Membrane Technology For Water Treatment Research Articles

Electrochemically Assisted Cobalt/MXene Membrane for Effective Water Treatment: Synchronously Improving Catalytic Performance and Anti-Interference Ability.

Catalytic membrane technology for water treatment is often constrained by a trade-off between permeability and catalytic efficiency as well as interference from coexisting anions and organic matter in natural water matrices. Herein, a novel cobalt-loaded MXene (Co/MXene) 2D membrane with good hydrophilicity, electrical conductivity, and PMS activation function is constructed. The negative voltage is exerted on the membrane to significantly enhance its PMS activation efficiency and anti-interference capacity toward effective water treatment. Under -2 V, the optimal Co/MXene catalytic membrane displays 100% rhodamine b (RhB) removal within a residence time of only 1.1 s, whose RhB degradation kinetic constant (k of 6.85 s-1) is 17.6 times higher than that of the Co/MXene catalytic membrane alone and is also greatly superior to other advanced catalysts and catalytic membranes. Meanwhile, the catalytic membrane displays obvious anti-interference ability in the presence of various coexisting substances of the water matrix and performs well in treating the secondary effluent of coking wastewater. The radical-dominated (SO4•- and •OH) mechanism accompanied by the nonradical species (1O2 and Co(VI)═O) is revealed in the system, and the reactive species production is obviously enhanced under negative voltage. Experimental results and theoretical calculations jointly confirm the key role of electrochemical assistance in enhancing membrane performance, which not only facilitates cycling of Co3+/Co2+ for enhanced PMS activation via improving PMS adsorption and promoting charge transfer from Co to PMS but also hinders interference from coexisting substances in water via electrostatic repulsion.

Advanced membrane technologies for water treatment: utilization of nanomaterials and nanoparticles in membranes fabrication

Advanced membrane technologies for water treatment: utilization of nanomaterials and nanoparticles in membranes fabrication

Novel catalytic membrane based on γ-FeOOH@PVDF/peroxymonosulfate for efficient ammonia recovery: Self-cleaning mechanism and emerging organic contaminant degradation performance

The resolution of membrane fouling issues is crucial for the commercial application of membrane distillation (MD) ammonia recovery. The peroxymonosulfate-based advanced oxidation process (PMS-AOP) exhibited conspicuous degradation of organic pollutants, and in-situ coupling with the MD process could probably achieve desirable antifouling performance. In this research, a novel γ-FeOOH@PVDF catalytic membrane was fabricated by gas–liquid self-deposition method and fluorination treatment. The γ-FeOOH nanosheets arrayed on the substrate membrane endowed the catalytic membrane with superhydrophobicity. The MD ammonia recovery of the digestate achieved a high recovery rate (97.3%), and no membrane fouling or wetting phenomena were detected by real-time monitoring by optical coherence tomography (OCT). The batch degradation experiments of thiamphenicol (TAP) validated the γ-FeOOH@PVDF/PMS system with superior degradation performance and stability. The electron paramagnetic resonance (EPR) coordinated free radical quenching experiment determined the active substance (SO4•-, 1O2, O2•- and •OH) in the degradation process. In addition, the potential self-cleaning mechanism of the radical and non-radical pathways of γ-FeOOH@PVDF was elucidated via density functionaltheory (DFT) calculation. The quinone groups in the organic pollutants facilitated the redox of Fe(Ⅲ)/Fe(Ⅱ) and accelerated the activation of PMS. Hence, the catalytic membrane developed in this research provided a novel instructive strategy for membrane fouling control and also exhibited significant potential of coupling catalysis and membrane technology for water treatment.

Upcycled PVC support layer from waste PVC pipe for thin film composite nanofiltration membranes

