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Welcome to Industrial Bioprocessing and
Bioremediation 2014 !(Environmental Biotechnology)
Unit coordinator background:
http://profiles.murdoch.edu.au/myprofile/ralf-cord-ruwisch/
This unit is different to your other biotechnology units as it focusses on the TECHNOLOGY part (engineering).
This requires being able to analyse processes, solve problems, predict outcomes, carry out mass balances, etc.
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Welcome to Industrial Bioprocessing and
Bioremediation 2014 !(Environmental Biotechnology)
Example processes: How to:
•make renewable biogas from organic wastes.
•remove polluting nutrients from wastewater
•breed microalgae for food or energy production
•make beer, yoghurt,
•mine ores by using bacteria (bioleaching)
•understand microbial processes in ocean, soil and bioreactors
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Fundamentals taught
Bioprocesses convert S to P
How much S to P?
Mass balance
How much hydrogen gas can we make as fuel from fermenting sugars ?
How much oxygen is needed for respiration?
How much electricity can be formed from sugar ?
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Week
Day Time Venue Topic Lecturer
1 MonJul 21
9.30-10.30 AMEN 2.023
1. Introduction, Diffusion, Bioreactor
RCR
MonJul 21
10.30-11.30 LB 3.032
RCR
TuesJul 22
8.30-9.30 AMEN 2.023
1.2 Oxygen solubility and transfer
RCR
WedJul 23
12.30-1.30 AMEN 2.023
1.3 Oxygen mass transfer coefficient kLa
RCR
2 MonJul 28
9.30-10.30 AMEN 2.023
2.1 Microbial oxygen uptake
RCR
MonJul 28
10.30-11-30
LB 3.032
Help with BioProSim1
RCR
TuesJul 29
8.30-9.30 AMEN 2.023
2.2 Oxygen steady state calculations
RCR
WedJul 30
12.30-1.30 AMEN 2.023
2.3 Online OUR monitoring
RCR
3 MonAug 4
9.30-10.30 AMEN 2.023
3.1 Fundamentals of microbial growth
RCR
MonAug 4
10.30-11-30
LB 3.032
RCR
TuesAug 5
8.30-9.30 AMEN 2.023
3.2 Microbial competition for substrate
RCR
WedAug 6
12.30-1.30 AMEN 2.023
3.3 Four growth constants determine growth
RCR
Lecture content over the next weeks
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Week Venue Topic Time1 LB 3.032
Small Comp Lab
Virtual Lab 1- BioProSim1 1.30-5.30pm
2
BS 2.050 Oxygen Transfer - RCR 1.30-5.30pm
3
BS 2.050 Oxygen Uptake - RCR 1.30-5.30pm
4
BS 2.050
Penicillin Production as a secondary metabolite demonstration – RCR
1.30-5.30pm
5 BS 2.050 Algal Biotechnology- NM 1.30-5.30pm
6 Study Break7
BS 2.050 Chemostat Project (or week 9) 1.30-5.30pm*
8
BS 2.050
Chemostat Project (or week 10)
All Week *
9
BS 2.050 Chemostat Project (or week 7) 1.30-5.30pm*
10 BS 2.050 Chemostat Project (or week 8) All Week*
11 Study Break12
LB 3.032Small Comp Lab
Bioprocess Modelling 1.30-5.30pm
13 Off Campus Visit of Industrial Bioprocessing Site 2.00pm offsite
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TBA TBA TBA
15 Study Break
Lab schedule over the next weeks
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Type Topic Marks
Due Week
Due Day
CBLA1) Oxygen solubility (OTR1) 1 1 FriCBLA1) Oxygen transfer (OTR2) 1 1 FriCBLA1) Oxygen uptake (OTR3) 1 2 FriGroup Instant Lab Report on oxygen
transfer1 2 Thurs
Group Instant Lab Report on oxygen uptake
1 3 Thurs
Individ.
BioProSim 1 mass transfer simulation
2 2 Fri
CBLA1) Microbial growth principles (GRO1)
1 3 Mon
CBLA1) Microbial growth kinetics (GRO2) 1 3 WedCBLA1) Microbial cell cultivation (GRO3) 1 3 FriIndivid.
