Special Issue "Advanced Membranes for Water Treatment"

A special issue of Water (ISSN 2073-4441).

Deadline for manuscript submissions: closed (31 December 2016).

Special Issue Editors

Guest Editor
Prof. Stephen Gray Website E-Mail
Institute for Sustainable Industries and Liveable Cities, Victoria University, Footscray Park, Ballarat Road, Footscray, PO Box 14428, Melbourne, Victoria, 8001, Australia
Interests: desalination; water recycling; membrane integrity monitoring; microfiltration/ultrafiltration
Guest Editor
Prof. Hideto Matsuyama Website E-Mail
Center for Membrane and Film Technology, Department of Chemical Science and Engineering, Kobe University, Rokkodai, Nada-ku, Kobe 657-8501, Japan
Interests: chemical engineering; membrane technology; separation technology

Special Issue Information

Dear Colleagues,

Globally, changes in climate and increasing urbanisation and population growth are putting strain on traditional water resources. As a result, poorer quality water sources, such as wastewater, seawater, and stormwater, are being used as water sources for municipal applications. Membranes are ideally suited to the processing of such waters, as they are able to reliably produce high quality water from low-grade water supplies, with failures usually associated with membrane fouling and loss of production. As such, water quality is generally maintained during fouling processes and health risks are kept low.

The importance of membranes to water treatment is demonstrated by their dominance as the technology of choice for desalination, water recycling and filtration of surface waters. Membrane bioreactors are also cost competitive at smaller scale and for treatment of industrial wastewaters, and the increasing application of membranes is demonstrated by their predicted annual growth rate being >9%.

This “Advanced Membranes for Water Treatment” Special Issue will bring together articles on new developments in the manufacture and use of membranes in water treatment applications. The special issue is requesting articles on all aspects of membranes, including manuscripts on membrane fouling, fabrication, characterisation, on-line monitoring, new membrane processes, such as forward osmosis and membrane distillation, and membrane applications.

Prof. Dr. Stephen Gray
Prof. Dr. Hideto Matsuyama
Guest Editors

Manuscript Submission Information

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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. Water 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 1600 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

  • membranes,
  • reverse osmosis,
  • nanofiltration,
  • ultrafiltration,
  • microfiltration,
  • membrane bioreactors,
  • forward osmosis,
  • membrane distillation,
  • membrane fouling,
  • membrane characterisation,
  • water recycling,
  • desalination

Published Papers (10 papers)

