Armfield Engineering Education
WATER TREATMENT PROCESSES
W10 Aeration Unit - Issue 8
The purpose of the Armfield Aeration Unit is to permit study of the oxygen transfer characteristics of diffused air systems and the physical and chemical parameters which influence their oxygenation capacity. These studies are a necessary prelude to the understanding of the biological treatment of waste waters.
ORDERING SPECIFICATION
• An aeration unit to permit the study of oxygen transfer characteristics of diffuse air systems.
• Comprising a 24.5 litre open tank with variable speed motor driven stirrer paddle and pumped air supply, via a valve and flow meter, to a diffuser.
• Sparger, single and treble airstone difusers are included in the supply.
• A battery powered dissolved oxygen meter provides intrumentation including direct reading of water temperature.
Demonstration Capabilities
• effects of oxygen transfer under non-steady state conditions
• measurement of the absorption coefficient Ks and the oxygenation
capacity R
• the effect on Ks and R of:
> degree of fluid mixing,
> water temperature,
> gas flow rate,
> depth of water,
> diffuser arrangement,
> water composition.
Description
The Armfield Aeration Unit comprises an open tank equipped with a paddle stirrer. Air is supplied by an electrically driven pump through a control valve and flow meter to a diffuser, adjustable for position, within the tank. A variety of diffusers is included. The dissolved oxygen content of the water in the tank is measured by means of an oxygen electrode and dissolved oxygen meter. The meter supplied gives an additional direct reading of water temperature. Operating from internal batteries, the meter may be used for field trials independently of the apparatus.
The equipment consists of a base and backboard standing on four rubber feet. Mounted on the base is the clear acrylic water tank which has a capacity of 24.5 litres. On the front of the tank is a depth scale and at the base a drainage tap. The lid of the tank is partially removable to allow filling. On the fixed part of the lid are mounted the stirrer motor, stirrer and clamping positions for the temperature probe, oxygen probe and aerator tube.
The oxygen/temperature meter is mounted on the backboard with the connecting leads to the appropriate probes.
Air is supplied to the tank by means of a pump (with filter and silencer assembly) and is controlled by a valved flow meter discharging through the aerator tube.
Three diffusers, sparger tube, treble airstone and single airstone, may be separately attached to the aerator tube.
Variable speed adjustment of the stirrer paddle provides different levels of turbulence in the tank.
Technical Details
Pump: Diaphragm type
Tank capacity: 24.5 litres
Flow meter range: 1-12 litres/min
Oxygen/temperaturemeter ranges:
-5 to 199%DO2
-5 to 25.0%DO2
-5 to 19.99mg/l
-10 to 105°C
Oxygen probe length: 300mm
Paddle: Variable sped controlled by D.C. shunt wound motor
Chemicals required: Sodium sulphite, (not supplied) Cobaltous chloride
Recommended Accessories/instruments
Stop clock
Triple beam top loading balance
100ml measuring cylinder
Requirements
Electrical supply:
W10-A: 220-240V/1ph/50Hz
W10-B: 120V/1ph/60Hz
W10-g: 220V/1ph/60Hz
Water supply:
Initial fill and laboratory drain.
Shipping specification
Volume 0.70m3
Gross weight: 100kg
Overall dimensions
Height: 0.75m
Width: 0.6m
Depth: 0.5m
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