VI.
RO CLEANING & SANITIZATION PROCEDURES
Page - 38
cleaned in parallel, multiply the resultant value by the number of vessels to
be cleaned in parallel) The pressure should be low enough that essentially
no product is produced.
h)
Recirculate until one tank volume of solution has passed through the
vessels and temperature has stabilized.
i)
Turn off the cleaning pump and close the cleaning skid outlet valve. Do
not drain unit. Proceed to Step 2 (Soak).
Cleaning Step 2: Soak
a)
Allow the solution from the Slow Flow step to remain in the unit for at
least one hour. Soak may continue overnight for highly fouled membranes.
b)
Flush the membranes by allowing RO feed water into the unit (without
starting the pump). Flush with a volume equal to two times that prepared
for the slow flow step.
c)
Drain the cleaning tank and RO unit before beginning Step 3 (High Flow).
Cleaning Step 3: High Flow
a)
Repeat steps 1-6 in Slow Flow cleaning procedure (above).
b)
Slowly open the cleaning skid outlet and adjust the cleaning recirculation
valve until the flow to the RO unit is equal to the rate presented in Table 5-
1 for the membrane diameter to be cleaned. (If more than one vessel is to
be cleaned in parallel, multiply the resultant value by the number of vessels
to be cleaned in parallel) The pressure should be low enough that
essentially no product is produced.
c)
Recirculate for 30 - 60 minutes.
d)
Turn off the cleaning pump and close the cleaning skid outlet valve.
e)
Flush the membranes by allowing RO feed water into the unit without
starting the pump. Flush with a volume equal to two times that prepared
for the High Flow step.
f)
Drain the cleaning tank and prepare new cleaning solutions prior to
cleaning subsequent stages.
D)
Sanitization
To reduce the number if bacterial counts within a Reverse Osmosis unit, it will
occasionally be necessary to perform a sanitization of the unit components &
piping. This sanitization can be performed solely on the RO unit, or may be
combined with the sanitization of upstream and downstream equipment.
1)
Sanitization Chemicals
To biologically disinfect the Reverse Osmosis membranes, a peracetic acid
based solution is recommended. Two solutions that are commercially available