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Research

Open AccessFeature PaperArticle
Polymer Inclusion Membranes with Strip Dispersion
Water 2017, 9(6), 399; https://doi.org/10.3390/w9060399 - 03 Jun 2017
Abstract
The present work investigated the permeation of indium ions through a polymer inclusion membrane (PIM), prepared with cellulose triacetate (CTA) as the base polymer, tris(2-butoxyethyl) phosphate (TBEP) as the plasticizer and di-(2-ethylhexyl)phosphoric acid (D2EHPA) as the extractant. With 5 M HCl aqueous solution [...] Read more.
The present work investigated the permeation of indium ions through a polymer inclusion membrane (PIM), prepared with cellulose triacetate (CTA) as the base polymer, tris(2-butoxyethyl) phosphate (TBEP) as the plasticizer and di-(2-ethylhexyl)phosphoric acid (D2EHPA) as the extractant. With 5 M HCl aqueous solution as the strip solution, we observed an initial indium permeability of 2.4 × 10−4 m/min. However, the permeability decreases with time, dropping to about 3.4 × 10−5 m/min after 200 min of operation. Evidence was obtained showing that hydrolysis of CTA occurred, causing a dramatic decrease in the feed pH (protons transported from strip to feed solutions) and a loss of extractant and plasticizer from the membrane, and then leading to the loss of indium permeability. To alleviate the problem of hydrolysis, we proposed an operation scheme called polymer inclusion membranes with strip dispersion: dispersing the strip solution in extractant-containing oil and then bringing the dispersion to contact with the polymer membrane. Since the strong acid was dispersed in oil, the membrane did not directly contact the strong acid at all times, and membrane hydrolysis was thus alleviated and the loss of indium permeability was effectively prevented. With the proposed scheme, a stable indium permeability of 2.5 × 10−4 m/min was obtained during the whole time period of the permeation experiment. Full article
(This article belongs to the Special Issue Advanced Membranes for Water Treatment)
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Open AccessArticle
A Thermodynamical Approach for Evaluating Energy Consumption of the Forward Osmosis Process Using Various Draw Solutes
Water 2017, 9(3), 189; https://doi.org/10.3390/w9030189 - 06 Mar 2017
Cited by 2
Abstract
The forward-osmosis (FO) processes have received much attention in past years as an energy saving desalination process. A typical FO process should inclu de a draw solute recovery step which contributes to the main operation costs of the process. Therefore, investigating the energy [...] Read more.
The forward-osmosis (FO) processes have received much attention in past years as an energy saving desalination process. A typical FO process should inclu de a draw solute recovery step which contributes to the main operation costs of the process. Therefore, investigating the energy consumption is very important for the development and employment of the forward osmosis process. In this work, NH3-CO2, Na2SO4, propylene glycol mono-butyl ether, and dipropylamine were selected as draw solutes. The FO processes of different draw solute recovery approaches were simulated by Aspen PlusTM with a customized FO unit model. The electrolyte Non-Random Two-Liquid (Electrolyte-NRTL) and Universal Quasi Chemical (UNIQUAC) models were employed to calculate the thermodynamic properties of the feed and draw solutions. The simulation results indicated that the FO performance decreased under high feed concentration, while the energy consumption was improved at high draw solution concentration. The FO process using Na2SO4 showed the lowest energy consumption, followed by NH3-CO2, and dipropylamine. The propylene glycol mono-butyl ether process exhibited the highest energy consumption due to its low solubility in water. Finally, in order to compare the equivalent work of the FO processes, the thermal energy requirements were converted to electrical work. Full article
(This article belongs to the Special Issue Advanced Membranes for Water Treatment)
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Open AccessArticle
A Pilot Study of the Sludge Recycling Enhanced Coagulation–Ultrafiltration Process for Drinking Water: The Effects of Sludge Recycling Ratio and Coagulation Stirring Strategy
Water 2017, 9(3), 183; https://doi.org/10.3390/w9030183 - 05 Mar 2017
Cited by 3
Abstract
The pilot-scale study on a sludge recycling enhanced coagulation–ultrafiltration (UF) process for surface water treatment is investigated in this paper. The impact of the sludge recycling ratio and coagulation stirring strategy on removal, sedimentation efficiency, and membrane fouling control was studied in this [...] Read more.
The pilot-scale study on a sludge recycling enhanced coagulation–ultrafiltration (UF) process for surface water treatment is investigated in this paper. The impact of the sludge recycling ratio and coagulation stirring strategy on removal, sedimentation efficiency, and membrane fouling control was studied in this work. Sludge recycling ratios of 0%, 5%, 10%, 15%, and 20% were applied, and the optimal ratio was found to be 10%. Moreover, four stirring strategies were also applied, and the best stirring strategy for coagulation was found to be rapid mixing (velocity gradient: 280 s−1), which is quite different from the coagulation stirring strategy without sludge recycling. This suggests that the adsorption effect of sludge could play a leading role during the procedure. Moreover, shortening the coagulation process makes it possible to reduce energy consumption. Full article
