Biochemical Engineering Flashcards
1
Q
Anaerobic Baffled (Regulator) Reactor (ABR):
A
An ABR is designed of several chambers (form 4 to 8); they are separated by Side walls that do not extend all the way.
-For liquid: flows from one chamber to the other by gravity.
-For biomass: settles down.
2
Q
Up-flow anaerobic sludge blanket Bioreactor (USAB)
A
-It is a form of anaerobic digester that is used in the treatment of wastewater.
-a methanogenic (methane-producing) digester that evolved from the anaerobic digestion.
-The biomass forms a layer at the bottom of the reactor (the blanket).
3
Q
Materials for encapsulation
A
Cellulose nitrate
Cellulose acetate
Nylon
Phospholipids
Sodium alginate
4
Q
Microbial cells immobilization methods:
A
- Entrapment
- Bounding
5
Q
En-trapment
A
- Matrix entrapment
- Micro-incapsulation
5
Q
Bounding
A
- Adsorption
- Covalent bonding
6
Q
Waste Water Treatment
A
The process of removing physical, chemical and biological contaminants from waste water.
Purpose of waste water treatment is to reduce BOD and COD
7
Q
Problems With Current Waste water Treatment Technologies:
A
- Mixed types of wastes
-Agriculture industry
-Food industry
-Pharmaceutical industry - Power consumption is very expensive
- Aeration is not easy to perform (when the wastes are too thick)
8
Q
Chemical Oxygen Demand (COD) (mg/L) (water consumes)
A
Is designed to measure the capacity of water to consume oxygen during the decomposition of organic matter and the oxidation of inorganic chemicals such as ammonia and nitrite
9
Q
Biochemical oxygen demand (BOD) (Microorganisms):
A
A parameter used to measure the amount of oxygen that will be consumed by microorganisms during the biological reaction of oxygen with organic material (degradation)
10
Q
Primary Treatment (organic waste)
A
Primary treatment removes the materials that can be easily collected from the raw wastewater and disposed off. (Separate liquids from solids, sedimentation so it takes time).
Fats will be floated on the surface and it mechanically removed.
11
Q
Secondary Treatment (for human waste)
A
is designed to degrade the biological content of the sewage such as derived from human waste, food waste, soaps , and detergent.
12
Q
Membrane Biofilm Reactor(MBR)
A
is the combination of a membrane process like microfiltration or ultrafiltration with a suspended growth bioreactor
-Degrade soluble organic contaminates.
13
Q
Bioreactor
A
Any device or system that supports a biologically active environment in controlled conditions. It differs in:
1- Size
2- Material of construction
3- Shape and configuration
4- Heat exchanger
5- Agitation method
14
Q
Heat exchanger (to maintain the bioprocess at a constant temperature)
A
-Microbial activities produce metabolic heat.
-Heat can kill those microbes.
-The microbes require low temperature for growth and this problem can be further increased by the friction heat form agitation.
15
Q
Tertiary treatment (Quality check)
A
Tertiary treatment provides a final stage to raise the effluent quality before it is discharged to the receiving environment.
-Involves a series of steps to further reduce organic concentration, turbidity, N, P, metals, and pathogens
16
Q
The organism is grown in a liquid medium vigorously aerated and agitated in large tanks called fermenters.
A
Submerged cultures fermentation
17
Q
(attached growth systems)
Microorganisms are grown as a biofilm on a solid growth support matrix.
A
Stagnant cultures fermentation
18
Q
Effluent polishing (tertiary)
A
More than one tertiary treatment process may be used at any treatment plant.
If disinfection is practiced, it is always the final process
19
Q
Tertiary treatment steps:
A
- Filtration
-Sand filtration removes suspended matter.
-Filtration over activated carbon removes toxins and odors. - Nutrient removal
-Nitrogen removal
-Phosphorus removal - Disinfection
20
Q
What are the Precautions?
A
A biological process requires:
1- Sterility
2- Use of enzymes catalysts
3- Be careful during operation under elevated temperature and pressure
21
Q
Agitation method
A
Ensures the proper distribution of substrates, biomass, products and heat.
