Membrane Cleaning Unit (CIP) – for 4 Inch Reverse Osmosis Systems

The Membrane Cleaning Unit brings the core equipment for chemical cleaning together on a single frame.

The Membrane Cleaning Unit is used for periodic membrane maintenance at sites running reverse osmosis systems with 4 inch membranes.

Industrial Reverse Osmosis SystemsProduction PlantsFood and Beverage ProductionTextile ApplicationsHotels & AccommodationBoiler Feed Water LinesPure Water Pre-TreatmentProcess Water Lines

The Membrane Cleaning Unit applies the method known in the industry as CIP (clean-in-place). The tank, pump and connection layout of a typical CIP set-up is explained in detail in this technical article on the design of reverse osmosis cleaning set-ups.

1. 1

   The System Is Stopped and Connected

   The reverse osmosis system is stopped; the unit’s delivery line is connected to the feed side of the system and its return line to the cleaning tank.

2. 2

   The Cleaning Solution Is Prepared

   The polyethylene tank is filled with reverse osmosis product water and a cleaning chemical suited to the type of fouling is added.

3. 3

   Circulated at Low Pressure

   The stainless pump passes the solution through the membranes at low pressure; the solution returning from the concentrate and product sides comes back to the tank.

4. 4

   Soaking and Circulation

   The solution is left to stand on the membrane surface for a while, then circulated again; the loosened build-up is carried to the tank.

5. 5

   Rinsing and Return to Service

   Before switching to a different chemical and at the end of the clean, the system is rinsed with product water; the reverse osmosis system is then returned to normal production.

When choosing the Membrane Cleaning Unit, the membrane diameter, the number of membranes and the type of fouling should be assessed together.

Used at the right time and with the right chemical, the Membrane Cleaning Unit helps preserve membrane performance.

• A clean should be planned when the normalised product water flow falls by 10%, or when salt passage rises by 5–10% or the differential pressure by 10–15%.
• For comparison, the steady operating figures from the first 48–72 hours after the system is commissioned should be kept on record.
• If cleaning is delayed and the loss of flow grows, it becomes harder to bring the membranes back to their original performance with a standard clean.
• Between acidic and alkaline cleans, the system should be rinsed thoroughly with product water; otherwise dissolved minerals can precipitate again.
• The cleaning chemical should be used within the pH and temperature limits allowed by the membrane manufacturer.
• After cleaning, the tank, pump and piping should be flushed with clean water; no chemical residue should be left in the unit.