(This article belongs to the Special Issue Advanced Membranes for Water Treatment)
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Open AccessArticle
Small Scale Direct Potable Reuse (DPR) Project for a Remote Area
Water 2017, 9(2), 94; https://doi.org/10.3390/w9020094 - 08 Feb 2017
Cited by 3
Abstract
An Advanced Water Treatment Plant (AWTP) for potable water recycling in Davis Station Antarctica was trialed using secondary effluent at Selfs Point in Hobart, Tasmania, for nine months. The trials demonstrated the reliability of performance of a seven barrier treatment process consisting of [...] Read more.
An Advanced Water Treatment Plant (AWTP) for potable water recycling in Davis Station Antarctica was trialed using secondary effluent at Selfs Point in Hobart, Tasmania, for nine months. The trials demonstrated the reliability of performance of a seven barrier treatment process consisting of ozonation, ceramic microfiltration (MF), biologically activated carbon, reverse osmosis, ultra-violet disinfection, calcite contactor and chlorination. The seven treatment barriers were required to meet the high log removal values (LRV) required for pathogens in small systems during disease outbreak, and on-line verification of process performance was required for operation with infrequent operator attention. On-line verification of pathogen LRVs, a low turbidity filtrate of approximately 0.1 NTU (Nephelometric Turbidity Unit), no long-term fouling and no requirement for clean-in-place (CIP) was achieved with the ceramic MF. A pressure decay test was also reliably implemented on the reverse osmosis system to achieve a 2 LRV for protozoa, and this barrier required only 2–3 CIP treatments each year. The ozonation process achieved 2 LRV for bacteria and virus with no requirement for an ozone residual, provided the ozone dose was >11.7 mg/L. Extensive screening using multi-residue gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–mass spectrometry (LC–MS) database methods that can screen for more than 1200 chemicals found that few chemicals pass through the barriers to the final product and rejected (discharge) water streams. The AWTP plant required 1.93 kWh/m3 when operated in the mode required for Davis Station and was predicted to require 1.27 kWh/m3 if scaled up to 10 ML/day. The AWTP will be shipped to Davis Station for further trials before possible implementation for water recycling. The process may have application in other small remote communities. Full article
(This article belongs to the Special Issue Advanced Membranes for Water Treatment)
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Open AccessArticle
Performance of a Novel Fertilizer-Drawn Forward Osmosis Aerobic Membrane Bioreactor (FDFO-MBR): Mitigating Salinity Build-Up by Integrating Microfiltration
Water 2017, 9(1), 21; https://doi.org/10.3390/w9010021 - 04 Jan 2017
Cited by 8
Abstract
In this paper, three different fertilizer draw solutions were tested in a novel forward osmosis-microfiltration aerobic membrane bioreactor (MF-FDFO-MBR) hybrid system and their performance were evaluated in terms of water flux and reverse salt diffusion. Results were also compared with a standard solution. [...] Read more.
In this paper, three different fertilizer draw solutions were tested in a novel forward osmosis-microfiltration aerobic membrane bioreactor (MF-FDFO-MBR) hybrid system and their performance were evaluated in terms of water flux and reverse salt diffusion. Results were also compared with a standard solution. Results showed that ammonium sulfate is the most suitable fertilizer for this hybrid system since it has a relatively high water flux (6.85 LMH) with a comparatively low reverse salt flux (3.02 gMH). The performance of the process was also studied by investigating different process parameters: draw solution concentration, FO draw solution flow rate and MF imposed flux. It was found that the optimal conditions for this hybrid system were: draw solution concentration of 1 M, FO draw solution flow rate of 200 mL/min and MF imposed flux of 10 LMH. The salt accumulation increased from 834 to 5400 μS/cm during the first four weeks but after integrating MF, the salinity dropped significantly from 5400 to 1100 μS/cm suggesting that MF is efficient in mitigating the salinity build up inside the reactor. This study demonstrated that the integration of the MF membrane could effectively control the salinity and enhance the stable FO flux in the OMBR. Full article
(This article belongs to the Special Issue Advanced Membranes for Water Treatment)
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Open AccessArticle
The Effect of Membrane Material and Surface Pore Size on the Fouling Properties of Submerged Membranes
Water 2016, 8(12), 602; https://doi.org/10.3390/w8120602 - 20 Dec 2016
Cited by 7
Abstract
