Renseanlæg Hvordan opfører efterklaringstankene under øgede hydraulisk belastning og udvikling af simple modeller som kan anvendes til styring af efterklaringstankene under regn. Hvilke metoder findes der for at forøge den hydrauliske kapacitet af renseanlæg under regn og praktiske erfaringer fra Spildevandscenter Avedøre ræsentation af det ambitiøse forskningsprojekt Storm- and Waste water Informatics SWI.

1. Modelling of water quality in sewer-
WWTP systems during normal and
extreme conditions
PhD student: Elham Ramin
Supervisor: Benedek Gy. Plósz (DTU Miljø)
Co-supervisors: Peter Steen Mikkelsen (DTU Miljø)
Michael R. Rasmussen (Aalborg University)
Lars Yde (DHI)
Period : Oct 2010 – Sep 2013

2. 15/03/20132 DTU Environment, Technical University of Denmark
Introduction

3. 15/03/20133 DTU Environment, Technical University of Denmark
Introduction

4. 15/03/20134 DTU Environment, Technical University of Denmark
Modelling of Secondary Settling Tanks
SST model selection
Calibration and evaluation
Output
variables
Complexity
level
Sensitivity
of target
outputs on
parameters
Realistic/
forced
parameter
setting
Simulation
Boundary
conditions
Engineering
objective
Ramin et al. (2013)

5. 15/03/20135 DTU Environment, Technical University of Denmark
Advection
Gravity settling
Compression settling
Lumped dispersion
Flocculation
Molecular viscosity
Turbulent viscosity
Turbulence
Density
Velocity gradient
PROCESS DIMENSIONALITY
Model selection
Calibration & Evaluation
Output
variables
Complexity
level
Output
sensitivity
on
parameters
Realistic/
forced
parameter
setting
Simulation
Boundary
conditions
Engineering
objectiveSecondary Settling Tank (SST) Modelling:
Complexity level
• One dimensional (1-D)
Takács et al. (1991)
• Two- and three-dimensional models:
Computational Fluid Mechanics (CFD)

6. 15/03/20136 DTU Environment, Technical University of Denmark
1-D Secondary settling tank models
 
z
Xv
z
X
U
t
X TSSsTSSTSS
∂
∂
∂
∂
∂
∂

Takács et al. (1991)

7. 15/03/20137 DTU Environment, Technical University of Denmark
1-D Secondary settling tank (SST) models
2
2
∂
∂
z
X
D TSS
C
Takács et al. (1991) Plósz et al., 2007
 
z
Xv
z
X
U
t
X TSSsTSSTSS
∂
∂
∂
∂
∂
∂


8. 15/03/20138 DTU Environment, Technical University of Denmark
1-D Secondary settling tank (SST) models
2
2
∂
∂
z
X
D TSS
C
   
 0
FNSpFNSH
S
XfXrXfXr
eevv


 
z
Xv
z
X
U
t
X TSSsTSSTSS
∂
∂
∂
∂
∂
∂


9. 15/03/20139 DTU Environment, Technical University of Denmark
1-D Secondary settling tank model
parameters
Measurable parameters:
(Settling Characteristics)
DTU Environment
2
2
∂
∂
z
X
D TSS
C
 
z
Xv
z
X
U
t
X TSSsTSSTSS
∂
∂
∂
∂
∂
∂

   
 0
FNSpFNSH
S
XfXrXfXr
eevv



10. 15/03/201310 DTU Environment, Technical University of Denmark
1-D Secondary settling tank model
parameters
Measurable parameters:
(Settling Characteristics)
Calibrated parameter:
(Design&flow Characteristics)
DTU Environment Marselisborg WWTP
2
2
∂
∂
z
X
D TSS
C
 
z
Xv
z
X
U
t
X TSSsTSSTSS
∂
∂
∂
∂
∂
∂

   
 0
FNSpFNSH
S
XfXrXfXr
eevv



11. 15/03/201311 DTU Environment, Technical University of Denmark
Phase I. Global sensitivity Analysis
Objective
Show the significance of explicit model parameters and dynamic
behavior of 1-D secondary settler models on the biokinetic model
prediction in WWTP models