-Bacterial fermentation requires less agitation than fungal fermentation
22
Q
Mechanically agitated reactors:
1- Continuous Stirred Tank Reactor (CSTR)
A
- The standard submerged culture fermenter , the main feature is its motive power, which is a direct mechanical drive
- Used in PHARMACEUTICALS and H2 production.
23
Q
Types of CSTR:
A
- Flat-blade turbine (High shearing)
- Marine propeller (for fragile cells)
- Multi-rod impeller
24
Accessories of CSTR:
1. Baffles: to help agitation.
2. Spargers and nozzles: to push or diffuse air in (shapes such as a pipe, ring, or spider)
3. Propellers
4. Foam breaker to prevent foam overflow to condenser.
5 Recycle loops allow separation of the immobilized enzyme from the product.
25
3 main Non-mechanically agitated reactors
1. Liquid agitated reactors
2. Gas agitated reactors
3. Hybrid Reactors
26
Liquid agitated reactors:
1. Tubular bioreactor (Plug-Flow)
2. Membrane (spiral wound bioreactor)
3. Packed bed
4. Fluidized-bed
5. Expanded-bed
6. Thin film (fixed film)
7. Anaerobic baffled reactor.
8. Anaerobic-sludge-blanket.
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Gas agitated reactors:
1. Air-lift
2. Deep jet
3. Pressure cycle
28
eutrophication
A build up of nutrients, which encourage the overgrowth of weeds, algae, and cyanobacteria in water tanks.
29
An immobilized enzyme
An enzyme that is physically connected to a solid support and is used to transform a substrate into a product.
30
Immobilization technologies are designed to:
reduce the mobility of contaminants by changing the physical characteristics of the contaminated matrix.
31
Benefits of Immobilization of enzymes:
-Saves valuable enzymes.
-Protect the enzyme from unfavorable conditions.
-Better process control (the ability to stop the reaction rapidly by removing the enzyme).
-Higher overall efficiency.
-Product is not contaminated with the enzyme.
32
Major Methods of Enzyme Immobilization:
1-Carrier-Binding
The binding of enzymes to water-insoluble carriers.
Depends on the nature of the enzyme itself, as well as the:
Particle size & Surface area
33
Major Methods of Enzyme Immobilization:
2- Cross-Linking
is a strategy where enzymes are interconnected through covalent bonding without carriers
34
Major Methods of Enzyme Immobilization:
3- Entrapping
Involves inserting enzymes into the structure of a semi-permeable gel or enveloping the enzymes in a semi-permeable polymer membrane.
-It is done in such a way as to retain protein(enzymes) while allowing penetration of substrate.
35
3 Major Methods of Enzyme Immobilization:
1-Carrier-Binding
2-Cross-Linking
3-Entrapping
36
The carrier binding mode of the enzymes are:
-Physical Adsorption (weak bond)
-Ionic Bond (weak bond)
-Covalent Bond (strong bond)
37
What is a carrier?
-The support material that holds the enzyme, which may be a matrix, a membrane or a solid support.
-Carrier specifications:
Inert
Durable = withstand
pH effect
38
Encapsulation
Pore size 100-400
-Using this approach, enzyme leakage can be easily avoided by changing the pore size of the polymeric network, allowing for unrestricted diffusion of either substrates or products.
39
Advantages of Encapsulation
Loading high capacity of the enzymes, low fabrication costs.
40
Example of some Methods of Immobilization:
-Adsorption
-Covalent bonding
-Cross linking
-Entrapment
-Encapsulation
41
Adsorption (Physical)
1-Weak bonding (Hydrogen bonding, ionic bonding, Van Der Waals, Hydrophobic)
2-Easy to do and regenerate.
3-Various material could be used.
42
Materials used for adsorption
Activated carbon
Silica gel
Alumina
Starch
clay
Cellulose
Resin
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Methods of immobilization by adsorption
(physical)
1.The static process.