Lab Report on Algal Biotechnology
4 5 Thurs
Group Penicillin a secondary metabolite?
2 7 Thurs
CBLA1) Bio-reaction oxidation states (OXS)
1 7 Fri
Individ.
BioProSim 2 chemostat simulation
8 8 Mon
Exam 2)
Mid-semester Exam 25 7
Group Chemostat Group Report 10 10 /12
Thurs
Exam 2)
End-semester Exam 40
Total 100
Assessed activities over the next weeks
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Type Topic Marks Due Week
Due Day
CBLA1) Oxygen solubility (OTR1) 1 1 FriCBLA1) Oxygen transfer (OTR2) 1 1 FriCBLA1) Oxygen uptake (OTR3) 1 2 FriGroup Instant Lab Report on oxygen transfer 1 2 ThursGroup Instant Lab Report on oxygen uptake 1 3 ThursIndivid. BioProSim 1 mass transfer simulation 2 2 FriCBLA1) Microbial growth principles (GRO1) 1 3 MonCBLA1) Microbial growth kinetics (GRO2) 1 3 WedCBLA1) Microbial cell cultivation (GRO3) 1 3 FriIndivid. Lab Report on Algal Biotechnology 4 5 ThursGroup Penicillin a secondary metabolite? 2 7 ThursCBLA1) Bio-reaction oxidation states (OXS) 1 7 FriIndivid. BioProSim 2 chemostat simulation 8 8 Mon Exam 2) Mid-semester Exam 25 7 Group Chemostat Group Report 10 10 /12 ThursExam 2) End-semester Exam 40 Total 100
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Type Topic Marks
Due Week
Due Day
Group Instant Lab Report on oxygen transfer
1 2 Thurs
Group Instant Lab Report on oxygen uptake
1 3 Thurs
Individ.
BioProSim 1 mass transfer simulation
2 2 Fri
Individ.
Lab Report on Algal Biotechnology
4 5 Thurs
Group Penicillin a secondary metabolite?
2 7 Thurs
Individ.
BioProSim 2 chemostat simulation
8 8 Mon
Exam 2)
Mid-semester Exam 25 7
Group Chemostat Group Report 10 10 /12
Thurs
Exam 2)
End-semester Exam 40
Total
10
Type Topic Marks
Due Week
Due Day
Group Instant Lab Report on oxygen transfer
1 2 Thurs
Group Instant Lab Report on oxygen uptake
1 3 Thurs
Individ.
BioProSim 1 mass transfer simulation
2 2 Fri
Individ.
Lab Report on Algal Biotechnology
4 5 Thurs
Group Penicillin a secondary metabolite?
2 7 Thurs
Individ.
BioProSim 2 chemostat simulation
8 8 Mon
Exam 2)
Mid-semester Exam 25 7
Group Chemostat Group Report 10 10 /12
Thurs
Exam 2)
End-semester Exam 40
Total
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Fundamentals taught
Bioprocesses convert S to P
Sugar to energy (biogas, ethanol, hydrogen, electricity)
Pollutants to harmless substances (dechlorination, degradation, dirty water to clean water
Need to be able to predict (modelling)
Quantify (rates)
Understanding (driving force, equilibrium)
12
Fundamentals taught
Bioprocesses questions:
Why ?
How ?
How fast?
What mechanism ?
Modelling
13
Learning tools used
Bioprocess analysis (theory) Computer simulation
Bioprocess execution and analysis (Chemostat project)
Spreadsheets for data processing and analysis
Peer reviewed websites of scientific analysis of literature
Using computer learning activities
Industry trip
Focussed scientific writing.
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Link between Research and Teaching
A number of undergraduates honours PhD Senior Engineers (Water Corporation, Design companies, Bioprocess Operators)
Teaching topics drawn from own research projects and publications.
Input from current researchers into the project
Link to industry.
