A LOG removal of 4 indicates what percentage of removal?

A LOG removal of 4 refers to a logarithmic scale used to express the reduction in the number of pathogens or contaminants in a water treatment process. Specifically, a LOG removal value quantifies the reduction in concentration by powers of ten: a LOG removal of 1 indicates a 90% reduction, LOG removal of 2 represents a 99% reduction, LOG removal of 3 reflects a 99.9% reduction, and a LOG removal of 4 signifies a 99.99% removal.

Thus, when a water treatment process achieves a LOG removal of 4, it implies that the treated water has a concentration of contaminants that is 0.01% of the original concentration, equating to a removal efficiency of 99.99%.

This understanding is crucial in water treatment operations, where achieving high levels of contaminant removal is necessary for ensuring safe drinking water.