Thin-film-composite (TFC) nanofiltration membranes represent the pinnacle of membrane technology in water treatment and desalination. These membranes typically consist of a polyamide (PA) selective layer and a membrane support layer, often constructed from commercially available materials like polyethersulfone (PES). However, there exists an alternative approach that involves the use of different polymers, preferably upcycled waste polymers, as a viable support layer for TFC membranes. Successfully implementing the upcycling of waste plastics into high-value support membranes can make a significant contribution to addressing the issue of plastic waste pollution. One of the primary challenges associated with utilizing upcycled polymers as support layers is the potential impact on the polyamide selective layer of TFC membranes, subsequently affecting their performance in terms of permeability, rejection, and antifouling properties. In this study, we demonstrate the successful fabrication of TFC membranes with a support layer crafted from upcycled waste PVC pipe. We conducted a comprehensive investigation into the effects of upcycled PVC on the structural and physicochemical properties of the polyamide layer. The ultrafiltration (UF) support membranes were fabricated from waste PVC pipe via the nonsolvent induced phase separation (NIPS) method. Subsequently, a polyamide layer was synthesized atop the Upcycled PVC membrane using interfacial polymerization (IP). The physicochemical properties and performance of the TFC membranes with upcycled PVC support layer were compared with membranes with research-grade (RG) PVC and commercial PES support layers. The results unveiled that the TFC membrane with upcycled PVC support layer exhibited higher water permeability (18.2 LMH/bar), in contrast to RG TFC (15.5 LMH/bar) and PES TFC membranes (13.7 LMH/bar). Furthermore, the salt rejection capabilities of the upcycled PVC TFC membrane were competitive and well within an acceptable range.

Ceramic membrane with double catalytic layer for efficient peroxymonosulfate activation and dissolved organic matter (DOM) membrane fouling control

Membrane fouling and low removal of dissolved organic matter (DOM) are the main obstacles for the wide application of ultrafiltration membrane technology in water treatment. Herein, we reported the preparation and application of a novel ceramic membrane, which embedded the cobalt oxide in the membrane support layer, and simultaneously loaded the CoAl composite bimetallic oxide on membrane surface layer. The double catalytic layer membrane (CoAl@AM-Co) enabled more efficient DOM removal and membrane fouling mitigation via in situ peroxymonosulfate (PMS) activation during filtration of actual raw water. Compared to the ceramic membrane with only single catalytic layer, the CoAl@AM-Co/PMS system could achieve much higher normalized membrane flux (0.79 vs. 0.63 and 0.49) and TOC removal (87.47 % vs. 58.35 % and 47.16 %); meanwhile, the molecular weight of DOM in the permeate water would also be significantly decreased. The FT-ICR MS results indicated that the total amount of DOM molecules of the permeate was reduced; the DOM with high H/Cwa and low O/Cwa value could be more easily removed, accompanied with the production of DOM with higher oxidation and unsaturation degree. Singlet oxygen and surface-bound radicals were proved to play a critical role in mitigating the membrane fouling by DOM. The design of ceramic membrane equipped with double catalytic layer and its application in advanced water purification were systematically elucidated for the first time in this work, which provided a new pathway for efficient treatment of surface water containing DOM.

Developments In Membrane Technology for Water Treatment Using the ELECTRE Method

Developments In Membrane Technology for Water Treatment Using the ELECTRE Method

Briefly Talking about the Application of Ultrafiltration Membrane Technology in Water Treatment of Environmental Engineering

Briefly Talking about the Application of Ultrafiltration Membrane Technology in Water Treatment of Environmental Engineering

ZIF-8 membrane: the synthesis technique and nanofiltration application

Membrane technology for water treatment is growing due to the increased demand for clean water and the stringent standard for water quality. Nanofiltration (NF) is widely used in membranes for water treatment due to lower energy consumption and higher flux rates. The application was not limited to only water treatment, yet NF showed excellent potential for solvent nanofiltration application. The utilization of MOF materials for the preparation of NF membranes to produce composite membranes has attracted more attention among researchers due to the advantages offered by the material. Zeolitic imidazolate framework-8 (ZIF-8) membrane has been considered a promising MOF membrane with its capabilities and promising performance due to the small aperture size of the compounds and the stability towards harsh chemical condition. The purpose of this review is to present the synthesis approaches on the preparation of ZIF-8 membranes and the application of ZIF-8 membrane for NF application. The challenges and prospects of ZIF-8 membranes are also discussed to further stimulate the development and the application of ZIF-8 membrane for NF.

