NIRE-170-1-6
13
Membrane Module
FIC
FI
L
H
L:CLOSE
H:OPEN
L
:OP
EN
H:CLOSE
Filtrate water outlet
Manifold
Lower Limit alarm
Air Outlet
Feed
Chemical
Air Diffuser
Membrane
Tank
PIA
PIA
“U-shape”
2. Flow Diagram of Membrane Filtration
Two (2) flow diagrams of the membrane filtration process are shown below. One is for gravity
filtration (when site conditions permit) and the other using a suction pump. Also depicted are
major ancillary devices required for the membrane filtration process.
To reduce the potential for membrane clogging, all activated sludge should pass
through a fine mesh screen having openings of 3 mm or less prior to being introduced
into the membrane tank.
Failure to incorporate the screen device may result in large
solids clogging or causing physical damage to the membrane surfaces.
In order to equalize BOD load and filtration flow capacity it is recommended that a
buffer/equalization tank be installed to help stabilize operation of the biological treatment and
membrane filtration process.
(1) Gravity filtration configuration
The filtration process can be accomplished by using elevation differences between the liquid
level of the membrane tank and the level of the filtrate outlet (see Fig. IV-2).
Fig. IV-2 Schematic Flow Diagram for Gravity Filtration
In order to obtain enough suction pressure for the filtration process, consider friction loss of
all pipes and valves. In addition, the filtrate water outlet should be located at least 3 m below
the surface of membrane tank water level.
LS
Wastewater
Fine Screen
FIC: Flow Rate Indicator/Controller
LS : Level Switch
PIA: Pressure Indicator/Alarm
FI : Flow Meter
