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Understanding the Basics of Membrane Filtration CHEN 320 – Group 7

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1 Understanding the Basics of Membrane Filtration CHEN 320 – Group 7
Lianne Monterroso Scott Shelton Patricia Stratton Emily Wilborn

2 Roadmap Introduction to Membrane Filtration
Pressure-Driven Membrane Separation Membrane Materials, Structure, and Morphology Membrane Format and Module Design MATLAB Code Common Membrane Applications Conclusion

3 Introduction to Membrane Filtration
Accounts for 40% to 70% of capital and operating costs in the chemicals industry Broad range of applications Process Water Treatment Wastewater treatment and reuse Metal and catalyst recovery Solvent recovery Gas separation Concentration of heat sensitive biological macromolecules and proteins

4 Two Main Types of Filtration
Membrane filtration can be accomplished with either dead end filtration or crossflow filtration. Dead-end: Filter cake can form reducing filtration capacity. Crossflow: Maintains more steady permeate flux and low pressure. Figure: Created by Group 7 Figure: Created by Group 7

5 Pressure-Driven Membrane Separation
Reverse Osmosis Nanofiltration Ultrafiltration Microfiltration

6 Reverse Osmosis Employs tightest membranes for liquid separation.
Only allows small water-soluble ions to go through membrane along with water.

7 Nanofiltration Removes multivalent ions and small molecules in nanometer range like sulfate ions, and sugars. The most common type used for nanofiltration is the spiral membrane.

8 Ultrafiltration Used to retain relatively large dissolved materials like proteins and starches. Ultrafiltration membranes are typically classified by their ability to retain component specific sizes.

9 Microfiltration Suspended solids and large colloids are rejected, while dissolved solids and macromolecules pass through Operate at low pressures of 10 psi or less.

10 Membrane Materials Structure and Morphology
Fabrication Desired Properties Classifications

11 Fabrication of Membranes
Membranes are fabricated from variety of materials Made of Inorganic and organic materials Metals, polymers, and ceramics are used for different applications based on their properties

12 Ceramics and Metals Ceramic and Metals used for aggressive media
Suitable for high temperature operations, acids, and strong solvent

13 Polymers Polymers are utilized most because of their price and versatility Polymer membranes are typically made up of a thin layer of polymer on a porous backing, creating a material with high permeability, selectivity, mechanical strength, and chemical stability

14 Desired Properties Desired properties of membranes include:
High porosity Narrow pore size distribution Sharp MWCO High mechanical strength Flexible High pH Chemical stability Surface properties Low fouling Low cost https://www.millipore.com/membrane/flx4/filter_properties_hm

15 Classification Membranes are classified according to structure, morphology, and application Two classifications of membranes Symmetric membranes Asymmetric membranes Composite membranes

16 Symmetric Membranes Very few commercially available membranes are symmetric throughout their thickness Some examples include: Polytetrafluoroethylene Polyethylene Polypropylene

17 Asymmetric Membranes Include most of the commercially available membranes Have either a thin microporous or dense permselective layer supported by a more-open porous substrate The membrane may by integrally skinned, formed in a single operation, or by separate steps An example of an asymmetric membrane is cellulose RO membrane, where both layers are made up of cellulose acetate.

18 Composite Membranes A composite membrane is a subset of asymmetric membranes The skin layer and support layer are made up of different polymers based on the individual properties The skin layer determines separation performance Support layer determines mechanical stability An example of a composite membrane is a polymide RO membrane which is made up of a thin polyamide permselective skin on a polysulfone UF support.

19 Membrane Module Design
Cassette Cartridge Spiral Wound Source:

20 Cassette Cassette membranes are used for UF and MF.
The membrane filtrates the fluid, while the gaskets are used to separate the permeate, feed, and retentate streams. Spacers introduce turbulence, which increases mixing and prevents the formation of a gel layer. However, spacers are sometimes prone to particulate clogging, and can be difficult to clean. Source: "Understand the Basics of Membrane Filtration." Wang, Hua. Hongyi, Zhou. GE Global Research.

21 Industrial/Large-Scale Cassette Module
Source:

22 Cartridge Utilizes laminar flow for MF, UF, or NF.
Composed of a large number of hollow-fiber membranes in a cylindrical housing with permeate ports and end caps. Has a very high packing density, therefore has a high surface area to volume ratio, making this particular filter ideal for product recovery. Source: Source: "Understand the Basics of Membrane Filtration." Wang, Hua. Hongyi, Zhou. GE Global Research.

