ILCHEMICAL-Reverse Osmosis Chemical Treatment

Product generated during the cleaning cycle should be returned to the cleaning tank to minimize changes in pH and cleaning solution concentration.

An optional soak and recirculation sequence can be used during cleaning.

Sample valves should be located to allow pH and TDS measurements off the RO cleaning pump discharge and the concentrate side recirculation line.

Note all the readings and observations in the cleaning log sheet.

Refer to instructions from membrane manufacturers.

Ensure that cleaning skid components can withstand the cleaning solution, pH, pressure and temperature.

Use chlorine free water for preparation of cleaning solution

Add cleaning chemicals to the water not water to the cleaning chemicals.

For pH adjustment use pure grade Sodium Hydroxide and Hydrochloric Acid.

Since small volumes of acid and alkalis can rapidly change the overall pH of the cleaning solution, addition should be made gradually.

If required, readjust the pH back to the target when it changes more than 0.5 pH units.

The pressure should be low enough that essentially no permeate is produced.

A low pressure minimizes redeposition of dirt on the membranes.

When cleaning multistage plant clean each stage separately.

Before starting the cleaning perform a low pressure flush by pumping water from cleaning tank through the pressure tubes for several minutes.

At the beginning of each cleaning step, slowly throttle the flow rates. 1/3 (5min)>2/3(5 min)>Max required flow rate

Dump the first 20% solution to the drain.

Warm water, (32 – 37 deg C) gives significantly better cleaning than lower temperature solutions.

Monitor the cleaning solution temperature carefully as heat is generated and imparted by the RO cleaning pump during recirculation.

After completion of each cleaning step a low pressure cleaning rinse with permeate water is required to remove traces of chemical from cleaning skid and RO.