AIRE-064-1-4
13
Membrane Module
dPIA
FIC
FI
L
H
L:CLOSE
H:OPEN
L:OP
EN
H:CLOSE
Permeate water
Outlet
Manifold
Upper Limit
Air Outlet
Feed Chemical
Air Diffuser
Membrane
Submerged
Tank
of this section.
(1) Filtration with natural water head
The filtration can be performed with using a natural water head differential pressure
generated from a vertical distance between the liquid level of the membrane submerged tank
and the level of the permeate water outlet (see Fig. IV-2). In order to obtain enough suction
pressure for the filtration, the permeate water outlet should be located enough below the
liquid level of the membrane submerged tank (normally located at the same level as the
bottom of the element block).
It is recommended that the piping from the permeate water manifold to the permeate water
outlet should directly penetrate the tank wall, as shown in Fig.IV-2. If the piping climbs over
the tank wall, it is required to install a suction pump to build a siphon. It is also recommended
to make the pipe just before the permeate water outlet U-shape to seal the piping with water.
Fig. IV-2 Schematic Flow Diagram for Natural Water Head Filtration
The permeate water flow is controlled with the automatic control valve (the permeate control
valve). And this control valve fully closes the permeate water line to stop the filtration when
the liquid level of the membrane submerged tank gets to the lower limit. When the liquid
level gets to the higher limit, the automatic shutter valve on the raw water feed line closes its
LS
Raw Water
Fine Screen
FIC: Flow Rate Indicator/controller
L S : Level Switch
dPIA:
Different
Pressure Indicator/Alarm
FI
：
Flow Meter
