Cleaning the commercial reverse osmosis membrane is the first step, in restoring the performance of a degraded Commercial RO Plant. Every reverse osmosis plant will eventually experience a loss in membrane performance, as a result of one or more different fouling situations.

As a result, the operating pressure rises, the permeate flow declines, and the salt passage widens.

In this blog, let us see how commercial RO plant membrane is cleaned!

Why is it important to clean commercial RO Plant membrane?

Cleaning of the Commercial RO Plant membrane is required so that we can recover operating performance, as well as bring all the operational parameters closer to design values.

Aside from cases involving fouling and low membrane performance, cleaning the RO membrane is advised right before every medium or long-term shutdown, or as part of the planned maintenance regimen, typically every 3 to 6 months.

How to decrease the frequency of Commercial RO Plant membrane cleaning?

1: Enhancing RO pre-treatment is the best way to reduce membrane fouling, and lengthen the times between reverse osmosis membrane cleanings.

2: Particles that reach the RO system will be reduced by sediment filters or media filters. When there are colloids in the feedwater, a coagulant injection upstream will aid in the removal of the colloidal particles.

3: When organics are present in the RO feed water, activated carbon filtration can produce positive results; however, caution must be exercised to prevent the development of bacteria in this media.

4: In the presence of hard water, water softeners are efficient in reducing the build-up of calcium carbonate scales, on the surface of reverse osmosis membranes.

5: Acid dosing is a substitute for water softening that helps lower the risk of calcium scaling in RO Plant membranes, by increasing the solubility of calcium salts.

The frequency of commercial RO Plant membrane cleaning can also be reduced, by other easily automated procedures that can assist in minimising membrane fouling and scaling, including:

· Opening the concentration valve will allow particles to be flushed off the membrane surface (auto-flushing)

· By recirculating permeate with minimal to no output.

RO membrane cleaning with chemicals

RO membranes should be cleaned at either a low pH, high pH, or a combination of both pH’s, depending on the type of issue. If an acid and caustic solution combination is chosen, it must be used separately; acids and caustic chemicals should never be mixed.

It should be mentioned that using the incorrect cleaning agent, or following the inappropriate cleaning procedure, can make the issue worse. Before choosing any cleaning process, it is usually advised to examine the specifications of the membrane and the membrane manufacturer.

One of the following procedures is typically used to clean a reverse osmosis membrane, both generally and for polyamide membranes:

· Low pH chemicals will be used to clear carbonate and sulphate scale, as well as inorganic colloidal fouling.

· Chemicals with a high pH will be used to clean organics and biofouling.

· Bacteria will be eliminated using either a high pH or specialised biocides.

It is typical to start with a low pH chemical to clean the mineral scale in the presence of organics and mineral scale, and then move on to a high pH chemical to remove the organics.

Although, the permitted pH range for the majority of composite polyamide reverse osmosis membranes is pH 10 to pH 12, we always advise a conservative approach when it comes to chemical cleaning, not going above the pH 4 to pH 10 range. If the conservative range doesn't produce the desired outcomes, it can be carefully widened.

How to clean commercial RO Plant membrane?

The other methods for cleansing commercial RO Plant membranes are:

Forward flush

Membranes are flushed with feed water or permeate water when forward flush is used. Compared to the production phase, the systems permeate or feed water moves through it more quickly. Particles that are absorbed by the membrane are liberated, and discharged as a result of the faster flow and the turbulence it causes.

The barrier that manages dead-ends is opened when forward flush is applied to a membrane. Without producing permeate, the membrane is momentarily doing cross-flow filtering at the same time.

Generally, the forward flush is intended to remove a built-up layer of pollutants from the membrane by generating turbulence. During forward flush, a significant hydraulic pressure gradient is required.

Backward flush

As particles enter membrane holes, they are not released. The only way to get rid of these particles is by flushing backward.

A reversed filtration process is called a backward flush. Under pressure, permeate is forced through the system's feed water side, using twice as much flux as was used for filtering. After back flushing, if the flux has not adequately recovered, a chemical cleaning procedure might be used. Thus, the holes are cleansed because the pressure on the permeate side of the membrane is greater, than the pressure inside the membranes.

As the permeate chamber should always be clear of the contamination, thus, the permeate is always used for the backward flush. A backward flush's effect is a reduction in process recovery. A backward flush must therefore take the least amount of time possible.

Chemical cleaning

Membranes are submerged in a solution of hydrogen peroxide, hydrochloric acid, or chlorine bleach, during a chemical cleaning procedure. Before applying a forward flush or backward flush, the fluid soaks into the membranes for a period of time, rinsing away the impurities.

Air flush

The 'air flush,' also known as the 'air/water flush,' is a more recent cleaning technique. This is a forward flush in which the supplier pipe is given a shot of air.

The use of air results in a significantly more turbulent cleaning method, but the water speed remains the same. When air is injected to the forward flush during an air flush, air bubbles form increasing turbulence. The fouling is eliminated from the membrane surface as a result of this turbulence. The advantage of the air flush over the forward flush is that it requires less pumping power to clean.

Are yo?u still confused about the cleaning procedure of commercial RO plant membrane?

We have the answer!

Netsol Water is the leading manufacturer, supplier, and exporter of a quality selection of Commercial RO Plants and Industrial RO Plants in India. We provide a wide range of water treatment services to businesses, including automobile, food & beverages, pulp & paper, textiles, pharmaceuticals, refinery, etc.

Call us at +91 9650608473 or email at enquiry@netsolwater.com for further information.