Quiz 3

Question 1

What are some inorganic immobilization materials?

Answer 1

Clays
Silicates
Glass beads
Ceramics

Question 2

What are some organic immobilization materials?

Answer 2

Cellulose
Starch
Alginate
Activated carbon
Keratin
Agar-agar
Loofa sponge

Question 3

What are some types of cell immobilization?

Answer 3

Biofilms
Flocs
Sludge
Entrapment (membrane of matrix)

Question 4

What are some benefits to cell immobilization?

Answer 4

1. High cell concentration in a reactor
2. Eliminates need for cell recycle
3. Eliminates cell washout at high dilution rates
4. Enhanced productivity
5. Improved genetic stability
6. Protects cells from toxic effects

Question 5

What are some challenges to cell immobilization?

Answer 5

1. Diffusion limitations can dominate
2. Microenvironmental conditions are difficult to control (causes heterogeneity)
3. Gas dispersion may cause problems

Question 6

What are 2 common applications for biofilms?

Answer 6

1. Wastewater treatment
2. Mold fermentations

Question 7

What are four advantages to solid-state fermenters?

Answer 7

1. Lower reactor volume
2. Lower capital and operating costs
3. Reduced chance of contamination by bacteria
4. Energy efficient

Question 8

What are two disadvantages to solid-state fermenters?

Answer 8

1. Poor mixing, high heterogeneity
2. Difficult to control operational parameters

Question 9

What are four types of solid-state fermenters?

Answer 9

1. Tray type fermenter
2. Packed-bed fermenter
3. Rotating drum design
4. Mixed and aerated bioreactor

Question 10

What are three benefits to internal mechanical agitation?

Answer 10

1. High oxygen transfer
2. Scalable to larger sizes
3. Accomodates high viscosities

Question 11

How large is a impeller diameter relative to its tank diameter in a typically internal mechanical agitation bioreactor?

Answer 11

30-50% of tank diameter

Question 12

Name fours types of impellers

Answer 12

1. Ruston impeller
2. Turbine impeller
3. Marine impeller
4. Paddle impeller

Question 13

What are 5 advantages to bubble columns

Answer 13

1. Simple design
2. High energy efficiency
3. Low-shear environment
4. Minimize entry of contamination
5. Effective in low viscosity liquid media

Question 14

What are 3 disdvantages to bubble columns?

Answer 14

1. Bubble and foam formation
2. Limited applications
3. Energy inefficiencies from perforated plates

Question 15

Name 3 advantages to loops reactors

Answer 15

1. Handles high viscosities
2. High oxygen transfers rates
3. Better cooling

Question 16

Name 4 advantages to single-use reactors

Answer 16

1. Rapid implementation
2. Greater responsiveness to market conditions
3. Ease in meeting sterilization requirements
4. Light-weight

Question 17

Name four disadvantages to single-use bioreactors

Answer 17

1. Limited ability of mixing and oxygen transfer
2. Possibility of leaching materials from plastic
3. Size limitations
4. Plastic waste generation

Question 18

What does the variable C_L represent?

Answer 18

Dissolved oxygen concentration

Question 19

What does the variable C* represent?

Answer 19

saturated dissolved oxygen concentration

Question 20

What is critical oxygen concentration?

Answer 20

Growth rates become independent of dissolved oxygen

Question 21

Oxygen transfer rates are dependent on which three variables?

Answer 21

1. Oxygen transfer coefficient
2. Dissolved oxygen conc.
3. Saturated oxygen conc.

Question 22

Oxygen uptake rates are dependent on which four variables?

Answer 22

1. Growth rate
2. Product yield coefficient
3. Cell conc.
4. Respiration rates

Question 23

Name three methods to determine kLa

Answer 23

1. Empirical method
2. Steady-state method
3. Dynamic method

Question 24

What is a main difference between the steady-state and dynamic method?

Answer 24

The OTR and OUR are not equal

Question 25

Name 4 common sensors in a reactor

Answer 25

1. Physical environment (pH, temperature, DO, pressure, viscosity 2. Inputs (volume, rates, power) 3. Gas flow rates 4. Chemical composition

Question 26

Name four types of products

Answer 26

1. Biomass (cells) 2. Extra cellular products 3. Intracellular product 4. Unconverted substrate

Question 27

Name the four steps to processing bioreactor broth

Answer 27

1. Remove particulates (cell debris, filtration) 2. Primary isolation 3. Purification 4. Final product isolation

Question 28

Name five options for sterilization of liquids

Answer 28

1. UV radiation 2. Sonication 3. Filtration (membranes) 4. Heating (using autoclave or pasteurization) 5. Chemical additions (ethanol, formaldehyde)

Question 29

What source of feedstock has the highest biomass yield

Answer 29

Microalgae (switchgrass second)

Question 30

List some sources of bioethanol

Answer 30

Corn stover Corn Wheat Cassava Sweet sorghum Sugar beet Sugar cane Switch grass Microalgae