The calcium concentration can be reduced to typically 20 mg/L as Ca (0.5 mMol/L; 50 mg/L as CaCO3). The Crystalactor removes calcium carbonate only. The conditions in the reactor prevent removal of magnesium in the form of magnesium hydroxide. On the one hand this is a disadvantage because complete removal of all hardness is not possible. On the other hand it is an advantage in many situations, because the presence of magnesium in drinking water is considered of health importance and because no chemicals are used for magnesium removal.
The heart of the Crystalactor treatment plant is the pellet reactor, partially filled with suitable seed material such as sand, garnet, or small crushed pellets.
The water is pumped in an upward direction, maintaining the pellet bed in a fluidised state. In order to crystallise calcium carbonate on the pellet bed, a driving force is created by a reagent dosage. Usually lime, caustic soda or soda ash is applied.
The pellets grow and move towards the reactor bottom. At regular intervals, a quantity of the largest fluidised pellets is discharged from the reactor and fresh seed material is added. After atmospheric drying, easy-to-handle and virtually water-free pellets are obtained. It is common practice to use these pellets, for example in the steel or glass industry.