The Efficacy of Ozonated Water in Biofilm Control in USP Purified Water Circulation and Storage

S torage and distribution systems for water and water-based fluids are both critical and ubiquitous in every industry, geography, and culture. Large scale industrial water handling systems require water storage and distribution for a range of applications from simple thermal control (cooling and heating systems) to Purified Water (PW) production and delivery. For more than 40 years, manufacturers of pharmaceutical products have been concerned about potential microbial contamination of their water systems. The action and alert limits commonly cited in literature are based on sampling of the water from a use point, inoculation and incubation of a nutrient plate, and counting the resulting bacteria. These point-of-use samples are simply the planktonic concentration of the bacteria in the water and may not represent other contamination sources, i.e., biofilms. This article provides a case study for the use of ozone to reduce the amount of biofilm contaminant in a pilot PW production and delivery system designed to represent typical large 316L stainless steel systems in biopharmaceutical companies. While there are a number of potential sources of contamination in storage and delivery systems for purified and sterile water, one of the most common problems facing PW production and delivery is the prevention and removal of biofilms. First described by Henrici and Zobel more than 60 years ago, these tenacious thin films form on almost any natural or synthetic surface and wherever surface-associated microbes are present. Once established, biofilm-producing microbes Excrete Polymeric exopolysacharrides (EPS) film that cannot be effectively removed using conventional antimicrobial Reagents. The EPS provides a matrix where nutrients are retained and microbes can thrive, thereby continuously contaminating the PW storage and distribution system. Biofilms occur in a wide variety of systems that can range from the biological (e.g., plant life, gastrointestinal tracts, etc.) to the highly technological (e.g., medical and dental implants). The removal of biofilms from the wetted surfaces of PW systems is thus a prerequisite for the maintenance of high purity water quality in many industries. Elimination of this source of microbial contamination is critical, but can be exceedingly difficult. Studies have shown that the chemical composition of biofilm matrices varies depending on both the source of the originating microbial contaminant and the environment within which the biofilm grows. This compositional variability makes targeted destruction of biofilms difficult, encouraging the use of non-specific treatments that can address its heterogenity. Conventional antimicrobials may not penetrate the protective EPS film, and microbes that in planktonic form can be controlled through the use of a particular biocide may instead become extremely resistant to decontamination when resident within a biofilm matrix. Biofilm removal treatments Reprinted from PHARMACEUTICAL ENGINEERING THE OFFICIAL TECHNICAL MAGAZINE OF ISPE