scholarly journals A Unified, One Fluid Model for the Drag of Fluid and Solid Dispersals by Permeate Flux towards a Membrane Surface

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 154
Author(s):  
Amgad Salama ◽  
Shuyu Sun ◽  
Tao Zhang
Keyword(s):  
Hyperbolic Equation ◽  
Membrane Fouling ◽  
Fluid Model ◽  
Membrane Surface ◽  
Numerical Approach ◽  
Domain Model ◽  
Permeate Flux ◽  
Modeling Framework ◽  
Computational Burden ◽  
Averaging Techniques

The drag of dispersals towards a membrane surface is a consequence of the filtration process. It also represents the first step towards the development of the problem of fouling. In order to combat membrane fouling, it is important to understand such drag mechanisms and provide a modeling framework. In this work, a new modeling and numerical approach is introduced that is based on a one-domain model in which both the dispersals and the surrounding fluid are dealt with as a fluid with heterogeneous property fields. Furthermore, because of the fact that the geometry of the object assumes axial symmetry and the configuration remains fixed, the location of the interface may be calculated using geometrical relationships. This alleviates the need to define an indicator function and solve a hyperbolic equation to update the configuration. Furthermore, this approach simplifies the calculations and significantly reduces the computational burden required otherwise if one incorporates a hyperbolic equation to track the interface. To simplify the calculations, we consider the motion of an extended cylindrical object. This allows a reduction in the dimensions of the problem to two, thereby reducing the computational burden without a loss of generality. Furthermore, for this particular case there exists an approximate analytical solution that accounts for the effects of the confining boundaries that usually exist in real systems. We use such a setup to provide the benchmarking of the different averaging techniques for the calculations of properties at the cell faces and center, particularly in the cells involving the interface.

Electroflocculation as potential pretreatment in colloid ultrafiltration

2006 ◽  
Vol 6 (1) ◽  
pp. 69-78 ◽  
Author(s):  
T. Harif ◽  
M. Hai ◽  
A. Adin
Keyword(s):  
Membrane Fouling ◽  
Colloidal Suspension ◽  
Membrane Surface ◽  
Constant Current ◽  
Permeate Flux ◽  
Batch Mode ◽  
Membrane Behavior ◽  
Flux Decline ◽  
Stainless Steel Cathode ◽  
Marginal Improvement

Electroflocculation (EF) is a coagulation/flocculation process in which active coagulant species are generated in situ by electrolytic oxidation of an appropriate anode material. The effect of colloidal suspension pretreatment by EF on membrane fouling was measured by flux decline at constant pressure. An EF cell was operated in batch mode and comprised two flat sheet electrodes, an aluminium anode and stainless steel cathode, which were immersed in the treated suspension, and connected to an external DC power supply. The cell was run at constant current between 0.06–0.2A. The results show that pre-EF enhances the permeate flux at pH 5 and 6.5, but only marginal improvement is observed at pH 8. At all pH values cake formation on the membrane surface was observed. The differences in membrane behavior can be explained by conventional coagulation theory and transitions between aluminium mononuclear species which affect particle characteristics and consequently cake properties. At pH 6.5, where sweep floc mechanism dominates due to increased precipitation of aluminium hydroxide, increased flux rates were observed. It is evident that EF can serve as an efficient pretreatment to ultrafiltration of colloid particles.

A Wall Film Model for Membrane Fouling

2018 ◽  
Author(s):  
Sina Jahangiri Mamouri ◽  
Volodymyr V. Tarabara ◽  
André Bénard
Keyword(s):  
Multiphase Flow ◽  
Membrane Fouling ◽  
Oil And Gas ◽  
Membrane Separation ◽  
Film Formation ◽  
Membrane Surface ◽  
Permeate Flux ◽  
Water Separation ◽  
Wall Film ◽  
Oil Water

