Using RO permeate water whenever possible, either acid or alkaline cleaning will depend on the type of foulant suspected. Acid cleaning should be performed first even when alkaline cleaning is desired, since if system performance recovers with acid cleaning, then alkaline cleaning is not necessary.
CLEANING SYSTEM When cleaning the system, begin by connecting the cleaning tank and pump system to the membrane system. Take care not exceed 60 psi pump pressure and it may be necessary to clean one tube at a time. Return permeate and concentrate tubes to the cleaning tank and include a 10 micron filter in the concentrate return line to the tank.
ACID CLEANING Preparing the Solution
Adjust water pH to between 2 and 3 by adding acid cleaner slowly (AM-44 for CA and AM-11 for TF elements) , mixing well. Wear protective clothing including face mask and rubber gloves and mix with care. CAUTION IS ADVISED.
Cleaning Procedure CAUTIONS: Cleaning solution temperatures not to exceed 120ºF. Flows not to exceed 4 gpm for 2 1/2" elements or 12 gpm for 4" elements. Recirculate the solution.
Run system at 50 psi for ten minutes. Maintain a flow rate of less than 1 gpm for 2 1/2" elements and less than 3 gpm for 4" elements. This allows the foulants to loosen. Increase flow rate for next 20 minutes to to 3 gpm for 2 1/2" elements and 9 gpm for 4" elements to clear foulants from the system. Add water and cleaner as necessary to prevent the tank from running dry. Discard cleaning solution and rinse the tank--and the drain--well. Fill tank with clean water and flush continuously for 10 to 15 minutes. Rinse until the concentrate and feedwater pH levels are close to the same.
ALKALINE CLEANING Preparing the Solution
Adjust water pH to a pH of 8 for CA elements and 11 for TF elements by adding alkaline cleaner slowly (AM-33 for CA elements and AM-22 for TF elements), stirring continuouslyand carefully until dissolved. Higher pH will damage membrane. Wear protective clothing including face mask and rubber gloves. Alkaline cleaner can cause severe eye damage. CAUTION IS ADVISED.