scholarly journals Concentration Polarization in Ultrafiltration/Nanofiltration for the Recovery of Polyphenols from Winery Wastewaters

Membranes ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 46 ◽  
Author(s):  
Alexandre Giacobbo ◽  
Andréa Moura Bernardes ◽  
Maria Filipe Rosa ◽  
Maria de Pinho
Keyword(s):  
Mass Transfer ◽  
Membrane Fouling ◽  
Concentration Polarization ◽  
Cross Flow ◽  
Variation Method ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Subsequent Decrease ◽  
Wide Range ◽  
Flow Velocities

Concentration polarization is intrinsically associated with the selective character of membranes and often means flux decline and which causes a subsequent decrease of ultrafiltration and nanofiltration performance. More important is the fact that it acts as a precursor of membrane fouling and creates severe fouling problems in the longer times range. The quantification of its dependence on the operating parameters of cross-flow velocities and transmembrane pressures makes recourse to the film theory to introduce mass-transfer coefficients that generally are calculated by dimensionless correlations of the Sherwood number as a function of the Reynolds and Schmidt numbers. In the present work, the mass-transfer coefficients are obtained through the fitting of experimental results by the pressure variation method. The ultrafiltration/nanofiltration of the winery wastewaters from the racking operation is carried out with the membranes ETNA 01PP (Alfa Laval) and NF 270 (Dow Filmtec) under a wide range of cross-flow velocities and transmembrane pressures up to 15 bar.

scholarly journals Atenolol removal by nanofiltration: a case-specific mass transfer correlation

2020 ◽  
Vol 81 (2) ◽  
pp. 210-216 ◽  
Author(s):  
Alexandre Giacobbo ◽  
Elisa Veridiani Soares ◽  
Andréa Moura Bernardes ◽  
Maria João Rosa ◽  
Maria Norberta de Pinho
Keyword(s):  
Mass Transfer ◽  
Membrane Fouling ◽  
Concentration Polarization ◽  
Membrane Separation ◽  
Film Theory ◽  
Operating Conditions ◽  
Transfer Coefficients ◽  
Specific Mass ◽  
Mass Transfer Coefficients ◽  
Mass Transfer Correlation

Abstract Concentration polarization is a phenomenon inherent to membrane separation operations and as a precursor of membrane fouling is frequently related to the decrease in the performance of these operations. In the present work, a case-specific mass transfer correlation was developed to assess the concentration polarization when nanofiltration, in different operating conditions, was applied to treat a pharmaceutical wastewater containing atenolol. NF runs with two membranes, two atenolol concentrations and three feed circulating velocities were conducted, and the corresponding experimental mass transfer coefficients were determined using film theory to describe the concentration polarization phenomenon. Higher velocities led to higher mass transfer coefficients and, consequently, lower concentration polarization. These mass transfer coefficients were correlated with the circulating velocity (Re), the solute diffusivity (Sc) and the membrane permeability (LP+) (the membrane is a permeable interface with effect on the concentration profiles developed from the interface towards the bulk feed), yielding the following correlation Sh = 1.98 × 104Re0.5Sc0.33LP+0.32. The good agreement between the calculated and the experimental results makes this correlation a valuable tool for water practitioners to predict and control the concentration polarization during atenolol-rich wastewater treatment by nanofiltration, thereby increasing its productivity and selectivity.

Liquid-liquid mass transfer studies in various stirred vessel designs

2015 ◽  
Vol 31 (4) ◽  
Author(s):  
Reza Afshar Ghotli ◽  
Abdul Raman Abdul Aziz ◽  
Shaliza Ibrahim
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Interfacial Area ◽  
Operating Conditions ◽  
Experimental Results ◽  
Dispersed Phase ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Wide Range

AbstractA general review on correlations to evaluate mass transfer coefficients in liquid-liquid was conducted in this work. The mass transfer models can be classified into continuous and dispersed phase coefficients. The effects of drop size and interfacial area on mass transfer coefficient were investigated briefly. Published experimental results for both continuous and dispersed phase mass transfer coefficients through different hydrodynamic conditions were considered and the results were compared. The suitability and drawbacks of these correlations depend on the operating conditions and hydrodynamics. Although the results of these models are reasonably acceptable, they could not properly predict the experimental results over a wide range of designs and operating conditions. Therefore, proper understanding of various factors affecting mass transfer coefficient needs to be further extended.

scholarly journals Concentration Polarization Quantification and Minimization in Cork Process Wastewater Ultrafiltration by an Ozone Pretreatment

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2182
Author(s):  
Miguel Minhalma ◽  
Maria Norberta de Pinho ◽  
Joaquin R. Dominguez
Keyword(s):  
Mass Transfer ◽  
Molecular Weight ◽  
Membrane Fouling ◽  
Concentration Polarization ◽  
Film Theory ◽  
Operating Conditions ◽  
Direct Oxidation ◽  
Cellulose Acetate Membranes ◽  
Wide Range ◽  
Ozone Pretreatment