Deoiling of produced or impaired waters associated with oil and gas production represents a significant challenge for many companies. Centrifugation, air flotation, and hydrocyclone separation are the current methods of oil removal from produced water [1], however the efficiency of these methods decreases dramatically for droplets smaller than approximately 15–20 μm. More effective separation of oil-water mixtures into water and oil phases has the potential to both decrease the environmental footprint of the oil and gas industry and improve human well-being in regions such as the Gulf of Mexico. New membrane separation processes and design of systems with advanced flow management offer tremendous potential for improving oil-water separation efficacy. However, fouling is a major challenge in membrane separation [2]. In this study, the behavior of oil droplets and their interaction with crossflow filtration (CFF) membranes (including membrane fouling) is studied using computational fluid dynamics (CFD) simulations. A model for film formation on a membrane surface is proposed for the first time to simulate film formation on membrane surfaces. The bulk multiphase flow is modeled using an Eulerian-Eulerian multiphase flow model. A wall film is developed from mass and momentum balances [3] and implemented to model droplet deposition and membrane surface blockage. The model is used to predict film formation and subsequent membrane fouling, and allow to estimate the actual permeate flux. The results are validated using available experimental data.

Influence of humic acid on the long-term performance of direct contact membrane distillation

2018 ◽  
Vol 30 (1) ◽  
pp. 109-120 ◽  
Author(s):  
Dong-Wan Cho ◽  
Gihoon Kwon ◽  
Jeongmin Han ◽  
Hocheol Song
Keyword(s):  
Humic Acid ◽  
Membrane Fouling ◽  
Coalbed Methane ◽  
Direct Contact ◽  
Membrane Surface ◽  
Membrane Distillation ◽  
Permeate Flux ◽  
Direct Contact Membrane Distillation ◽  
High Level

In this study, the influence of humic acid on the treatment of coalbed methane water by direct contact membrane distillation was examined with bench-scale test unit. During short-term distillation (1000 min), high level of humic acid above 50 ppm resulted in significant decrease in permeate flux, while low level of humic acid (∼2 ppm) had little influence on the flux. For the long-term distillation (5000 min), the flux decline began at 3400 min in the presence of 5 ppm humic acid and 5 mM Ca2+, and decreased to ∼40% of initial flux at 5000 min. The spectroscopic analysis of the membrane used revealed that the surface was covered by hydrophilic layers mainly composed of calcite. The membrane fouling effect of humic acid became more significant in the presence of Ca2+ due to more facile calcite formation on the membrane surface. It was demonstrated that humic acid enhanced CaCO3 deposition on the membrane surfaces, thereby expediting the scaling phenomenon.

Chemical pretreatment of feed water for membrane distillation

2008 ◽  
Vol 62 (1) ◽  
Author(s):  
Marek Gryta
Keyword(s):  
Membrane Fouling ◽  
Membrane Surface ◽  
Membrane Distillation ◽  
Feed Water ◽  
Chemical Pretreatment ◽  
Permeate Flux ◽  
Membrane Scaling ◽  
Water Pretreatment ◽  
Energy Dispersion Spectrometry ◽  
Process Operation

AbstractMembrane distillation was used to produce demineralized water from ground water. The influence of feed water pretreatment carried out in a contact clarifier (softening with Ca(OH)2 and coagulation with FeSO4 · 7H2O) followed by filtration, on the process effectiveness was evaluated. It was found that the chemical pretreatment decreased the membrane fouling; however, the degree of water purification was insufficient because precipitation of small amounts of deposit on the membrane surface during the process operation was still observed. The permeate flux was gradually decreasing as a result of scaling. The morphology and composition of the fouling layer were studied using scanning electron microscopy coupled with energy dispersion spectrometry. The presence of significant amounts of silica, apart from calcium and magnesium, was determined in the formed deposit. The removal of foulants by heterogeneous crystallization performed inside the filter (70 mesh), assembled directly at the module inlet, was found to be a solution preventing the membrane scaling.

A real trial of a long-term non-fouling membrane bioreactor for saline sewage treatment

2011 ◽  
Vol 63 (7) ◽  
pp. 1519-1523 ◽  
Author(s):  
Peng Bai ◽  
Jin Wang ◽  
Guang-Hao Chen
Keyword(s):  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Membrane Surface ◽  
Pilot Trial ◽  
Sewage Treatment ◽  
Power Source ◽  
Permeate Flux ◽  
Mixing Condition ◽  
Water Ratio

This paper reports on a pilot trial of a novel MBR developed with coarse-pore membrane module by the authors. The plant was operated for 370 days with up to 7 m3/d raw saline sewage after 3-mm screening. The plant performed successfully without membrane fouling for 270 days except an accidental power source failure for 30 h, during which membrane was fouled under no aeration and mixing condition. EPS increases in both the reactor and the bio-cake on the membrane surface explained this fouling. The average TSS, COD and TKN removal efficiency were 92, 90, and 93%, respectively, under a high effective permeate flux of 4.8 m/d and a low air-to-water ratio of 15.

