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1 Challenge the future
D-SHIT Adithya Thota Radhakrishnan
Domestic Slurry Hydraulics In Transport systems
a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
2 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4
Sanitation systems
Planned 5
• Simple to Complex
• Industrialised countries
• High water consumption
• Expensive treatment
• Loss of resource
3 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Objective 2 Rheology 3 Modelling 4
New sanitation concept
Introduction 1 Planned 5
Source separation
Resource recovery
Low water consumption
4 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4
New sanitation: elements
Treatment
Transport
Collection
Source Separation
Vastly overlooked
Planned 5
D-SHIT project??
Transport design for domestic slurry of Grinded Kitchen Waste + Feces + Urine?
Collection tank
WWTP D-SHIT
5 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4
What does this mean for us?
Planned 5
Increase in
total solid
concentration
Vacuum toilets +
Kitchen grinder
Example: Ketchup vs. Water
6 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4
D-SHIT Objective?
Planned 5
• To study the flow of domestic slurry at various solid concentration and temperature
• To determine the optimum design conditions for the slurry transport
• To determine the optimum dilution for the slurry
7 Challenge the future
Rheology
Rheology of Concentrated Domestic Slurry A mixture of Brown water (Faeces + Urine) and Grinded Kitchen Waste
8 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Modelling 4
Complexity of CDS
Planned 5
0
0,2
0,4
0,6
0,8
1
1,2
0 50 100 150 200 250 300 350
Shear
stre
ss (
Pa)
Shear rate (1/s)
Water Low mix Medium mix High mix
Non-Newtonian
Objective 2 Rheology 3
9 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4
Rotating viscometer
Rotating viscometer to measure Torque vs Rotation speed
Shear stress vs Shear rate Yield stress
Temperature Solid concentration Slurry lifetime
Influence of
Output
Rheological model
Sisko model
Herschel-Bulkley
Combined Herschel-Bulkley
Planned 5
10 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Modelling 4
0
1
2
3
4
5
6
0 100 200 300 400 500
Sh
ea
r str
ess (
Pa
)
Shear rate (1/s)
GKW 6% GKW 11% Fit 6% Fit 11%
0
5
10
15
20
25
30
35
40
45
0 50 100 150 200 250 300
She
ar
str
ess (
Pa)
Shear rate (1/s)
GKW 18% Fit 18%
At temperature 10º C At temperature 10º C
Combined Herschel-Bulkley model
Bingham model
Viscosity increases with concentration
Rheology 3 Planned 5
11 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Modelling 4
0
0,5
1
1,5
2
2,5
0 100 200 300
Sh
ea
r str
ess (
Pa
)
Shear rate (1/s)
BrW 1.8% BrW 3% BrW 4%
Sisko 1.8% Sisko 3% Sisko 4%
0
10
20
30
40
0 50 100 150 200 250 300
Sh
ea
r str
ess (
Pa
)
Shear rate (1/s)
GKW 18% Combined Herschel-Bulkley 18%
Sisko model
Combined Herschel-Bulkley model
At temperature 10º C At temperature 10º C
Viscosity increases with concentration
Rheology 3 Planned 5
13 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Modelling 4
0
2
4
6
8
10
12
14
16
18
20
0,1 1 10
Defo
rmation (
rad)
Stress (Pa)
GKW 6% GKW 11% GKW 18%
0
2
4
6
8
10
12
14
16
18
20
0,1 1 10
De
form
ation
(ra
d)
Stress (Pa)
Mix 3.4% Mix 7% Mix 11%
Yield stress increases with concentration
Rheology 3 Planned 5
14 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Modelling 4
0
5
10
15
20
25
30
35
40
45
0 100 200 300
Sh
ea
r str
ess (
Pa
)
Shear rate (1/s)
18% 10C 18% 20C 18% 30C 18% 40C 18% 60C
0
2
4
6
8
10
12
14
0 2 4 6 8 10 12 14
De
form
ation
(ra
d)
Stress (Pa)
18% 10C 18% 20C 18% 30C 18% 40C 18% 60C
Viscosity and yield stress decreases with temperature
Rheology 3 Planned 5
15 Challenge the future
Modelling
Why? To aid the design process. How to model Concentrated Domestic Slurry?
