SPECIALIZED ENGLISH – SEMTESTER 5MANAGEMENT Chapter 24 FUNDAMENTALS OF BIOLOGICAL Dr.. 2011 WASTEWATER TREATMENT & REUSE Bacterial growth Bacterial reproduction Bacterial growth pattern
Trang 1SPECIALIZED ENGLISH – SEMTESTER 5
MANAGEMENT
Chapter 24 FUNDAMENTALS OF BIOLOGICAL
Dr Tran Thi My Dieu
Sep 2011
WASTEWATER TREATMENT & REUSE
Bacterial growth
Bacterial reproduction
Bacterial growth patterns in a batch reactor
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Bacterial growth patterns in a batch reactor
Bacterial growth and biomass yield
BACTERIAL REPRODUCTION
Is it important in biological treatment?
Binary fission
1 original cell becomes 2 new ones
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Bacteria reproduce by Asexual mode
Budding
new ones
Generation time ~ 20 min - days
Rapid change in biomass
BACTERIAL REPRODUCTION
Is it important in biological treatment?
Spherical-shaped bacteria
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Assume 1 m diameter
Specific gravity of 1.0 Generation time ~ 30 min
Estimate bacteria mass after 12 h?
BACTERIAL REPRODUCTION
Is it important in biological treatment?
Estimate bacteria mass after 12 h?
Weight of 1 cell ~ 5.0 x 10 -13 g
6
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Bacteria mass in 12 h ~ 8.4 x 10 -6 g
Number of cell is quite large compared to the mass
In biological treatment systems, bacteria would not
continue to divide indefinitely because of
environmental limitations (substrate and nutrient)
BACTERIAL GROWTH PATTERNS IN A
BATCH REACTOR
Lag phase Exponential growth phase
Stationary phase Dead phase
Substrate
To acclimate to new environment Multiplying at max rate
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Time
Substrate
Biomass
Batch process biomass growth phases with changed in substrate and biomass versus time
Amount of growth is offset
by the death of cells
No growth
Trang 2BIOMASS YIELD Biomass yield Y = g biomass produced
g substrate utilized
g biomass/g COD removed
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g biomass/g BOD removed
g biomass/g VFAs used
g biomass/g N-NH 4 oxidized
How to measure biomass?
BIOMASS YIELD
How to measure biomass?
Increase in biomass can be measured by Volatile suspended solids (VSS) or pCOD
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Volatile suspended solids (VSS) or pCOD Protein content (growth relates to true microbial mass) DNA (if the reactor solids contain proteins) ATP (if the reactor solid contain proteins) Turbidity (if very low biomass concentration) Bacterial cell counts
BACTERIAL GROWTH AND
BIOMASS YIELD
How to estimate biomass yield?
Estimating biomass yield and oxygen
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requirements from stoichiometry
Estimating biomass yield from bioenergetics
BACTERIAL GROWTH AND BIOMASS YIELD
Estimating biomass yield from stoichiometry
3C 6 H 12 O 6 + 8O 2 + 2NH 3 2C 5 H 7 O 2 N + 8CO 2 + 14H 2 O
Substrate Oxygen Nutrient Biomass
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The yield based on glucose consumed
Y =
g biomass produced
g glucose used
g C 5 H 7 O 2 N
g C 6 H 12 O 6
=
2 x 113
3 x 180
=
Y = 0.42 g cells/g glucose used
BACTERIAL GROWTH AND
BIOMASS YIELD
Estimating biomass yield from stoichiometry
In practice, used COD and VSS ~ organic & cells
Determine COD of glucose
C H O + 6O 6CO + 6H O
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C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O
180 6 x 32
COD of glucose =
6 x 32 180
= 1.07 g O 2 /g glucose
Y =
g C 5 H 7 O 2 N
g (glucose as COD)
= 0.39 g cells/g COD
2 x 113
3 x 180 x 1.07
=
BACTERIAL GROWTH AND BIOMASS YIELD
Estimating oxygen requirement from stoichiometry COD utilized = COD cells + COD of oxidized substrate
Oxygen consumed
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C 5 H 7 O 2 N + 5O 2 5CO 2 + NH 3 + 2H 2 O COD cells =
5 x 32 113
= 1.42 gO 2 /g cells
Trang 3BIOMASS YIELD
Estimating oxygen requirement from stoichiometry
Oxygen consumed = COD utilized – COD cells
= 1 07 gO /g glucose x 3 moles x 180 g glucose/mole
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= 1.07 gO 2 /g glucose x 3 moles x 180 g glucose/mole
- 1.42 gO 2 /g cells x 2 moles x 113 g cells/mole
= 577.8 g O 2 – 320.9 g O 2 = 256.88 g O 2
BIOMASS YIELD
Estimating oxygen requirement from stoichiometry Oxygen consumed per unit of COD used:
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Oxygen consumed Glucose as COD
=
256.88 g O 2
3 moles x 1.07 gCOD/g glucose x 180 g glucose/mole
= 0.44 g O 2 /g COD used
BACTERIAL GROWTH AND
BIOMASS YIELD
Estimating oxygen requirement from stoichiometry
Oxygen consumed per unit of COD used:
3C 6 H 12 O 6 + 8O 2 + 2NH 3 2C 5 H 7 O 2 N + 8CO 2 + 14H 2 O
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3 x 180 8 x 32
Oxygen consumed
Glucose as COD
=
8 x 32
3 x 180 x 1.07
= 0.44 g O 2 /g COD used
ASSIGNMENT 2
Estimate biomass yield in term of g cells/g saccharose
saccharose used and g cells/g COD used if used and g cells/g COD used if
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C 12 H 22 O 11 + O 2 + NH 3 C 5 H 7 O 2 N + CO 2 + H 2 O