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1.6
AERATION
Sterile air is introduced into the medium through the ring sparger, and is controlled by
the needle valve of the flowmeter. It is able to provide 1.5 (working volume) of sterile
air thru 0.2 μm replaceable cartridge filter (Fig. 1). The filter is sterilizable with the
vessel. With the system, Oxygen Transfer Rates of 350 mMO 2 /L/Hr may be obtained.
1.7
pH CONTROL
pH is controlled in the range of 2.00-12.00 (± 0.01). The pH is sensed by a glass
electrode. Control is maintained by PID controller which operates two peristaltic
pumps, connected to acid and base addition ports (Fig. 1).
1.8
DO CONTROL
DO is controlled in the range of 5-95% (± 1%). It is sensed by the DO electrode and
control is maintained by the PID controller which changes the speed of agitation.
1.9
FOAM CONTROL
Foam is controlled during batch fermentation by the antifoam probe which is located
in the headplate. The controller operates the antifoam addition pump that adds
chemical defoamer through the port in the wall of the vessel (Fig. 1). Sensitivity and
time adjustments are made on potentiometers located on a small printed circuit board
mounted on the underside of the electronic shelf, easily accessible when the rear door
is open. The potentiometer on the right (P1) is for sensitivity adjustment and the
potentiometer on the left (P2) is for percent pump on time adjustment.
1.10 MEDIUM FLOW CONTROL
A nutrient feed peristaltic pump is provided for use during continuous culture
fermentation. The maximum flow rate can be found in section 3.8.
1.11 EXHAUST SYSTEM
The exhaust gases pass into the exhaust condenser where moisture is removed and
returned to the vessel. The air remaining passes through the 0.2 μm exhaust filter and
goes to the atmosphere (Fig. 1).
1.12 SAMPLING SYSTEM
The sampler is attached to a sampling tube that extends to the liquid of the vessel.
The
sampler has a rubber suction bulb to facilitate collection of representative samples
M1226-0050
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