Controlling the hydraulic resistance of membrane biofilms by engineering biofilm physical structure

The application of membrane technology for water treatment and reuse is hampered by the development of a microbial biofilm. Biofilm growth in micro-and ultrafiltration (MF/UF) membrane modules, on both the membrane surface and feed spacer, can form a secondary membrane and exert resistance to permeation and crossflow, increasing energy demand and decreasing permeate quantity and quality. In recent years, exhaustive efforts were made to understand the chemical, structural and hydraulic characteristics of membrane biofilms. In this review, we critically assess which specific structural features of membrane biofilms exert resistance to forced water passage in MF/UF membranes systems applied to water and wastewater treatment, and how biofilm physical structure can be engineered by process operation to impose less hydraulic resistance (“below-the-pain threshold”). Counter-intuitively, biofilms with greater thickness do not always cause a higher hydraulic resistance than thinner biofilms. Dense biofilms, however, had consistently higher hydraulic resistances compared to less dense biofilms. The mechanism by which density exerts hydraulic resistance is reported in the literature to be dependant on the biofilms’ internal packing structure and EPS chemical composition (e.g., porosity, polymer concentration). Current reports of internal porosity in membrane biofilms are not supported by adequate experimental evidence or by a reliable methodology, limiting a unified understanding of biofilm internal structure. Identifying the dependency of hydraulic resistance on biofilm density invites efforts to control the hydraulic resistance of membrane biofilms by engineering internal biofilm structure. Regulation of biofilm internal structure is possible by alteration of key determinants such as feed water nutrient composition/concentration, hydraulic shear stress and resistance and can engineer biofilm structural development to decrease density and therein hydraulic resistance. Future efforts should seek to determine the extent to which the concept of “biofilm engineering” can be extended to other biofilm parameters such as mechanical stability and the implication for biofilm control/removal in engineered water systems (e.g., pipelines and/or, cooling towers) susceptible to biofouling.

A Review on the Use of Membrane Technology Systems in Developing Countries.

Fulfilling the demand of clean potable water to the general public has long been a challenging task in most developing countries due to various reasons. Large-scale membrane water treatment systems have proven to be successful in many advanced countries in the past two decades. This paves the way for developing countries to study the feasibility and adopt the utilization of membrane technology in water treatment. There are still many challenges to overcome, particularly on the much higher capital and operational cost of membrane technology compared to the conventional water treatment system. This review aims to delve into the progress of membrane technology for water treatment systems, particularly in developing countries. It first concentrates on membrane classification and its application in water treatment, including membrane technology progress for large-scale water treatment systems. Then, the fouling issue and ways to mitigate the fouling will be discussed. The feasibility of membrane technologies in developing countries was then evaluated, followed by a discussion on the challenges and opportunities of the membrane technology implementation. Finally, the current trend of membrane research was highlighted to address future perspectives of the membrane technologies for clean water production.

Application of Microfiltration membrane Technology in Water treatment

In wastewater treatment, membrane technology is called a major technology in the field of water treatment in the 21st century. With the development of membrane technology and the development of other emerging technologies in combination, microfiltration membrane technology is widely used in the treatment of various types of wastewater such as radioactive wastewater and heavy metal wastewater. The application of microfiltration technology in radioactive and heavy metal wastewater is described. It provides a solid guarantee for deepening the research and application of water treatment.

Molecular Understanding of Ion Effect on Polyzwitterion Conformation in an Aqueous Environment.

Polyzwitterions (PZs) are promising materials for the antifouling in reverse osmosis and nanofiltration membrane technology for water treatment. Fundamental understanding of the structure and molecular interactions involving zwitterions is crucial to the optimal design of antifouling in membrane separation. Here we employ the umbrella sampling and molecular dynamics simulations to investigate molecular interactions between sulfobetaine/carboxybetaine zwitterions and different metal ions (Na+, K+, and Ca2+) in an aqueous solution. The simulation results show that these ions can form stable or metastable contact ionic/solvent-shared-ionic pairs with zwitterions. Simulations at different grafting densities of PZ brush arrays reveal complex competitive association mechanisms, which are attributed to nonbonded electrostatic and van der Waals interactions among zwitterions, water molecules, and different metal ions in an aqueous environment. While the high-grafting density of the PZ brush array leads to a strong branch association between different zwitterions in water, this association is decreased at intermediate- and low-grafting densities due to strong zwitterion-water interactions. More importantly, adding ions into water at intermediate- and low-grafting densities further breaks down the zwitterion branch association, resulting in a randomly oriented and dispersed branch configuration with significant swelling of the polymers. The degree of swelling depends on the type of ions, which further changes the surface electrostatic potential of PZ coatings.

