By James McDonald and Dave Christophersen, CWT
There are numerous makeup water pretreatment strategies for boiler systems including softeners, dealkalizers, demineralizers, and reverse osmosis. Factors such as makeup water characteristics, economics, manpower, system familiarity, boiler requirements, space requirements, and so forth will determine which pretreatment strategy is used. Reverse osmosis (RO) has come of age in the past decade as a real, economical alternative for boiler pretreatment. RO pretreatment produces a higher quality water than many other pretreatment strategies but can come with some operational trade-offs. These trade-offs may be positive or negative depending upon the situation.
In order to gain a better, practical understanding of using RO for boiler pretreatment, it is helpful to compare a typical soft water pretreatment program to that of an RO pretreatment program.