Download BABE Bio-Augmentation Batch Enhanced NITRIFICATION

BABE
Bio-Augmentation Batch Enhanced
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Principles
Benefits
Operational aspects
Example
NITRIFICATION
• Nitrification is the limiting step in the design of
activated sludge WWTP
(SRT is the key design parameter in AS systems)
• Certainly at lower temperatures
• Augmentation of nitrifiers to the activated sludge plant
effectivelyy reduces the minimal SRT needed.
SRTm =
1
_________________________
μAmT - bAmT + addition rate
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NITRIFICATION – BIOAUGMENTATION (1)
• Addition of externally cultivated nitrifyers
Often not effective because bacteria are not adapted to
specific conditions of wastewater treatment plant
If suspension of cells is used
the bacteria fall prey
to protozoa
p
NITRIFICATION – BIOAUGMENTATION (2)
• Cultivate bacteria on the ammonium present in the
sludge digestor effluent
- Grow in flocs – Prevent predation
- Combined effect: Less load to main treatment line and
increased activity of nitrifyers in main line
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BIO-AUGMENTATION (BABE) REACTOR (1)
Influent
Effluent
Return sludge line
Reject water from digester
(T~>28oC)
BABE reactor
BIO-AUGMENTATION (BABE) REACTOR (2)
• Only small fraction of return sludge used, using
temperature advantage
• Cultivate already present nitrifying population
• 1 or 2 tank system to include denitrification
• No need for biomass retention
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BIO-AUGMENTATION (BABE) REACTOR (3)
BABE: Bio-Augmentation Batch Enhanced
Complete design and concept developed by mathematical
simulation
All processes relatively well known
Many design variables can be easily tested
Trial at lab scale will not easilyy be representative
p
Trial at pilot scale almost as expensive as full scale
HIGH LOADED SYSTEM - EFFLUENT NH4-N
With increase fraction of
Nitrogen load in BABE
reactor better nitrification at
lower temperature
60
Efffluent NH4 -N (m g/l)
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normal
50
5%
40
10%
30
20%
20
30%
10
0
6
8
10
12
14
16
18
20
22
o
Ambient Temperature ( C)
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UPGRADING THE WALCHEREN WWTP (1)
BY APPLYING THE BABE TECHNOLOGY
Anoxic tank
Aeration tanks
680 m3
5320 m3
Influent
Q= 43215
S ttl
Settler
m3/d
Effluent
Return sludge line
Excess
sludge
Sludge compartment
1650 m3
UPGRADING THE WALCHEREN WWTP (2)
BY APPLYING THE BABE TECHNOLOGY
Influent
Anoxic tank
Aeration tanks
680 m3
5320 m3
Settler
Q= 43215 m3/d
Effluent
Return sludge line
Recirculation
Excess
sludge
Sludge compartment
1650 m3
Reject water
Aerobic
Anoxic
500 m3
350 m3
BABE reactor
+
COD addition
(for pH balance)
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UPGRADING THE WALCHEREN WWTP (3)
Results of applying the BABE technology to the
Walcheren wwtp
Fractions
F
ti
(mg/l)
S O2
Total-N
S NH
27 mg/l
Without
BABE
Process
Concentration
in the main
aeration tank
0.8
With BABE Process
Reject water: return sludge
1:1
T BABE = 22 oC
Concentration
in the main
aeration tank
0.8
25.4
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S NO
2.2
7
X aut
80
2.5%
2800
154
4.7%
3100
%(X aut/X total)
MLSS
Reject water: return sludge
5:1
T BABE = 28 oC
Concentration
in the main
aeration tank
0.8
Total-N
16 mg/l
10
40%
improvement
6.6
148
4.2%
3100
COMPARISON: Conventional vs. BABE Upgrading
Upgrading the treatment Upgrading the treatment
Item
plant by conventional
plant by applying the
method
BABE concept
Increase (additional volume/old volume) (%)
Aeration volume
Anoxic volume
Side stream reactor
Total increase
88
1300
0
225
50%
reduction in
area
requirement
22
370
14
75
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EFFECT SRT IN BABE REACTOR ON AUGMENTATION
AMO
OUNT OF NITRIFYERS ADDED
D TO AT
15,0
12,5
10,0
7,5
5,0
2,5
0,0
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
-2,5
25
-5,0
SLUDGE RETENTION IN BABE REACTOR (DAYS)
A short SRT of around 0.3 to 0.8 days helps to increase
nitrifiers population in more than 10%.
COST ANALYSIS at WWTP WALCHEREN
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Saving in construction costs of 750.000 Euro;
Additional costs for COD addition of 35
35.000
000 Euro/year;
Additional sludge handling costs of 30.000 Euro/year;
Saving in energy costs of 70.000 Euro/year;
• The net yearly saving is about 115.000 Euro
(Interest rate 6% , Depreciation 30 years).
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CONCLUSIONS
• SIDE STREAM TREATMENT OFFERS MANY NEW
POSSIBILITIES FOR UPGRADING PLANT
PERFORMANCE
• EVALUATE EFFECT OF SIDE STREAM TREATMENT ON
TOTAL PLANT EFFLUENT
• PROCESS CHOICE IS HIGHLY PLANT SPECIFIC
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