2. The dynamic batch process.
44
The static process
The solution containing the enzyme is allowed to contact the carrier **without** agitation.
- Most inefficient, requires more time.
45
The dynamic batch process
The carrier is placed into the enzyme solution and mixed **by agitation**.
46
Covalent Bonding Advantages:
-100 times bonding power
- Immobilized enzyme systems can be utilized under **broad spectrum of pH** , **ionic strength** and **uncontrolled variable conditions.**
47
Covalent Bonding(strong) disadvantages :
Enzyme denaturation in reaction media.
48
Materials used in Covalent bonding:
1- Cellulose
2-Agrose
3-Dextarn
49
Materials used for Crosslinking:
-Glutaraldehyde
-Ethylene/Maleic anhydride
co-polymerization
50
Materials used in Entrapment
Polyacrylamide
Starch
Collagen
Silicon rubber
51
Nitrification
Biological oxidation of nitrogen from ammonia to nitrite to nitrate using the action of MO
52
Nitrogen removal:
-Nitrification.
-Denitrification
-Conditions must be anoxic
53
Denitrification
(Reduction)
The reduction of nitrate to nitrogen gas that could be released to the atmosphere thus removed from the water.
54
Phosphorus Removal
Specific bacteria, called **polyphosphate** accumulating organisms accumulate large quantities of phosphorus within their cells.
-With salts of iron( expensive)
-Exposing mixed liquor to anaerobic/aerobic sequence in bioreactor selects microorganisms with higher intracellular phosphorus levels, removing phosphorus as a fixed biological material in waste sludge.
55
Disinfection
-Substantially reduce the number of microorganisms in the water to be discharged back into the environment.
-used to prevent the spread of diseases via the water supply.
56
Disinfection
1. Ozonation (works better in virus inactivation)
Oxygen subjected to UV irradiation = O3
Function: Degrades dyes and pesticides as well
57
Disinfection:
2. Chlorination (works better on bacterial inactivation)
1-low cost and long-term history of effectiveness.
2-chlorination of residual organic material can generate chlorinated-organic compounds that may be carcinogenic.
3- Residual chlorine is toxic to aquatic species.
58
Disinfection
3. UV Disinfection
1. Causes damage to the genetic structure of bacteria, viruses, and other pathogens
2. Need for frequent lamp maintenance and replacement.
3.Need a highly treated effluent to ensure that the target microorganisms
59
Hybrid Reactors:
1. Completely-Filled
2. Plunging Jet
3. Trickling Bed
60
Plug Flow Reactor (PFR)
1. Structure: Liquid (plug) flows through parallel tubes, ensuring proper agitation.
2. Uses: PFRs are used to simulate the chemical change of substances as they travel through "pipes"-like devices.
- Gasoline production
- Synthesis of ammonia from its elements
-Oxidation of sulfur dioxide to sulfur trioxide
- Oxidation of nitrogen compounds
61
Plug Flow Reactor (PFR) reactions:
1.Large-scale reactions.
2. Fast reactions.
3. Homogeneous/ heterogeneous reactions.
4. Continuous production.
5. High-temperature reactions.
62
Advantages and Disadvantages(heat) of PFR
**Advantages of PFR:**
-High volumetric unit conversion
-Run for long periods of time
**-Heat transfer** rate can be optimized
**Disadvantages:**
-Temperatures are hard to control.
-Can result in undesirable temperature gradients.
-PFR maintenance is also more expensive than CSTR
63
Fluidized bed reactor (FBR)?
A reactor device that can perform a wide range of multiphase chemical processes.
64
Fluidization
The fluid velocity is increased, then the force of the fluid on the solids is enough to balance the weight of the solid material.
65
How does Fluidized bed reactor (FBR) work?
-A fluid (gas or liquid) is forced through a granular solid material at **high enough speed**s to suspend the solid and make it to behave like a fluid.
-**When this minimal velocity is exceeded,** the contents of the reactor bed begin to expand and swirl around like an agitated tank. The reactor is now a fluidized bed.
