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TRANSCRIPT
Engineering
Optimum Configuration of SkyJuice Membranes for Humanitarian Applications
Adam HalmyA/Prof Pierre Le-Clech, Dr. Raquel García-Pacheco
Objectives
Background
Results and Discussion
Conclusion• Dead end configuration modules have the highest permeability values as well as the highest flux rates.• The positive head driving force was the optimum configuration for all the modules. Although all fibres were the same and hence
should have similar permeability values, further investigations should be done to identify the causes of these differences.• Fouling testing should also be undertaken to observe differences in the rate of fouling and rejection rates.
Methodology
1 SkyJuice Foundation ‘Squirt’ Information https://www.skyjuice.org.au/squirt/
Characterise six newly developed SkyJuice modules to identify theoptimum membrane for filtering drinking water in rural areas.
Compare the differences between positive head and suction drivenconfiguration and discuss the benefits and disadvantages of each method.
Fig. 2 An image of the commercial ‘Squirt’ module. Dimensions: 38.5cm x 6cm
ObjectivesCharacterise six newly developed SkyJuice modules to identify the
optimum membrane for filtering drinking water in rural areas.Compare the differences between positive head and suction driven
configuration and discuss the benefits and disadvantages of each method.
Fig. 2 An image of the commercial ‘Squirt’ module. Dimensions: 38.5cm x 6cm
Set up of positive head apparatus with three modules.
200LTank
Module
SplitterPT
1.67
25m
Fig. 3 Diagram of the positive head apparatus set up
Flushing out of preservative solution in modules using RO water at constant head until permeability is stabilised.
Using five different water levels, permeability values were calculated at five heads making sure at each level the values had stabilised.
Steps and were repeated with the suction driven apparatus set up. To alternate the suction pressure, the tubing in red (Fig. 5) were raised.
200LTank
Module
Splitter
PT
1.67
25m
Fig. 5 Diagram of the suction apparatus setup
All preceding steps were repeated with the other three membranes. Additionally, Step was repeated with alternate pipe diameters for suction tubing highlighted in red on Fig. 5.
Fig. 4 Image of the lower portion of the positive
head set up
Conclusion• Dead end configuration modules have the highest permeability values as well as the highest flux rates.• The positive head driving force was the optimum configuration for all the modules. Although all fibres were the same and hence
should have similar permeability values, further investigations should be done to identify the causes of these differences.• Fouling testing should also be undertaken to observe differences in the rate of fouling and rejection rates.
Background
Module Summary
Fig. 6 Image of the suction set up
0
100
200
300
400
500
600
700
0 100 200 300 400 500 600 700 800 900
Flux
(L/m
2 /h)
Time (min)
Calculating Flux and Permeability
Varying HeadConstant Head
Fig. 8 Experimental Flux for Module A. The red lines indicate times of paused operationwhen bubbles were removed. The black lines indicate periods of relaxation overnight.Observation of the permeability trend showed there was a steady increase as thepressure decreased. The initial data was adjusted using pressure loss models and isshown in Fig. 9, however, it made a difference of <1% as the permeability is intrinsicallylinked to the pressure. Most modules experienced an increase in permeability of around10% over the pressure range tested in this experiment.
Positive Head vs. Suction
Why?
Fig. 9 The permeability of Module A and F for both before and after pressure modelling.The solid line is a linear fit to the post pressure model and the dotted line represents theexpected trend.
Fig. 10 Estimated permeability results forall six modules at a transmembranepressure of 11kPa for positive head andsuction driven conditions.• Positive-head configurations for these
modules performs approximately 25%better than suction at high fluxes and7% at low fluxes as shown in Fig. 10.
• With 12mm tubes, the permeabilityimproved for module A, but was reducedin Module F. This is likely due to theinefficient suction force that often had airentering the tube was observed due toF’s low flux.
2
4
6
8
10
12
6 8 10 12 14 16Perm
eabi
lity
(L/m
2 /h/k
Pa)
Pressure (kPa)
Module A
Module F
0
2
4
6
8
10
12
A B C D E F
Perm
eabi
lity
(L/m
2 /h/k
Pa)
Module
12mm Positive Head6mm Suction12mm Suction
Fig. 1 Current guide to operating the Squirt Modules
Fig. 7 The two configurations of the fibres in themodules are ‘looped’ (a) or ‘dead end’ (b).
Feed Stream FlowModule Shell
FibrePlate
Hollow Fibres (Semi-Permeable)
• Research into drinking water treatment methodsfor rural areas or humanitarian relief is importantto enable everyone to have access to water thatis at appropriate standards for consumption
• Globally, 2.1 billion people do not have accessto safe water (WHO, 2017)
• SkyJuice Foundation1 have developed a low-cost, zero power and portable ultrafiltrationmodule called ‘Squirt’. These need to becharacterised and compared againstcommercial options.
• In previous studies, a positive head filtrationwas utilised and is currently the recommendedprocedure for consumers.
• Investigations into an alternative configurationof suction driven filtration will be explored todetermine if this configuration enhances thedaily capacity or quality of the treated water.
(b)(a)
Module Configuration Area (m2)
Capacity (L/h) Permeability (L/m2/h/kPa)
PH Suc. PH Suc.
A Dead End 0.75 90.4 66.8 10.95 8.09
B Dead End 0.75 79.3 57.5 9.62 6.97
C Looped 0.75 40.6 34.3 4.92 4.15
D Looped 0.75 41.6 37.0 5.05 4.49
E Long Looped 1.4 48.0 35.1 3.11 2.28
F ½ Fibre Dead End 0.37 25.9 24.2 6.37 5.95
Hollow Fibre Ultrafiltration
Tab. 1 A table outlining the configuration and permeability for positive-head (PH) and Suction (Suc.) filtration at a transmembrane pressure of 11kPa.
The membrane’s flux during the wetting is shown in Fig. 8. The initial steady increase isdue to the removal of salt preservatives which eventually stabilises as expected.
Taste of Research Summer Scholarship Program
Research Theme: Resources and Infrastructure for the Future - Water and Wastewater Engineering
• The difference in suction and pressurehead can be explained through thedifference in flow dynamics between thetwo configurations.
• Looped modules are performing less dueto the reduced active membrane areadue to the alternate configuration.
Pre Pressure ModelPost Pressure Model