This powerpoint presentation begins by providing a brief overview of risk analysis and sensitivity analysis. Study objectives were to: develop a QMRA Monte Carlo model to assess the relative risk of
infection associated with the presence of Cryptosporidium and
Giardia in drinking water,
Before: Including SCADA data,
Now : Developing a CT model to evaluate ozonation performance;
compare different treatment scenarios based on microbial risk
reduction;
assess the impact of treatment shutdown periods on the
estimated risk; and,
complete a sensitivity analysis to estimate the effect of the
variability of each input parameter on the response's model
(risk). Methodology
objectives included:
using combined data of plants A and B to represent
the source contamination;
broadening the applicability of the ozonation model;
verifying the impact of one process downtime in the
case of multiple barriers;
justifying the presence of multiple barriers;
completing sensitivity analysis to estimate the effect
of each input parameter on the response model and to
classify them according to their degree of sensibility; and,
sensitivity analysis is a key step in making
decisions concerning construction and
improvement of the QMRA model. Presentation conclusions indicate the following: multi-barriers minimize the overall risk during normal operation and
temporary shutdown periods of various treatment processes;
UV disinfection performance considerably reduces microbial risk,
more so than optimizing direct filtration; mean risk with UV is,
however, significantly influenced by shutdown periods (not 90th
percentile);
allowed downtime duration must be included in risk assessment,
especially when only one barrier is present; and, for this case, the sensitivity analysis identified the
main sources of variance of the risk estimates.
The uncertainty on these inputs should be critically
reviewed for:
a better estimation of parasite occurrence in raw water, dose-response
relationship and fraction of infectious oocysts;
a full-scale validation of the use of spore removal as an indicator
of parasite removal; and,
an assessment of the correlation between the removal or
inactivation of parasites and their concentration. Includes figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.2 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 23 |
| Published : | 11/01/2008 |
