MANOWNROSM
SYSTEM MAINTENANCE
US Filter
17
After flushing the sanitant from the RO system, the permeate water should be
checked for residual levels of sanitizing agent before the system is placed back
on line. Use the following guidelines to determine if the system is clear of
residual sanitizing agents.
1.
Formaldehyde
The product water should be analyzed with the Fast Formalert or other
formaldehyde test kit until detection limits are reached.
2.
Hydrogen Peroxide
The product water should be analyzed with a hydrogen peroxide test kit.
3.
Peracetic Acid
The product water should be analyzed with the Minncare Residual Test
Strip or other peracetic acid test kit. For ordering information call the
number provided on the cover of this manual.
D.
Methods of Sanitization
Sanitization is most effective when the RO system is operating at normal
pressure and flows. This allows the maximum amount of sanitant to penetrate
through the membrane, ensuring adequate sanitization of the product side of the
system. Three methods of sanitization may be used: Continuous Injection,
Recirculation and Static Soak.
1.
Continuous Injection Method
In this method of sanitization, an accessory chemical feed system injects
concentrated sanitant into the feed line while the RO is operating at
normal flows and pressure. Both the product and reject streams are sent
directly to drain.
The continuous injection method is most typically used to sanitize with
hydrogen peroxide. It is not practical for formaldehyde sanitization
because the dilution ratio used for formaldehyde (1:10 to 1:20) would
require the use of a very large chemical feed pump. The advantages of
the continuous injection method are minimal chemical handling and
minimal dead legs in the system piping. One disadvantage is the
relatively high chemical consumption.
The basic steps for continuous injection sanitization are as follows:
a.
Reject and product lines from the RO are diverted to drain.
b.
The system is placed in the normal operating mode.
c.
An accessory chemical feed system is turned on to inject
concentrated sanitant into the feed water. The sanitant is diluted
by the feed water to the recommended concentration.
d.
The system is left running in the normal operating mode for 30 to
60 minutes.
e.
The chemical feed pump and the RO system are shut down, and
the sanitant solution is allowed to sit in the system (optional).
