How to clean and maintain the reverse osmosis membrane?

How to maintain the reverse osmosis membrane?

With the widespread use of water purification equipment in the water treatment industry, reverse osmosis membranes are gradually being taken seriously. The cost of reverse osmosis membranes is one of the main concerns of consumers and good maintenance will help to extend the life of the membrane.

After commissioning the equipment, we two methods to protect the reverse osmosis membrane. Equipment test run for two days (15 ~ 24h), then use 2% formaldehyde solution maintenance; or after running 2 ~ 6h, with 1% of the aqueous solution of NaHSO3 for maintenance of reverse osmosis membrane (should exhaust the air in the equipment pipeline, to ensure that the equipment does not leak, close all the import and export valves). Both methods can give satisfactory results, the first method is more costly and is used when idle for a long time, while the second method of maintaining the reverse osmosis membrane is used when idle for a short time.

Storage conditions for reverse osmosis membranes:

(1) New membranes (before use)

①Membrane elements must be kept in a moist condition at all times. Even if they need to be opened temporarily to confirm the quantity of the same package, they must be kept in this condition without piercing the plastic bag and should be kept in this condition until the time of use.

When storing in an atmosphere of more than 10°C, avoid direct sunlight and choose a well-ventilated place. In this case, the storage temperature should not exceed 35°C.

(3) Physical breakage can occur if freezing occurs, so take measures to keep it warm and not allow it to freeze.

(2) Membrane elements after the water has been passed

①Membrane elements must be kept in a dark place at all times, at a temperature of no more than 35°C and out of direct sunlight.

②There is a possibility of freezing when the temperature is below 0℃, and anti-freezing measures should be taken.

③Composite series membrane elements should be soaked in pure water or reverse osmosis filtered water containing storage chemicals (sodium bisulphite, 500 to 1000mg/L, pH 3 to 6).

④ In no case should the membranes be left in a dry state when stored.

⑤ The concentration and pH of the storage solution should be maintained within the above range and should be checked regularly. If deviations from the above range are likely to occur, the storage solution should be reconstituted.

How to clean reverse osmosis membranes?

Contamination of the reverse osmosis membrane is an important factor in the efficiency and service life of a reverse osmosis system. Membranes generally have a service life of around 2-3 years and will be discarded and replaced after 3 years (the cost of replacing a new membrane with a membrane cleaning can be a good effect). At Lithia Membrane Cleaning, we will develop different types of cleaning agents, cleaning procedures and cleaning methods according to different customers. We specialise in providing water quality analysis, formulation screening and cleaning of reverse osmosis membranes, and can clean used membranes online or offline using our exclusive cleaning formulations, which can extend the cleaning effect by 1-2 years on top of the original life and guarantee that.

Your system should be cleaned immediately when there are changes in the following parameters of the reverse osmosis system.

Differential pressure between segments of the system: differential pressure in one section ≤ 0.2Mpa; differential pressure in the second section ≤ 0.1Mpa.

With the system operating parameters unchanged, the water production of the system is restored to more than 85% of the design water production through temperature correction.

Produced water desalination rate changes no more than 5%

Cleaning steps:

Pump clean, free of free chlorine reverse osmosis product water from the cleaning tank (or corresponding water source) into the pressure vessel and discharge for a few minutes.

Prepare the cleaning solution in the cleaning tank with clean product water.

Circulate the cleaning solution in the pressure vessel for 1 hour or a pre-set time.

When cleaning is complete, drain and rinse the tank and then fill the tank with clean product water for the next rinse.

Clean, free chlorine free product water is pumped from the wash tank (or appropriate water source) into the pressure vessel and drained for a few minutes.

After flushing the reverse osmosis system, run the reverse osmosis system with the product water drain valve open until the product water is clean and free of foam or detergent (typically 15 to 30 minutes).    

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