66
Uses of FBR (Oils) :
1. Gasoline and other fuels.
2. Oil and petrochemical industries.
3. Polymers like rubbers
67
Advantages and Disadvantages of FBR
**Advantages of FBR:**
-Uniform Particle Mixing.
-Uniform Temperature Gradients.
-Ability to Operate Reactor in Continuous State.
**Disadvantages of FBR:**
-Increased Reactor Vessel Size.
-Pumping Requirements and Pressure Drop.
-Particle Entrainment (Fine particles).
-Erosion of Internal Components.
68
Packed bed (PBR)?
A tubular reactor filled with solid catalyst particles is used for **separation processes like absorption and distillation** at lower fluid velocities, ensuring solids remain in place as fluid pass through.
69
Thin Film (Fixed Film)? (Has bacteria)
This type of reactor depends on the formation of an active biofilm on the surface of a carrier
70
The Advantages of Thin Film:
1. Will always be renewed with new cells
2. Thickness of biofilm ensures proper aeration and good contact between microbes and substrates
71
How does **Thin film** work?
1. By bubbling compressed air through liquid in a tank, **ATUs** create a highly oxygenated (aerobic) environment for bacteria, which uses the organic matter as an energy source
72
Function of Up-flow anaerobic sludge blanket Bioreactor (USAB)?
UASB uses an anaerobic process **to form a granular sludge blanket**, which is **processed by microorganisms** and suspended by gravity.
-The by-product, biogas with high methane concentration, can be captured and **used for electricity generation.**
73
GAS AGITATED REACTORS
1. Air-lift
-Air-lift fermenters have **no mechanical agitation** system but utilize the air circulating within the fermenter to bring about the **mixing of the medium**
-Are designed in such a way that aeration provides both the agitation of the broth and the dispersal of oxygen.
74
Air-lift design
-A large head space above the draft tube.
-facilitating gas transfer, increasing the liquid's density and specific gravity, and re-gassing it to rise again.
75
Advantages of uses of Air-lift:
Advantage: have Reduced shear forces compared to the more conventional CSTRs.
Uses: Cell cultures and Algae cultures
76
GAS AGITATED REACTORS:
2. Deep Jet
This type is used when a **large volume of air** is needed and the cells are unstable to shear stress. (Same as Air-lift)
77
GAS AGITATED REACTORS
3. Pressure Cycle
ICI's modified 3000 m3 air-lift reactor, designed for **cooling purposes, operates well with low broth viscosity, controlling contamination**, and ensuring good air distribution due to extra pressure.
78
The Accessories of Fermentors:
1- PH electrode
2- Dissolved oxygen electrode
3- Foam electrode
4- Foam breaker
5- Temperature sensor
6- Impellers
7- Pressure transmitter
79
Biomass
Refers to living biological material that can be used for industrial production.
80
Major steps of downstream Processing
-Separate and recover end product
-Concentration.
-Purification.
81
5 methods of Solid /Liquid separation mechanisms:
1. Sedimentation
2. Flocculation
3. Filtration
4. Disintegration of cells
5. Centrifugation
82
Sedimentation
The accumulation of suspended particles in slurry to settle out of the fluid in response to the forces acting on them: These forces can be caused by either gravity or electromagnetism.
83
Flocculation
A process where colloids come out of suspension in the form of floc or flake; either spontaneously or due to the addition of a clarifying agent.
-Alum – Ferric Chloride – Silica gel- Polymers
84
Filtration
1. To separate filamentous microorganisms.
2. A unit operation in which a mixture of solids & liquid is forced through a porous medium in which solids are deposited or entrapped.
3. The solids form a “cake” on the surface of the medium & the clarified liquid or “filtrate” is discharged.
85
4 Filtration mechanisms:
a- Surface filtration
b- Depth Filtration
c- Centrifugal Filtration
d- Cake filtration
In filtration the driving force: is Pressure.
86
1-SURFACE FILTERS
Work by direct interception of particles larger than the pore size of the media.
87
2-DEPTH FILTERS
These filters use several types of polymers (resins) to achieve the goal of holding particles. The fluid must take a longer path through the filter before exiting.
