Microbial Survival with Dissipating Disinfectant

treatment time

t

treat

6.

c(t)

exponential

linear

c(t) concentration parameters

c

0

0.4

a

1

0.2

a

2

0.1

log s(t) survival parameters

n

0.75

c

l

0.1

k

3.

axes limits

t

max

15.

log s

min

-6.

This Demonstration simulates a microorganism's survival in water treated with a chemically unstable or volatile disinfectant. It generates the disinfectant's concentration dissipation curve, which can be smooth or wavy, and the corresponding survival curve using a simplified version of the Weibull-log logistic (WeLL) inactivation model. The survival curve is the numerical solution of an ordinary differential equation derived from the notion that under dynamic conditions, the momentary inactivation rate is the static rate at the momentary disinfectant concentration, at the time which corresponds to the momentary survival ratio.