Aerobic Digester

consists of a 2 gallon reactor vessel mounted on a steel base, with a liquid feed pump, air supply, and instrumentation for monitoring and controlling the process.

The cylindrical wall of the reactor is made from 2 layers of porous plastic material to retain the suspended solids, while allowing treated water to pass through to the outer, annular exit chamber.

This design allows 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 liners are removable for cleaning, and a spare liner is supplied.

Waste water is drawn from a feed tank by a 120V motor driven peristaltic pump. Flow rate is controlled by a variabe run time control that determines the minutes of run time within a 10 minute cycle.

The pump delivers the feed to the reactor vessel through a transparent lid. Air is supplied at a measured rate by a small air pump, and discharges into the base of the reactor via an air distribution device.

This provides the necessary oxygen for the digestion process, as well as produces sufficient bubbling for stirring and reaction.

The liquid level in the reactor is maintained at a constant value of 1 or 2 gal. by an 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 3-term PID controller which varies power to an immersion heater within the vessel. Any temperature between ambient and 95°F may be selected, with 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

Specifications :

Feed pump

    120V, peristaltic, 10 rpm, variable run time

     control corresponding to 0–13 gal. per day

Air pump

 240V/120V, 0–1.35 gpm

Reactor vessel

2 gal. maxium capacity

pH meter

Range 0.00 to 14.00

Dissolved oxygen meter

Range 0–100% saturation, resolution 2%

Reactor heate 

Electrical immersion 250W

Temperature controller

3-term PID, temperature limit set at 95°F

Anaerobic

Digester is comprised of two 1.3 gallon upward flow packed bed reactors, with feed rate and  Temperature controls to allow steady, continuous operation at up to 1.1 gallons per day.

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 peristaltic pumps. The  Temperature of each reactor is controlled by an electric heating tape wrapped around the external wall.

The temperature distribution within each reactor is maintained to ±1°F. Reactor temperatures may be separately set at any desired value in the range ambient to 131°F.

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 that 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. Liquid and gas sampling points are located at all strategic points around the reactors.

Technical Specifications :

Reactors

Two identical reactors—nominal capacity, 1.3 gal.; packed volume, 1.1 gal.; 6.25" ID diameter by 10" high.

Reactor packing 

1" diameter bio-balls.

Temperature control

For each reactor—836W heating jacket with PID control from a temperature sensor positioned inside the reactor, set point within range ambient to 131°F; the jacket is thermostatically protected by a cutout set at 185°F.

pH Meter

Range: 0.00 - 14.00

Feed pumps

Two identical peristaltic pumps—variable speed using a potentiometer to 12 rpm, with flow rates from 0.04 to 1.1 gal. per day.

Gas collection vessels

Two identical—linear scale, 0–1.3 gal. capacity

A bench top unit comprising a vacuum formed ABS plastic plinth with integral electrical console onto which is mounted the stirred reactor vessel sampling circuit with peristaltic pump, tubular coil heat exchanger and polarimeter device.

• A temperature sensor and heater mounted in the reactor vessel and linked to a PID controller for accurate reaction temperature control.

• A polarimeter device measuring optical transmission and angle of rotation.

• Protection devices for all electrical circuits.

• Three displays: PID temperature control (reactor temperature), display for angle of rotation, display for optical transmission or temperature at polarimeter.

• Sensor signals are routed to the I/O port for connection to a PC

This is a reactor system specially designed to perform batch enzyme reaction utilizing the glucose isomerisation reaction catalyze by glucose isomerase. The unit is used to demonstrate batch enzyme kinetics and enzyme characteristics.

The fourth reactor - stirred tank reactor in series - is mounted on a dedicated unit.

The reactors use the saponification reaction between ethyl acetate and sodium hydroxide. This provides a well understood and safe reaction for the students to investigate the different reactor types.

It consists of a bench-top unit onto which is mounted a reactor vessel in which the glucose isomerase-mediated reaction takes place. The reactor itself is made of clear acrylic, which gives good visibility. A cruciform geometry impeller constructed from stainless steel mesh retains the immobilised enzyme whilst allowing efficient mixing with the liquid reactant (glucose solution). The impeller is a variable speed type. The reaction temperature is maintained using two heaters and a temperature sensor mounted within the reactor. These are linked to a PID controller, which is programmed to maintain the desired set-point temperature. Safety interlocks prevent the heaters being activated when there is a low reactor liquid level or when the impeller is inactive.

 A continuous sampling loop driven by a peristaltic pump removes liquid from the reactor and transfers it to a tubular coil heat exchanger where it is cooled prior to passing through a polar meter where the angle of rotation of polarised light is measured. From this angle measurement the concentration of both glucose reactant and fructose product can be determined. This eliminates the need for manual glucose assays. The measurement system relies on the fact that both glucose and fructose solutions rotate beams of polarised light, glucose to the right and fructose to the left. The polarimetry measurement method allows the progress of the reaction to be monitored on-line.

A benchtop unit comprising a vacuum formed ABS plastic plinth with integral electrical console on to which is mounted the packed bed reactor columns, feed pump, optical sensor and optional Flow Injection Analysis (FIA) system.

The unit is supplied as standard with two reactor columns for chemical catalysis.

A third column can be optionally added to the system for biological (enzymic) catalysis.

A heated water supply to the column jackets allows automatic control of reaction temperature to a set point value.

Feed flow rate can be varied between 0 and 15 ml/min. The FIA pump can be adjusted to give flow rates up to 2.5 ml/min.

All electrical circuits are fitted with appropriate protection devices.

The console has two digital meters. The first, associated with the controller, shows the temperature of water supplied to the column jackets, and the second shows the optical sensor reading which provides a measure of product concentration. Corresponding signals are routed to the I/O port for connection to a PC.Description:

The introduces students to the fundamentals of packed bed catalytic reactors. It is a benchtop unit available with either two or three reactor columns. Using two columns with a chemical catalyst allows a different particle size exchange resin to be used in order to study the effect of particle size on reactor kinetics. It is possible to use a third column to investigate biological catalysis, using the enzyme invertase, and compare this with chemical catalysis. An optional flow injection analysis (FIA) module is available. This module is positioned on the CEU plinth and provides an easy on-line measurement of product yield, eliminating the need for manual assays.

This is a reactor system specially designed to perform batch enzyme reaction utilizing the glucose isomerisation reaction catalyze by glucose isomerase. The unit is used to demonstrate batch enzyme kinetics and enzyme characteristics.

The fourth reactor - stirred tank reactor in series - is mounted on a dedicated unit.

The properties of different chemical reactors can be investigated by performing a saponification reaction using this trainer. The contact time and reaction temperature can be varied. Their influence on the conversion of reactants is observed in the respective reactor. The reactors are available as accessories. The unit contains two supply tanks for the liquid chemicals. Two variable speed diaphragm pumps pump the reactants through the reactor. Reactant conversion and reaction temperature are measured with a combined conductivity and temperature measuring unit. It is also possible to use PC data acquisition. The reaction is moderated using a controlled hot water circuit. The resulting reaction product is collected in a stainless steel tray in the unit.

Features:

Efficient performance

Easy to install

Easy to maintain