Influence of aeration and permeate flux on deposition of particulates on membrane surface

2010 ◽  
Vol 10 (6) ◽  
pp. 979-986
Author(s):  
Rupak Aryal ◽  
Saravanamuthu Vigneswaran ◽  
Jaya Kandasamy ◽  
Bivek Baral ◽  
Alain Grasmick
Keyword(s):  
Particle Deposition ◽  
Membrane Surface ◽  
Particle Diameter ◽  
Transmembrane Pressure ◽  
Physical Parameters ◽  
Permeate Flux ◽  
Composite Effect ◽  
Maximum Particle ◽  
The Difference ◽  
Two Parameters

In microfiltration, a deposit of foulant tends to form on the membrane surface and this usually controls the performance of the filtration process. This paper discusses the influence of physical parameters such as aeration and permeates flux on migration and deposition of above micron particles on the membrane surface. Kaolin clay suspension of particle 3.7–8 μm with mean particle diameter 4.1 μm was used in this study. Equal amount of mass of deposited particles on the membrane surface created different transmembrane pressure (TMP) when operated at different aeration rates and permeate flux showing that there is a composite effect. The particle deposition rate at the beginning at lower flux was almost linear which changed to a sharp logarithamic rise at higher flux. The difference in TMP rise for the same amount of deposit demonstrated the selective nature of particle deposition. The mass of the particle deposition on the membrane surface could be described by two parameters: maximum deposition and time using a simple empirical logarithamic equation y=k/[1+exp(b−at)], where k, a, and b are constant; y is the particulate mass deposit (g/m2) and t is the time. The maximum particle mass deposition growth could be described by the equation dy/dt=1/4ka.

Surface water clarification by ultrafiltration with an immersed membrane system: effect of coagulation/aeration on flux enhancement

2003 ◽  
Vol 3 (5-6) ◽  
pp. 393-399 ◽  
Author(s):  
P. Choksuchart ◽  
M. Héran ◽  
A. Grasmick
Keyword(s):  
Ferric Chloride ◽  
Membrane Surface ◽  
Membrane System ◽  
Critical Conditions ◽  
Transmembrane Pressure ◽  
Permeate Flux ◽  
System Effect ◽  
Fiber Network ◽  
Membrane Cleaning ◽  
Concentrated Suspension

A new clarification system was developed to intensify a clarification step by ultrafiltration. Membrane modules equipped with capillary fibers were immersed in a reactor where a horizontal water circulation and a vertical air bubble circulation could assist in minimizing clogging inside the fiber network. Experiments were conducted with a clay particle suspension. Ferric chloride was added to induce coagulation of suspended particles. Results show that when filtering was operated under supracritical conditions clay deposit was observed on the membrane surface and a rapid increase in transmembrane pressure (TMP) value appeared. Air bubbling, and above all adding ferric chloride, allowed an actual enhancement of the filtering conditions. In optimal conditions, a very high concentrated suspension (5.0 g SS/L), filtering evolution was comparable to a clear water filtration until a 65 L/h/m2 permeate flux value (obtained under a 0.16 bar TMP), further a rapid fouling inside the fiber network appeared and obliged us to undertake specific membrane cleaning. The chosen membrane cleaning procedure showed that the particle deposit was the main fouling cause when filtering above the critical conditions.

Improvement of microfiltration performance in water treatment: is critical flux a viable solution?

2000 ◽  
Vol 41 (10-11) ◽  
pp. 309-315 ◽  
Author(s):  
S. Vigneswaran ◽  
D.Y. Kwon ◽  
H.H. Ngo ◽  
J.Y. Hu
Keyword(s):  
Membrane Fouling ◽  
Particle Deposition ◽  
Material Balance ◽  
Transmembrane Pressure ◽  
Operational Mode ◽  
Permeate Flux ◽  
Critical Flux ◽  
Viable Solution ◽  
Crossflow Microfiltration

In this study, three definitions for critical flux were introduced based on the crossflow microfiltration (CFMF) experiments conducted under an operational mode of constant permeate flux. The critical flux based on material balance was calculated from the rate of particles deposition. The highest permeate flux results in no particle deposition being taken at the critical flux. The second definition was based on the increase in transmembrane pressure (TMP). The critical flux based on the TMP increase is the flux below which the membrane fouling does not occur. The third definition was based on the direct observation of particles deposition through microscope. Detailed experiments were conducted with synthetic suspension of different sizes of latex particles. Long term experiments conducted with polydispersed kaolin clay suspension indicated that the critical flux based on material balance concept is more realistic in field conditions.