So, on many of the topics you talk to science experts, not just “teachters that obtained their knowledge from books”
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Bioprocessing – Biotechnology: Make money from bioprocesses
Inputs are of lower value than outputs (products)
Computer based learning activities (CBLA) are on
http://sphinx.murdoch.edu.au/units/extern/BIO301/teach/index.htm
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17
18
19
20
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Lecture overview L1-3
Lecture 1: Intro, study guide, what is a bioreactor,Learning by interacting
Lecture 2: What is diffusion, how can we predict the behaviour of a randomly moving molecule? moving dots, entropy, driving force, equilibrium, rate of diffusion, first order kinetics, kLa
Lecture 3: oxygen transfer rate, kLa value. Graphical method of determining the kLa. Mathematical (2 point) determination of kLACalculation and prediction of oxygen transfer as function of DO. Oxygen transfer efficiency. Bacterial OUR, DO. steady state
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Molecular diffusion relies on random movement resulting in uniform distribution of molecules
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Oxygen Transfer Rate (OTR)Overview
Diffusion, how does it work, how can we predict it?
Diffusion is random …. and yet predictable.A simple model simulation can show that although the diffusion movement is random, it can be precisely predicted for large number of molecules (e.g. Fick’s law of diffusion)
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Oxygen Transfer Rate (OTR)(diffusion, convection)
LowOTR High
OTR
Transfer by diffusion is extremely slowand depends on surface area
Wind
Oxygen transfer by convection(turbulences) is more efficient
Air In
••
•
••• • ••
• • Bioreactors combine maximum convectionwith maximum diffusion
• Course bubbles cause more convection,fine bubbles more diffusion
How soluble is oxygen?25
The net transfer of oxygen from
•gas phase to solution reaches a dynamic equilibrium
•O2 input = O2 output
•equilibrium results in defined saturation concentration (cs).
•The saturation concentration is also the oxygen solubility
•How soluble is oxygen?
Oxygen solubility (cS)
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Oxygen is not very polar poorly soluble in water.
Oxygen Solubility is described by Henry’s Law which applies to all gases
p = k*cSp = partial pressure of oxygenk = constant depending on gas type, solution
and temperaturecS = concentration of oxygen dissolved in water
• Meaning: The amount of oxygen which dissolves in water is proportional to the amount of oxygen molecules present per volume of the gas phase.
• Partial pressure ~ number of O2 molecules per volume of gasincreases with O2 concentration in gas
increases with total gas pressure
How to calculate partial pressure? (refer to CBLA)
Oxygen solubility (cS)
27
Examples of using the proportionality between partial pressure of oxygen in the atmosphere and the saturation concentration cS:
p = k*cSp = partial pressure of oxygenk = constant depending on gas type, solution
and temperaturecS = concentration of oxygen dissolved in water
• If the reactor is operated under 2 times atmospheric pressure (200kPa instead of 100 kPa air pressure), the new saturation concentration will be abou 16 mg/L instead of 8 mg/L.
• If air (partial pressure = 0.21* 100 kPa) is replaced by pure oxygen atmosphere (partial pressure 100kPa) the oxygen saturation concentration is about 40 mg/L (more precise 8*100/21) instead of 8 mg/L.
How to calculate partial pressure? (refer to CBLA)
Oxygen solubility (cS)
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Effect of temperature
Oxygen solubility decreases with increasing temperature.
Overall: oxygen is poorly soluble (8mg/: at room temp.)
More important than solubility is oxygen supply rate (oxygen transfer rate OTR).
0
5
10
15
0 20 40 60
cs =468
(31.6 + T)
Oxy
gen
Sat
ura
tio
n
Co
nce
ntr
atio
n c
s (
mg
/L)
Temperature (°C)
Oxygen solubility (cS)
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Oxygen Transfer Rate (OTR)(gradient, driving force)
Question: What is the driving force for oxygen dissolution?
