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What is the primary driving force in rotary vacuum filters?
What happens when the available space in a plate and frame filter press is filled with cake?
Which of the following is an advantage of using a plate and frame filter press?
What is a key disadvantage of the plate and frame filter press?
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What is continuously scraped from the rotary filter cloth?
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Which type of filter uses centrifugal force as its driving mechanism?
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What is a common application of the plate and frame filter press?
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What distinguishes rotary vacuum filters from other types of filters?
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What is the primary factor determining high selectivity in porous membranes?
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Which type of membrane uses carrier molecules to facilitate separation?
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What defines non-porous membranes?
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Which range of pore dimensions characterizes microporous membranes?
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Why is high permeability important in membrane structures?
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In what applications are carrier membranes most commonly utilized?
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What mechanism determines separation in non-porous membranes?
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What is a key characteristic of porous membranes used in microfiltration?
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What is the main distinguishing feature of crystallization compared to other separation processes?
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Which method is commonly used to achieve crystallization from a solution?
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In commercial crystallization, why is size uniformity of crystals important?
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What does membrane separation primarily rely on for separating components?
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What type of membranes are used in microfiltration and ultrafiltration?
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What is the role of the sweep in membrane separation?
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Which component of membrane separation is retained and does not pass through the membrane?
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Which of the following is NOT an example of crystallization in food technology?
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What is the typical particle size range that microfiltration can separate?
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Which type of membrane is primarily used for reverse osmosis?
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What is the hydrostatic force required for microfiltration?
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What is the pore size range for ultrafiltration membranes?
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Which material is used for gas separation processes?
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In nanofiltration, which type of ions are allowed to pass through the membrane?
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Which of the following applications is microfiltration least suitable for?
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What is the molecular weight range for particles that ultrafiltration separates?
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What is one of the primary purposes of reverse osmosis?
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What is the size range of particles that reverse osmosis can effectively filter?
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What role does external pressure play in the reverse osmosis process?
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Which type of water is likely to utilize reverse osmosis?
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What does the module in a reverse osmosis system primarily do?
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Which particle characteristic enhances separation in reverse osmosis?
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What is typically necessary to overcome osmotic pressures in reverse osmosis?
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Which substance can reverse osmosis effectively filter out?
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Study Notes
Plate and Frame Filter Press
- Used for solid-liquid separation in food processing
- Plates with filter cloths are hung vertically, operating in parallel
- Feed liquor is pumped into the press, passing through filter cloths
- Liquid flows down grooved plate surfaces and drains through outlet channels
- Filter cake builds up on the cloth, increasing pressure drop
- In the early stages, filtration is constant rate, later becomes constant pressure
- When frame space fills with cake, the press is dismantled for cleaning
- Advantages: Low capital costs, high flexibility, reliable, easy maintenance
- Disadvantages: Difficult to mechanize, time-consuming, labor intensive
Rotary Filters
- In rotary filters, slurry flows through rotating cylindrical cloth
- Filter cake is continuously scraped off
- Pressure or vacuum can provide the driving force
- Rotary vacuum filters are particularly useful
- Cloth is supported on a horizontal drum that dips in slurry
- Vacuum is applied where cake is building up
- Vacuum is broken where cake is scraped off
- Filtrate is removed through trunnion bearings
- Advantages: Mechanized, convenient
- Disadvantages: Expensive
Centrifugal Filters
- Use centrifugal force to separate solids from liquids
- Centrifuges have perforated bowls with filter cloths
- Driving force provided by centrifugal force
Crystallization
- Solid-liquid separation process that produces a solid product
- Crystallization differs from other separation processes due to solid product
- Achieved by lowering temperature or concentrating the solution
- Forms a supersaturated solution, causing solutes to crystallize
- Important in manufacturing sucrose, glucose, lactose, salt, and processing ice cream
- Crystal size and shape are crucial for yield, purity, and handling
Membrane Separation
- Separates components in a feed using a semi-permeable membrane
- Feed is separated into a retentate (retained) and a permeate (passes through)
- Feed, retentate, and permeate can be liquid, gas, or solid
- Sweep can be used to remove permeate
Types of Membrane Separation Technologies
- Non-porous membranes: Separate molecules of the same size, gases and liquids
- Porous membranes: Used in microfiltration and ultrafiltration, pore size determines separation
- Carrier membranes: Separation occurs by carrier molecules transporting desired components
Membrane Structures
- Porous membranes: Used in microfiltration and ultrafiltration, with pore sizes of 0.1 to 10 µm
- Non-porous membranes: Separate molecules of the same size, gases and liquids, by diffusion
- Carrier membranes: Separation based on carrier molecule affinity, for gases or liquids
Membrane Materials
- Various natural or synthetic polymers are used, such as polypropylene, polysulfone, polyamide, cellulose, polyacrylonitrile
- Membrane materials are selected based on desired separation process and pressure
Classification of Membrane Separation Processes
- Microfiltration, ultrafiltration, nanofiltration, and reverse osmosis are classified by pore size
- Pore size determines the particle size that can be separated
- Separation systems are named based on the size range they operate in
Microfiltration
- Separates particles from 0.1 to 10 µm or molecular weight greater than 1000 kDa
- Examples include yeast cells, red blood cells, coal dust, some bacteria
- Used for sterile filtration, cell harvesting, fruit juice clarification
- Least used due to finer membrane systems available
Ultrafiltration
- Separates colloidal or molecular particles using suction or pressure
- Uses semi-permeable membranes
Nanofiltration
- Separates particles from 0.001 to 0.01 µm or molecular weight between 250 and 400 kDa
- Allows some salts to pass, rejecting divalent and multivalent ions
- Used for sugar concentration, dye desalting, water softening, color removal, bacteria removal
Reverse Osmosis (RO)
- Finest membrane size, separating particles smaller than 0.001 µm or molecular weight less than 125 kDa
- Counters natural osmosis by applying external pressure
- Removes inorganic salts, non-ionic organic compounds, and small organics
- Used for potable water, boiler feed water, pharmaceutical water, beverage production
Membrane Configuration
- Membrane and support are called a module
- Modules are assembled to form a filtration system
- Modules must accommodate large membrane areas in small volume and withstand pressure
- Designed to maintain a clean membrane surface
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Description
This quiz explores two important methods of solid-liquid separation in food processing: Plate and Frame Filter Press and Rotary Filters. It covers their operation principles, advantages, and disadvantages, helping you understand the practical applications of each system in the industry.