Application Of Membrane Technology Research Articles

Gravity-driven membrane filtration treating manganese-contaminated surface water: Flux stabilization and removal performance

Severe membrane fouling caused by iron and manganese limited the intensive application of ultrafiltration (UF) technologies. In the present study, an innovative biofilm based UF process, gravity driven membrane (GDM) filtration, was employed to evaluate its possibility to directly treat manganese-contaminated surface water at high concentration. Surprisingly, an extremely short and stable ripening period (less than 10 d) of iron and manganese removal was achieved in GDM filtration, with average removals of 90% and 58%, respectively, attributing to the effective rejection of active catalytic manganese oxides and fast colonization of iron- and manganese-oxidizing bacteria (e.g Acinetobacter and Lysobacter) within the biofilm due to the efficient rejection by UF membrane. Importantly, the presence of iron and manganese did not influence the occurrence of flux stabilization, and fluxes stabilized at 7–9 L m−2 h−1 during long-term filtration. Furthermore, a highly rough, porous and heterogeneous biofilm was observed on the membrane surface, which was potentially responsible for the flux stabilization. Additionally, pre-coating manganese oxides on the membrane surface can efficiently enhance the removals of manganese and iron, and engineer even highly heterogeneous structures of biofilm to improve the stable flux. Therefore, the findings are relevant to develop new strategies for the treatments of manganese-contaminated water resource at high concentration, and to encourage extensive applications of membrane technologies for decentralized drinking water supply.

Correlation of chemically irreversible fouling with organic constituents of feed water during membrane filtration

Nowadays, fouling remains a huge obstacle for the application of membrane technology. Chemically irreversible fouling (CIF) is not cancelled by chemical cleaning (CC) and can cause long-term permeability loss. However, the characteristics of CIF foulants have not been systematically investigated yet. In this work, a pilot-scale long-term microfiltration process for surface water treatment with periodic CC was carried out to identify the nature of CIF foulants. A chemically irreversible fouling index (CIFI) approach was proposed to quantify CIF potential, and Pearson correlation analysis was further adopted to correlate CIFI with the organic constituents of feed water in terms of hydrophilicity/ hydrophobicity, molecular weight (MW) distribution and fluorophores. It was found that CIFI was significantly correlated to neutral hydrophilic fractions (R2 = 0.728, p-value = 0.007) and MW<1 kDa components (R2 = 0.749, p-value = 0.006), whereas no reliable correlation could be established of CIFI with fluorescent substances (humic-like or protein-like substances). Further, we found polysaccharides (PS) had a strong linear correlation with CIFI (R2 = 0.939, p = 0.0008) and the result was also supported by the detection of Fourier transform infrared spectroscopy. To sum up, the organics consisting of low MW (<1 kDa) and neutral hydrophilic PS-like constituents were mainly responsible to CIF. For the first time, we systematically reported the nature of CIF foulants in a low-pressure membrane filtration process.

Effects of Gamma Irradiation on Organic Membrane Materials

Membranes have been widely used in low-level radioactive wastewater (LLRW) treatment and are under irradiation as a result of radioactive nuclides present in the wastewater, which may cause damage to the membranes and weaken their performances. Irradiation-induced material property changes of several organic membrane matrices and modifiers at different gamma irradiation doses were investigated in this work. The organics and membrane samples were irradiated using a 60Co source at a range of irradiation doses of 0 to 100 kGy. The effects of irradiation on these materials were detected using Fourier transform infrared spectroscopy spectra, ultraviolet spectra, and ion chromatography (used to detect membrane leakage). The results indicated that chain scission and cross linking occurred simultaneously in the membrane matrices, while the modifiers tended to polymerize during the irradiation process. As the irradiation dose increased, the chain scission and polymerization became more significant. The polyamide membrane was observed to be more irradiation tolerant in comparison with the other membranes used in this study. In regard to the modifiers, polyvinyl alcohol and 2,3-epoxypropyl trimethyl ammonium chloride showed significant structural changes at an irradiation dose of 2 kGy and polyetherimide and methyl methacrylate at an irradiation dose of 100 kGy, while chain scission was not detected in the other modifiers at irradiation doses of 2, 10, and 100 kGy, indicating that they remained relatively stable at these irradiation doses. These findings provide useful information for the application of membrane technologies in treating LLRW.

