The anaerobic digester comprises two five-litre upward-flow packed bed reactors with feed rate and temperature control facilities. This allows steady, continuous operation at up to seven litres per day over periods of several days. The reactors may be operated in series or parallel. A buffer vessel between the reactors permits discharge of excess flow from the first reactor when the second reactor is operated in
series but at a lower flow rate. The flow rates to the vessels are set and controlled by calibrated peristaltic pumps. The temperature of each reactor is controlled by an electric heating mat wrapped around the external wall. The temperature distribution within each reactor is maintained to ±0.5°C. Reactor temperatures may be separately set at any desired value in the range ambient to 55°C. The gas off-take
from each reactor is taken to a volumetrically calibrated collector vessel operating by water displacement.
A constant head, liquid seal device ensures the gas pressure in the reactor is maintained at a constant value throughout the test run. The collected gas can be exhausted from the vessel and the volume refilled with water during a run without breaking the liquid seal.
Demonstration Capabilitie
Effluent treatability studies, including solids, carbon and biogas balances to determine purification (COD/BOD)
Determining optimum operating temperatures, feed rates and ratios
Observing effect of pH and influent nutrient concentration
Process stability studies
Determination of controlling kinetics
100% scale-up to industrial requirement
Specification
A benchtop anaerobic digester for waste water treatment studies
Equipped with two 5l packed bed, upward-flow reactors
Each reactor has gas sampling & collection facilities
Reactors may be operated in series or parallel flow arrangement, using variable-speed peristaltic
pumps
Feed flow rate to each reactor can be accurately and independently controlled to any temperature between
ambient and 55°C, using 200W heating jackets
Thermostatic cut-out set to 110°C
An instruction manual describing test and practical work capabilities, including details of a proven
feedstock (synthetic waste water) is included
Reactors: Two, identical
Nominal capacity: 5 litres
Packed volume: 4 litres 150mm dia x 250mm high
Reactor packing: 25mm diameter Bio-balls
Temperature control: For each reactor:
200W heating jacket with PID control from a temperature sensor positioned inside the reactor, set
point within range ambient to 55°C, the jacket is thermostatically protected by a cut-out set at 85°
Feed pumps:
Two identical peristaltic pumps: variable speed using 10 turn potentiometer to 4rpm supplied with
three tube diameters, 1.6, 3.2 and 4.0mm, flow rates from 0.2 to 5.8 l/day
Gas collection vessels: Two, identical – linear scale, 0-5 litre capacity
