Demineralization of Water

Water softening is a process that is common in the food industry. In some sectors like the beverage industry, it is also required to demineralize the water. The systems used for demineralizing utilize multi-bed systems. Mixed-bed systems are more compact and require less space, while producing high-quality water. Multi-bed and mixed-bed exchangers are sometimes used in sequence to produce high-quality demineralized water.

The mixed-bed system works well on water with limited alkalinity or acidity caused by mineral acids. It will produce water with low conductivity. When the raw water has high alkalinity or mineral acidity, water with high purity can be obtained with a two-bed followed by a mixed-bed system. The water passes through a cation exchanger, where cabonates are converted to carbon dioxide that is removed in a decarbonator. In the anion exchanger, anionic impurities are removed. For final purification, the water passes through a mixed-bed ion exchanger. Mixed-bed exchangers have both cation and anion exchange resins in the same vessel. Here most of the dissolved, ionizable solids will be removed.The removal of silica (SiO 2 ) in a demineralizing system depends upon the use of a strong base anion exchanger.