Review on structural control and modification of graphene oxide-based membranes in water treatment: From separation performance to robust operation

Abstract Membrane separation has become an important technology to deal with the global water crisis. The polymer-based membrane technology is currently in the forefront of water purification and desalination but is plagued with some bottlenecks. Laminated graphene oxide (GO) membranes exhibit excellent advantages in water purification and desalination due to the single atomic layer structure, hydrophilic property, rich oxygen-containing groups for modification, mechanical and chemical robust, anti-fouling properties, facile and large-scale production, etc. Thus the GO-based membrane technology is believed to offer huge opportunities for efficient and practical water treatment. This review systematically summarizes the current progress on the water flux and selectivity intensification, stability improvement, anti-fouling and anti-biofouling ability enhancement by structural control and modification. To improve the performance of the laminated GO membrane, interlayer spacing tunability and surface modification are mainly used to enhance its water flux and selectivity. It is found that the stability and biofouling also block the service life of the GO membrane. The crosslinking method is found to effectively solve the stability of GO membrane in aqueous environment. Introducing nanoparticles is a widely used method to improve the membrane biofouling ability. Overall, we believe that this review could provide benefit to researchers in the area of GO-based membrane technology for water treatment.

Laser-Induced Graphene Biofilm Inhibition: Texture Does Matter

Biofilm formation on surfaces in technology and the environment is a problem that can lead to high costs and can endanger human lives. Namely, infrastructure, medical implants, and food processing units, as well as oil refineries, ship hulls, and membrane technology for water treatment, are affected and underline the importance of identifying low fouling surfaces. Recently, surfaces coated with laser-induced graphene (LIG) were shown to strongly resist biofilm formation. Here we investigated the role of LIG texture and surface chemistry on biofilm formation and showed that the rough LIG surface texture correlated to enhanced biofilm inhibition. Fabrication conditions of LIG led to rough surfaces containing carbon nanofibers (250–750 nm diameter), and micropores (1–25 μm), which were shown to inhibit the attachment and proliferation of bacterial cells. In contrast, LIG surfaces with crushed nanofibers and covered micropores resisted biofilm formation less effectively. By oxidizing the LIG surface using oxy...

Application of Ozone-Assisted Membrane Cleaning for Natural Organic Matter Fouled Membranes

ABSTRACTThe popularity of membrane technology in water treatment has been rising for over last 50 years due to wide range of filtration processes and applications, cost effective production and installation as well as safe and efficient water production. However, the development and improvement of membranes is ongoing due to number of weaknesses. Membrane fouling is a major drawback of membrane application in water and waste water treatment. Mostly caused by natural organic matter (NOM), fouling forms a layer on top of the membrane and blocks pores reducing the water permeation and can be potentially destructive to the membrane structure. The issue of membrane fouling can be addressed during membrane manufacturing, maintenance and operation. In the current study, the graphene-based nanomaterials (GBN) were incorporated in polyvinylidene fluoride (PVDF) to manufacture membranes via the phase-inversion technique. The resulting membranes show significant improvement to the properties of the pure PVDF membranes and their antifouling ability. The addition of GBN enhanced the water permeation by over 79% as a result of increased membrane hydrophilicity. Although this enhancement is beneficial, membrane fouling remained an issue despite the observed improvement. In this study, ozone, which is an effective oxidant, was evaluated as a novel technique for the cleaning of humic acid-fouled membranes. When ozone cleaning was applied to the humic acid-fouled membranes, reestablishment of close to original flux values was observed after just 30 min of cleaning. This statement is supported by SEM images that give an insight into the fouling of the membrane surface after the application of the cleaning methods. The data indicate that ozone is an effective technique for membrane cleaning against NOM-induced fouling.

“Membrane Technologies for Water Treatment: Removal of Toxic Trace Elements with Emphasis on Arsenic, Fluoride and Uranium”

“Membrane Technologies for Water Treatment: Removal of Toxic Trace Elements with Emphasis on Arsenic, Fluoride and Uranium”

Novel titanium dioxide/iron (III) oxide/graphene oxide photocatalytic membrane for enhanced humic acid removal from water

Membrane fouling caused by natural organic matters such as humic acid has been one of the major obstacles inhibiting the wide application of membrane technologies for water treatment. In this work, a novel membrane made of interconnecting TiO2 nanowires, Fe2O3 nanoparticles, and graphene oxide (GO) sheets was prepared via a simple hydrothermal, colloidal blending, and vacuum filtration method. Membrane performance of humic acid removal under simulated solar irradiation and in the dark were compared for membranes with different Fe2O3/TiO2/GO compositions. It was demonstrated that enhanced humic acid removal was achieved due to the greater adsorption of humic acid by Fe2O3 nanoparticles and the improved photocatalytic activity of TiO2 by the GO sheets that can facilitate separation of photo-induced electron-hole. An optimal Fe2O3:TiO2:GO weight ratio of 50:100:10 was identified, and over 98% humic acid removal was achieved in a short-term test (2h) and 92% removal in a 12h test under solar irradiation. By contrast, only 51% humic acid removal was obtained by the same membrane in dark in the 12h test. A lower pressure drop across the membrane was also observed under solar irradiation (20kPa) compared with that in the dark (50kPa). This nanomaterial-based novel membrane contributes to the development of a more effective water treatment technology.