We aimed to investigate the relationship between membrane material and the development of membrane fouling in a membrane bioreactor (MBR) using membranes with different pore sizes and hydrophilicities. Batch filtration tests were performed using submerged single hollow fiber membrane ultrafiltration (UF) modules with [...] Read more.
We aimed to investigate the relationship between membrane material and the development of membrane fouling in a membrane bioreactor (MBR) using membranes with different pore sizes and hydrophilicities. Batch filtration tests were performed using submerged single hollow fiber membrane ultrafiltration (UF) modules with different polymeric membrane materials including cellulose acetate (CA), polyethersulfone (PES), and polyvinylidene fluoride (PVDF) with activated sludge taken from a municipal wastewater treatment plant. The three UF hollow fiber membranes were prepared by a non-solvent-induced phase separation method and had similar water permeabilities and pore sizes. The results revealed that transmembrane pressure (TMP) increased more sharply for the hydrophobic PVDF membrane than for the hydrophilic CA membrane in batch filtration tests, even when membranes with similar permeabilities and pore sizes were used. PVDF hollow fiber membranes with smaller pores had greater fouling propensity than those with larger pores. In contrast, CA hollow fiber membranes showed good mitigation of membrane fouling regardless of pore size. The results obtained in this study suggest that the surface hydrophilicity and pore size of UF membranes clearly affect the fouling properties in MBR operation when using activated sludge. Full article
(This article belongs to the Special Issue Advanced Membranes for Water Treatment)
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Open AccessArticle
Predicting the Specific Energy Consumption of Reverse Osmosis Desalination
Water 2016, 8(12), 601; https://doi.org/10.3390/w8120601 - 16 Dec 2016
Cited by 15
Abstract
Desalination is often considered an approach for mitigating water stress. Despite the abundance of saline water worldwide, additional energy consumption and increased costs present barriers to widespread deployment of desalination as a municipal water supply. Specific energy consumption (SEC) is a common measure [...] Read more.
Desalination is often considered an approach for mitigating water stress. Despite the abundance of saline water worldwide, additional energy consumption and increased costs present barriers to widespread deployment of desalination as a municipal water supply. Specific energy consumption (SEC) is a common measure of the energy use in desalination processes, and depends on many operational and water quality factors. We completed multiple linear regression and relative importance statistical analyses of factors affecting SEC using both small-scale meta-data and municipal-scale empirical data to predict the energy consumption of desalination. Statistically significant results show water quality and initial year of operations to be significant and important factors in estimating SEC, explaining over 80% of the variation in SEC. More recent initial year of operations, lower salinity raw water, and higher salinity product water accurately predict lower values of SEC. Economic analysis revealed a weak statistical relationship between SEC and cost of water production. Analysis of associated greenhouse gas (GHG) emissions revealed important considerations of both electricity source and SEC in estimating the GHG-related sustainability of desalination. Results of our statistical analyses can aid decision-makers by predicting the SEC of desalination to a reasonable degree of accuracy with limited data. Full article
(This article belongs to the Special Issue Advanced Membranes for Water Treatment)
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Open AccessArticle
Metal–Organic Framework-Functionalized Alumina Membranes for Vacuum Membrane Distillation
Water 2016, 8(12), 586; https://doi.org/10.3390/w8120586 - 08 Dec 2016
Cited by 10
Abstract
Nature-mimetic hydrophobic membranes with high wetting resistance have been designed for seawater desalination via vacuum membrane distillation (VMD) in this study. This is achieved through molecular engineering of metal–organic framework (MOF)-functionalized alumina surfaces. A two-step synthetic strategy was invented to design the hydrophobic [...] Read more.
Nature-mimetic hydrophobic membranes with high wetting resistance have been designed for seawater desalination via vacuum membrane distillation (VMD) in this study. This is achieved through molecular engineering of metal–organic framework (MOF)-functionalized alumina surfaces. A two-step synthetic strategy was invented to design the hydrophobic membranes: (1) to intergrow MOF crystals on the alumina tube substrate and (2) to introduce perfluoro molecules onto the MOF functionalized membrane surface. With the first step, the surface morphology, especially the hierarchical roughness, can be controlled by tuning the MOF crystal structure. After the second step, the perfluoro molecules function as an ultrathin layer of hydrophobic floss, which lowers the surface energy. Therefore, the resultant membranes do not only possess the intrinsic advantages of alumina supports such as high stability and high water permeability, but also have a hydrophobic surface formed by MOF functionalization. The membrane prepared under an optimum condition achieved a good VMD flux of 32.3 L/m2-h at 60 °C. This study may open up a totally new approach for design of next-generation high performance membrane distillation membranes for seawater desalination. Full article