Stimulatory effects on bacteria induced by chemical cleaning cause severe biofouling of membranes

Abstract Chemical cleaning with hypochlorite is routinely used in membrane-based processes. However, a high-transient cleaning efficiency does not guarantee a low biofouling rate when filtration is restarted, with the physiological mechanisms largely remaining unknown. Herein, we investigated the microbial regrowth and surface colonization on membrane surfaces after NaOCl cleaning had been completed. Results of this study showed that the regrowth of model bacteria, Pseudomonas aeruginosa, was initially subject to inhibition due to the damage of key enzymes' activity and the accumulation of intracellular reactive oxygen species although the oxidative stress induced by NaOCl had been removed. However, with the resuscitation ongoing, the stimulatory effects became obvious, which was associated with the enhanced production of N-acyl homoserine lactones and the secretion of eDNA that ultimately led to more severe biofouling on the membrane surface. This study elucidates the inhibition–stimulation mechanisms involved in biofilm reformation (membrane biofouling) after membrane chemical cleaning, which is of particular significance to the improvement of cleaning efficiency and application of membrane technologies.

Modification of covalent organic frameworks with dual functions ionic liquids for membrane-based biogas upgrading

Development of high-performance membranes for biogas upgrading is an urgent demand for the application of membrane technology in the field of renewable energy. Covalent organic frameworks (COFs) exhibit promising potential in membrane-based separation for their highly ordered crystalline porous structure, total organic backbone and tailored functionality. However, the limited functional groups on frameworks and relatively larger pore size of existing COFs restrict further improvement in the separation efficiency especially for gas mixtures. This work reports a novel strategy for modifying the pore of COF-300 with imidazolium-based ionic liquid [bmim][Tf2N] by post-impregnation and then incorporate the composite particles IL@COF-300 into Pebax matrix to prepare mixed matrix membranes (MMMs). The IL decreases the pore size of COF-300 from 1.28 nm to 1.09 nm and increases the diffusion coefficient difference (DCO2/DCH4) between CO2 and CH4. Moreover, the presence of IL with high CO2 solubility endows the COF-300 pores with CO2-facilitating ability and thus increasing the solubility difference (SCO2/SCH4). The dual functions of IL lead to an enhanced separation performance of the resultant IL@COF-300/Pebax MMMs with an optimal permeability of 1601 Barrer and a CO2/CH4 gas selectivity of ~39, i.e. 209% and 87% higher than the pristine Pebax membrane, respectively, breaking the trade-off between permeability and selectivity and surpassing the Robeson 2008 upper-bound. The membrane also exhibits superior long-term operation stability during two months.

Drinking water treatment with membrane ultrafiltration

Ultrafiltration was investigated within the pilot-plant tests at the Rozgrund water treatment plant during the treatment of surface water originating from the Rozgrund reservoir. Fully automated ultrafiltration equipment with the membrane module UA-640 (Microdyn-Nadir) was used. On the base of filtration cycles, the effectiveness of membraned technology was evaluated. By the application of membrane technology used, the required quality of treated water has been achieved.

Using electrodialysis technology for regeneration of hydrochloric acid from sour pectin extracts

The article focuses on investigation of efficiency of electrodialysis membrane technology for regeneration of hydrochloric acid in pectin extracts. Traditional methods involving using ethanol, encounter various technical problems. Application of electrodialysis membrane technology is considered to be an efficient solution. The study aims at evaluating the capacity of the membrane method in the process of hydrochloric regeneration in apple and beet pectin extracts and the way it affects the characteristics of pectin molecules of both types. The experiments show the possibility of almost full regeneration of hydrochloric acid for a reuse in the process of further extraction of apple and beet pectins. Such approach also enhances an increase in the degree of esterification and molecular mass of pectins, which is especially important in the case of less low-molecular beet pectin. The increase in the esterification degree boosts its jellying effect, but reduces its detoxicant capacity.

Application of membrane technology for separation CO2 from natural gas

Natural gas consists of a mixture of hydrocarbons with the largest share of methane, and non-hydrocarbon impure components such as N2, CO2 and H2S. In order to fulfill the gas market requirements, it is necessary to separate these unwanted components from the natural gas stream. There are several available technologies for the separation of CO2 from natural gas, such as: polymeric membranes, cryogenic distillation, absorption and adsorption. In this paper is presented the mechanism of CO2 separation using membrane technology, as well as the process of separation CO2 depending on the number of membranes in the system for a typical gas reservoir in Serbia.

