Six basic water-purification technologies--distillation, ion exchange, carbon adsorption, reverse osmosis, microporous membrane filtration, and ultrafiltration--represent the standard methods for removing impurities. However, because some of these procedures tend to remove only a single type of contaminant, an effective water purification system should consist of a combination of techniques to achieve the desired water quality, industry experts recommend.
"If you look at the bulk flow of water, starting with tap water coming into the laboratory, about 90 to 99 percent of the particles, dissolved ions, organics, and bacteria should be removed in a pretreatment stage," says Byron Stewart, a product manager in the laboratory water division of Bedford, Mass.-based Millipore Corp. "This process could be reverse osmosis, distillation, or deionization." A polishing stage to remove trace levels of contaminants is required to produce the highest-quality, ultrapure water and is recommended as a final treatment for most life-sciences applications, taking the water ...
