Search results
Results from the WOW.Com Content Network
Log reduction is a measure of how thoroughly a decontamination process reduces the concentration of a contaminant.It is defined as the common logarithm of the ratio of the levels of contamination before and after the process, so an increment of 1 corresponds to a reduction in concentration by a factor of 10.
Z-value is a term used in microbial thermal death time calculations. It is the number of degrees the temperature has to be increased to achieve a tenfold (i.e. 1 log 10) reduction in the D-value. The D-value of an organism is the time required in a given medium, at a given temperature, for a ten-fold reduction in the number of organisms.
In microbiology, in the context of a sterilization procedure, the D-value or decimal reduction time (or decimal reduction dose) is the time (or dose of an antimicrobial drug) required, at a given condition (e.g. temperature) or set of conditions, to achieve a one-log reduction, that is, to kill 90% of relevant microorganisms. [1]
What is often called a "log reduction" (technically a reduction by one order of magnitude) represents a 90% reduction in microbial population. Thus a process that achieves a "6-log reduction" (10 −6 ) will theoretically reduce an initial population of one million organisms to very close to zero.
This is usually done by thermal processing and finding ways to reduce the number of bacteria in the product. Time-temperature measurements of bacterial reduction is determined by a D-value, meaning how long it would take to reduce the bacterial population by 90% or one log 10 at a given temperature.
In autecological studies, the growth of bacteria (or other microorganisms, as protozoa, microalgae or yeasts) in batch culture can be modeled with four different phases: lag phase (A), log phase or exponential phase (B), stationary phase (C), and death phase (D). [3] During lag phase, bacteria adapt themselves to growth conditions.
CT Values are an important part of calculating disinfectant dosage for the chlorination of drinking water.A CT value is the product of the concentration of a disinfectant (e.g. free chlorine) and the contact time with the water being disinfected.
Reduction of fecal coliform in wastewater may require the use of chlorine and other disinfectant chemicals, or UV disinfection treatment. Such materials may kill the fecal coliform and disease bacteria. They also kill bacteria essential to the proper balance of the aquatic environment, endangering the survival of species dependent on those ...