Advanced applications of membrane technology in biological detection

Membrane creates the functions of protection, supporting, dispersion and separation. More functions can be designed by modifying membrane surface and grafting/loading selective ligands or catalysts on the membrane, thus membrane technology has been widely applied in biological detection, and its application approaches becomes diverse. Rational design of functional membranes can meet the demands in different steps of biological detection process, including sample pretreatment, preparation, response and sensing. This review summarized the functionalization methods of filtration membranes, applications of membrane technology in sample preparation and detection process, as well as the research on the integration of functional membranes. By revisiting the research progress on functional membrane design, preparation and applications for biological detection, it is expected to take better advantage of membrane materials structure and performance for constructing efficient and stable detection platform, which is more "adapted" to the detection environment.

Microfiltration membranes modified by silver-decorated biomimetic silica nanopollens for mitigating biofouling: Synergetic effects of nanopollens and silver nanoparticles

Applications of membrane technologies for water and wastewater treatment call for antibiofouling membranes. Inspired by nature's spiky topological features of pollen grains, we developed silver-decorated biomimetic silica nanopollens (SNPs) to modify a polyvinylidene fluoride microfiltration membrane. The modified membrane demonstrated compelling antibiofouling performance compared to the pristine membrane, which was attributed to the synergetic effects of SNPs and loaded silver nanoparticles. The surface spikes of SNPs could act as multiple ‘entry claws’ to bind to the cell membrane upon contact, inducing physical deformation and metabolic disturbance of cells. More importantly, the SNPs could serve as a delivery vector for silver ions that were released from silver nanoparticles loaded in SNPs, further leading to cell damage due to the generation of reactive oxygen species and respiratory inhibition. These synergetic effects of SNPs and loaded silver nanoparticles imparted the modified membrane with potent antibiofouling behavior both in batch and continuous flow tests using model bacteria, Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive), respectively. Our strategy provides a novel pathway using biomimetic materials to fabricate antibiofouling membranes for water and wastewater treatment.

Microfiltration in Water Treatment for Removal of Suspended Solids and Natural Organic Matter

At this article are presented membrane separate processes – microfiltration, ultrafiltration, nanofiltration in water treatment and materials and modules used in application of various membrane technologies. Theoretical part is completed with results from pilot plant experiments realised in water treatment plant Klenovec, where was used the microfiltration technology for removal of insoluble substances (expressed by a number of particles) from water. Over the last years water quality has deteriorated in water-supply reservoir Klenovec and this technology was tested for the purposes of modernization of the inefficient technology in water treatment plant. The pilot-plant tests for membrane filtration examination were carried out by using the microfiltration unit AMAYA 5 with a performance of 5 m3/h. Coagulation and flocculation run in two stages. At the first stage, the coagulant is dosing into a static mixer, which led the mixture to the second stage from. The second stage represents the tubular flocculator. In the membrane module, there is placed one ceramic element with a membrane surface of 25 m2, pores size of 0.1 μm, and consisting of 2000 tubules with a diameter of 2.5 mm. The results obtained from pilot plant experiments in WTP Klenovec supported theory, that this process with high efficiency of treatment surface water is suitable for this kind quality of water to obtain water for drinking purposes.

A new strategy to simultaneously improve the permeability and antifouling properties of EVAL membranes via surface segregation of macrocyclic supra-amphiphiles

Herein, we propose a new strategy to improve the flux and antifouling properties of ethylene vinyl alcohol (EVAL) membranes by blending with macrocyclic supra-amphiphiles (cyclodextrin; CD). The amphiphilic ‘molecular cage’ geometry of CD, consisting of a hydrophobic cavity segment and hydrophilic rim segment, induces spontaneous surface segregation of CD to form a CD-enriched layer on the membrane surface. The membrane matrix structure was observed by SEM-EDX, wherein elemental composition indicated a gradient distribution of elemental O content from the top to the bottom layer of the cross-section. The layer segregation was governed by the synergistic interactions with hydrophobic and hydrophilic segments of amphiphilic CD polymer during the phase inversion process. When clickable azide-β-CD was fixed into the clickable alkyne-EVAL matrix as a comparative experiment, no surface segregation was observed. The aggregation of hydrophilic CD on the membrane surface increased the surface roughness, hydrophilicity, and water flux (200 L/m2h) of the membrane. Furthermore, the macrocyclic supra-amphiphile-blended membrane showed better antifouling performance than raw EVAL membrane, with a lower water flux decline (21%) and higher water flux recovery (89%). The proposed 3D strategy based on macrocyclic supra-amphiphiles shed lights on the formation of hydrophilic membrane surface with potential applications in membrane technology.

