Why is it necessary to clean Reverse Osmosis Membranes?
1: Cleaning the reverse osmosis membrane is the first step in restoring the performance of a failing RO system. Membrane performance will eventually deteriorate in every reverse osmosis plant due to one or more fouling scenarios.
2: As a result, the operating pressure rises, the permeate flow falls, and the salt channel expands. At this stage, cleaning the RO membranes, restoring operating performance, and bringing all operational parameters closer to design values become important.
3: Apart from fouling and low membrane performance, RO membrane cleaning is needed prior to any medium or long-term shutdown or as part of the periodic maintenance regimen, which is normally every 3 to 6 months.
4: Because RO membranes account for a sizable amount of the total reverse osmosis investment, protecting the membranes from physical and chemical deterioration should be a maintenance priority, and the methods to assist the cleaning process should be included in the initial system design.
5: It is critical to clear the membranes before they become significantly clogged. When membranes are severely degraded, the efficiency of the chemicals is jeopardized because penetration into the foulant is limited.
Methods for cleaning RO membranes
Once fouling or scaling is detected and the implications are obvious, RO membrane cleaning is the sole choice for restoring system capacity.
When membrane breakdown is severe or occurred within a short period of time, the best approach is to extract one of them and determine the root reason. Typical membrane productivity difficulties include:
-Sulphate scale or calcium carbonate scale;
-Silica scale;
-Iron, manganese, or aluminium fouling;
-Bacterial growth;
-Colloidal fouling.
When membrane degradation cannot be linked to a single cause but is caused by a combination of them, chemicals can be employed to obtain the best cleaning.
Cleaning of RO Membranes using pH Chemicals
RO membranes should be cleaned at low pH, high pH, or a combination of both depending on the type of problem. When combining acid and caustic solutions, it must be done individually, and by never combining acids with caustic substances.
|
pH type |
Chemical used |
|---|---|
|
Low (Acid) |
Hydrochloric Acid (20%) |
|
High (Caustic) |
Sodium Hydroxide (10%) |
Cleaning Procedure for RO Membranes
The basic methods for cleaning a reverse osmosis membrane are as follows:
1: Turn on the concentration valve.
2: Flush the system with permeate water if possible.
3: Connect the recirculation pump's membrane feed inlet to the membrane feed inlet.
4: Connect the chemical tanks permeate and concentrate exits.
5: Recirculate the cleaning solution for one hour while keeping the pH under control.
6: Rinse the membrane well, preferably with permeate water, to remove any residues of chemical.
7: Repeat the cycle if more than one cleaning chemical is required.
Membrane cleaning in reverse osmosis plants: Off-site vs. On-site
On-site cleaning:The most prevalent cleaning method for commercial and industrial reverse osmosis systems is on-site RO membrane cleaning, commonly known as Clean-in-Place (CIP). On-site cleaning is performed in-situ, while the pressure vessels and membranes remain within, and is faster and less expensive than off-site cleaning.
Off-site cleaning:It entails eliminating the membranes from the pressure vessels and transporting them to another location. Off-site RO membrane cleaning is usually more efficient, is performed by specially trained specialists, and the outcomes are more easily recorded. The expense, however, will be much higher.
All Netsol commercial and industrial reverse osmosis systems are delivered clean-in-place, complete with all hydraulic connections needed for on-site membrane cleaning.
Conclusion
Reverse osmosis membrane cleaning is an important step that will be required by any RO system at some point and should be included in the RO planned maintenance protocol.
To determine whichtreatment is best for reverse osmosis membrane cleaning, the foulant/scalant must first be identified. The cleaning station will then be connected to the membranes and run for at least one hour.
What do we offer?
Netsol Water is a renowned producer of water and wastewater treatment plants. Based on client feedback and job quality, we are the most demanding organization in the water industry. We have a reputation for being the top commercial RO plant manufacturer, industrial RO plant manufacturer, sewage treatment plant manufacturer, effluent treatment plant manufacturer, and much more.
We can assist you in the following ways:
-Determining the cause of the RO system's poor performance;
-Recommending the most effective cleaning chemical for the RO membranes;
-Creating and implementing the RO membrane cleaning protocol;
-Providing the chemicals and cleaning stations.
Our USP is 24x7 customer assistance. For further inquiry, or product-purchase-related questions, give us a call on +91-9650608473 or email at enquiry@netsolwater.com.