TORAY MBR
Instruction Manual
06-G-MB2-NHPAF-220801
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Blower(s) and air piping for membrane scouring should be completely separated from the
biological aeration system so that the membrane scouring air flow rate would not be affected
by DO control in oxidation process. Membrane scouring blower(s) must have enough
capacity to satisfy the scouring air flow rate requirements for all modules. About 10 kPa or
100 mbar of the pressure loss with the fine-bubble air diffusers should be considered when
choosing blowers.
Rotary, turbo, or centrifugal blowers can be used for membrane scouring. Oil-free blowers
are recommended in order to avoid the accidental contamination of the scouring air with oil,
which could result in damage of the membrane diffuser. Depending on the atmosphere, the
use of a suction filter to protect the diffuser from dust or sand is recommended. An air filter
that removes more than 99.5% of 2-micron dust is a suitable example.
It is necessary to install an air flow meter and valve and recommended installing a pressure
gauge in the air supply to check the air flow situation and to adjust the air flow rate just in
case.
(2) Pipe Arrangement for the Filtrate Water Manifold
Fig.IV-10 and Fig.IV-11 illustrate two approaches of the filtrated water piping from the
Membrane Tank. Fig.IV-10 shows downward piping and Fig.IV-11 shows upward piping.
The downward piping is incorporated when sufficient suction can be developed via siphon
(the filtrate discharge lower than the tank level). The upward piping is for operation when a
suction pump is required (the pump is above the membrane tank).
In both upward and downward piping, the chemical injection valve and the air discharge
valve should be installed on a pipe tee between the pipe from the filtrate water manifold to
the filtrate water control valve. These devices are necessary for chemical cleaning and are
detailed in sections VIII-3 to VIII-6.
It is advised that you prepare and attach a “riser pipe” to connect two filtrate
manifolds of two element-decks for ease of piping and handling
(out of Toray’s scope of
supply).
Fig.IV-12 shows example of the riser pipe. In case of using a riser pipe, the two
element-decks have to be stacked and connected so that filtrate manifolds of both
decks come to the same side.
In case of NHPA150-3F and 4F, prepare separate riser pipes for the lower two
element-decks and the upper one/two element-deck(s), and do not connect all decks
to one single riser pipe. Refer to Fig.IV-13.
It is also advised confirming that the diameter of filtrate piping is suitable for the assumable
maximum flow velocity at each point, especially after aggregating filtrate flow from several
manifolds such as header pipes.