The equipment consists of a ten-litre reactor vessel mounted on a vacuum-formed plastic base. A liquid feed pump, air supply and instrumentation is included for monitoring and controlling the process. The cylindrical wall of the reactor is made from a porous plastic material to retain the suspended solids while enabling treated water to pass through to the outer, annular exit chamber. This design enables the essential features of the aerobic treatment process to be studied without the distractions of having to settle the solids adequately enough for external recycle – a well-known laboratory problem. The porous liner is removable for cleaning, and a spare liner is supplied. 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
Demonstration Capabilities
Acclimation of a completely mixed biological reactor
Measurement of COD and MLSS changes as criteria of performance
Establishing the stoichiometry and kinetics of aerobic biological 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
– temperature
– pH stability
– nutrient deficiency
Specification
A 1.5l 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
Feed pump: 24V DC, peristaltic, 0-30rpm corresponding to 0-40 l/day
Air compressor: 120-240V, 0-3.0 l/min (STP)
Reactor vessel: 1-51 max capacity
pH meter range:0.00-14.00
Dissolved oxygen meter range: 0-100% saturation
Dissolved oxygen meter resolution: 2%
Reactor heater: Toughened glass, electrical immersion 200W
Temperature controller: Three-term PID, temperature limit set at 35°C