Control and cleaning of membrane biofouling by biogenic silver nanoparticles

Membrane biofouling as the main obstacle strongly hinders the wider application of membrane technology. The control of biofouling development and the fouled membrane cleaning still are the big challenge in membrane industry. The present study investigated the control of initial bacterial attachment, biofilm development and finally the membrane cleaning by biogenic silver nanoparticles (Bio-Ag0-6) using commercial microfiltration membranes as the substrate. The results revealed that the Bio-Ag0-6 could inhibit the development of biofilm by decreasing the attachment of cells and the production of extracellular polymeric substances (EPS). Significant improvements of flux recovery ratio (FRR), the distribution of fouling resistances and the decrease of total fouling resistance ( Rf ) were achieved when introducing Bio-Ag0-6 to dead-end microfiltration systems. The membrane cleaning experiment verified the enhanced biofilm detachment from membrane surface by Bio-Ag0-6. It shows that Bio-Ag0-6 would be a good alternative to relieve membrane biofouling.

The role of membrane technology in acid mine water treatment: a review

The activities of mining industries are attracting more scrutiny as the concern of limitations of conventional technology for wastewater treatment and the potential use of wastewater have resulted in accelerated attention in membrane technologies. The paucity of water and industrial environmental guidelines has resulted in the application of membrane technologies in wastewater treatment, especially in the mining industry. Although many conventional physical and chemical processes have been employed to treat acid mine drainage (AMD), they have, however, demonstrated low efficiency and high cost. Membrane technologies have proven to be an important part in the treatment of AMD in order to reduce water paucity. Apart from addressing water paucity, membrane technologies meet high-level application with respect to ease of use, adaptability and environmental impacts. This paper reviews the use of membrane in the published literature for the treatment of acid mine waters and, for the recovery of valuable metals from acid mine drainage effluents. The role of membrane technology in acid mine water treatment is discussed together with the factors that determine membrane performance for AMD treatment. The challenges of membrane technology in acid mine water treatment were reviewed and some solutions to the challenges are presented.

Development of Cellulose Acetate – PVP blend membrane and UV irradiation treatment to increase membrane selectivity for clove oil purification

Clove oil obtained from clove leaves and stems has low oil quality. This is caused by the low levels of eugenol which is around 60-80%. The application of membrane technology to purify clove oil is constrained by the almost similar size of the eugenol and caryophyllene molecules. The aim of this study is to improve membrane selectivity by increasing the hydrophilic properties of the membrane. The eugenol will penetrate easily through hydrophilic membrane than caryophyllene. Cellulose acetate membrane was fabricated by dissolving 17 wt-% CA polymer in acetone and then casted via dry-wet phase inversion method. Poly vinyl pyrrolidone (PVP) is added to the dope solution to improve the hydrophilic properties of the membrane. The results of contact angle analysis showed that the addition of PVP by 1% was able to reduce the contact angle from 41° to 32° which means the hydrophilic increased significantly. The combination of PVP addition with nano ZnO incorporation can increase eugenol concentration from 75% to 88% but decrease the permeate flux from 6.78 to 5.33 L.m−2h−1bar−1.

Grafting d-amino acid onto MF polyamide nylon membrane for biofouling control using biopolymer alginate dialdehyde as a versatile platform

Biofouling is the Achilles heel to membrane-based separations. Development of novel fouling control approaches is very demanding for world-wide application of membrane technologies. Herein, a synergistic effect due to surface hydrophilicity and anti-microbial properties was endowed by d-tyrosine grafting onto a commercial microfiltration polyamide nylon membrane using alginate dialdehyde (ADA) as a green facile platform. The d-tyrosine grafted membrane surfaces were characterized using ATR-FTIR, XPS, SEM-EDX, and AFM. d-tyrosine and ADA grafting significantly increased membrane hydrophilicity and vastly decreased surface roughness thereby mitigating biofouling with improved permeability performance. During pure water filterability test about 74% higher permeability was observed compared to the pristine membrane. Further, the flux recovery ratio for the d-tyrosine-ADA-nylon membrane (91%) was significantly higher than the pristine membrane (42%). Also, the d-tyrosine-ADA-nylon membrane demonstrated excellent antibiofouling performance when incubated with E. Coli culture. Henceforth, this novel membrane functionalization establishes a new green facile platform to alleviate biofouling with the synergistic effects of anti-microbial and surface hydrophilicity properties. Moreover, this functionalization is quite simple and direct, having the potential for scaled-up industrial application.

Constructing Antifouling Hybrid Membranes with Hierarchical Hybrid Nanoparticles for Oil-in-Water Emulsion Separation.

