Special Issue "Membrane Hybrid Processes"

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A special issue of Membranes (ISSN 2077-0375).

Deadline for manuscript submissions: closed (10 May 2014)

Special Issue Editor

Guest Editor
Prof. Dr. Massoud Pirbazari (Website)

Sonny Astani Department of Civil and Environmental Engineering, University of Southern California, Los Angeles, CA 90089-2531, USA
Fax: +1 213 740 0592
Interests: integrated membrane filtration processes; membrane bioreactors; ultrafiltration; nanofiltration; reverse osmosis; water reclamation; wastewater treatment; water purification; membrane fouling; flux enhancement; rejection; membrane synthesis and nano-materials

Special Issue Information

Dear Colleagues,

Membrane technologies have recently emerged as an additional category of separation processes to the well-established conventional processes, and their applications water reclamation, wastewater treatment, water purification, and industrial separations in pharmaceuticals, biotechnology, chemicals, electronics and other sectors. Membrane technologies offer advantages over existing conventional technologies including high selectivity, low energy consumption, high productivity, moderate cost to performance ratio, and compact modular design. Membrane-based hybrid processes combining either a membrane process with a conventional process or another membrane process might be optimal for several applications, and may sometimes achieve separations that are otherwise impractical or impossible to achieve through conventional processes.

Membrane hybrid processes fall into two categories: those combining a membrane process with conventional process, and those combining different membrane processes. Membrane processes may include microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), electro-dialysis (ED), membrane bioreactor (MBR) or per-vaporation (PV), membrane distillation (MD). In the first category, a membrane processes may be combined with conventional processes such as ion-exchange, adsorption (using activated carbon or resins), microbial degradation, air-stripping and several others. In the second, one or more membrane processes are integrated to overcome the problems arising in single membrane processes, and shall include combinations of MF-RO, UF-RO, NF-ED, PV-RO, UF-MD, UF-NF-RO-MD or unique combinations thereof for specific applications. In this regard, new materials and fabrication technologies have been developed and applied to novel membrane synthesis and modification, exemplified by carbon nanotubes-based membranes and nano-composite membranes. Novel membrane processes have been developed with improved membrane materials and designs. These major breakthroughs often lead to greatly enhanced process efficiency arising from permeate flux enhancement, fouling control, and performance improvement.

This Special Issue offers a perfect site to document state-of-the-art developments and innovations in these areas. Authors are invited and encouraged to submit their original papers and reviews.

Prof. Dr. Massoud Pirbazari
Guest Editor

Submission

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. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as 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 refereed through a 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 quarterly 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 500 CHF (Swiss Francs). English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.


Keywords

  • water and wastewater treatment
  • industrial processes and separations
  • water reclamation and reuse
  • hybrid or integrated membrane processes
  • membrane synthesis and modification
  • membrane rejection
  • contaminant removal
  • membrane fouling
  • permeate flux enhancement
  • energy requirements

Published Papers (4 papers)

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Research

Open AccessArticle Recovery of Flavonoids from Orange Press Liquor by an Integrated Membrane Process
Membranes 2014, 4(3), 509-524; doi:10.3390/membranes4030509
Received: 19 June 2014 / Revised: 14 July 2014 / Accepted: 30 July 2014 / Published: 11 August 2014
Cited by 2 | PDF Full-text (492 KB) | HTML Full-text | XML Full-text
Abstract
Orange press liquor is a by-product generated by the citrus processing industry containing huge amounts of natural phenolic compounds with recognized antioxidant activity. In this work, an integrated membrane process for the recovery of flavonoids from orange press liquors was investigated on [...] Read more.
Orange press liquor is a by-product generated by the citrus processing industry containing huge amounts of natural phenolic compounds with recognized antioxidant activity. In this work, an integrated membrane process for the recovery of flavonoids from orange press liquors was investigated on a laboratory scale. The liquor was previously clarified by ultrafiltration (UF) in selected operating conditions by using hollow fiber polysulfone membranes. Then, the clarified liquor with a total soluble solids (TSS) content of 10 g·100 g−1 was pre-concentrated by nanofiltration (NF) up to 32 g TSS 100 g−1 by using a polyethersulfone spiral-wound membrane. A final concentration step, up to 47 g TSS 100 g−1, was performed by using an osmotic distillation (OD) apparatus equipped with polypropylene hollow fiber membranes. Suspended solids were completely removed in the UF step producing a clarified liquor containing most part of the flavonoids of the original press liquor due to the low rejection of the UF membrane towards these compounds. Flavanones and anthocyanins were highly rejected by the NF membrane, producing a permeate stream with a TSS content of 4.5 g·100 g−1. An increasing of both the flavanones and anthocyanins concentration was observed in the NF retentate by increasing the volume reduction factor (VRF). The final concentration of flavonoids by OD produced a concentrated solution of interest for nutraceutical and pharmaceutical applications. Full article
(This article belongs to the Special Issue Membrane Hybrid Processes)
Figures

