title: [Microbial growth in mixed-bed ion exchange columns].
abstract: The microbial growth in ion-exchange columns of Christ GmbH Leonberg (Germany) was studied under differing water processing conditions. Continuous processing led to the same or slightly higher microbial counts in the product water compared to the feed water. Feeding the considerably contaminated column with slightly contaminated water (less than 40 CFU/100 ml) also didn't prevent microbial growth in the column. If water was withdrawn on demand only, an overnight no-demand period with closed inlet of the column led to considerable microbial growth, raising the microbial counts of the product water to well above the feed water level. But lower microbial counts were found in the product water than in the feed water by tightly closing the outlet of the column and hereby keeping the column at the same pressure as exists in the piping system. This was observed in several months long experiments operating with disinfected as well as freshly regenerated resin. The passage through a column of freshly regenerated resin led to a germ reduction of approximately 2 powers of ten and to an elimination of pyrogens.
mesh_terms: D001419:Bacteria / Q000254:growth & development*; D002852:Chromatography, Ion Exchange; D014871:Water Microbiology; D014881:Water Supply / Q000592:standards*
vernacular_title: Uber die Verkeimung von Mischbett-Ionenaustauschern.