23
(1)
Open the air exhaust valve (V-4) and the drainage valve (V-3).
(2)
Open the backwashing valve (V-6), run the NaClO feed pump and the
backwashing pump to feed the chemical enhanced backwash water to the
membrane module.
The flow rate of backwash water is set up in advance for 1.0 to 1.5 times
filtrate water flow rate (Do not exceed Max. Backwash Flow described in
Table 4).
(3)
As soon as the NaClO is detected in the drainage water, close the drainage
valve (V-3).
(4)
After making sure water comes out from upper part of the side nozzle of the
membrane module, stop the NaClO feed pump, close the backwashing
valve (V-6) and stop the backwashing pump.
(5)
Soak the membrane in the chemical for a fixed time (normally 20 minutes).
And then, open the air-scrubbing valve (V-2) for a fixed time (normally 60
seconds).
The air flow rate for air-scrubbing should be within
the range below. Excessive air flow rate may
damage the hollow fiber membrane.
HFUG-2020AN: 4.8 – 9.0 Nm
3
/h, normally 6.0 Nm
3
/h
(2.8 – 5.3 scfm, normally 3.5 scfm)
The maximum required air pressure during the
air-scrubbing for inside of the module will be 40 kPa
(6 PSI).
(6)
Close the air-scrubbing valve (V-2), open the drainage valve (V-3) to drain
the chemical from the membrane module.
(7)
Close the drainage valve (V-3), and then open the backwashing valve (V-6)
and run the backwashing pump (normally 30 seconds). Stop the