scholarly journals Studies of polypropylene membrane fouling during microfiltration of broth with Citrobacter freundii bacteria

2015 ◽  
Vol 17 (4) ◽  
pp. 56-64 ◽  
Author(s):  
Marek Gryta ◽  
Marta Waszak ◽  
Maria Tomaszewska
Keyword(s):  
Membrane Fouling ◽  
Membrane Surface ◽  
Transmembrane Pressure ◽  
Citrobacter Freundii ◽  
Permeate Flux ◽  
Process Duration ◽  
Polypropylene Membrane ◽  
Flux Decline ◽  
Cake Layer ◽  
Scanning Electron

Abstract In this work a fouling study of polypropylene membranes used for microfiltration of glycerol solutions fermented by Citrobacter freundii bacteria was presented. The permeate free of C. freundii bacteria and having a turbidity in the range of 0.72–1.46 NTU was obtained. However, the initial permeate flux (100–110 L/m2h at 30 kPa of transmembrane pressure) was decreased 3–5 fold during 2–3 h of process duration. The performed scanning electron microscope observations confirmed that the filtered bacteria and suspensions present in the broth formed a cake layer on the membrane surface. A method of periodical module rinsing was used for restriction of the fouling influence on a flux decline. Rinsing with water removed most of the bacteria from the membrane surface, but did not permit to restore the initial permeate flux. It was confirmed that the irreversible fouling was dominated during broth filtration. The formed deposit was removed using a 1 wt% solution of sodium hydroxide as a rinsing solution.

scholarly journals Effect of operation paramaters on the filtration behavior in microfiltratration of TiO2 suspended

2021 ◽  
Vol 10 (1) ◽  
pp. 84-92
Author(s):  
Chinh Pham Duc ◽  
Thuy Nguyen Thi Thu ◽  
Tham Bui Thi ◽  
Quang Phan Ngoc ◽  
Cuong Pham Manh ◽  
...  
Keyword(s):  
Ph Value ◽  
Complete System ◽  
Membrane Surface ◽  
Experimental System ◽  
Transmembrane Pressure ◽  
Permeate Flux ◽  
Cake Layer ◽  
Mechanical Separation ◽  
Set Up ◽  
The Relationship

The photocatalytic reaction using TiO2 suspended to degrade the residues of toxic organic compounds has been extensively studied, but the ultilization of this process has not been recorded on an industrial scale. One of the primary reasons is the separation of TiO2 catalyst from the treated solution mixture. Conventional mechanical separation methods such as centrifugation, flocculation-deposition do not allow for thorough separation and catalytic reuse, whereas the microfiltration / ultrafiltration membrane process has been demonstrated to be capable of composting isolates very suspended particles. Accordingly, in this study, an experimental system separating TiO2-P25 suspension by microfiltration membrane 0.2 µm on laboratory scale was set up. Effects of operating factors: TiO2 concentration, pH value, transmembrane pressure and crosss flow velocity were investigated. Result shown that TiO2 concentration greater than 1 g / l will fundamentally diminish the permeate flux, futhermore, in the transmembrane  pressure differential (∆P) fluctuating from 0.3 to 1.2 bar, the relationship between J and ∆P is a linear relationship. In addition, the study likewise shown that the formation of the cake layer (scale) on the membrane surface is the fundamental driver of the permeate flux degradation over time. These results are the basis for integrating membrane and photocatalytic processes into a complete system for degradation toxic organic compound residues.

Investigation Into the Crossflow Microfiltration Process Utilizing Ceramic Membrane Applied to Bacteria Reduction and Clarifying of Ac¸ai Juice

2008 ◽  
Author(s):  
Renata Natsumi Haneda ◽  
Se´rgio Rodriques Fontes
Keyword(s):  
Pore Size ◽  
Ceramic Membrane ◽  
Average Pore Size ◽  
Membrane Surface ◽  
Polymeric Membrane ◽  
Euterpe Oleracea ◽  
Permeate Flux ◽  
Average Pore ◽  
The Difference ◽  
Crossflow Microfiltration