Concentration polarization and membrane fouling have been identified as the main problems during the ultrafiltration treatment of cork processing wastewaters. These problems drastically reduce the permeate fluxes and, therefore, their potential applications. In this work, a soft ozonation pretreatment was applied to minimize these undesirable effects. A new systematic study was carried out for membranes with different molecular weight cut-offs and at different operating conditions to monitor and quantify the concentration polarization caused by the wastewater’s remaining ozonated compounds. Film theory was used to correlate the mass transfer coefficient, k, and the intrinsic rejection coefficient, f′, with the resistance introduced by concentration polarization. The ultrafiltration treatment was carried out under varying hydrodynamic operating conditions (circulating flow rates of 100–200 L/h) and transmembrane pressures (1–3 bar) for a set of four cellulose acetate membranes covering a wide range of molecular weight cut-offs (5000–100,000 Da) and hydraulic permeabilities (25–110 kg/h/m2/bar). The ozone pretreatment (at wastewater pH) reduced the phenolic content selectively (direct oxidation) by more than 50%, reducing membrane fouling and concentration polarization and increasing permeate fluxes (by 22–45%) and mass transfer coefficients (up to six times).

scholarly journals A comparative study between stirred dead end and circular flow in microfiltration of China clay suspensions

2015 ◽  
Vol 16 (2) ◽  
pp. 481-492 ◽  
Author(s):  
Norazanita Shamsuddin ◽  
Chengcheng Cao ◽  
Victor M. Starov ◽  
Diganta Bhusan Das
Keyword(s):  
Mass Transfer ◽  
Energy Consumption ◽  
Concentration Polarization ◽  
Membrane Surface ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
China Clay ◽  
Dead End ◽  
Flow Filtration ◽  
Clay Suspensions

A well-defined comparative study between stirred dead end and circular crossflow for microfiltration of china clay suspensions has been undertaken. The comparisons have been made with respect to convective mass transfer coefficients, permeation and rejection rates, and energy consumption. Similar operating and hydrodynamic conditions were implemented for the comparison. According to our experimental data the circular crossflow module was proven to perform better as compared with the stirred dead end system due to the higher mass transfer coefficients, higher permeation rates and lower energy consumption. The mass transfer coefficients observed are comparable to those previously found in vortex flow filtration and dead end flow filtration. The presence of Dean vortices in the circular crossflow module promotes flow instabilities in the curved channel flow path which reduce the concentration polarization effect during the filtration process. The concentration polarization effect however deteriorated due to solute build up (high solute concentration at the membrane surface) and decrease of the shear stress, i.e., the particle lift forces on the membrane surface. This resulted in deposition of particles on the membrane surface. In terms of energy consumption, for the same energy cost the limiting flux reached in circular crossflow was found to be higher than in the stirred dead end unit.

scholarly journals Mass transfer coefficients in cross-flow ultrafiltration

1989 ◽  
Vol 47 (1-2) ◽  
pp. 25-51 ◽  
Author(s):  
G.B. van den Berg ◽  
I.G. Rácz ◽  
C.A. Smolders
Keyword(s):  
Mass Transfer ◽  
Cross Flow ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients

Henry's constants and mass transfer coefficients of halogenated organic pollutants in an air stripping packed column

1998 ◽  
Vol 38 (6) ◽  
pp. 287-294 ◽  
Author(s):  
Pen-C. Chiang ◽  
Chung-H. Hung ◽  
J. C. Mar ◽  
E. E. Chang
Keyword(s):  
Mass Transfer ◽  
Methylene Chloride ◽  
Packed Column ◽  
Transfer Coefficients ◽  
Chlorinated Organic Compounds ◽  
Air Stripping ◽  
Mass Transfer Coefficients ◽  
Equilibrium Partition ◽  
Henry's Constants ◽  
Chlorinated Organic

Both Henry's constants and volumetric mass transfer coefficients (KLa) of eight priority chlorinated organic compounds including 1,1-dichloroethene, methylene chloride, chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, and 1,4-dichlorobenzene in an air stripping packed column were investigated in this study. The liquid and gas phase EPICS (Equilibrium Partition in Closed System) and direct calculating methods were applied to determine the Henry's constants of VOCs. The interference of co-solute on Henry's constants was also investigated. Experimental results indicated that decrease in Henry's constants of VOCs was observed in the presence of humic acid but no apparent effect on Henry's constants was detected when there was NaCl and surfactant in solution. Four different configurations of packing media including Intalox Saddle, Super Intalox Saddle, Telleret, and Hedgehog made of polypropylene were respectively packed in the air stripping tower and investigated in the study. The dependence of hydraulic loading, air-water ratio, and configurations of packing media on mass transfer coefficients of VOCs was discussed.

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