W11 Aerobic Digester
The continuous activated sludge process has been successfully employed in public health engineering installations for nearly a century.
The Armfield Aerobic Digester is a benchtop unit designed as a comprehensive study facility of this process.
A synthetic waste water feed may be used to gain a working knowledge of the operational parameters and purification efficiencies.
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.
Feed pump: 24V DC, peristaltic, 0-30rpm corresponding to 0-40 L/day
Air compressor: 120V/240V, 0-3.0 L/min (STP)
Reactor vessel: 10L maximum capacity
pH meter range: 0.00 to 14.00
DO meter range: 0-100% saturation, resolution: 2%
Reactor heater: Toughened glass, electrical immersion 200W
Temperature controller: 3-term PID (temperature limit set at 35°C)
Features & Benefits
- Small Scales bench mounted design
- Provides demonstration of continuous activated sludge process
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- Acclimation of a completely mixed biological reactor
- Measurement of COD and MLSS changes as criteria of performance
- Establishing the stoichiometry and kinetics of aerobic processes
- Gas/liquid mass transfer
- Residence time distributions
- 100% scale-up to industrial requirements
- Studying the effect on effluent quality of:
Inflow substrate concentration (‘loading rate’)
Liquid flow rate and reactor volume (‘detention time’)
Air flow rate
- A 10L bench mounted aerobic digester, complete with peristaltic feed pump, air compressor and temperature control system
- Dissolved oxygen and pH probes and meters are included
- The reactor comprises a cylindrical porous liner held in position with sealing rings between the lid and the base to facilitate removal for cleaning and replacement
- Suspended solids are held within the reactor volume, while treated water permeates through the porous liner into an outer annular exit chamber
- The water level is maintained by an adjustable constant head overflow device
- This digester system is designed to operate safely and reproducibly for periods of several days
- The equipment is mounted on a moulded plastic base, equipped with an internally moulded drain channel, designed to cope with spillages and washdown water
- Operational manual with teaching exercises
CW17 – Chilled Water Circulating Unit
Plastic feed and product tanks – capacity typically 30-50l, floor standing (not supplied)
Synthetic waste water (not supplied)
Packed and crated shipping specifications
Gross weight: 40Kg
- CW17 (optional)