In some special cases it is suggested to install an Ultrafiltration unit in the pre-treatment section of the PW plant. The typical molecular cut off of such kind of Ultrafiltration is 100 – 150 kDalton. This unit can be used as a removal step for bacterial content reduction, as well as a silica reduction. Stilmas design of UF units takes particular care of the wettability of the membranes, by providing a high internal water recycle.
In case of special requirement for Purified Water quality, e.g. Highly Purified Water, or Purified Water with low endotoxyn content. In this case, especially if a PW generation system based on RO+EDI is installed, a final treatment of the produced PW is necessary to reduce the content of endotoxyn. In order to obtain this result, Stilmas may install an UF section composed by sanitary feed pump and ultrafiltration module downstream the electro-deionizer, granting a very low final endotoxyn content. The UF membranes can be sanitized chemically or by hot water.