Foreword

Effective microbiological control is an important aspect of a successful cooling water treatment program. It has often been said that more cooling water treatment programs fail because of poor microbiological control than for any other single reason. Consequences of poor biological control typically include biological fouling, microbially influenced corrosion (MIC), accelerated decay of cooling tower wood, and potential amplification of disease-causing microorganisms such as Legionella pneumophila.

Bacteria, fungi, algae, and protozoa are the microorganism classes of concern in cooling water systems. To control the growth of these organisms, programs employing oxidizing microbicides, nonoxidizing microbicides, and biodispersants are often used. This technical committee report discusses specific technologies used to control these classes of microorganisms. This report provides owners, engineers, contractors, and operators with specific information on the types of organisms found in cooling systems, a list of common chemistries used for their control, and methods that are typically employed to monitor systems. Its intent is not to serve as a guide to set up a microbiological control program, but to assist users in understanding the components of in-place programs and discuss the treatment program typically used to avoid misapplication. While this report includes a list of common technologies used to treat biofouling, it is not meant to be exhaustive.

This technical committee report was prepared by Task Group (TG) 151 on Biocide Monitoring and Control Techniques. TG 151 is administered by Specific Technology Group (STG) 11 on Water Treatment and sponsored by STG 46 on Building Systems and STG 62 on Corrosion Monitoring and Measurement—Science and Engineering Applications. It is issued by NACE International under the auspices of STG 11.