The design of the plants is determined by different aspects. The standard models already consist of a thermal de-gasification to reduce the CO2 concentration and several heat exchangers in order to achieve a sufficient energy balance. The size of the plant, especially the diameter and the amount of evaporation columns (2 -8 pieces) is in general depending on the desired performance, the space given on site and the desired energy saving concept. Besides the choice of the components different materials, surface finishing methods and sterile connection systems can be used. For an effective operation of the plant it is also possible to use the first column of a multi-effect still to produce WFI and Pure Steam. The twin systems for PS and WFI help to reduce operation costs and to shrink investment costs.