NIRE-170-1-6
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Keep the membranes wet once they get wet. If the membranes are
allowed to dry out, the permeability of the membranes may be
permanently reduced.
8. Storage Products after Use
Take the following steps to preserve and store used
“NHP210 Series” modules.
(1) In case of module storage inside sludge (without sludge drainage), stop filtration
and aeration should be stopped or intermittent e.g. five (5) minutes every hour to
agitate and supply minimal DO to the sludge.
Continuous aeration should not be applied from the viewpoint of membrane protection.
Also open air discharge valve on filtrate piping during aeration to avoid the possible air
accumulation inside module and subsequent module damage.
(2) For long-term storage of used module (i.e. just for membrane preservation), take
following steps.
•
Drain the sludge in the membrane tank.
•
Using a water hose wash sludge off the modules with clean water. In addition wash
off any remaining sludge on the tank walls. Never use a pressure washer machine
on the membrane module and element.
•
Fill the membrane tank with clean water until the module is completely covered.
Periodically check the water level and add more water if needed to keep the module
covered with water. Open air discharge valve before pouring water and keep it open
during storage.
•
A periodic dosing of the membrane tank storage water to a < 50 ppm concentration
of sodium hypochlorite will help inhibit the growth of algae/microorganism during the
storage period. Maintaining a hypochlorite concentration higher than 50 ppm for a
long time interval could cause damage to stainless steel components.
•
If aeration is required during long term storage, the aeration cycle should be
controlled to aerate only five (5) minutes every hour.
(3) Before re-commissioning of the modules, it is strongly recommended to conduct a
chemical cleaning of the modules to remove any biofilm growth that may have
developed on the membrane surface and piping during the storage period.
If used module (after washing off sludge) has to be kept out of water, its duration should be
limited within 24 hours and periodic sprinkling of water on the modules (especially membrane
surfaces) is needed. In that case, it is required to cover the module (especially top and sides)
CAUTION
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