OTR At oxygen saturation concentration (cs): dynamic equilibrium exists between oxygen transferred from the air to water and vice versa. No driving force
Answer: The difference between cS and the actual dissolved oxygen concentration (cL) is the driving force. OTR is proportional to the that difference. Thus:
OTR ~ (cS – cL)
Need to determine the proportionality factor
30
1. Deoxygenation (N2, sulfite + Co catalyst)2. Aeration and monitoring dissolved oxygen concentration (D.O. or cL) as function of time
3. OTR = slope of the aeration curve (mg/L.h or ppm/h)
Significance of OTR: critical to know and to control forall aerobic bioreactors
0 5 10
8 Air On
cL (
pp
m)
Time (min)
OTR – depends on DO (cL)
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OTR = kLa (cs - cL)
Mg/L/h h-1 mg/L
4. Observation: OTR decreases over time (and with incr. cL)
5. OTR is not a good measure of aeration capacity of a bioreactor
6. OTR is highest at cL = zero (Standard OTR)
7. OTR is zero at oxygen saturation concentrations (cs)
8. OTR is negatively correlated to cL
9. OTR is correlated to the saturation deficit (cs - cL),
which is the driving force for oxygen transfer
9. The factor of correlation is the volumetric mass transfer
coefficient kLa
OTR – depends on DO (cL)
32
First: steep step in oxygen (top layer saturated, next layer oxygen free)
Then: buildup of a gradient of many layers.
Each layer is only slightly different from the next Transfer from layer to layer has little driving force.
Gradient build-up inhibits fast diffusion
OTR –Significance of gradient
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10. OTR is not a useful parameter for the assessment of the aeration capacity of a bioreactor. This is because it is
dependent on the oxygen concentration (cL)
11. The kLa value is a suitable parameter as it divides OTR by saturation deficit:
12. kLa = the key parameter oxygen transfer capacity. How to determine it?
OTR(cs - cL)
kLa =
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Lec 2 summary:
Oxygen is poorly soluble depending mainly on •partial pressure in headspace•Temperature
OTR is driven and proportional to driving force (cS-cL)
kLa is the proportionality factor (first order kinetics)
kLa describes the performance of a bioreactor to provideOxygen to microbes
Next lecture: quantify kLA
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Lec 3 outlook:
•Aeration curve•Quantify OTR at a given point of an aeration curve•Quick estimate of kLa•Graphical determination of kLa•Mathematical determination of kLa•Run computer simulation to obtain data•Oxygen transfer efficiency (OTE)•OTR proportional to cs-cL•OTR inverse proportional to cL
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OTR – Quick estimate of kLAExample: determine OTR at 6 mg/L
OTR is the slope of the tangent for each oxygen concentration
OTR = ∆ cL/ ∆ t = 5 mg/L/ 4.5 min = 1.1 mg/L/min = 66 mg/L/h
0 5 10
8 Air OncL
(m
g/L
)
Time (min)
6
4.5 min
5 mg/L
37
kLa = OTR
= 66 ppm / h
(cs-cL)
= 3.3 h-1
(8 ppm – 6 ppm)
Q: Problem with this method?
A: based on one single OTR slope measurement and unreliable to obtain from real data.
OTR – quick estimate of kLA
Time
DO
38
1. Monitor aeration curve
2. Determine graphically the OTR at various oxygen concentrations (cL)
8
2
4
6
0 5 10
3. Tabulate OTR and corresponding cL values
cL (
pp
m)
0.53.04.06.08.0
Time (min)
7.55.04.02.00.0
306050250
cL (mg/L) Cs - cL (mg/L) OTR (mg/L/h)
At 6 ppm: OTR = 25 mg/L/h
At 4 ppm: OTR = 50 mg/L/hAt 3 ppm: OTR = 60 mg/L/h
At 0.5 ppm: OTR = 30 ppm/h
OTR – Graphical determination of kLa
39
0
50
100
0 2 4 6 8
4. Plot OTR values as a function of cs - cL.O
TR
(m
g/L
/h) Standard OTR
cs
cs- cL (mg/L)
5. A linear correlation exists between kLa and the saturation deficit (cs - cL) which is the driving force of the reaction.