This paper reports the results of the crossflow microfiltration process applied to the reduction of bacteria and retention of particles in suspension of ac¸ai (Euterpe oleracea Mart.) juice. A commercial membrane of α-alumina (Al2O3) in the form of a tube with 1.2μm of average pore size was utilized to investigate the reduction of the bacteria of ac¸ai juice without using high temperatures (pasteurization). This pore size of the ceramic structure was utilized in an attempt to reduce the polarization phenomenon and improve the permeate flux without utilizing the usual enzymatic treatment made in the microfiltration processes that utilize polymeric membrane (Cianci et al., 2005 and Ushikubo et al., 2006). An anthocyanin concentration was also observed during the microfiltration process followed by suspended particles retention as an indicator of ac¸ai juice clarifying. The Scanning Electronic Microscopy (SEM) was utilized as an essential tool to characterize the morphology of the ceramic micro porous structure and to evaluate the formation of a polarization layer on the membrane surface, while the Optical Microscopy was used to analyze the difference in the characteristics between samples of concentrate and permeate.

Regional deposition of inhaled particles in human lungs: comparison between men and women

1998 ◽  
Vol 84 (6) ◽  
pp. 1834-1844 ◽  
Author(s):  
Chong S. Kim ◽  
S. C. Hu
Keyword(s):  
Particle Deposition ◽  
Fine Particles ◽  
Particle Diameter ◽  
Flow Rates ◽  
Men And Women ◽  
Inhaled Particles ◽  
Regional Deposition ◽  
Delivery Technique ◽  
Deposition Fraction ◽  
The Difference

We measured detailed regional deposition patterns of inhaled particles in healthy adult male ( n = 11; 25 ± 4 yr of age) and female ( n = 11; 25 ± 3 yr of age) subjects by means of a serial bolus aerosol delivery technique for monodisperse fine [particle diameter ( D p) = 1 μm] and coarse aerosols ( D p = 3 and 5 μm). The bolus aerosol (40 ml half-width) was delivered to a specific volumetric depth (Vp) of the lung ranging from 100 to 500 ml with a 50-ml increment, and local deposition fraction (LDF) was assessed for each of the 10 local volumetric regions. In all subjects, the deposition distribution pattern was very uneven with respect to Vp, showing characteristic unimodal curves with respect to particle size and flow rate. However, the unevenness was more pronounced in women. LDF tended to be greater in all regions of the lung in women than in men for D p = 1 μm. For D p = 3 and 5 μm, LDF showed a marked enhancement in the shallow region of Vp ≤ 200 ml in women compared with men ( P < 0.05). LDF in women was comparable to or smaller than those of men in deep lung regions of Vp > 200 ml. Total lung deposition was comparable between men and women for fine particles but was consistently greater in women than men for coarse particles regardless of flow rates used: the difference ranged from 9 to 31% and was greater with higher flow rates ( P < 0.05). The results indicate that 1) particle deposition characteristics differ between healthy men and women under controlled breathing conditions and 2) deposition in women is greater than that in men.

Deposit membrane fouling: influence of specific cake layer resistance and tangential shear stresses

2014 ◽  
Vol 70 (1) ◽  
pp. 40-46 ◽  
Author(s):  
A. Charfi ◽  
J. Harmand ◽  
N. Ben Amar ◽  
A. Grasmick ◽  
M. Heran
Keyword(s):  
Membrane Fouling ◽  
Membrane Surface ◽  
Suspended Solid ◽  
Shear Stresses ◽  
Permeate Flux ◽  
Recirculation Flow ◽  
Resistance Evolution ◽  
Cake Layer ◽  
Macro Scale ◽  
The Difference

Cake fouling is the leading cause of membrane permeability decrease when filtering mixed liquor suspension containing high suspended solid concentrations. A simple model is proposed to simulate the cake resistance evolution with time by considering a macro-scale fouling linked only to the accumulation of particles on the membrane surface. This accumulation appears as the difference between the flux of deposited particles due to the filtration and the flux of particles detached from the membrane surface due to the tangential shear stresses caused by recirculation flow in the sidestream membrane bioreactor (MBR) or gas sparging close to the membrane surface for submerged MBR configuration. Two determining parameters were then highlighted: the specific cake resistance and the ‘shear parameter’. Based on these parameters it is possible to predict model outputs as cake resistance and permeate flux evolution for short-time filtration periods.

