Guidelines for the Proper Use of RO Reverse Osmosis Membranes

1. Warning! These improper operations can directly damage the RO reverse osmosis membrane

The performance of RO reverse osmosis membranes appears stable, but minor operational oversights can lead to premature failure, primarily concentrated in three categories of issues

Residual gas not fully expelled under high pressure can cause the "pneumatic hammer" to damage the membrane

When residual gas inside the equipment operates under high-pressure conditions, it can create a "water hammer effect," directly impacting the membrane elements and causing physical damage. This situation often occurs in two scenarios:

When the equipment restarts, the gas has not been fully purged: After purging the equipment, restart the operation. If air is not completely expelled and pressure is rapidly increased, the residual gas will violently impact the membrane. The correct procedure is to operate at a low pressure of 2~4 bar first, and only gradually increase the pressure once no bubbles are visible in the flow meter (indicating complete air removal).

Poor pipeline sealing allows air intake: If the connection between the pretreatment equipment (e.g., microfilter) and the high-pressure pump leaks or is improperly sealed, insufficient pretreatment water supply (e.g., reduced flow due to microfilter clogging) creates a vacuum in the pipeline, leading to air suction. Solutions include promptly cleaning or replacing the clogged microfilter, inspecting and repairing leaking pipelines, and ensuring no air enters during operation.

2. Incorrect shutdown method leads to film scaling and contamination

Many people believe that "shutting down = immediate power-off," but this can leave hidden risks for RO membranes, primarily involving two issues:

Pressure reduction without rinsing can lead to scaling on the concentrate side: During RO membrane operation, the inorganic salt concentration on the concentrate side is significantly higher than that in the feed water. If pressure is rapidly reduced upon shutdown without thorough rinsing, the inorganic salts in the concentrate will adhere to the membrane surface, eventually forming scale deposits that clog the membrane pores and reduce filtration efficiency over time.

Rinse with water containing chemical reagents: Some users rinse the membrane elements with pretreatment water containing chemical reagents, which is not advisable. During equipment downtime, water containing chemical reagents may react with the membrane or leave residues that contaminate the membrane, affecting the quality of subsequent effluent.

3. Inadequate disinfection and maintenance can lead to microbial "colonization" of the membrane

Composite polyamide material is a common choice for RO membranes, but it has a drawback: poor resistance to residual chlorine. If disinfectants like chlorine are not properly dosed during operation, coupled with insufficient attention to microbial contamination, bacteria and microorganisms in the water will proliferate on the membrane surface, forming biofilms. This not only clogs the membrane pores but also leads to microbial contamination in the output water (the root cause of many manufacturers' substandard pure water microbial levels lies here).