4 key tips for the bio-decontamination of water for pharmaceutical use

Constrained by a strict regulatory framework, the management of water for pharmaceutical use is the focus of much attention from professionals in the sector. But guaranteeing the microbiological cleanliness of your purified water installation is a real challenge. The main cause is the micro-organisms lining the walls of the circuit which, escaping any dosage, threaten the conformity of the system.

Free bacteria vs biofilm

To maintain a purified water production and distribution system in satisfactory bacteriological condition, ideally it should be possible to assess its actual level of bacterial contamination. In practice, however, this is a complex matter. Microbiological sampling only provides information on the concentration of free micro-organisms, i.e. those circulating in the installation and carried by the flow. Bacterial colonies temporarily attached to the walls - the most numerous - escape this measurement. This biofilm is a real time bomb, as it regularly releases free cells that move further along the circuit before settling in turn to generate new colonies. It is therefore essential to limit the formation of this surface microbial ecosystem. There are a number of effective ways of preventing and decontaminating it.

Take care of the walls and connections of your installation

Choosing a quality installation is essential: beware of minimum investments, which can prove more costly in the long term to maintain in good bacteriological condition. To limit the build-up of biofilm, stainless steel is preferable to plastic, and particular attention should be paid to the finish: surface roughness, particularly at welds and junctions, is a breeding ground for bacterial colonies.

Prevent the entry and proliferation of free cells

To prevent the formation of biofilm, it is of course necessary to limit the entry of free micro-organisms into the network and destroy all traces of contamination even before they attach to the walls. In addition to existing sterilising filtration, a number of bio-decontamination solutions can be used: raising the temperature (60 to 65°C is enough to destroy most pioneer micro-organisms), using ozone, or exposure to UV radiation.

Dislodging an established biofilm

When the presence of a biofilm in the network is suspected, a treatment must be implemented to eliminate it, using an oxidising chemical agent. This shock treatment will destroy all microbiological life, whether isolated or in the form of biofilm. The use of oxidising agents must be carefully considered beforehand. In addition to the oxidising power of the chemical species chosen, the chemical concentration required to eradicate the biofilm must be taken into account. Using an effective species, even in small doses, will limit the rinsing time, the amount of water required and the downtime of the equipment. As the buffering capacity of purified water is low, attention should also be paid to potential variations in the pH of the solution circulating in the network, which can reduce the effectiveness of the chemical species used for decontamination, particularly that of chlorinated formulations. Available chemicals include ozone, hydrogen peroxide and peracetic acid.