Numerical Simulation of Filtration of Charged Oil Particles in Stationary and Rotating Tubular Membranes

2015 ◽  
Author(s):  
Sina Jahangiri Mamouri ◽  
Volodymyr V. Tarabara ◽  
André Bénard
Keyword(s):  
Flow Field ◽  
Electric Field ◽  
Electric Potential ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Cross Flow ◽  
Solid Cylinder ◽  
Permeate Flux ◽  
Cross Flow Filtration ◽  
Flow Filtration

Cross flow filtration (CFF) is a common membrane separation process with applications in food, biochemical and petroleum industries. In particular, membranes can be used for liquid-liquid separation processes such as needed in oil-water separation. A major challenge in cross flow filtration is membrane fouling. It can decrease significantly the permeate flux and a membrane’s efficiency. Membrane fouling can be mitigated by inducing shear on the membrane’s surface and this can be enhanced by inducing a swirl in the flow. In addition, a possible approach to improve membrane efficiency consists of repelling droplets/particles from the porous surface toward the centerline using a repulsive electric force. For this purpose, the surface of the membrane can be exposed to electric potential and droplets/particles are also induced to have the same electric charge. In this work, numerical simulations of charged non-deformable droplets moving within an axially rotating charged tubular membrane are performed. The results show that by increasing the electric potential on the membrane surface, the repelling force increases which obviously improves the grade efficiency of the membrane. However, the electric field gradients found in the flow field require large potentials on the membrane surface to observe a noticeable effect. Hence, a smaller solid cylinder is located in the centerline of the flow channel with zero potential. This solid cylinder enhances the electric field gradient in the domain which results in higher repelling forces and larger grade efficiency of the membrane at small potentials. The addition of a small cylinder in the flow field also improves the grade efficiency increases due to the higher shear stress near the membrane surface.

scholarly journals Fouling Mitigation via Chaotic Advection in a Flat Membrane Module with a Patterned Surface

Membranes ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 724
Author(s):  
Kyung Tae Kim ◽  
Jo Eun Park ◽  
Seon Yeop Jung ◽  
Tae Gon Kang
Keyword(s):  
Growth Rate ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Film Theory ◽  
Groove Depth ◽  
Membrane Module ◽  
Chaotic Advection ◽  
Permeate Flux ◽  
Fouling Mitigation ◽  
Flat Membrane

Fouling mitigation using chaotic advection caused by herringbone-shaped grooves in a flat membrane module is numerically investigated. The feed flow is laminar with the Reynolds number (Re) ranging from 50 to 500. In addition, we assume a constant permeate flux on the membrane surface. Typical flow characteristics include two counter-rotating flows and downwelling flows, which are highly influenced by the groove depth at each Re. Poincaré sections are plotted to represent the dynamical systems of the flows and to analyze mixing. The flow systems become globally chaotic as the groove depth increases above a threshold value. Fouling mitigation via chaotic advection is demonstrated using the dimensionless average concentration (c¯w*) on the membrane and its growth rate. When the flow system is chaotic, the growth rate of c¯w* drops significantly compared to that predicted from the film theory, demonstrating that chaotic advection is an attractive hydrodynamic technique that mitigates membrane fouling. At each Re, there exists an optimal groove depth minimizing c¯w* and the growth rate of c¯w*. Under the optimum groove geometry, foulants near the membrane are transported back to the bulk flow via the downwelling flows, distributed uniformly in the entire channel via chaotic advection.

scholarly journals Membrane surface properties and their effects on real waste oil-in-water emulsion ultrafiltration

Water SA ◽  
2019 ◽  
Vol 45 (3 July) ◽  
Author(s):  
Marjana Simonič
Keyword(s):  
Surface Properties ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Cross Flow ◽  
Influential Factors ◽  
Permeate Flux ◽  
Chemical Cleaning ◽  
Water Emulsion ◽  
Oil In Water ◽  
Oil In Water Emulsion