Novel anti-fouling Fe2O3/TiO2 nanowire membranes for humic acid removal from water

Membrane fouling is one of the major obstacles inhibiting the wide application of membrane technologies for water treatment. Membranes with surface modification of titanium dioxide (TiO2) nanoparticles or TiO2 nanowire membranes (Ti–NWM) have demonstrated reduced membrane fouling due to the photocatalytic capability of TiO2 in degrading foulants on the membrane surface. However, the wide band gap of TiO2 makes it only absorb ultraviolet light, which limits its applications under solar irradiation. In this study, a novel membrane made of interwoven iron oxide (Fe2O3) nanowires and TiO2 nanowires (FeTi–NWM) has demonstrated superior anti-fouling capability in removing humic acid (HA) from water. Results showed that under simulated solar irradiation the FeTi–NWM achieved nearly complete HA removal during a 2h short-term test at an initial HA concentration of 200mg/L, compared with 89% HA removal by Ti–NWM. During a 12h long-term test, the FeTi–NWM maintained 98% HA removal, while the Ti–NWM showed only 55% removal at the end. Without solar irradiation, the FeTi–NWM was severely contaminated and by contrast, a clean surface was maintained under solar irradiation after the 12h test and the transmembrane pressure change was minimal. The improved HA removal by FeTi–NWM compared with Ti–NWM and its excellent anti-fouling capability under solar irradiation can be attributed to (1) the enhanced HA absorption by Fe2O3 nanowires and (2) the formed Fe2O3/TiO2 heterojunctions that increase photo-induced charge transfer and improve visible light activity.

Effect of hydrodynamic diameter on the sieving of waterborne carbon nanotubes by porous membranes

Carbon nanotubes (CNTs) are rapidly influencing the development and applications of membrane technology for water treatment. Passage of CNTs through membrane pores is becoming a fundamental question to water industries, as the toxicity and environmental fate of waterborne CNTs are largely unknown. This study utilized CNTs and membranes with known properties to investigate the applicability of the Ferry–Renkin sieving equation to the rejection of CNTs by porous membranes. The results demonstrate that the hydrodynamic size of CNTs is more important than their physical dimensions for rejection. Moreover, the classical sieving equation provided reasonable predication of the experimental results. Important for water industries, current membranes used in drinking water treatment should be efficient barriers for waterborne CNTs leached from composite membranes or released from wastewater effluents. Further, process streams containing CNTs may be treated using membrane filtration for CNT recovery. However, micron-pore-size membranes used in previous studies for CNT-membrane fabrication may not be efficient in protecting CNT breakthrough. Since the hydrodynamic diameters of waterborne CNTs are usually above 150nm, as a general rule of thumb, membranes with pore size smaller than 100nm need to be used to ensure the safety of CNT membranes.

Membrane Technology in Water Treatment in the Mediterranean Region (PROMEMBRANE)

The complex dimensions of the Mediterranean freshwater resources, their fragility and their scarcity have been highlighted and have received considerable attention as a primary priority issue politically, technically and scientifically. Membrane technology, with its different applications in water treatment (desalination, potable water treatment, wastewater treatment and reuse) has showed to be a powerful tool to abate the water crisis in the Mediterranean region. The primary objective of Membrane Technology in Water Treatment in the Mediterranean Region is to support the current research and development activities in membrane technology focused on water treatment in the Mediterranean area, providing an international stage to local research organisations and universities devoted to the development of membrane technologies in the following areas: municipal and industrial wastewater treatment, surface water purification and brackish and sea water treatment for drinking purpose. It covers the identification, mapping and evaluation of the on-going research, in order to propose future research and co-operation strategies. Visit the IWA WaterWiki to read and share material related to this title: http://www.iwawaterwiki.org/xwiki/bin/view/Articles/MembraneTechnologyinWaterTreatmentintheMediterraneanRegion