characteristics of nutrient removal in vertical membrane ......1 the 2nd mbr workshop at hokkaido...
TRANSCRIPT
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The 2nd MBR workshop at Hokkaido University
Characteristics of Nutrient Removalin Vertical Membrane Bioreactors
Prof. Hang-Sik Shin
Dept. of Civil and Environmental EngineeringDept. of Civil and Environmental EngineeringKKorea orea AAdvanced dvanced IInstitute of nstitute of SScience and cience and TTechnologyechnology
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Content
Research Background
Operating factors for vertical MBR
Nutrient removal in vertical MBR
Remediation of fouling in vertical MBR
Conclusions
3
Mechanisms of membrane bioreactors
Water
NH4-N NO3-N
Organic
NO3 T-P
N2 gas Ortho P
Mem-brane
Anoxic reactor
Ortho P
A I R
Oxic reactor
Organic
Water
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Research Objectives and Scope
Novel MBR(Anoxic/Oxic vertical)
Membrane fouling
• Characterization• Dynamic membrane• Remediation
Membrane foulingMembrane fouling
•• CharacterizationCharacterization•• Dynamic membraneDynamic membrane•• RemediationRemediation
Operating factors
• Hydraulic retention time• Internal recycle rate• C/N ratio
Operating factorsOperating factors
•• Hydraulic retention timeHydraulic retention time•• Internal recycle rateInternal recycle rate•• C/N ratioC/N ratio
Modelling
• Kinetic study• Sludge production • EPS accumulation
ModellingModelling
•• Kinetic studyKinetic study•• Sludge production Sludge production •• EPS accumulationEPS accumulation
Nutrient removal
• Various carbon source• EBPR activity• Population dynamics
Nutrient removalNutrient removal
•• Various carbon sourceVarious carbon source•• EBPR activityEBPR activity•• Population dynamicsPopulation dynamics
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Operating factors in vertical MBR
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Objective and Scope
Aerobic tank
Settling tank
Anoxic tank
-Denitrification-Phosphorus release
-Nitrification-Organic oxidation-Phosphorus uptake
-Liquid/solid separation
Distribution devicesDistribution devices
High MLSS conc. High MLSS conc. anoxic zoneanoxic zone
Internal recycleInternal recycle
Aerobic zoneAerobic zone
Aeration Aeration devicesdevices
EffluentEffluent
P
InfluentInfluent
PP
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Test phases
[Q is the influent flow rate]
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Characteristics of the membrane used
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I.R. (3Q 4Q 5Q): T-N= 68 83%, T-P= 51 80%
C/N ratio (4 10): T-N= 55 80%, T-P= 38 76%: Phosphorus removal is more dependent on the content of
organics than nitrogen
HRT (12 6 hrs): at least 8 hrs HRT was needed
Desirable operating conditions; internal recycle rate = 4Q, HRT > 8 hrs
Sludge production = 1 - 6% of the CASP
Summary of Results
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Nutrient removal in vertical MBR
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4242Objective and Scope
GlucoseMBR3
Propionic acidMBR2Sodium acetateMBR1Laboratory
Ax (12L) +Ox (20L)
SubstrateReactorScale
Nutrient removal
EBPR activity
Municipal wastewater
PilotAx (500L) +Ox (833L)
SubstrateScale
[EBPR= Enhanced Biological Phosphorus Removal]
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Materials and Methods
Characteristics of laboratory-scale MBRs
400%Internal
recycle rate
96 L/dayCapacity
2012Volume (L)
+257-147ORP (mV)
2.25.7MLSS (g/L)
53HRT (hr)
30SRT(d)
OxAxItem
[MLSS= mixed liquor suspended solid]
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Characteristics of synthetic wastewater
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Experimental conditions for lab-scale MBRs
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Characteristics of a pilot-scale MBR
2.3m
1m
400%Internal
recycle rate
4 m3/dayCapacity
833500Volume (L)
+274-153ORP (mV)
4.218.68MLSS (g/L)
53HRT (hr)
60SRT(d)
OxAxItem
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Experimental conditions for a pilot-scale MBR
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Characteristics of municipal wastewater
Total COD/Total N = 5.5 insufficient for nutrient removal
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Characteristics of external carbon source
Food waste Fermenter(100 - 120 oC, 12 hr)
Condensate of food waste(CFW)
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Time (min)
0 15 30 45 60
Nitr
ate-
N c
once
ntra
tion
(mg/
l)
0
5
10
15
20
25
30
35
CO
D concentration (m
g/l)
0
50
100
150
200
250
300
Nitrate-N COD
COD source: CFWMLVSS: 4.1 g/l
