Until recently, it was only possible to produce WFI for the European market using distillation. However, as of April 1, 2017, the revised European Medicine Agency (EMA) Pharmacopeia allows, for the first time, WFI to be obtained using other comparable processes.
“Our generation unit is specially designed to meet the EMA requirements,” explained Dr John Medina, Sales Manager at the Bosch subsidiary Pharmatec, which developed the unit.
The generation unit employs the “cold” membrane processing methods reverse osmosis and electrodeionisation, together with an additional ultrafiltration step.
Reverse osmosis is a physical filtration process that removes ions from the water, and the subsequent electrodeionisation further reduces the remaining salt content through a combination of ion exchange and electrodialysis. The unit’s ultrafiltration module then separates out particles such as microbes and pyrogens on the basis of their weight and molecular size .
Until now, in the European Union this method was only approved for the production of highly purified water (HPW), while in the USA and Japan it has already been approved for obtaining WFI. In the future, the process will also be permitted by European authorities – albeit with additional, specific requirements.
Essentially, the unit must produce water under conditions that prevent the growth of microorganisms and other impurities. For reverse osmosis systems, the EMA stipulates regular sanitisation of the unit using hot water – primarily to prevent the formation of biofilms. Biofilms are caused by microbes, such as bacteria, and are difficult to remove from industrial systems. For additional protection, chemical sanitization must also be an option.
Medina added: “The unit [that was] on display at interpack allows routine thermal sanitisation. When it comes to hot water sanitisation, temperatures of 85°Celsius can be reached.”
In addition, the EMA recommends chemical sanitisation using ozone, to minimise the risk of microbial contamination. The unit offers this option as well. To prevent contamination as a result of insufficient barrier properties, the membranes’ integrity is checked on a regular basis.
Bosch has now reworked the WFI unit, including a more hygienic design and built-in measuring technology to monitor the system. The stainless steel used in the storage and distribution systems does not affect the water quality. Further, the system allows all the components to be thermally sanitised at any time.
Process monitoring is essential for water quality
“Monitoring all the processes in the production chain is essential to guaranteeing the microbial quality of the water,” said Medina, “which is why we fitted the unit with various sensors and measuring devices to monitor the water quality throughout the process and to check the individual steps.”
Total organic carbon (TOC) is a key indicator of the water’s quality, and since it is also a parameter for the risk of microbial contamination in the overall system, it has to be continually monitored. Conductivity is another important parameter, and here the EMA stipulates inline process control. The unit is equipped with an online measuring system to monitor specific conductivity.
