technische universität münchen kordula schwarzwälder flow3d madrid simulation of fate and...
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Technische Universität München
Kordula SchwarzwälderFlow3D Madrid
Simulation of fate and transport of fecal indicator
bacteria (FIB) with FLOW-3D
Technische Universität München
Project
Why simulating bacteria?
• FIBs in river Isar due to CSOs• we need to know the processes and rates of
sedimentation and resuspension of FIBs and • we need to quantify the influence of the biofilm
Technische Universität München
Project What we need and how we get it….
• Through experimental work investigate interaction of FIB between bulk phase and biofilm
• Develop a model which describes/quantifies transport and turnover processes observed in experiments and incorporates hydrodynamics of Isar
Technische Universität München
Actors…Bacteria are of different size, density, shape….
a) E. colib) Enterococcic) Clumps of E. coli and Cocci
(http://www.sciencephoto.com)
a)
b)
Technische Universität München
Actors…They can be found as freely suspended bacteria and clumps, as well as particle associated.
Clumps of E. coli and Cocci
(http://www.sciencephoto.com)
Technische Universität MünchenTechnische Universität München
Actors…Biofilm is a thin film with a special roughness and the ability to embed bacteria
Technische Universität MünchenTechnische Universität München
Actors…
app. 25 mm
Biofilm can be very stong and thin….
Technische Universität München
Biofilm and Waste Water
(E. Walters)
Technische Universität München
Processes
Suspended particles
Erosion Abrasion Shearing
Particle- associated microbes
Freely suspended/aggl. of microbes
Desorption
Sorption
Point Source e.g. CSO
Consolidation
UV Inactivation UV Inactivation
Transport
Growth?Decay
Sedimentation &
Resuspension
Point Source e.g. CSO
Sedimentation &
Resuspension
Biofilm-associated microbes
Sediment-associated microbes
(K.Schwarzwälder, E. Walters)
Technische Universität München
Processes with special interest
How to simulate sedimentation of bacteria:• Contaminant transport?• Particle transport/Sediment module?
How to consider the biofilm:• Source/Sink?• Roughness?
Technische Universität München
Data acquisition
Technische Universität München
L = 1.2 m; W = 7.1 cm; D = 4 cmSubstratum = Ceramic bathroom tilesBulk Phase = Isar WaterQ = 290 cm³/s u = 10 cm/s
2.3 cm × 2.3 cm
Small scale flume in Garching
Technische Universität München
L = 12 m; W = 0.5 m; D = 0.5 mSubstratum = Isar gravelBulk Phase = Isar WaterQ = 200 l/s u = 80 cm/s
2.3 cm × 2.3 cm
Large scale flume in Obernach
Technische Universität München
0 10 20 30 40 50 60 70 80 90 1000
200
400
600
800
1000
1200
1400
1600
1800
time [h]
con
cent
ratio
n [
MP
N m
L-1]
Fate of E. coli in the Bulk Phase
r² = 0.99thalf = 6.2h
(E. Walters, K.Schwarzwälder)
Results
Technische Universität München
0 10 20 30 40 50 60 70 80 90 1000
5
10
15
20
25
30
time [h]
con
cent
ratio
n [
MP
N c
m2 ]
Fate of E. coli in the Benthic Biofilm
(E. Walters, K.Schwarzwälder)
Results
Technische Universität München
(K.Schwarzwälder, M. Graml)
Results
Technische Universität München
17
Flume in FLOW-3D
Technische Universität München
ProblemsSimulating bacteria as concentration can work, but we have to simulate interaction bacteria / biofilm as well?!
How should we deal with UV-inactivation if we are not simulating particles?
How can we simulate the biofilm?
Technische Universität München
as contamination....
Convective diffusion
Convective diffusion in vector notation
Technische Universität München
as contamination....
Temporal change
Advective transport Diffusive transport
Reaction
kj rate constant of reaction jnjn order of reaction j with respect to constituent n
Technische Universität München
(K.Schwarzwälder)
Problems
Interaction with biofilm?
Technische Universität München
(K.Schwarzwälder)
Problems
Roughness?Too big for “roughness” in GeometryToo natural for this artificial roughness below…
Technische Universität München
(K.Schwarzwälder)
Problems…
Technische Universität München
Thank you for your attention!
Project DFG fundedKordula Schwarzwälder
Eve Walters