The most important part of an industrial reverse osmosis (RO) system is the pretreatment process. The performance of the reverse osmosis system depends directly on the effectiveness of the pretreatment process. If the pretreatment system has problems, then the reverse osmosis system will also have problems and it will require increased cleanings and possibly membrane replacements. It is  important to condition the feedwater before it reaches the RO membranes to extend the life of the system.

There are three main reasons why a reverse osmosis system requires feed water that needs to be pretreated before it goes into the reverse osmosis system.

1. It reduces the amount of suspended solids before it goes into the reverse osmosis system. Having suspended solids will foul the RO system and shut down production.
2. It removes oxidizers, such as chlorine and chloramine, that damage the RO membrane. Irreversible damage will occur if an oxidizer encounters the RO membranes.
3. Pretreatment can add a scale inhibitor, also called an antiscalant. The antiscalant is a chemical that is injected into the feed water to delay or prevent scale formation within the RO membrane. This is done to increase the recovery of the RO system and to avoid scaling.

It is important to remember that even with a good pretreatment system, the reverse osmosis system membranes will eventually foul, scale, or decline in performance due to normal wear and tear. However, having a good pretreatment process reduces the frequency of cleaning and replacing membranes.

Learn more about water pretreatment for RO systems.