16 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4
How to model domestic slurry?
Multiphase
models
Eulerian-
Eulerian
Eulerian-
Lagrangian
Inhomogeneous Homogeneous
Torque derieved from the shear stress being a bulk property; comparing the measured shear stress to the one simulated provides a valid measure for the verification of the model.
0
10
20
30
40
50
60
70
80
0 100 200 300 400 500 600
Shear
stre
ss (
Pa)
Shear rate (/s)
Secondary flow
Planned 5
17 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Planned 5
Single-phase Homogeneous fluid!
25
30
35
40
45
50
55
60
65
70
75
100 200 300 400 500
Shear
stre
ss (
Pa)
Shear rate (1/s)
Results from CFD, comparing the shear rate and stresses, derived from Torque and Rotational rate
Modelling 4
18 Challenge the future
Planned
Preparation of Artificial Slurry. Pressure drop experiments. Turbulence pressure drop model for slurries.
19 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4 Planned 5
Rheological models
Bingham
Sisko
Herschel-Bulkley
Combined Herschel-Bulkley
Different models for same slurry
20 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4 Planned 5
Experimental setup Appropriate pipe lengths are provided to reach a completely developed flow
21 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4 Planned 5
Experimental setup
• Tank capacity of 4m3 to provide require
NPSHA and fill the system
• Di of 0.20m
• 6 to 8 pipe lengths for the development of
flow
• Components
• Horizontal pipe
• Vertical pipe
• Inclined pipe 60°
• Inclined pipe 45°
• Butterfly valve
• Gate valve
• Bend 90°
• Bend 180°
22 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4 Planned 5
Artificial slurry
Preparation of artificial slurry to mimic the rheological behaviour of the CDS • To mimic the yield stress • To mimic the power law behaviour
Criteria for artificial slurry
• Environmentally friendly • Easily disposable • Easily preparable • Preferably transparent
Possible mixtures of
• Bentonite, Xanthum gum, glucose
23 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4 Planned 5
Pipeline experiment
Single phase experiments
•Pressure drop for non-Newtonian fluids •Velocity range of 1 – 2 m/s •For different slurry concentrations
Multiphase experiments
•Pressure drop for non-Newtonian fluids + gas (air) •Studying the flow regimes at different superficial velocities •For different slurry concentrations
24 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4 Planned 5
Turbulence pressure drop model for slurries
Pressure loss using hydraulic friction factor
Using mixing length theory to derive the velocity gradient in the boundary layer
Assumption At high velocity, due to near wall lift force, only water is predominantly present.
Kinetic energy
Friction coefficient
25 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4 Planned 5
Turbulence pressure drop model for slurries
Comparing this with the standard friction loss for water flow using Darcy-Weisbach friction, we can find a relative measure for pressure loss
Integrating we get an expression for
velocity difference
But, one problem! Verification of the assumption is required.
26 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Introduction 1 Objective 2 Rheology 3 Modelling 4 Planned 5
Model approach!
Equation of continuity
Equation of motion
Integrating using non-Newtonian viscosity relation
Adopting the energy loss equations.
Equation for pressure drop in the turbulence regime.
27 Challenge the future a.k.thotaradhakrishnan@tudelft.nl
Bridging the gap in future sanitation!
Summary
For CDS •Viscosity and yield stress increase with concentration •Viscosity and yield stress decrease with temperature (higher thermal motion) •CDS can be modelled as a single-phase homogeneous fluid represented by its bulk viscosity and density
Planned •Preparation of artificial slurry •Performing the single phase experiments •Building the turbulence model
Thank you!
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