Bacterial Growth and Biofouling Control in Purified Water Systems

Purified water used in product formulation, cleaning, and cooling operations has evolved from a process fluid to an essential raw material. Levels of biological and abiological contaminants which were undetectable five years ago are now regarded as unacceptable for many products and processes. While recent advances in analytical chemistry and fine particle physics have resulted in dramatic reductions in abiological contaminants, biological contamination of purified waters used in these critical industries remains a significant challenge to future product development. In the semiconductor industry, 1 pm and smaller line-width devices are subject to fatal defects as a result of bacteria present in “ultrapure water.” Active ingredient degradation and pyrogen contamination of heat labile biological and medical devices have been linked to purified water contamination. The extent of bacterial growth and biofilm formation in 18 MOhmcm waters is a function of materials selection, systems design, and preventative maintenance protocol Limiting essential growth factors — C, N, P, S, trace elements, light — in purified water systems is an important key to the control of biological contamination. Development of on-line, real time biofouling detection systems is currently underway. These evolving systems, which include supercritical fluid extraction of signature biomarkers and electrochemical impedance spectroscopy should provide insight into conditions pro-moting the development of fouling biofilms. Future applications of novel detection and treatment systems will include advanced life support systems such as those found on the space station.