23 Spiral Wound Spiral Wound are used predominantly for RO.
They are composed of a multi-layered assemble of flat sheet membranes, and spacer screens. These components are all rolled around a perforated tube, which seals the membrane and spacer layers on three sides. Source: "Understand the Basics of Membrane Filtration." Wang, Hua. Hongyi, Zhou. GE Global Research.

24 Spiral Wound Module used for RO
They are built to have a high packing density by utilizing thin spacer screens. Industrially, large-scale operations use these RO modules connected in parallel with one another. Source:

25 Plot of Cake Resistance vs
Plot of Cake Resistance vs. Specific Resistance with the Area of the Membrane and Cake Volume held constant >> % Rc: cake resistance >> % r: specific cake resistance >> % Vs: volume of cake >> % Am: area of membrane >> >> %Plot of Rc vs. r (Vs = m^3, Am = .01 m^2) >> r = linspace(0,10);>> Vs = 0.001;>> Am = .01; >> Rc = r*Vs/Am; >> plot(r,Rc,'-') >> legend('Vs and Am constant') >> title('Plot of Rc vs. r') >> xlabel('r (m^-2)') >> ylabel('Rc (m^-1)') Figure: Created by Group 7 Source for Filtration equation:

26 Plot of Cake Resistance vs
Plot of Cake Resistance vs. Cake Volume with the Area of the Membrane and specific resistance held constant >> % Rc: cake resistance >> % r: specific cake resistance >> % Vs: volume of cake >> % Am: area of membrane >> >> %Plot of Rc vs. Vs (r = 5 m^-2, Am = .01 m^2) >> r = 5; >> Am = .01; >> Vs = linspace(1e-6,1,400); >> Rc = r*Vs/Am; >> plot(Vs,Rc,'-') >> legend('r and Am constant') >> title('Plot of Rc vs. Vs') >> xlabel('Vs (m^-3)') >> ylabel('Rc (m^-1)') Figure: Created by Group 7 Source for Filtration equation:

27 Plot of Cake Resistance vs
Plot of Cake Resistance vs. Area of the Membrane with the specific resistance and Cake Volume held constant >> % Rc: cake resistance >> % r: specific cake resistance >> % Vs: volume of cake >> % Am: area of membrane >> >> %Plot of Rc vs. Am (r = 5 m^-2, Vs = .001 m^3) >> Am = linspace(.0001,1,400); >> r = 5;>> Vs = .001; >> Rc = r*Vs./Am; >> plot(Am,Rc) >> title('Plot of Rc vs Am') >> legend('r and Vs held constant') >> xlabel('Am (m^2)') >> ylabel('Rc (m^-1)') Figure: Created by Group 7 Source for Filtration equation:

28 Common Membrane Applications
Desalinization using RO Industrial water treatment Biopharmaceutical manufacturing Clarification steps in cellulosic ethanol production Picture:

29 Desalination for Reverse Osmosis
Picture: "Understand the Basics of Membrane Filtration." Wang, Hua. Hongyi, Zhou. GE Global Research. Cost-effective Produce clean water from seawater in regions with limited access to fresh water Removes salts, organic substances, algae, bacteria, and suspended particles

30 Industrial Water Treatment
High purity water needed for: Boiler feed water Cooling tower water Process water in many industries Picture:

31 Membrane filtration technology minimizes land, construction, and operating costs:
Conventional Treatment Membrane Treatment Picture: "Understand the Basics of Membrane Filtration." Wang, Hua. Hongyi, Zhou. GE Global Research.

32 Industrial Microfiltration Uses
Picture:

33 Biopharmaceutical Manufacturing
For biological products: Recovery Purification Concentration Picture: "Understand the Basics of Membrane Filtration." Wang, Hua. Hongyi, Zhou. GE Global Research.

34 Ultrafiltration Used for: Buffer exchange Final product concentration
Virus filtration Picture: Created by Group 7

35 Cellulosic Ethanol Production
Clarification of the pretreated liquor prior to hydrolysis Clarification of the hydrolyzate stream prior to fermentation Source: Concentration fermentation pre-cursors

36 Cellulosic Ethanol Production: Clarification Uses
Picture:

37 Conclusion Different types of membranes can be applied to various applications based on particle size: Reverse Osmosis (Smallest constituent) Nanofiltration Ultrafiltration Microfiltration (Largest constituent) Membrane filtration has lots of applications! Several types of driving forces for membrane filtration: Pressure Difference Concentration Difference Temperature Difference Used in many industrial processes: Desalination Wastewater and process water treatment Biopharmaceutical applications

38 Suggested Work For Improvements
Add a chemical to the solution being filtered to make membrane more durable Combine multiple driving forces Introduce turbulent flow to prevent clotting


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