Determination of low bacterial and viral concentrations in water and selective removal of pathogenic bacteria in water filtration systems

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Pathogens in drinking water and their associated waterborne diseases are of great concern to the public health. More work related microbial detection and removal is needed. In this research, new methods using lanthanum-based chemical flocculation for concentration of bacteria and virus in water was successfully developed. The results showed that compared to traditional flocculants, LaCl3 had the highest recovery efficiencies for bacteria and viruses detection based on microrespirometric assay, real-time PCR enumeration and infectivity assay. Compared to direct cartridge filtration using Nanoceram[copyright] and 1MDS, the lanthanum-based chemical concentration method coupled with modified membrane filtration procedures has advantages in eliminating the use of expensive cartridge filters with improved virus detection efficiency. A mixture of bacteriophages isolated from municipal wastewater was used to control and remove biofilms. The results showed that P. aeruginosa phages effectively controlled and removed the bacterial biofilms. A combined use of phages and chlorine inhibited P. aeruginosa biofilm formation and removed pre-existing biofilms to a greater extent. Phages were also used to remove P. aeruginosa selectively in water filtration systems. The results indicate that for clean GAC filter, phage treatment not only effectively removes P. aeruginosa cells on the surface of filter media but also those located in the interior. The addition of phage did not affect the nitrification in the anthracite filtration system while the conversion of nitrite was affected to some extent in the GAC filter.