Armfield Engineering Education
WATER TREATMENT PROCESSES
W7 Model Sedimentation Tank - Issue 8
This unit has been designed to demonstrate the hydraulic characteristics
and settling efficiencies of a model settling basin. Although scale-up to
industrial size sedimentation tanks is difficult, relevant deductions can
be made as to how non-uniform flows occur and how these interact with the
settling characteristics of particular suspensions.
ORDERING SPECIFICATION
• A rigid acrylic settling tank of 80L capacity can be fed by a mains water or a slurry supply. Slurry is pumped from a 120L sump tank via a centrifugal pump. A sparging device in the sump tank keeps the slurry in suspension.
• Both supplies are fitted with a flow meter. Mains water flow meter range 0.5 - 5.0 litres/min; slurry flow meter range 0 - 2 litres/min.
• A dye injection system is incorporated to allow hydraulic tracer and flow visualisation studies.
• Measuring flow regimes using a dye tracer and comparison of these with idealised flow models.
• Effect of variables such as flow rate and baffle position on flow regimes.
• Measurement of sediment removal efficiencies.
Demonstration Capabilities
> measuring flow short-circuiting and dead space using a tracer
> comparison of real flow regimes with idealised flow models
> effect of flow rate and baffle position on dispersion
> measuring sediment removal efficiencies and relating these to the hydraulic
characteristics.
Description
Water is taken from the laboratory mains supply and is fed to the settling tank via a flow meter. For studies of sedimentation, a slurry is prepared in a sump tank and pumped via a specially designed flow meter to join the fresh water stream just before entry to the settling tank.
A well-mixed slurry of known concentration and flow enters the tank uniformly under an inlet weir. This may be comparatively analysed by the Imhoff cone technique or more accurately by drying and weighing.The sump tank is continually agitated by a flow sparge device to prevent settling of solids during an experiment.
For hydraulic tracer and visualisation studies, an accurate dye injection system is provided. A known volume of dye solution is injected just before the entry to the settling tank.
Technical Details
Settling tank: 1000 x 400 x200mm
Sediment sump tank capacity: 120 litres Water flow meter range: 0.5-5l/min
Sediment suspension flow meter range: 0-2l/min
Pump flow rate: 25l/min at 5m head
Motor: 0.1kW
Recommended Accessories/instruments
Armfield Sedimentation Studies Apparatus (W2) to characterise settling
regimes of selected suspension
Precipitated calcium carbonate
Balances
Colorimeter - 7 narrow band-pass filters covering wavelengths 450 to 700mm
Requirements
Electrical supply:
W7-A: 220-240V/1ph/50Hz
W7-B: 120V/1ph/60Hz
W7-G: 220V/1ph/60Hz
Water supply:
5 litres/min @ 1 bar
Shipping specification
Volume 2.9m3
Gross weight: 310kg
Overall dimensions
Height: 1.55m
Width: 1.90m
Depth: 0.60m
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