6. The slope of the plot OTR versus cs - cL is the kLa value.
7. The standard OTR (max OTR) can be read from the intercept with the cs line. (Standard OTR = 96 ppm/h)
kLa = = 12 h-170 mg/L/h
6 mg/L
OTR – Graphical determination of kLa
40
Mathematical Determination of kLa1. OTR is a change of cL over time, thus = dcL/dt
Integration gives2. kLa = dcL/dt
(cs- cL)
( )cs - co3. kLa = ln cs - ci
ti - to
( )8 - 3 ppm kLa = ln 8 - 6 ppm
10.5 - 6.1 min
= 0.21 min-1 = 12.5 h-1= ln 2.5
4.4 min
•
•D
isso
lved
Oxy
gen
Con
cent
ratio
n (m
g/L)
ci = 6
co = 3
to ti Time (min)
cs
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4. This method should be carried out for 3 to 4 different intervals. By aver
5. Once the kLa is known it allows to calculate the OTR at any given oxygen concentration:
OTR = kLa (cs - cL)
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Factors Affecting the Oxygen Transfer Coefficient kLa
kLa consists of:
• kL = resistance or thickness of boundary film• a = surface area
Bubble BulkLiquid
Cell
[Oxy
gen
]
Distance
Main boundary layer = steepest gradient→ rate controlling, driving force 43
Effect of Fluid Composition on OTR
The transfer across this boundary layer increases with:
1) ↓ thickness of the film, thus ↑ degree of shearing (turbulence)
2) ↑ surface area
3) ↓ surface tension
4) ↓ viscosity (best in pure water)
5) ↓ salinity
6) ↓ concentration of chemicals or particles
7) detergents?
8) ↑ emulsifiers, oils, “oxygen vectors”
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Oxygen Transfer Efficiency (OTE)
OTE =oxygen transferred
oxygen supplied
Significance of OTE: economical, evaporation
Calculation of OTE (%):
% OTE =oxygen transferred (mol/L.h)
oxygen supplied (mol/L.h)X 100
Why do students find this type calculation difficult?Units are disregarded. Molecular weights are misused.
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Oxygen Transfer Efficiency (OTE)
A bioreactor ( 3 m3) is aerated with 200 L/min airflow. If the OTR is constant (100 mg/L/h) determine the %OTE.
1. Convert the airflow into an oxygen flow in mmol/L/h
200 L air /min = 12000 L air/h
= 2520 L O2/h
= 102.9 mol O2/h
= 34.3 mmol O2/L.h
(x 21%)
(÷ 24.5 L/mol)
(÷ 3000 L)
2. OTR
(x 60)
100 mg/L.h = 3.1 mmol O2/L.h (÷ 32 g/mol)
% OTE =3.1 (mmol/L.h)
34.3 (mol/L.h)X 100
= 9% 46
Oxygen Transfer Efficiency (OTE)
OTE is dependent upon the cL in the same way than OTR
OTE decreases with increasing airflow(more oxygen is wasted)
% O
TE
5
10
Airflow
47
Engineering Parameters Influencing OTR
Increase depth vessel
Decrease bubble size
Increase air flow rate
Increase stirring rate
Deeper vessel bubbles rise a long way ↑ OTR, OTE but more pressure required ↑ $$
Larger surface area ↑ OTR, OTEsmaller bubbles rise slower more gas hold up ↑ OTR, OTE
↑ Number of bubbles ↑ OTR but ↓ OTE
↑ turbulence ↓ thickness of boundary layer ↑ OTR, OTE
↓ Bubble size ↑ OTR, OTE 48
Rate is proportional to concentration First order kinetics
Slope = kLa
max OTR
OT
R (
mg
/L.h
)
Dissolved oxygen [mg/L]
OTR = kLa (O2 saturation (cS) – O2 concentration (cL))
(first order kinetics)
Aeration Curve
Time
Dis
solv
ed O
xyg
enAir on(cs)
OTR – from aeration curve to kLa summary
49
During aeration of oxygen free water, the dissolved oxygen increases in a characteristic way
OTR – Aeration curve from CBLA
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Can the relationship between rate and DO be expressed mathematically?
•Highest Rate at lowest dissolved oxygen concentration
•Rate of zero when DO reaches saturation concentration
OTR – aeration curve from CBLA
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