Model:W11
Use:The Armfield Aerobic Digester is a benchtop unit designed as a comprehensive study facility of this process.
Waste water is drawn from a floor-standing feed tank (not supplied) by a DC motor-driven peristaltic pump. Rotational speed – and thus flow rate – is accurately set by a ten-turn potentiometer.
The pump delivers the feed to the reactor vessel through a transparent lid. Air is supplied at a measured rate by a small compressor, and discharges into the base of the reactor via a spider-arm dispenser. This design prevents blockages and produces sufficient bubbling for stirring and reaction. The liquid level in the reactor is maintained at a constant value of five to ten litres, by an adjustable overflow device connected to the outer annular chamber of the vessel. Discharge is by gravity to a floor-standing product tank (not supplied).
The reactor temperature is maintained by a three-term controller, which varies power to an immersion heater within the vessel. Any temperature between ambient and +35°C may be selected, the best conditions being a few degrees above the diurnal maximum in the user’s laboratory.
Dissolved oxygen and pH probes and meters are included.
The reactor lid contains a gas exit port, suitable for sampling the gases for subsequent analysis.
Inflow substrate concentration (‘loading rate’)
Liquid flow rate and reactor volume (‘detention time’)
Air flow rate
Temperature
pH stability
Nutrient deficiency