Seawater reverse osmosis technology is widely used in many applications due to its special advantages. Many users who are not technical might suffer a lot of problems about how to clean RO device, so it is necessary to manage sea water reverse osmosis system well for avoiding serious problems. There are mainly three kinds of cleaning ways for SWRO system as follows:
1.Low-pressure flushing Seawater reverse osmosis system
It is beneficial to remove the fouling at the surface of RO membrane in seawater desalination and maintain membrane performance by high flow flushing, low-pressure flushing, and low PH flushing of RO device regularly. Or when the SDI of water in RO device is suddenly above 5.5, it should adopt low-pressure flushing, and start up again after adjusting SDI.
2.SWRO system shutdown protection cleaning
Due to production fluctuation, seawater reverse osmosis system unavoidably often shut down. It is necessary to take protective action when stopping at a short time or long time. Inappropriate treatment will lead to the membrane performance declining and not easy to recover.
Short time preservation is suitable for the system that shuts down less than 15 days, and it can adopt every 1 day to 3 days low-pressure flushing to protect RO device. It is found that, when the temperature of the water is above 20?, water in RO device of seawater desalination will get stink within 3 days, and breed a lot of bacteria. Therefore, it is suggested that it adopts low-pressure flushing once every 2 days or 1 day when water temperature above 20?. And it adopts low-pressure flushing once every 3 days when water temperature below 20?. Every time it should shut down all the inlet and outlet valves of RO device after flushing.
Longtime shutdown protection is suitable for the system of above 15 days, at this moment it has to use protection fluid (bacteriostat) to protect RO device. Common bacteriostat is 1% sodium bisulfite solution(quality score)
3.SWRO membrane chemical cleaning
SWRO membrane might be also polluted by inorganic fouling, colloid, microbes, and metal oxide in the normal running conditions. When these substances accumulate at the surface of the membrane, it will cause the output of seawater reverse osmosis plant or desalination rate declining, rise the pressure difference and even damage membrane greatly. Thereby, to better recover production and desalination rate performance, chemical cleaning for RO membrane is also required.
Whatever one of the following conditions, membrane element is requested to be cleaned:
- Standardized production flow declines above 10%.
- The standardized pressure difference between inlet and concentrated increases by 15%.
- Standardized desalination rate increases by 5%.
- It is verified that there is pollution or scaling; Even though pressure difference does not increase by 15%, it has run for 3~4 months; When it requires to stop operating long time, it should be cleaned before stopping.
The cleaning temperature is demanded below 15? because lower temperature can cause cleaning effect. Selected cleaning pump can overcome security filter declining, membrane element declining and pipelines loss, etc. Generally the selected pressure is 0.3~0.5MPa.