12. 15/03/201312 DTU Environment, Technical University of Denmark
Relative importance of secondary settling
tank models in WWTP simulations – A
global sensitivity analysis using BSM2
Elham Ramin, Xavier Flores-Alsina, Gürkan Sin, Krist V. Gernaey, Ulf Jeppsson,
Peter Steen Mikkelsen, Benedek Gy. Plósz*
ANOX1 ANOX2 AER1 AER2 AER3
PRIM SEC2
AD
THK
DW
ST
INFLUENT
WASTEWATER
EFFLUENT
WASTEWATER
SLUDGE FOR
DISPOSAL
muH = [3; 5]
KS = [5 ;15]
KOH = [0.1; 0.3]
KNO = [0.25; 0.75]
bH = [0.29 ;0.32]
muA = [0.48 ;0.53]
KNH = [0.50 ;1.50]
KOA = [0.3 ;0.5]
.
.
.
DSVI = [50 ;200]
rP = [2.7e-3;10e-3]
fns = [1.23e-3 ;2.59e-3]
VF,CON = [25; 40]
VOV,DIS= [10; 22]
Parameters Monte Carlo Simulation Sensitivity rankings
Sensitivity index i
0 0.2 0.4 0.6 0.8 1
bH
fPob
YH
XI2TSS
NH4
in reject water (mg N/l)
Sensitivity index i
0 0.2 0.4 0.6 0.8 1
YH
XI2TSS
rP
rh
,v0
Effluent TSS (mg SS/l)
Sensitivity index i
0 0.2 0.4 0.6 0.8 1
iXB
YH
nyg
KOA
KNH
XI2TSS
KOH
rP
rh
,v0
Effluent Quality Index (kg/day)
ParameterssignificancerankinginScenario1
Scenario 4
Scenario 3
Scenario 2
Scenario 1

13. 15/03/201313 DTU Environment, Technical University of Denmark
Phase II. Fluid dynamics in secondary
settling tanks (CFD simulations)
Objective
To generate numerical experimental data sets using transient-
to-steady-state (and, if possible, dynamic) CFD simulations for
secondary settling tanks with different design and flow
boundary conditions. We then use the obtained data sets to
optimize and calibrate 1-D secondary settling tank models.

14. 15/03/201314 DTU Environment, Technical University of Denmark
1. Sub-model optimization and calibration
Phase II. CFD simulations
0 10 20 30 40 50 60
0
10
20
30
40
50
60
70
80
Heightcm
time min
4.2 g/l
3.7 g/l
2.9 g/l
2.1 g/l
1.5 g/l
0.8 g/l
0 50 100 150 200 250
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Shear rate 1/sShearstressPa
8.4 g/l
7.1 g/l
5.6 g/l
4.1 g/l
3 g/l
Settling test Rheology test

15. 15/03/201315 DTU Environment, Technical University of Denmark
2. CFD simulation of the settling tank
Phase II. CFD simulations
Sludge distribution Velocity field
Lundtofte WWTP, Clarifier number 3

16. 15/03/201316 DTU Environment, Technical University of Denmark
-0.5 0 0.5
0
0.5
1
velocity [cm/s]
Normalizedheight
-0.5 0 0.5
0
0.5
1
velocity [cm/s]
-0.5 0 0.5
0
0.5
1
velocity [cm/s]
-0.5 0 0.5
0
0.5
1
velocity [cm/s]
0 10 20
0
0.5
1
TSS [g/l]
Normalizedheight
0 10 20
0
0.5
1
TSS [g/l]
0 20 40
0
0.5
1
TSS [g/l]
0 10 20
0
0.5
1
TSS [g/l]
r = 3 m r = 5 m r = 7 m r = 10 m
3. Model evaluation
Measurement campaign on
a full-scale secobdary
settling tank
Phase II. CFD simulations
Lundtofte WWTP, Clarifier number 3
TSS and velocity sensors used
for profile measurements

17. 15/03/201317 DTU Environment, Technical University of Denmark
-5 0 5
0
0.2
0.4
0.6
0.8
1
velocity [cm/s]
Normalizedheight
-2 0 2
0
0.2
0.4
0.6
0.8
1
velocity [cm/s]
-1 0 1
0
0.2
0.4
0.6
0.8
1
velocity [cm/s]
-1 0 1
0
0.2
0.4
0.6
0.8
1
velocity [cm/s]
0 10 20
0
0.2
0.4
0.6
0.8
1
Normalizedheight
TSS [g/l]
0 10 20
0
0.2
0.4
0.6
0.8
1
TSS [g/l]
0 20 40
0
0.2
0.4
0.6
0.8
1
TSS [g/l]
0 10 20
0
0.2
0.4
0.6
0.8
1
TSS [g/l]
CFD
measured
Measured vs. simulated profiles
Phase II. CFD simulations

18. 15/03/201318 DTU Environment, Technical University of Denmark
Phase II. CFD simulations
In terms of design and flow boundary conditions
4. Creating an inventory of CFD simulations

19. 15/03/201319 DTU Environment, Technical University of Denmark
Phase III. optimize and calibrate 1-D
secondary settling tank models
Objective
A more mechanistic way for hydrodynamics modeling in 1-D that
could account for different design and flow boundary conditions

20. 15/03/201320 DTU Environment, Technical University of Denmark
1-D model optimization
Approach I: calibrate dispersion, downward convection and dynamic-
feed layer position models to account for different clarifier design.
Approach II: Testing theories that could unify 1-D hydrodynamic
model calibrations obtained for different SST structure

21. 15/03/201321 DTU Environment, Technical University of Denmark
Thank you!