Minimizing Corrosion Concerns with Oxidizing Biocides by a Targeted Biofilm Control Approach, PaperCon 2010 Conference

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Oxidizing biocides programs based on haloamines, such as monochloramine (MCA), are in wide use by the paper industry. This stabilization of active chlorine into the form of haloamine extends the persistence of chlorine improving the biocidal performance in white water. The haloamines, however, present potential issues with vapor phase corrosion.

This study compared the vapor phase corrosiveness of several common oxidizing biocide systems. Monochloro-5,5-dimethylhydantoin (MCDMH) was found to present a minimal vapor phase corrosion risk. MCDMH is highly effective against primary-biofilm forming bacterial but is less effective against free-swimming (planktonic) bacteria. Primary-biofilm formers cannot be monitored by standard bacterial plate counts. A new monitoring technique called the PiBa assay to specifically measure the biofilm formers will be described.

The PiBa assay allows the implementation of combined biofilm control programs to minimize corrosion risks. In a patent pending approach, MCDMH is applied where corrosion risks are significant and biofilm control is of the utmost importance. Haloamines are applied where vapor phase corrosion is a lower concern, such as the broke systems. Data will also be presented which shows MCDMH and MCA are chemically compatible so there is no risk of degrading the performance of either material in a combined system.