Purified water - i.e. water that is virtually free from colony forming units - forms the basis of many processes in the pharma sector. Ozone ensures an effective disinfection of deionised purified water, and the Steritron process by Christ, a member of the Christ Water Technology Group, produces ozone by electrolysis from the purified water available.
The oxidation potential of the gas destroys the cell wall and membrane of micro-organisms without chemically or physically modifying the water. Furthermore, the pyrogeneous decomposition products of the organisms are reduced and not least a lasting TOC and endotoxin reduction is ensured. This is valid for the entire purified water distribution system including storage tanks.
The ozonation thus ensures the disinfection of the whole system and simultaneously avoids recontamination. This allows meeting limit values for micro-organisms stipulated in the pharmacopoeia even for cold storage of purified water.
The Christ Steritron plant is available in various sizes - 1, 4, 8 or 12g O3/h - and is installed into the loop as a bypass. The ozone is dissolved in the passing water in the bypass and is distributed to the loops and storage tanks.
A flow-electrolysis cell was specially developed to generate ozone based on the catalytic splitting of the fed demineralised water. A polymeric cation exchange membrane is used as electrolyte. Feeding direct current to the cell causes the splitting of water at the specially coated anode into oxygen, ozone and hydrogen ions and the formation of hydrogen gas at the cathode. The purified water is the oxygen source, solvent for the produced ozone and coolant for the electrolysis cell. Simultaneously, it avoids ionic contamination.
This process allows the generation of ozone in high concentrations - up to 18 w % of ozone in oxygen. At an average ozone content of less than 0.1 mg/l and a sufficient duration, the number of micro-organisms in the water loop can be reduced to below 1/100 ml. For the disinfection of 10m3/h purified water 1g O3/h is sufficient.
The low-maintenance Steritron is easy to install and does away with operating stops for rinsing cycles. Furthermore, steam sterilisation of the plant distributing purified water is no longer necessary.