IONIC Zero PPB, Operator'S Manual

Page: 38 / 54

Maintenance Procedures
38
Cleaning Your RO
Eventually the day comes when your RO system will require cleaning.
Cleaning is recommended when your RO shows evidence of fouling, just prior
to a long-term shutdown, or as a matter of scheduled routine maintenance.
Fouling characteristics that signal you need to clean are a 10-15% decrease
in normalized permeate flow, or a 10-15% decrease in normalized permeate
quality.
RO cleaning frequency due to fouling will vary by location. A rough rule of
thumb as to an acceptable cleaning frequency is once every 3 to 12 months. If
you have to clean more than once a month, then it is likely that the pre-filters
are not being properly maintained/replaced or that the water softener is not
being regenerated properly or frequently enough. It is also likely that the
system has insufficient water softener capacity, in which case you should be
able to justify further capital expenditure for improved RO pre-treatment
(additional water softening).
One RO maintenance procedure that is commonly over-looked in reducing
RO cleaning frequency is the use of RO permeate water for flushing foulants
from the system. Soaking the RO elements during standby with permeate can
help dissolve scale and loosen precipitates, reducing the frequency of
chemical cleaning. (refer to section about Winterising and Storage).
What you clean for can vary location to location, depending on the foulant.
Complicating the situation frequently is that one more than one foulant can be
present.
Typical foulants are:
- Calcium carbonate scale
- Sulfate scale of calcium, barium or strontium
- Metal oxides of iron, manganese, aluminum, etc.
- Silica scale
- Colloidal deposits (inorganic or mixed inorganic/organic)
- Organic material of natural origin or man-made origin
- Biological (biofilm, mold, or fungi)
There are a number of factors involved in the selection of a suitable cleaning
chemical (or chemicals) and proper cleaning protocol. The first time you
consider that RO performance has deteriorated it is recommended to contact
Ionic Systems Ltd or one of its agents.