UFC 3-240-13FN
25 May 2005
4-4.4.2
Non-Oxidizing Biocides. Non-oxidizing biocides are microbiocides that
act as "poisons;" they disrupt the metabolic or reproductive processes of micro- and
macro-organisms and are therefore toxic. Non-oxidizing biocides are organic
compounds that are very toxic to organisms, including human beings and animals. They
are usually liquids, but some are available as dry products (e.g., pellets, solids). A major
consideration for their use is their persistence with respect to the discharge limitations
for water (effluent) containing these toxic substances. Also, when choosing and
applying a non-oxidizing biocide, you must consider the cooling tower system's
operating parameters, such as pH and retention time. The applied dosages of
microbiocides should never exceed EPA maximum limits, which are always printed on
the container labels. The labels will also identify the active microbiocide ingredient, the
percentage of each chemical that is present in the formulation, and the EPA registration
number. Control programs often combine both oxidizing and non-oxidizing biocides. The
most important aspect of bio-fouling control is to match the non-oxidizing biocide to the
problem organism. Table 4-7 provides guidelines for non-oxidizing biocide
effectiveness.
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