4 issues to ensure the regular operation of reverse osmosis equipment

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To ensure the regular operation of reverse osmosis equipment, we should pay attention to what issues?

The reverse osmosis membrane separation technique (also known as RO technology) is a novel and valuable water treatment method; its long-term performance stability is indispensable. The successful long-term performance of the RO system depends on standard operation and maintenance, including commissioning the complete procedure, start-up and shutdown, cleaning and maintenance, membrane surface fouling and scale prevention, etc.

So, how can we ensure the proper operation of the RO system, and what should we pay attention to?



(1) Before starting the process, fully clean the pre-treatment part, flush out impurities and other pollutants, and do not make unqualified water injected into the membrane element.
(2) in the case of the original water tank with water, open the mechanical filter upper inlet valve and lower discharge valve, open the actual pump power, at this time, the metering pump automatic dosing, water from the upper inlet valve into the mechanical filter, the lower discharge valve discharge, to be clear, open the activated carbon filter upper inlet valve and lower discharge valve, automatic filter discharge valve, of the mechanical filter lower discharge valve, at this time the water into the activated carbon filter, test the mechanical filter water pollution index, while the activated carbon filter water clear, RO host open thick water valve, pure water discharge
(3) open the RO system inlet valve, close the activated carbon filter under the discharge valve so that the low pressure and low flow of water flush out the air in the components and pressure vessel so that the pressure is 0.2-0.4MPa while opening the security filter exhaust valve to exhaust the air.
(4) Make sure that all pipeline joints and valves are leak-free during flushing.
(5) After flushing for a few minutes and the air is removed, start the high-pressure pump and run it at low pressure for a few minutes, then gradually close the return water valve and the thick water discharge valve to make the pressure rise slowly until the ratio of fresh water and stagnant water is close to the design ratio, but not more, and make the pressure not exceed the design upper limit.
(6) to be stable operation, the conductivity of produced water to meet the requirements, open the pure water tank into the water valve, close the hygienic water discharge valve, the qualified made water into the new water storage tank.


Conventional power on

Once the RO system starts to operate, theoretically, it should be used continuously in a stable condition. Still, in fact, the RO system needs to be closed and frequently started, which results in changes in pressure and flow, thus causing mechanical stress to the membrane element, so try to reduce the times of openings and shutting, while the standard start-up procedure is the smoother, the better, in principle, it should be the same procedure as the first start-up, and most importantly, the inlet water pressure should rise slowly.


Normal shutdown

When shutting down the RO system, open the high pressure concentrated water valve gradually before the high-pressure pump is shut down, forbid to lower the pressure suddenly, and then flush with permeate or high-quality feed water to remove the high salt content in the membrane module until the conductivity of the concentrated solution reaches the conductivity value of the feed water. Flushing is conducted at low pressure (about 3Kg/cm2), and high inlet water flow is beneficial for cleaning.
The water used for flushing must be free of chemicals used for pre-treatment. It must not have scale inhibitors, so stop adding anti-scaling agents and sulfuric acid when flushing.
After flushing, completely close the water injection valve. When the end of the concentrate line is lower than the pressure vessel, the air outlet must be a higher position than the highest point of the pressure vessel. Otherwise, the pressure vessel must be emptied by siphoning.

When the system has been closed for more than 48 hours, attention must be paid.
1 component must not be dried out; dry ingredients will lose flux and cannot be recovered.
2 the system can be effectively protected from microbial derivation or flushed regularly every 24 hours; if fail to wash the membrane tube with water every 24 hours, the system must be preserved with a chemical preservation solution for systems that have been shut down for more than 48 hours.
3 The system needs to be protected from extreme temperature changes.



1. When using the high-pressure pump for the first time, the exhaust valve must be opened to discharge the high-pressure pump’s residual air.
2. Idling the high-pressure pump without water is absolutely banned.
3The high-pressure pump’s job is to increase the pressure in the reverse osmosis membrane feed water; the usual post-pump pressure is 10-12 kg.
4. RO concentrated water pressure regulating valve is to adjust the pressure of the high-pressure pump outlet; it is strictly prohibited to close the concentrated water regulating valve all. Full water pressure regulating valve open the more significant, the smaller the high-pressure pump outlet pressure, the more closed, the larger the high-pressure pump outlet pressure. It must be strictly prohibited to close all.
5. the temperature of the reverse osmosis equipment. It can be based on the temperature of the base to speculate if the use of oil holes to measure the temperature is more accurate. Shaft temperature from the beginning to the operation, the temperature rises continuously. It tends to stabilize after 1-2 hours of operation. If the shaft is not fitted correctly, the temperature rises quickly, resulting in a high temperature. Mainly due to an excess of lubrication.
6. slight mechanical manual rotation to confirm the smoothness of the process. Because there are scratches, foreign bodies, etc., and the course is not smooth, mainly because the installation of the base is not sound and caused by.
7. large machinery can not manually rotate to confirm the first cut off the power, check whether there is vibration, noise, etc., after confirming that there is no difference in the operation.

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John Lau.

John Lau.

John Lau, a project manager holding an engineering bachelor's degree, became fascinated with optimizing beverage production equipment during his university days. As an overseas project manager, he firmly believes that educating clients on achieving efficient workflows through customized equipment design is one of the most impactful aspects of his job.

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