This powerpoint presentation begins by providing a brief overview of pathogen disinfection research in
water network biofilms, along with pathogen surrogates, unique research aspects of
pathogen adhesion to
biofilm, and chlorine dioxide as an
alternative disinfectant. The objectives of this research were to:
develop a correlation between chlorine and
chlorine dioxide during disinfection of B. globigii;
determine the CT values at different concentrations
needed to reach 1, 2 and 3 log reductions;
identify the CTlag value that each disinfectant
requires to overcome mass transfer limitations
due to its properties at the specified disinfection
pH and spore surface charge by using the
delayed Chick-Watson model; and,
determine the effect of exposure time and
concentration on the inactivation rate. Initial experiments consisted of the following:
model distribution system was a Biofilm Annular
Reactor (BAR) with iron coupons;
surrogates were pulse injected
(lebsiella pneumoniae (Burkholderia mallei) and
Bacillus globigii (Bacillus anthracis)); and, the
objective was to determine the disinfection of these
organisms in biofilms growing on rusted iron
using chlorine. Topics presented include: preliminary B. globigii disinfection
research with chlorine; bulk disinfection experiment
results; delayed Chick Watson Model; Watson Plot Analysis; Watson Plots for bulk
experiments; biofilm development; biofilm disinfection Watson
Plots; chlorine dioxide results; cement and cement-lined pipe; results relative to
cast iron pipe; and, concrete pipe conclusions. Includes figures.