sectors worldwide, and has considerable potential for the sustainable fractionation of lignocellulosic biomass to provide valuable compounds. Ultrafiltration (UF) is a suitable separation technique for the profitable production of hemicelluloses from [...] Read more.
The pulp and paper industry is one of the most important industrial sectors worldwide, and has considerable potential for the sustainable fractionation of lignocellulosic biomass to provide valuable compounds. Ultrafiltration (UF) is a suitable separation technique for the profitable production of hemicelluloses from process water from thermomechanical pulping (ThMP), but is limited by membrane fouling. Improvements in cleaning protocols and new alternative cleaning agents are required to ensure a long membrane lifetime, and thus a sustainable process. This study, therefore, focuses on the cleaning of polymeric UF membranes after the filtration of ThMP process water, comparing alkaline with enzymatic cleaning agents. The aim was to develop a cleaning procedure that is efficient under mild conditions, resulting in a lower environmental impact. It was not possible to restore the initial permeability of the membrane when cleaning the membrane with enzymes alone, but the permeability was restored when using a two-step cleaning process with enzymes in the first step and an alkaline cleaning agent in the second step. Scanning electron microscopy gave a deeper inside into the cleaning efficiency. Attenuated total reflectance Fourier-transform infrared spectroscopy analysis confirmed that not only polysaccharides, but also extractives are adsorbed onto the membrane surface. Full article
(This article belongs to the Special Issue Fouling and Cleaning in Membrane Processes)
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Graphical abstract

Open AccessArticle Utilization of DES-Lignin as a Bio-Based Hydrophilicity Promoter in the Fabrication of Antioxidant Polyethersulfone Membranes
Received: 13 August 2018 / Revised: 4 September 2018 / Accepted: 5 September 2018 / Published: 8 September 2018
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Abstract
Enhancement of membrane permeability at no detriment of its other performances, e.g., selectivity, is a goal-directed objective in membrane fabrication. A novel antioxidant DES-lignin (lignin extracted from birch wood by using a deep eutectic solvent) polyethersulfone (PES) membrane, containing 0–1 wt % DES-lignin, [...] Read more.
Enhancement of membrane permeability at no detriment of its other performances, e.g., selectivity, is a goal-directed objective in membrane fabrication. A novel antioxidant DES-lignin (lignin extracted from birch wood by using a deep eutectic solvent) polyethersulfone (PES) membrane, containing 0–1 wt % DES-lignin, was fabricated with the phase inversion technique. The performance and morphology of the fabricated membranes were characterized by a pure water flux, polyethylene glycol (PEG) retention, Fourier transform infrared spectroscopy, scanning electron microscopy, and contact angle measurements. Membranes with less negative charge and better hydrophilicity were obtained when the DES-lignin content in the polymer solution was increased. With the highest dosage, the incorporation of DES-lignin in the membrane matrix improved the membrane permeability by 29.4% compared to a pure PES membrane. Moreover, no leakage of DES-lignin from the membrane structure was observed, indicating good compatibility of DES-lignin with the PES structure. It was also found that the improvement of both rejection and pure water flux could be achieved by using a small dosage of DES-lignin (0.25 wt %) in membrane fabrication. The membranes incorporated with DES-lignin showed higher DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) scavenging activity compared to the pure membrane, where 2.6 and 1.1 times higher DPPH and ABTS scavenging activity was observed with the highest DES-lignin content (1 wt %). Thus, the results of this study demonstrate well the feasibility of utilizing DES-lignin as an antioxidant bio-based hydrophilicity promoter in the fabrication of ultrafiltration membranes. Full article
(This article belongs to the Special Issue Fouling and Cleaning in Membrane Processes)
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Graphical abstract

Open AccessArticle Concentration Polarization in Ultrafiltration/Nanofiltration for the Recovery of Polyphenols from Winery Wastewaters
Received: 22 June 2018 / Revised: 9 July 2018 / Accepted: 18 July 2018 / Published: 21 July 2018
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Abstract
Concentration polarization is intrinsically associated with the selective character of membranes and often means flux decline and which causes a subsequent decrease of ultrafiltration and nanofiltration performance. More important is the fact that it acts as a precursor of membrane fouling and creates [...] Read more.
Concentration polarization is intrinsically associated with the selective character of membranes and often means flux decline and which causes a subsequent decrease of ultrafiltration and nanofiltration performance. More important is the fact that it acts as a precursor of membrane fouling and creates severe fouling problems in the longer times range. The quantification of its dependence on the operating parameters of cross-flow velocities and transmembrane pressures makes recourse to the film theory to introduce mass-transfer coefficients that generally are calculated by dimensionless correlations of the Sherwood number as a function of the Reynolds and Schmidt numbers. In the present work, the mass-transfer coefficients are obtained through the fitting of experimental results by the pressure variation method. The ultrafiltration/nanofiltration of the winery wastewaters from the racking operation is carried out with the membranes ETNA 01PP (Alfa Laval) and NF 270 (Dow Filmtec) under a wide range of cross-flow velocities and transmembrane pressures up to 15 bar. Full article
(This article belongs to the Special Issue Fouling and Cleaning in Membrane Processes)
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Graphical abstract

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