Veolia Hydrex Membrane Cleaner Chemicals in Oman and GCC
Veolia Hydrex membrane cleaner chemicals are the products we reach for when an RO plant in Oman loses output and the cause is scale or biofouling rather than a mechanical fault. UV Water Systems supplies Hydrex 4730 and Hydrex 4731 in 25 kg packing across Oman and the wider GCC.
This article explains which of the two cleaners to use, how to run a clean-in-place cycle, and how to tell from plant data that a clean is due.
Hydrex 4730 and 4731: Which Veolia Hydrex Membrane Cleaner to Use
The two products are not interchangeable. Using the wrong one wastes a cleaning cycle and can set the foulant harder onto the membrane.
| Hydrex 4731 (acidic) | Hydrex 4730 (alkaline) | |
|---|---|---|
| Cleaning pH | 2 – 3 | 11 – 12 |
| Removes | Calcium carbonate, calcium sulphate, metal oxides, iron, manganese | Biofilm, organics, silica, colloidal clay, oil and grease |
| Typical symptom | Rising differential pressure with stable salt rejection | Falling permeate flow with rising salt passage |
| Dose | 2% solution in permeate | 2% solution in permeate |
When both scale and biofouling are present, clean alkaline first, then acidic. Cleaning acid first on a biofouled membrane drives organic matter into the membrane surface and the flux never fully recovers.
When to Clean the Membranes
Do not clean on a calendar. Clean on normalised plant data. Log feed pressure, permeate flow, permeate conductivity, differential pressure and temperature daily. Any one of these triggers a clean:
- Normalised permeate flow has dropped 10% from commissioning values
- Differential pressure across a stage has risen 15%
- Normalised salt passage has risen 10%
Waiting until the plant is at 30% loss makes the clean far less effective. Membranes cleaned early recover almost all of their original flux. Membranes cleaned late often do not, and the replacement cost of a set of DuPont FilmTec brackish water membranes is many times the cost of two cans of cleaner.
Running a Clean-In-Place Cycle
A standard CIP with Veolia Hydrex membrane cleaner runs as follows:
- Stop the plant and flush the vessels with permeate at low pressure to displace the feed water
- Prepare a 2% solution of the cleaner in permeate in the CIP tank. Heat to 30 – 35°C if the tank has a heater — do not exceed the membrane maker’s temperature limit
- Check and correct pH. Acidic cleaning at pH 2 – 3, alkaline at pH 11 – 12
- Circulate through one stage at a time at low pressure and high flow, with the return to the CIP tank, for 30 to 60 minutes
- Soak for one hour. For heavy fouling, soak overnight and circulate again in the morning
- Flush with permeate until the conductivity and pH of the flush return to feed values
- Restart in reject-to-drain mode until permeate conductivity meets specification
Circulate one stage at a time. Cleaning all stages together carries foulant from the lead elements onto the tail elements.
Practical Points from Omani Sites
Several things come up repeatedly on plants across Muscat and the interior:
- Always use permeate, never raw feed water, to make up the cleaning solution. Hardness in the make-up water reacts with the alkaline cleaner and precipitates onto the membrane
- Replace cartridge filters after every clean. Foulant released during the cycle ends up in the filter housing
- Record pH during circulation. Acid cleaner is consumed as it dissolves carbonate scale and pH drifts up. Top up to hold pH in range
- Do not exceed 40°C. Higher temperature speeds cleaning but shortens membrane life
- Dispose of spent solution correctly. Neutralise before discharge in line with Omani environmental requirements
Preventing the Next Clean
Frequent cleaning points to a problem upstream. If cleans are needed more often than every three to four months, check the antiscalant dose first. Most cases we attend come down to a dosing pump running at the wrong setting or a chemical tank that ran empty unnoticed.
A correctly dosed antiscalant such as Nalco PermaTreat PC-191T or Veolia Hydrex 4109 should keep a brackish water plant clean for six months or more. Where biofouling is the recurring issue, Culligan Bio Guard 41H01 on the feed line controls the bacterial load before it reaches the membranes.
Guidance on cleaning limits and sequence is published in the DuPont Water Solutions technical manual, which we follow on all plants we service.
Frequently Asked Questions
How much Hydrex cleaner does one CIP use?
A 2% solution in a 200 litre CIP tank uses 4 kg. A typical 10 m³/h plant with a 400 litre tank uses 8 kg per cleaning step, so one 25 kg can covers around three cycles.
Can Hydrex 4730 and 4731 be mixed?
No. They neutralise each other and both cleaning actions are lost. Flush fully between the alkaline and acid steps.
Do you supply Hydrex outside Oman?
Yes. We supply across the GCC in 25 kg packing. Lead time depends on destination and quantity.
Can our own operators run the clean?
Yes, with training. We run the first cycle with the site team and leave a written procedure for the plant. For sites without a CIP skid, we bring a mobile unit and carry out the clean under contract.
Order or Book a Cleaning Service
We stock Hydrex 4731 acid cleaner and Hydrex 4730 alkaline cleaner in Muscat for immediate delivery, and carry out membrane cleaning under annual maintenance contracts across Oman.
Call +968 9763 7786 or email sales@waterfilteroman.com with your plant details and recent operating log.
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