Nitrogen removal potential of the CFW
20
21
Phosphorus release potential of the CFW
Time (min)
0 15 30 45 60
Orth
o-P
con
cent
ratio
n (m
g/l)
0
10
20
30
40
50
CO
D concentration (m
g/l)
0
50
100
150
200
250
300
NO
3-N
con
cent
ratio
n (m
g/l)
0.0
0.2
0.4
0.6
0.8
1.0
Ortho-PCODNitrate-N
COD source: CFWMLVSS: 4.1 g/l
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Results and Discussion
Time (day)
0 50 100 150 200 250 300 350 400 450
CO
D c
once
ntra
tion
(mg/
l)
0
10
20
30
40
50
T-N concentration (m
g/l)
0
5
10
15
20
T-P concentration (m
g/l)
0
2
4
6
8
10
COD T-N T-P
Phase 1 Phase 2 Phase 3
C/N=10 C/N=5 C/N=5 + 5
Effluent quality of lab-scale MBR fed with sodium acetate
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Stage
In Anoxic Oxic Out
CO
D c
once
ntra
tion
(mg/
l)
0
50
100
150
200
250
300
350
Phase 1Phase 2Phase 3
Stage
In Anoxic Oxic Out
pH
7.0
7.2
7.4
7.6
7.8
8.0
Phase 1Phase 2 Phase 3
Behaviors of pH and pollutants in the reactor
Stage
In Anoxic Oxic Out
NH
3-N
con
cent
ratio
n (m
g/l)
0
5
10
15
20
25
30
35
NO
3 -N concentration (m
g/l)
0.0
2.5
5.0
7.5
10.0
12.5
15.0
Phase 1Phase 2Phase 3
Stage
In Anoxic Oxic Out
Orth
o-P
con
cent
ratio
n (m
g/l)
0
5
10
15
20
Phase 1Phase 2Phase 3
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Removal efficiencies of organics and nutrients
Sodium acetate
Propionic acid
Glucose
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Characteristics of EBPR activity with various substrates
Experimental conditions for assessment of EBPR activity
C/N=10C/N=10
C/N=5C/N=5
C/N=5+C/N=5+55
C/N=5+C/N=5+55
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Results of the assessment of EBPR activity with various substrates
1316171116154
7111579133
2362352
57104681
GlucosePropionic acidAcetateGlucosePropionic
acidAcetate
P uptake (mg P/g VSS)P release (mg P/g VSS)Batch test
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Removal efficiencies of nutrients
HRT
10 hr10 hr8 hr6 hr4 hr
8 hr +CFW 0.43%8 hr +CFW 0.86%
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Behaviors of nitrogen and phosphorus in the pilot-scale reactor
Stage
In Anoxic Oxic Out
Am
mon
ia-N
con
cent
ratio
n (m
g/l)
0
5
10
15
20
25
30
35
Nitrate-N
concentration (mg/l)
0
2
4
6
8
10
12
Phase 1APhase 2Phase 6
Stage
In Anoxic Oxic Out
Orth
o-P
con
cent
ratio
n (m
g/l)
0
1
2
3
4
5
6
Phase 1APhase 2Phase 6
- Phase 1A = 10 hr HRT w/o internal barrier- Phase 2 = 8 hr HRT- Phase 6 = 8 hr HRT + CFW 0.86%
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Removal efficiencies of nutrients at various temperatures
-- HRT=8 hrsHRT=8 hrs
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Photographs of the formation of dynamic membranes
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The role of dynamic membrane in removal of pollutants
Experimental conditionsExperimental conditions
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Schematic diagram of dynamic membranes
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Reuse potential of the effluent in the pilot-scale vertical MBR
34[Source: The STOWA, 2002]
Normal effluent quality(N=10, P=1 mg/L)
Stringent effluent quality(N=2.2, P=0.15 mg/L + disinfection)
100%
Civil
Mechanical
Electrical
Membrane
CASP MBR CASP
For a 2,500 m3/d treatment plant
Comparison of capital costs
135%125%
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Condensate of food waste (CFW) great potential as a carbon source for nutrient removal !
In the lab-scale vertical MBRs (acetate, propionic acid, glucose),- Average removal efficiency of nitrogen was about 80%- Removal efficiencies of phosphorus decreased in order of acetate (87%), propionic acid (83%), and glucose (78%) at C/N = 10
- Addition of the CFW (50% of COD) improved nitrogen and phosphorus removal efficiencies by 2 - 4% and 4 - 11%, respectively.
Assessment of EBPR activity (batch test)- P release/uptake activity; acetate > propionic acid > glucose
several kinds of PHAs were detected inside the cells
Summary of Results
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In the pilot-scale MBR treating municipal wastewater, - Average removal efficiency of total COD, T-N, and T-P
96%, 74%, and 78%, respectively at 8 hr HRT and C/N = 5.5- As the CFW was supplemented (0.86%), T-N and T-P removal
efficiencies increased to 81% and 91%, respectively.- At differing temperature (13 - 25 °C),
Nitrification efficiency = 79 - 81% Phosphorus removal efficiency = 77 - 81%
- Additional removal by the formation of dynamic membranesOrganics (8%), nitrification (5%) and denitrification (4%)
- The effluent quality could satisfy the current drinking water standards except for ammonia-N.