88
The volume of filtrate which can be collected in a given time in:
1- Filter area.
2- Viscosity of fluid.
3- Pressure drop across the filter medium and deposited filter cake
4- The resistance of the filter medium and filter cake
89
Rotary Drum Vacuum Filters
It’s the most widely used device for separation of microorganisms from the fermentation broth
90
Mechanism of Rotary Drum Vacuum Filters:
-A steam-heated drum which is slowly rotating.
Evaporation takes place and solids are obtained dry.
The vapor run through condensers to recover the
solvent.
-It sucks liquid, leaving solids on the membrane surface, and features a knife discharge.
91
Membrane Filtration:
Under hydrostatic pressure, small particles will pass through a suitable membrane if the applied pressure exceeds the osmotic pressure of the solution
92
Reverse Osmosis Filtration(RO)
A separation in which there is forcing of a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure.
Applications:
1- Desalination (removing the salt from sea water)
2- Purify fresh water for medical
93
Disintegration of cells
If the metabolite is intracellular, no need for the supernatant, so Cells must be broken to get the metabolite without damaging the desired cell components.
94
Mechanical (Physical) methods of Disintegration of cells
1. Freezing (break cell wall) and thawing (release metabolite).
2. Pressure (high pressure break cell wall).
3. Shear by grinding
4. Ultra-sonic waves
95
Non-mechanical methods of of Disintegration of cells
Thermal, chemical or enzymatic
96
Chemical methods of of Disintegration of cells
-Changing osmotic pressure (cell wall explode).
-Drying
-Treatment with acids
-Solvents
97
Biological methods of of Disintegration of cells
-Enzymatic lysis of cell wall using lysozyme and
proteases.
-Enzymes are added during fermentation process at
certain stage which inhibit the formation of cell wall
98
Concentration methods:
Evaporation:
Direct evaporation of whole culture broth is used for low grade products.
Ex: Falling film evaporator
99
Falling film evaporator
-A continuous flow evaporator that allows the concentration of products.
-A large heat transfer surface allows minimal temperature difference between heating medium and the solution.
100
Working Principle
-The evaporator: disperses feed uniformly through heating tubes, partially evaporating and forming a thin layer.
-Steam: delivers heat, and gravity moves liquid and vapor downhill.
Vapour flow: aids liquid descent, and concentrated product and vapor are separated at the bottom.
101
Drying – water removing
-The process involves reducing moisture content in powder. -stabilizing moisture-sensitive materials, ensuring stable handling and storage, and using methods that minimize temperature rise.
102
Methods used for drying of heat-sensitive products:
A- Vacuum drying:
-It is applied in batch mode in chamber dryers, or continuously as in rotating drum vacuum dryers.
-is a method that removes moisture from a solid sample or air.
103
The principle is to use a vacuum in:
To lower the boiling point of moisture or solvent. Simultaneously, molecules diffuse to the surface and evaporate due to the low pressure.
104
Vacuum tray dryer
A vacuum tray dryer is a laboratory equipment used to dry materials sensitive to oxygen or thermal energy.
105
Rotating Drum Vacuum dryer (made from chromium plated steel):
The solution or slurry is run onto steam heated drum which is slowly rotating, evaporation will take place and solids are obtained dry
106
Vacuum drying examples:
-Vacuum tray dryer
-Rotating Drum Vacuum dryer
-Spray dryer
-Freeze drying (Lyophilization)
107
Spray dryer
-Can be used for drying of enzymes or antibiotics, used widely in food industry
-The solution or slurry is atomized by a nozzle or rotating disc.
108
Freeze drying (Lyophilization)
is a process in which water is transferred by the direct transition of water from solid (ice) to vapor, thus omitting the liquid state.
Uses: Drying antibiotics, dehydration of bacteria, vaccines, tissues, serum
109
Crystallization
is used especially in the recovery of acids, solvents, and in the purification of various compounds
110
Chromatographic techniques
are commonly used in the isolation and purification of fermentation products.
