1
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]
8
Characteristics of the membrane used
9
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
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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
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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
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Schematic diagrams of fouling remediation techniques
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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
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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
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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
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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
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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]