Application of air backflushing technique in membrane bioreactor

1997 ◽  
Vol 36 (12) ◽  
pp. 259-266 ◽  
Author(s):  
C. Visvanathan ◽  
Byung-Soo Yang ◽  
S. Muttamara ◽  
R. Maythanukhraw
Keyword(s):  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Hollow Fiber Membrane ◽  
Membrane Surface ◽  
Operation Time ◽  
Transmembrane Pressure ◽  
Stable Operation ◽  
Aeration Tank ◽  
Permeate Flux ◽  
Cake Layer

The optimum air backflushing and filtration cycle was investigated for a 0.1 μm hollow fiber membrane module immersed in an activated sludge aeration tank. It was found that 15 minutes filtration and 15 minutes air backflushing gave the best result both in terms of flux stability and net cumulative permeate volume. Although this cyclic operation could not completely remove the clogging, this process improved the flux by up to 371% compared to the continuous operation. During the long term runs, three different hydraulic retention times (HRT) of 12, 6 and 3 hours, corresponding to 0.16, 0.32 and 0.64 m3/m2.d of permeate flux respectively, were investigated. Stable operation was obtained at the HRT of 12 hours. Decrease in HRT led to rapid formation of a compact cake layer on the membrane surface thus increasing the transmembrane pressure. It was also noted that filtration pressure increases with increase in bioreactor MLSS concentration. With operation time, the MLVSS/MLSS value decreased without significant effect on the process performance, indicating that inorganic mass constantly accumulated in the bioreactor. All the experimental runs produced more than 90% removal of COD, and TKN. In terms of physical, chemical, biological and bacteriological parameters, the membrane bioreactor effluent was superior to the conventional activated sludge process.

scholarly journals Optimizing the operational conditions of a membrane bioreactor used for domestic wastewater treatment

2005 ◽  
Vol 48 (spe) ◽  
pp. 119-126 ◽  
Author(s):  
Priscilla Zuconi Viana ◽  
Ronaldo Nobrega ◽  
Eduardo Pacheco Jordão ◽  
José Paulo Soares de Azevedo
Keyword(s):  
Municipal Wastewater ◽  
Membrane Surface ◽  
Domestic Wastewater ◽  
Transmembrane Pressure ◽  
Permeate Flux ◽  
Operational Parameters ◽  
Operational Conditions ◽  
Air Supply ◽  
Aeration System ◽  
Domestic Wastewater Treatment

This study evaluated the performance of a sidestream membrane module combined with an aeration system for the treatment of municipal wastewater. To investigate the membrane's behavior and to control fouling, trials in laboratory units were conducted. In these tests, optimal values were established for some operational parameters, such as crossflow velocity, transmembrane pressure and air supply to continuously flush the membrane surface. Air supply improved the behavior of the permeate flux over time. After six hours operation, the stabilized flux was 35 L/m².h at a total pressure of 0.40 bar (wastewater pressure of 0.05 bar and air pressure of 0.35 bar) and Reynolds Number of 4,600. All permeate samples analyzed indicated absence of fecal coliform and Escherichia coli.

Effects of particle size distribution on the cake formation in crossflow microfiltration

2002 ◽  
Vol 2 (2) ◽  
pp. 305-311 ◽  
Author(s):  
S. Kim ◽  
S.-H. Cho ◽  
H. Park
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Particle Deposition ◽  
Membrane Surface ◽  
Particle Diameter ◽  
Feed Concentration ◽  
Cake Formation ◽  
Effective Particle ◽  
Monodisperse Suspensions ◽  
Crossflow Microfiltration

In crossflow microfiltration, the tendency of particle deposition of polydisperse suspensions has been established experimentally and compared with that of monodisperse suspensions. The mass transfers of particles are different according to size in polydisperse suspensions. The most particles, which deposit to membrane surface without clogging pore in microfiltration, are much larger than 0.1 μm. Among these particles, smaller particles are easier to deposit than larger particles because of shear-induced diffusion and particle deposition depends on the size distribution of small particles. Effective particle diameter is introduced as a representative particle size which can reflect the diffusivity of each particle according to size and it describes the tendency of particle deposition very well in polydisperse suspensions. The effect of effective particle diameter is larger than that of feed concentration. The most important factor affecting particle deposition of polydisperse suspensions is effective particle diameter. The results of our research suggest that the effective particle diameter can be an important factor which can represent the potential for cake formation.

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