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Ben-Gurion University of the Negev (2015)

Indicators detection in pipes of drinking water distribution systems

Bawab, Omar

Titre : Indicators detection in pipes of drinking water distribution systems

Auteur : Bawab, Omar

Etablissement de soutenance : Ben-Gurion University of the Negev

Grade : Master of Science (MS) 2015

Contamination of drinking water is a major concern to health officials, researchers and the public at large. Although in most cases external sources might be the cause for contamination, recent events have indicted the occurrence of internal contamination, resulting in failure to meet standard quality measures for drinking water. Internal contamination might result from the detachment of microorganisms inhabiting the surface of the drinking water distribution system (DWDS) pipes. It was suggested that changes in the DWDS flow direction could result in bacterial count increase due to detachment of the bacteria from the pipes’ surface. To test this prediction we monitored fecal indicators in drinking water after flow direction change in the main pipeline of the Israeli National Water Carrier and in biofilm sampled during the annual pipeline maintenance. Concurrently, we used controlled experiments to characterize bacterial biofilms detachment during flow change. To that end we cultivated Escherichia coli biofilm on glass and concrete surfaces while periodically changing the flow direction in the flow cell and monitoring bacterial concentration in the outflow. Our results suggest that in controlled experiments inversion in flow direction will increase the bacteria concentration in the outflow by up to two orders of magnitude and dramatically affect the biofilm structure. We detected fecal coliforms in samples taken from biofilm on the DWDS pipes’ surfaces, however no indicators were detected in the drinking water after flow inversions. We thus conclude that changing the flow direction may play a role in the detachment of bacteria from pipe surface biofilms and preventative measures should be taken when flow direction is changed, although the risk to public health is negligible

Présentation et version intégrale (PRIMO)

Page publiée le 21 décembre 2022