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Bio Eng Quiz 2 and 3 > Quiz 3 - Pt. 3 (Factors - Thermal Sterilization > Flashcards

Quiz 3 - Pt. 3 (Factors - Thermal Sterilization Flashcards

1
Q

Factors for Consideration in Reactor Design

A

Heat removal
Foam Control
Providing Oxygen
Sterilization

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2
Q

Cellular metabolism produces heat, removed by internal coils or reactor jackets.

A

Heat removal

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3
Q

Cellular metabolism produces compounds that promote foaming.

A

Foam Control

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4
Q

Controlled by mechanical foam breakers and chemical additives.

A

Foam Control

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5
Q

Cellular respiration requires oxygen. Sparged air, impeller makes smaller bubbles and increases residence time.

A

Providing Oxygen

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6
Q

Single organism desired. Steam and filtering.

A

Sterilization

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7
Q

What Factors Limit Size of Reactors?

A

Ability to provide oxygen and remove heat.

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8
Q

Types of reactors

A
  1. Stirred-tank
  2. Bubble column
  3. Airlift
  4. Propeller Loop
  5. Jet Loop
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9
Q

_____
* Empirical
* Make the ______ the same in the small scale as in the large scale

A

Scale-Up
Controlling regime

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10
Q

Scale - Up Criterion

  • Power Input - ____
  • _____ - mixing time
  • Tip speed - _____
  • Reynolds number - _____
A
  • OTR
  • Liquid circulation rate
  • Shear
  • Geometry
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11
Q
  • Scale-up by requiring characteristic times to be constant between the small and large scale.
  • Many types of characteristic times: related to ____ (5)
A

mixing
diffusion
oxygen mass transfer
reaction
growth

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12
Q

type of reactor?

  • Good oxygen mass transfer
  • High energy requirement for mixing
  • Seal to maintain, keep sterile
A

Agitated Tank

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13
Q

type of reactor

  • Low shear environment
  • No seal needed
  • Restricted to low viscosity
  • Less mixing than agitated tank
  • Bubble coalescence limits upper air flow rate
A

bubble column

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14
Q

type of reactor?

  • Better mixing than bubble column with same low shear and energy requirements and lack of seal
  • work with higher viscosity liquids than bubble columns
  • Still less mixing than agitated tank
A

Loop reactors

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15
Q

Agitated Tanks pt. 1

  • _____ breaks bubbles into smaller ones to provide for better oxygen mass transfer
  • _____ are typically glass, ____ are typically stainless steel
  • Heat removal/addition is typically by ____ along the wall, or a ____ around the tank
A
  • impeller
  • bench-top tanks, commercial fermenters
  • coils, water jacket
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16
Q

Agitated Tanks Pt. 2

  • _____ prevents foaming problems, but can cause additional _____ transfer resistance
  • “_____”- volume of liquid in tank; does not include head space
  • _____ for agitator shaft must not allow contamination
  • _____ are used to augment mixing and gas dispersion
A
  • Antifoam, mass
  • working volume
  • seal
  • baffles
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17
Q

type of impeller?

  • ____ : disc with ____ blades.
  • Pumps fluid in a ____ direction.
  • Compartmentalization with ____ impellers on a shaft.
A
  • rushton impeller
  • 6 to 8
  • radial
  • multiple
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18
Q

type of impeller?

  • ____: pumps liquid in a ____ direction.
  • Lower energy for the same oxygen mass transfer.
  • Lower shear rates.
A
  • Axial flow impeller
  • vertical
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19
Q

Oxygen Mass transfer mechanism

  1. ____ phase oxygen concentration
  2. Transfer across stagnant ____ layer
  3. Partitioning into the ____ phase (C” at saturation)
  4. Transfer across stagnant ____ layer
  5. ____ concentration (C₁)
  6. Transfer across stagnant liquid layer to ____
A
  1. Bulk gas
  2. gas
  3. liquid
  4. liquid
  5. bulk liquid
  6. cell
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20
Q

Common On-line Instrumentation

A
  • pH
  • Temperature
  • Dissolved oxygen
  • Foam
  • Flow rates
  • Level Off-gas composition (CO2, O2, VOCs)
21
Q

Control

  • Fermentation process control is generally not as sophisticated as _____ process control due to a lack of on-line sensors.
A

chemical production

22
Q
  • Why is there a lack of on-line sensors?
  • Each probe into the fermentor increases the _____,
  • difficult to sterilize some probes,
  • probe fouling,
  • probe placement (gradients within the fermentor).
A
  • probability of contamination
23
Q