Open AccessArticle Theoretical and Experimental Investigations of the Potential of Osmotic Energy for Power Production
Membranes 2014, 4(3), 447-468; doi:10.3390/membranes4030447
Received: 11 May 2014 / Revised: 27 June 2014 / Accepted: 22 July 2014 / Published: 8 August 2014
Cited by 1 | PDF Full-text (463 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a study on the potential of osmotic energy for power production. The study includes both pilot plant testing and theoretical modelling as well as cost estimation. A projected cost of £30/MWh of clean electricity could be achieved by using [...] Read more.
This paper presents a study on the potential of osmotic energy for power production. The study includes both pilot plant testing and theoretical modelling as well as cost estimation. A projected cost of £30/MWh of clean electricity could be achieved by using a Hydro-Osmotic Power (HOP) plant if a suitable membrane is used and the osmotic potential difference between the two solutions is greater than 25 bar; a condition that can be readily found in many sites around the world. Results have shown that the membrane system accounts for 50%–80% of the HOP plant cost depending on the salinity difference level. Thus, further development in membrane technology and identifying suitable membranes would have a significant impact on the feasibility of the process and the route to market. As the membrane permeability determines the HOP process feasibility, this paper also describes the effect of the interaction between the fluid and the membrane on the system permeability. It has been shown that both the fluid physical properties as well as the membrane micro-structural parameters need to be considered if further development of the HOP process is to be achieved. Full article
(This article belongs to the Special Issue Membrane Hybrid Processes)
Open AccessArticle On The Relationship between Suspended Solids of Different Size, the Observed Boundary Flux and Rejection Values for Membranes Treating a Civil Wastewater Stream
Membranes 2014, 4(3), 414-423; doi:10.3390/membranes4030414
Received: 11 March 2014 / Revised: 3 June 2014 / Accepted: 21 July 2014 / Published: 4 August 2014
Cited by 4 | PDF Full-text (259 KB) | HTML Full-text | XML Full-text
Abstract
Membrane fouling is one of the main issues in membrane processes, leading to a progressive decrease of permeability. High fouling rates strongly reduce the productivity of the membrane plant, and negatively affect the surviving rate of the membrane modules, especially when real [...] Read more.
Membrane fouling is one of the main issues in membrane processes, leading to a progressive decrease of permeability. High fouling rates strongly reduce the productivity of the membrane plant, and negatively affect the surviving rate of the membrane modules, especially when real wastewater is treated. On the other hand, since selectivity must meet certain target requirements, fouling may lead to unexpected selectivity improvements due to the formation of an additional superficial layer formed of foulants and that act like a selective secondary membrane layer. In this case, a certain amount of fouling may be profitable to the point where selectivity targets were reached and productivity is not significantly affected. In this work, the secondary clarifier of a step sludge recirculation bioreactor treating municipal wastewater was replaced by a membrane unit, aiming at recovering return sludge and producing purified water. Fouling issues of such a system were checked by boundary flux measurements. A simple model for the description of the observed productivity and selectivity values as a function of membrane fouling is proposed. Full article
(This article belongs to the Special Issue Membrane Hybrid Processes)
Open AccessArticle Filtration Characterization Method as Tool to Assess Membrane Bioreactor Sludge Filterability—The Delft Experience
Membranes 2014, 4(2), 227-242; doi:10.3390/membranes4020227
Received: 8 March 2014 / Revised: 25 March 2014 / Accepted: 21 April 2014 / Published: 30 April 2014
Cited by 3 | PDF Full-text (282 KB) | HTML Full-text | XML Full-text
Abstract
Prevention and removal of fouling is often the most energy intensive process in Membrane Bioreactors (MBRs), responsible for 40% to 50% of the total specific energy consumed in submerged MBRs. In the past decade, methods were developed to quantify and qualify fouling, [...] Read more.
Prevention and removal of fouling is often the most energy intensive process in Membrane Bioreactors (MBRs), responsible for 40% to 50% of the total specific energy consumed in submerged MBRs. In the past decade, methods were developed to quantify and qualify fouling, aiming to support optimization in MBR operation. Therefore, there is a need for an evaluation of the lessons learned and how to proceed. In this article, five different methods for measuring MBR activated sludge filterability and critical flux are described, commented and evaluated. Both parameters characterize the fouling potential in full-scale MBRs. The article focuses on the Delft Filtration Characterization method (DFCm) as a convenient tool to characterize sludge properties, namely on data processing, accuracy, reproducibility, reliability, and applicability, defining the boundaries of the DFCm. Significant progress was made concerning fouling measurements in particular by using straight forward approaches focusing on the applicability of the obtained results. Nevertheless, a fouling measurement method is still to be defined which is capable of being unequivocal, concerning the fouling parameters definitions; practical and simple, in terms of set-up and operation; broad and useful, in terms of obtained results. A step forward would be the standardization of the aforementioned method to assess the sludge filtration quality. Full article
(This article belongs to the Special Issue Membrane Hybrid Processes)

Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Type of Paper: Article
Title: About How to Replace Efficiently the Secondary Clarifier in a Step Sludge Recirculation Reactor by Membranes
Authors: Marco Stoller* and Luca Di Palma
Affiliation: Department of Chemical Materials Environmental Engneering, University of Rome "La Sapienza", Via Eudossiana 18, 00184 Rome, Italy
Abstract: The "hybrid system" consists in the coupling of a step sludge recirculation (SSR) reactor with membranes (replacing the last stage of sedimentation of the biomass more efficiently). The paper will focus on the membrane process, in particular: (1) efficiency to separate bacteria from protozoa from the purified wastewater stream. The separation of the two biological spices is of great advantage since optimized dosage may occur at different stages of the SSR. The discussion will show how the formation of "secondary membranes" by the organic content in the wastewater sticking over the membrane increases this selectivity; (2) membrane fouling. The analysis will follow threshold flux measurements on the system, and how to maintain for long operating times productivity of the membrane, despite the need of limited fouling to increase the selectivity as shown at point 1.

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