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User Manual
4.8 Membrane Integrity Checks and Leak Arrest
Fiber breakages will compromise the quality of the filtrate and lead to downstream contamination. It is,
therefore, good practice to do regular checks and tests on the integrity of the membranes. For example, one
may conduct such checks straight after a CIP cleaning.
Should there be any fiber breakages, it is recommended that those fibers be plugged (leak arrested) immediately.
Poor quality filtrate not only causes problems downstream, but can contaminate the membranes as well since
the filtrate is used as backwash water. Fouling or contamination of the membranes on the filtrate/ lumen side
is difficult to clean and remove.
Nevertheless, on certain occasions, one may have to perform the integrity checks and leak arrests ad hoc due to
the significant deterioration of the filtrate water quality (as can be seen by the notable increase of filtrate
turbidity and SDI values).
There are two ways to assess if there may be fiber breakage in the module(s). The easiest and quickest way is to
have clear pipes vertically installed near the connecting pipes/ hoses (filtrate side) of each module so that should
there be fiber breakages, continuously flowing bubbles will be observed within those clear pipes during air
scouring (backwash).
Another way is to conduct a Pressure Decay Test (PDT). The procedure for PDT is as below:
1.
Stop filtration/ operation.
2.
Close all valves except for concentrate recirculation, concentrate discharge and filtrate.
3.
Open air valve and introduce 2 bar of air into the module.
4.
Wait for about 2 mins for some excess water to be discharged from the system.
5.
After that close all valves except for the filtrate valve.
6.
Monitor the air pressure for 5 mins.
7.
If, after 5 mins, the feed pressure shows a significant drop (more than 10%), fibre integrity is likely to
have compromised.
If it is indeed determined that fiber breakages have occurred, then a leak arrest must be conducted. The
procedure for fiber leak arrest for the ETUF-9060R is as below:
1.
Drain the modules to be repaired.
2.
Remove filtrate and concentrate connections.
3.
Remove the filtrate end cap clamps after unscrewing the bolts and nuts.
4.
Insert a flat screwdriver/ file into the rectangular slot located between the end cap and collar, then pry
open the end cap. Set the upper part of the end cap aside.
5.
Pour some water into the end socket over the top of the now-exposed fibers.
6.
Open the air valve to allow about 0.5 bar of air into the module.
7.
Look out for significant and continuous amounts of air bubbles coming out from any of the fibers. Mark
out such fibers (with nylon wires*).