Analysis of population dynamics- As C/N ratio decreased, the number of microbial species decreased- Species of the beta subclass or Proteobacteria are considered toplay an important role in EBPR.
- When the CFW was added, Geothrix fermentans appeared.
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Remediation of membrane foulingin a vertical MBR
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Objective and Scope
Characteristics of membrane fouling
Membraneresistance
Physical factorsPhysical factors
Chemical factorsChemical factors
Biological factorsBiological factors
`̀Ax/Ox vertical MBR Ax/Ox series MBRLab-scale (glucose)
Ax/Ox vertical MBRPilot-scale (sewage)
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Ax/Ox series MBR
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Operating conditions: lab-scale MBRs
- Organic source = glucose- COD : N : P = 160 : 40 : 6
Operating conditions: pilot-scale vertical MBR
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Results and Discussion
Time (day)
0 10 20 30 40 50 60 70 80 90 100
Per
mea
te fl
ux (L
/m2 /h
)
0
2
4
6
8
10
Transmem
brane pressure (kPa)
0
10
20
30
40
50
Permeate fluxTMP
Variations of flux and TMP in the series MBR
42
Variations of flux and TMP in the vertical MBR
Time (day)
0 10 20 30 40 50 60 70 80 90 100
Per
mea
te fl
ux (L
/m2 /h
)
0
2
4
6
8
10
Transmem
brane pressure (kPa)
0
10
20
30
40
50
Permeate fluxTMP
43Time (day)
0 10 20 30 40 50 60 70
Perm
eate
flux
(L/m
2 /h)
0
2
4
6
8
10
Transmem
brane pressure (kPa)
0
10
20
30
40
50
Flux at HRT of 8 hrsTMP at HRT of 8 hrs
Variations of flux and TMP in the pilot-scale vertical MBR
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Effect of EPS concentration on fouling at various HRTs
Total EPS concentration (mg/g VSS)
0 25 50 75 100 125 150 175 200
Ra
+ R
p (x
1012
m-1
)
0
10
20
30
40
50R
c (x 1012 m
-1)
0
10
20
30
40
50
Rt (x 10
12 m-1)
0
10
20
30
40
50
Adsorption + Pore blockingCake layerTotal resistance
R2= 0.997Rt = 12.38 -0.2197X + 2162X2
10hrs 4hrsHRTs
45
Effect of particle size on fouling at various HRTs
Nominal particle size (µm)
0 20 40 60 80 100 120 140
0
10
20
30
40
50
0
10
20
30
40
50
0
10
20
30
40
50
Adsorption + Pore blockingCake layerTotal resistance
Ra
+ R
p ( x
1012
m-1
) Rc ( x 10 12 m
-1)HRT
Y = -22.88 + 0.55X (R2=0.999)
Rt ( x 10 12 m
-1)
10 hrs 4 hrs
46
Schematic diagrams of fouling remediation techniques
47
Fouling remediation by outside air supply
Time (day)
0 10 20 30 40 50 60 70
Perm
eate
flux
(L/m
2 /h)
0
5
10
15
20
Transmem
brane pressure (kPa)
0
10
20
30
40
Permeate fluxTMP
Designed permeate flux = 18.6 L/m2/h
48
Fouling remediation by inside air supply
Time (day)
0 10 20 30 40 50 60 70
Per
mea
te fl
ux (L
/m2 /h
)
0
10
20
30
Transmem
brane pressure (kPa)
0
10
20
30
Permeate fluxTMP
18.6 LMH 27.9 LMH40 40
49
1. Series MBR vs. Vertical MBR (SRT = 30 days)- Vertical-type MBR; relatively low MLSS concentration
(EPS and viscosity) reduce membrane fouling !- Cake layer resistance was about 60-70% of the total resistance
2. Lab-scale vs. Pilot-scale vertical MBR- PPilot-scale showed relatively higher values of EPS and viscosity,
smaller particle size severe fouling !- In pilot-scale MBR (HRT=10 8 6 4 hrs);
EPS content and particle size increasedCake layer resistance appeared to be the controlling factor of the total resistance
3. Fouling remediation- The inside air supply was more efficient than the outside air supply
Summary of Results
50
Final Conclusions
High MLSS conc. High MLSS conc. anoxic zoneanoxic zone
Internal recycleInternal recycle EffluentEffluentP
P Stable and desirable effluent quality
Aerobic zoneAerobic zone Low sludge productionLow membrane fouling
Bulking problem ignore!
High nutrient removal efficiencyP
InfluentInfluentDistribution devicesDistribution devices
51
52
Enhanced Biological Phosphorus Removal (EBPR)
Anaerobicenvironment
Organics
SCFAs
Glucose SCFAs PHAs
Poly-P
ortho-P
Gly
PAOs
Gly
PHAsPoly-P
ortho-P
Aerobicenvironment
[Source: Smolders et al., 1995]