Membrane surface properties and their effect on the efficiency of ultrafiltration (UF) of real waste oily emulsions was studied. Experiments were performed in cross-flow operation at total recycle condition in a lab-scale system. The ceramic UF membrane in the tubular type module was employed. During the experiments permeate flux was measured. The most important influential factors, such as temperature, TMP, and pH, were considered during the experiments. Zeta potential was measured in order to explain the phenomena on the membrane surface. The isoelectric point of the fouled membrane was shifted to the alkaline range. COD removal efficiency reached 89%. Gas chromatography measurements were performed in order to determine the composition of waste emulsions. SEM micrographs showed the formation of calcite on the membrane, which contributed to membrane fouling. Chemical cleaning was examined using alkaline and acid solutions, and a cleaning strategy was determined.

scholarly journals Performance of integrated sequencing batch reactor (SBR) and reverse osmosis (RO) process for leachate treatment: effect of pH

2022 ◽  
Author(s):  
Izabela Anna Tałałaj
Keyword(s):  
Organic Matter ◽  
Reverse Osmosis ◽  
Membrane Fouling ◽  
Removal Rate ◽  
Membrane Surface ◽  
Ammonia Nitrogen ◽  
Electrostatic Repulsion ◽  
Permeate Flux ◽  
Leachate Treatment ◽  
Good Efficiency

Abstract Purpose In this paper the performance and effectiveness of the reverse osmosis (RO) process for the biologically pretreated leachate was investigated. The RO process was carried out separately for two different pH: 8.0 and 9.3. Methods A general pollution parameters as well as organic and inorganic indicators were determined in raw, biologically pretreated and RO treated leachate. The performance characteristics of the reverse osmosis system were made on the basis of permeate flux, electroconductivity removal rate, concentration factor and efficiency in removal of analyzed parameters. Results The use of SBR pretreatment had very good efficiency in BOD (97.3%) and ammonia nitrogen (95.4%) removal. The lowest effectivity was observed for chloride (11.6%), boron (3.9%) and TDS (1.2%). Pretreated leachate was subjected to RO system. The normalized average flux was 0.53 (42.3 L/m2·h) for pH = 8.0 and 0.68 (33.5 L/m2·h) for pH = 9.3. The lower membrane fouling at higher pH can be explained by electrostatic repulsion between the negatively charged membrane surface and organic substances. Independently of the process pH, a two-step membrane fouling was observed. The greatest differences in removal rates were observed for boron, which had a higher retention rate at higher pH, and ammonia nitrogen, whose removal rate decreased at higher pH. The obtained permeate pH after RO process was lower than the feed pH in two analyzed value of pH. Conclusions The higher flux value at pH = 9.3 is result of high content of organic matter in leachate, which is better rejected at higher pH because of higher electrostatic repulsion between organic matter and membrane surface. This indicates that the organic matter content should be taken into account when determining the operating parameters (pH values) of the RO system.

scholarly journals Performance of an indigenous integrated slurry photocatalytic membrane reactor (PMR) on the removal of aqueous phenanthrene (PHE)

2018 ◽  
Vol 77 (11) ◽  
pp. 2642-2656 ◽  
Author(s):  
C. Nirmala Rani ◽  
S. Karthikeyan
Keyword(s):  
Membrane Fouling ◽  
Membrane Reactor ◽  
Membrane Surface ◽  
Continuous Process ◽  
Permeate Flux ◽  
Toc Removal ◽  
Recovery Potential ◽  
Cake Layer ◽  
Alkaline Conditions ◽  
Photocatalytic Membrane Reactor

Abstract In this study, a slurry photocatalytic membrane reactor (PMR) was developed and evaluated for the degradation of aqueous phenanthrene (PHE). During continuous process with a hydraulic retention time (HRT) of 140 min, the maximum PHE degradation and total organic carbon (TOC) removal efficiencies were found to be 97% and 79%, respectively. The reuse and recovery potential of TiO2 was studied with continuous recycling. The major intermediates during photodegradation of PHE were found to be phenanthrenequinone, phenanthenol and fluorine. This study also includes an investigation of membrane fouling caused by hydrophilic nano TiO2. The cake layer observed on the membrane surface was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive spectroscopy (EDS). In addition, the effect of operating parameters such as pH and permeate flux on membrane fouling were also investigated. Low permeate flux and alkaline conditions reduced membrane fouling.

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