Our membrane cleaning chemicals are highly effective for removing even the most stubborn scales and foulants from membranes. Our membrane cleaning chemicals are formulated for all types of RO and UF membrane systems, ranging from those used in Food and Beverage applications to Water Reuse applications.

The outcome of a membrane cleaning is as dependent on procedure as it is on the cleaning chemical. However, an optimal procedure isn’t always possible to implement due to limitations in the design of the Clean-In-Place (CIP) system.  Membrane Works can provide recommendations on CIP system design, and can provide training on best practices and procedures to enhance RO membrane cleaning results and to reduce frequency of CIP’s.  Additionally, we offer cleaning studies that allow us to identify the optimal temperature, pH and cleaning time for the membrane foulant in your specific system.

Cleaner Product Range

High pH and low pH chemicals are available in both liquid and powder form.

All of our cleaning chemicals are NSF approved for use in potable membrane systems.

Sulfate

• AWC® C-238 High pH liquid RO membrane cleaning formulation for disintegration of gypsum scale.
• AWC® C-239 Low pH liquid RO membrane cleaning formulation specifically designed for removal of sulfate scales.

Silica

• AWC® C-219 Membrane cleaning compound for dissolution of heavy silica deposits.

Organic / Biofilm & Colloidal

• AWC® C-218 Low foaming liquid formulation designed for use as a high pH cleaner of polyamide thin film composite membranes.
• AWC® C-227LF Low foaming high strength powder formulation specifically designed for removal of heavy organic fouling from membrane surfaces
• AWC® UF-428 Chlorinated high pH powder MF/UF membrane cleaning chemical for removal of heavy biological and organic fouling. Compatible with most PES membranes.
• AWC® UF-429 Chlorinated high pH powder MF/UF membrane cleaner for removal of heavy biological and organic fouling. Compatible with most PVDF membranes.

Carbonate / Phosphate & Metal Oxide

• AWC® C-217 Specialised Liquid formulation designed for the removal of iron and manganese from reverse osmosis and UF membranes.
• MW C-101 Liquid formulation designed for the removal of carbonate scales and metal oxide scales such as iron.

What is the procedure for cleaning RO membranes? What CIP chemicals should be used?

Membrane cleaning should be performed with high and low pH CIP chemicals. The high pH cleaning should always be performed first to penetrate and disperse biological or organic foulants. Specialty high pH cleaning chemicals more effectively penetrate heavy organic and biological foulants, making them more effective than commonly used CIP chemicals such as sodium hydroxide. While many choose the lowest cost CIP chemicals, their annual cost will end up being significantly higher because of the higher frequency of cleaning, this incurs more labour costs, chemical costs, and downtime. It’s always best to perform a cleaning study to ensure that membrane performance is fully restored after CIP.

We strongly against the use of citric acid prior to conducting a caustic clean as organic foulants lose their anionic charge if a low pH cleaning is performed first, and since some permeate is almost always produced during CIP, the foulants will be compacted into the membrane and become more difficult to penetrate.

What is the Best Method for Cleaning RO Membranes?

Membrane CIP results will be best if each stage is cleaned individually. This will allow for the maximum flow velocity during cleaning. If both stages of a system with a 2:1 array are cleaned simultaneously, each pressure vessel in the second stage will receive twice the flow velocity as the first stage. This would cause membrane telescoping in the second stage if the first stage elements are cleaned at optimal flow velocity. Alternately, by basing the flow velocity on the second stage, the first stage membranes would not receive sufficient surface scouring.

Performing RO Membrane Cleaning

The total volume in the system should always be considered when determining how much CIP chemicals to add. You can use the AWC RO CIP Calculator to help you calculate the correct amount of chem

When performing a cleaning of a RO system, the first 20% of the cleaning solution is flushed through the membranes directly to drain, instead of circulating. This will prevent contamination of the cleaning solution with loose foulants and large suspended solids.

The remaining solution is then circulated through the system while carefully monitoring the pressure differential (dP). dP should not exceed 0.7 bar per membrane element. Every 30 – 60 minutes, the circulation can be stopped to allow the membranes to “soak” for about 30 – 60 minutes. Circulation should then be started again to flush off the disintegrated foulant and to bring fresh cleaning chemical to the membrane surface. pH should be checked every 15- 30 minutes during circulation. If the pH of the cleaning solution has changed, more cleaning chemical should be added to adjust the pH back to the target range.

Soaking and circulating can be repeated alternately until cleaning is complete. Low pH cleaning is determined to be complete when the pH stabilizes, but the length of a high pH cleaning should be based on a predetermined time. The length of time required for optimal CIP results can either be obtained by trial and error, or by performing a cleaning study.

A high pH cleaning is usually performed at a pH of 11 – 12 using a cleaning chemical such as AWC® C-219 for silica, AWC® C-218  for biofouling or AWC C-227 for heavy organics fouling. More chemical is added during the cleaning every time the pH drops below 11. If the solution becomes very dark or turbid, it should be drained and a new cleaning solution should be prepared.

A low pH cleaning should be performed at a pH of 2 – 3 using CIP chemicals such as C-101 combined with hydrochloric acid to pH 2-3. If the pH of the cleaning solution increases above 3 at any time during the cleaning, more cleaning chemical must be added to reduce the pH to its target range of 2 – 3.

Need help solving your scaling problem?

Membrane Works can help provide advice and support for optimising your chemical treatment. Contact us today to learn more