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3-1-1 Cleaning Methods
●
Maintenance cleaning
Maintenance cleaning is performed to remove membrane surface fouling regularly to inhibit thickening
of the cake layer and prevent the trans membrane pressure from rising for stable operation of the
product.
Follow the procedure below to perform maintenance cleaning.
1.
Suspend aeration.
2.
Inject NaClO.
If flux is set high (0.4 m
of 300 to 500 mg/L in the amount of 2 L/m
constant rate from the permeate side for 15 to 30 minutes about once a week.
3.
Restart steady operation.
RE F ER E NC E
Normally, NaClO with an effective chlorine concentration of 300 to 500 mg/L is sufficient, but
NaClO with an effective chlorine concentration of about 300 to 1,000 mg/L may be used
when membrane clogging is a concern.
Maintenance cleaning can be omitted if flux is set low (0.4 m
domestic wastewater on a small scale.
●
Recovery cleaning
Recovery cleaning, which is performed every 3 months or when the suction pressure (the trans
membrane pressure index) has exceeded the set value (the initial value of suction pressure -15 kPa as
the absolute value) (i.e., when the trans membrane pressure rises), is intended to remove element
fouling and restore the trans membrane pressure close to its initial value.
Follow the procedure below to perform recovery cleaning.
1.
Suspend aeration.
2.
Inject NaClO.
Inject NaClO with an effective chlorine concentration of 3,000 mg/L in the amount of 2 L/m
unit membrane area plus the piping volume at a constant rate from the permeate side for 30
minutes.
3.
When the NaClO has been injected, leave the module as it is for 30 to 90 minutes.
4.
Start up the dilution water pump, and restart the removal of chemicals in the system and
aeration. Between 0 to 15 minutes after aeration restarts, restart suction and return to
steady filtration operation.
5.
If trans membrane pressure is still high after recovery cleaning by NaClO, perform in place
using acid. Refer to "3-1-2 Acid Cleaning" (p.21) for information on acid cleaning.
STERAPORE 5700 Series (FF) Instruction Manual
3
2
•d) or greater), inject NaClO with an effective chlorine concentration
/(m
2
per unit membrane area plus the piping volume at a
Chapter 3 Chemical Cleaning
3
2
•d) or less), when treating
/(m
2
per
18/58
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