Side 10 af 16
7. When the cleaning is finished, the system is closed down as describ
ed in “Part III –
After using Bluebox 1800UF
” (see ill.) and the 3 front-filters have to be changed. If
the first filter, 25 micron, is not too damaged (clogged), it can be rinsed and brushed
down and reinstalled (see ill.).
8. After more than 14 days of standstill and before storing, the Bluebox 1800UF must
undergo a complete cleaning process as described above.
9. If the unit is not in use for longer than 14 days or stored, the membranes can be
treated with a 20% glycol solution, which will also protect it against freezing
temperatures. Pure H2O can also provide a membrane conservation product in
powder form for optimal transport. This product does not possess an anti-freeze
feature.
10. Remember to run a cleaning process of the system before taking into use
afterwards.
Cleaning Procedure with RoClean products
The RO plant is organically or biologically fouled and requires cleaning. Avista
Technologies recommend cleaning with low pH then high pH cleaners RoClean P303 and
RoClean P3111. This stepwise approach has been found to give good results in the past
with each wash reaching deeper layers of the foulant.
Caution
When cleaning with low pH first it should be certain that no hydrocarbon fouling can have
occurred on the membranes. If in doubt reverse the order of cleaner application and start
with the high pH clean.
All cleaning procedures should be carried out within the membrane
manufacturers’
guidelines which in this case are:
DO NOT EXCEED
LIMIT
Cleaning Temperature
45
o
C
Cleaning pH (not below lower or above upper)
2
– 11
Cleaning Flowrate
9-10 m
3
/hr/8” pressure vessel
Cleaning differential pressure (MAX)
65 psi (6 element vessel)
Each array of membranes should be cleaned in parallel and the production of
permeate should be minimised by keeping the differential pressure low. The permeate
lines should be kept slightly open to prevent backpressure damage.
We would additionally recommend that the differential pressure should not exceed
40psi during recirculation and that temperature should be raised as close to the
membrane temperature limit as practical to achieve the most efficient clean possible.
This is most important for the alkaline clean.