Methods:
Silver comparisons
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*Batch tests with 4 different treatments used, all at 50 ug/L:
*Colloidal silver
*Silver ion (from silver nitrate)
*Colloidal silver permeable through 0.22 µm membrane (likely includes both ions and small colloids)
*Control (zero silver)
*All 4 treatments run at same time to achieve similar initial bacteria concentrations
*4 replicates of the test conducted on different dates
*MPN technique used with two time points