Oxygen Mass Transfer

  • Transfer rate at steady state is determined by the _____ (just like on a highway).
A

slowest rate

24
Q
  • As we have seen before, for an oxygen-transfer rate limited process or at steady state
  • _____ is not the rate at which you provide air to the reactor.
  • You will actually provide much more oxygen to the ____ than is transferred to the ____.
A
  • oxygen mass transfer
  • reactor, cell
25
Q

the value of the product K_La (volumetric transfer coefficient) often determined the ____

A

maximum cell mass X

26
Q

absence of detectable viable organisms

A

sterilization

27
Q

reduction in the amount to detectable, viable organisms.

A

Disinfection

28
Q
  • Sterilization is ______: some portion of the the population is more resistant to sterilizing agents than other portions.
A

probabilistic

29
Q

Determining O_{2} Mass Transfer

  • Correlations can be used to predict the _____ k_{L}*a
A
  • volumetric transfer coefficient
    *
30
Q

Methods of Sterilization

A
  • filter
  • heat
  • radiation
  • chemical
31
Q

: Heat sensitive liquids and gases. Most common for gases - P important.

A

filter

32
Q

: Most common for liquids and equipment. Steam. Typically 121°C. Time and T important. Risk degrading medium components.

A

heat

33
Q

method of sterilization
* Radiation: Surfaces.
* Chemical: Risk toxic residues.

A
  • radiation
  • chemical
34
Q

a faster growing contaminating organism can outgrow the desired organism and cause washout of the desired organism.

A

chemostat

35
Q
  • the product can be biologically contaminated (could be lethal) or the purity profile could be significantly effected (indust. fermentations 100 kl).
A

batch

36
Q

Experimental Determination of O₂ Mass Transfer

  • The previous correlation offer design estimates.
  • Medium components, _____, and ____ can affect k_La and oxygen solubility
  • ____ experiments can be done to measure k_La
  • Unsteady state, steady state, dynamic and sulfite methods to measure k_La
A
  • temperature, pressure
  • simple
37
Q

Fill the reactor with medium only no cells. Measure the DO concentration in the medium. Remove oxygen from the medium by sparging with N₂. Introduce air, and record the increase in DO.

A

Unsteady Method

38
Q
  • to clean with the purpose of removing possible biological and nonbiological threats to human health.
A

sanitize

39
Q

to greatly reduce the number of living organisms.

A

disinfect

40
Q
  • to eliminate all viable organisms present (often our goal).
A

sterilize

41
Q

can be sterilized by heat, microfiltration, radiation, chemical agents, UV light

A

fluids and process equipment

42
Q
  • a cell, spore, or virus that is dead will not reproduce (cells and viruses) or germinate (spores) under conditions favorable for growth (opposite is “viable”).
A

death

43
Q

Requires an oxygen gas analyzer for the effluent air.Perform an O, mass balance to obtain OUR.

A

Steady-State Method

44
Q

Dynamic Method
* Utilizes a fermentor with ____.
* Requires only a DO meter.
* The air to the fermentor is shut off, and the DO decreases due to ____ by the microorganisms. The air is then turned on, and the the DO increases.

A
  • actively growing cell
  • consumption
45
Q
  • When the air is off, k, a = 0, so the slope of DO vs. time is equal to -qo2X.
  • The slope of the _____ with time can be determined from ____ to the curve. The slope of the plot dC₁/dt-q02X vs (C-CL) will be k₁a.
A
  • ascending curve
  • tangents
46
Q

Specific Agents pt. 1

  • Thermal sterilization a common method.
  • Ethylene oxide is common for the insides of reactors that can’t be heat or steam sterilized.
  • Media that can’t be heat sterilized (___) must be filter sterilized using filters with narrow pore-size distributions.
A
  • thermal sterilization
  • ethylene oxide
  • heat labile vitamins, proteins, sugars
47
Q

Specific Agents pt. 2

  • ____ in water with HCl to pH 2 is a good sterilizing fluid.
  • Weak (3%) ____ is commonly used to sterilize filtration equipment.
A
  • 70% v/v ETOH
  • sodium hypochlorite solution
48
Q

is often assumed to be a function of temperature (as before):

A
  • k_{d} - specific death constant

Bio Eng Quiz 2 and 3 (9 decks)

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