1. The method of reverse osmosis equipment shutdown is incorrect
Quick decompression without thorough washing during shutdown.
Because the concentration of inorganic salt on the water side of the concentrated membrane is higher than that of raw water, it is easy to scale and pollute the membrane.
B. rinse with pretreatment water with chemical reagents.
Water containing chemical reagents may cause membrane contamination during equipment shutdown.
When the reverse osmosis equipment is ready to shut down, it shall stop adding chemical reagents and gradually reduce the pressure to about 3bar and rinse with pretreated water for 10min, until the TDS of concentrated water is very close to the TDS of raw water.
2. Prevent damage of film performance
The new reverse osmosis membrane elements are usually soaked in 1%NaHSO3 and 18% glycerin aqueous solution and stored in a sealed plastic bag.
In the case of plastic bags not broken, storage for about a year, will not affect its life and performance.
When plastic bags open, should be used as soon as possible, so as not to NaHSO3 in the air oxidation, adverse impact on the components.
Therefore, the membrane should be opened before use.
After testing the reverse osmosis equipment, we used two methods to protect the film.
Test run the equipment for two days (15-24h), and then use 2% formaldehyde solution for maintenance;
Or after operation for 2 to 6 hours, use 1% NaHSO3 aqueous solution for maintenance (exhaust the air in the equipment pipeline to ensure that the equipment does not leak, close all the inlet and outlet valves).
Satisfactory results can be obtained by both methods.
The first method costs more and is used for long idle time, while the second method is used for short idle time.