(This article belongs to the Special Issue Advanced Membranes for Water Treatment)
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Open AccessArticle
Optimizing Hollow Fibre Nanofiltration for Organic Matter Rich Lake Water
Water 2016, 8(10), 430; https://doi.org/10.3390/w8100430 - 30 Sep 2016
Cited by 6
Abstract
Over the years, various technologies have been utilized for Natural Organic Matter (NOM) removal with varying degrees of success. Conventional treatment methods comprising of coagulation, flocculation, sedimentation, or filtration are widely used to remove NOM. An alternative to these conventional methods is to [...] Read more.
Over the years, various technologies have been utilized for Natural Organic Matter (NOM) removal with varying degrees of success. Conventional treatment methods comprising of coagulation, flocculation, sedimentation, or filtration are widely used to remove NOM. An alternative to these conventional methods is to use spiral wound membranes. These membranes tend to remove too much hardness whilst being ineffective in disinfection. They also have a low tolerance to chlorine and thus, have limited chemical cleaning options. In this study, we investigated how an alternative and new innovative filtration concept, based on capillary NF membranes from modified polyethersulfone (PES), may be used to treat soft but humus-rich surface waters. Comprehensive performance tests, with a fully automated membrane pilot equipped with a full-scale sized test module (40 m2 membrane surface), were conducted at WTP Görvälnverket, which is operated by the water utility Norrvatten, providing drinking water from Mälaren (SUVA = 2.7–3.3, TOC = 7.0–10.0 mg·L−1) for about 500,000 people in the northern part of the Swedish capital of Stockholm. The removal of both UV and DOC was modeled using a solution diffusion approach. The optimized parameters allow deducing optimal operation conditions with respect to energy, water consumption, and permeate water quality. Optimal cross flow velocity was determined to be 0.75 m·s−1 at 80% recovery and a flux of 12–18 L·m−2·h−1. Under these conditions, 80% of the UV, 75% of the Humic Substances (MW = 600) and 70% of TOC were removed (from 8 to below 2 mg·L−1). A higher cross flow velocity led to marginal improvement (+2%) while both higher and lower membrane fluxes degraded permeate water quality. Apparent optimized diffusion coefficients for UV and TOC were around 1.2–2.4 × 10−10·m2·s−1 and were similar to values found in the literature. Due to their higher diffusion coefficients and higher permeability coefficient, only 40% of the low molecular weight acids (MW = 300–400) were retained. Approximately 30%–40% of the low molecular weight acids in the permeate can be further removed using GAC post NF. The resulting energy consumption of a hypothetical four-stage design, at average operating temperature of 5.73 °C, was calculated to be around 0.6 kWh·m−3 produced water. Full article
(This article belongs to the Special Issue Advanced Membranes for Water Treatment)
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Open AccessArticle
Retention of Silica Nanoparticles in a Lab-Scale Membrane Bioreactor: Implications for Process Performance and Membrane Fouling
Water 2016, 8(7), 277; https://doi.org/10.3390/w8070277 - 04 Jul 2016
Cited by 2
Abstract
In conventional activated sludge (CAS) involving aerobic biological processes, the retention of silica nanoparticles (SiO2 NPs) has no detrimental effect on chemical oxygen demand (COD) and ammonia nitrogen (NH3–N) removal. However, for the membrane bioreactor (MBR) system, which is also [...] Read more.
In conventional activated sludge (CAS) involving aerobic biological processes, the retention of silica nanoparticles (SiO2 NPs) has no detrimental effect on chemical oxygen demand (COD) and ammonia nitrogen (NH3–N) removal. However, for the membrane bioreactor (MBR) system, which is also based on the activated sludge process in addition to the membrane separation process, it has implications not only on the process performance but also on membrane fouling. To investigate these two implications in lab-scale experiments, we continuously operated a control MBR and two experimental MBRs, in which the 28 nm SiO2 NPs and 144 nm SiO2 NPs were added separately to the influent at a final concentration of 100 mg/L. Although the retention of SiO2 NPs in the MBR, as confirmed by dynamic light scattering (DLS) analysis, did not compromise the COD and NH3–N removal, it resulted in substantial increases in the transmembrane pressure (TMP) suggesting the onset of membrane fouling. Analyses by batch-dead end filtration revealed the same fouling trend as observed during the continuous MBR experiments; membrane fouling is aggravated in the presence of SiO2 NPs. This was evident from permeate flux decline of between 30% and 74% at very low TMP (5 kPa) and the further increases in the total resistance. Full article
(This article belongs to the Special Issue Advanced Membranes for Water Treatment)
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