Biocides microbial level

With some biocide treatments there is a simple direct relationship between ATP and viable cell counts. However, where the mechanism of biocide action is related to influences on cell bioenergetics, or the concentration range employed is biostatic and affects cell metabolism, then ATP results may not follow the same pattern as microbial counts. Under these circumstances low ATP results at relatively high microbial levels might be expected but it is also possible that ATP levels increase over a period of time. 

Certain additives not classified as biocides can promote resistance to mieroorganisms, even though they may be intended for some other purpose uneonnected with microbial activity, but their dose level may be insuffieient for complete protection. 

The impact of each biocide on microbial populations, together with the compatibility studies, can be used to select the most effective biocidal treatment. The biocides are first evaluated for their ability to inhibit metabolic activity at the time of maximum growth activity this maximum time is determined from growth curves of the microbial populations of the formation and river wastes. Growth curves are then measured for the selected biocide(s) at different concentrations to determine the optimum level of biocide required and the period necessary for alternate slugging of the injection waters. The biocidal treatment is then determined from the growth-concentration curves and the compatibility studies. 

The complex relationship between the parameters of temperature, pH and concentration for glutaraldehyde has been mentioned previously. The pH level has been proposed as the single most important factor for understanding the reaction of glutaraldehyde with the microbial cell (see [49]) and has significant effects on the stability and biocidal activity of the aldehyde [13, 51, 54-61 ]. Alkaline glutaraldehyde solutions become unstable and lose biocidal activity over time (Figure 4.1). Freshly prepared solutions, for which... 

Biocides are designed to protect uncontaminated products from occasional microbial contamination and, at typical use concentrations, most preservatives are not able to withstand continual repeated challenges of high levels of microorganisms. In such situations, the biocide may be consumed and the product will no longer be protected from subsequent microbial infection. 

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