The development of antifouling membranes plays a vital role in the widespread application of membrane technology, and the hybridization strategy has attracted a significant amount of attention for antifouling applications. In this work, TA/PEI@TiO2 hierarchical hybrid nanoparticles (TPTi HHNs) are first synthesized through a simple strategy combining the multiple catechol chemistries of phenolic tannic acid (TA) with the biomimetic mineralization chemistry of titania. The TPTi HHNs are used as nanofillers to prepare PVDF/TPTi hybrid membranes. The TPTi HHNs endow the membrane with higher porosity, hierarchical roughness, greater hydrophilicity, and underwater superoleophobicity. Upon TPTi HHN loading, the PVDF/TPTi hybrid membranes exhibit enhanced antifouling performance. The flux recovery ratio can reach 92% when utilized to separate oil-in-water emulsion. Even being applied to the three-cycle filtration of oil-in-water emulsion with much higher concentration, the PVDF/TPTi membrane can still maintain a high flux recovery ratio about 85%. This study will provide a facial polyphenol-based platform to fabricate antifouling hybrid nanofillers and antifouling hybrid membranes with promising applications in oil/water separation.

Hydrophilic polysulfone/Lantana camara mixed matrix membranes for the removal of dyes from water

The decline in pressure driven membrane performance as a result of fouling is still a major challenge in membrane technology application to wastewater treatment. Efforts have been directed at mitigating fouling of pressure driven membranes by modifying the polymer through addition of hydrophilic materials. However, these materials are not yet a viable solution because are they are not cost-effective. Polysulfone (PSf) membranes incorporated with hydrophilic Lantana camara powder were prepared using the phase inversion method via the immersion precipitation technique to obtain PSf/LC (L. camara) mixed matric membranes. L. camara is one of the invasive and ready available plant species in Southern Africa. The PSf/ LC membranes were used for the removal of dyes from water. Contact angle measurements of modified membranes revealed higher hydrophilicity (contact angle of 44°). Addition of L. camara in PSf membranes improved the water permeability up to 91% compared to the pure PSf membrane. The highest salt rejection recorded amongst the modified membranes was 20% for NaCl and 27% for MgSO4. Congo red dye rejection was 99% at pH 4. Therefore L. camara can be used as an additive in membrane technology to improve the hydrophilicity and permeability of PSf membranes.

Novel conductive membranes breaking through the selectivity-permeability trade-off for Congo red removal

The permeability-selectivity trade-off remains the major drawback limiting application of membrane technology. This study provided a new strategy to break through this trade-off. A novel conductive membrane prepared by electroless Ni plating of the polyvinylidene fluoride (PVDF) membrane was used for dyeing wastewater treatment by applying an electric field. Series analyses demonstrated success of immobilizing a Ni/NiO layer on the pristine PVDF membrane. The conductive membrane possessed improved hydrophilicity indicated by the water contact angle decrease from 75.5° to 45.0°. Moreover, the conductive PVDF membrane integrating electric field voltage of 20 V simultaneously possessed high selectivity (97.93% rejection) and extremely high permeability (202.51 ± 9.63 L m−2 h−1 at 0.1 MPa) for filtration of Congo red (CR) solution, significantly breaking through the permeability-selectivity trade-off. The filtration performance was quite stable even after 6 filtration cycles, indicating the feasibility of the conductive membrane for long-term treatment of CR wastewater. In addition, the conductive membrane showed high antifouling ability to methylene blue (MB), rhodamine B (RB), CR and microorganisms. The conductive membranes, together with the new strategy, offered in-depth insights into membrane fabrication.

Research Update: Liquid gated membrane filtration performance with inorganic particle suspensions

Membrane filtration technology is widely used across several industries. But its efficiency is plagued by fouling, which ultimately deteriorates the membrane’s performance. This paper provides a research update on the biologically inspired liquid-enabled gating mechanism that acts as a novel filtration and separation approach offering reduction in transmembrane pressure (TMP), improved throughput, and reduced fouling. We study the performance of such Liquid Gated Membranes (LGMs) and present their benefits for filtration in the presence of model inorganic (nanoclay particles) fouling. We show over twofold higher throughput, nearly threefold longer time to foul, more than 60% reduction in irreversible fouling, ability to return to baseline pressures after backwashing along with reduction in use of backwash water, and 10%-15% reduction in TMP for filtration of nanoclay particles. Fouling models exhibit not only delayed onset of fouling for LGMs compared to the control but also different fouling characteristics. These results demonstrate the potential of the liquid gating mechanism, which can lead to breakthroughs in membrane technology applications in particle filtration, microfiltration, and ultrafiltration.