The role of physical and biological processes in biofilms in drinking water

Tsagkari, Erifyli (2017) The role of physical and biological processes in biofilms in drinking water. PhD thesis, University of Glasgow.

Abstract

Microorganisms, such as bacteria, fungi, viruses and protozoa, colonise the inner surfaces of drinking water pipes and form biofilms. Drinking water biofilms act to protect the microorganisms that they house from the harsh conditions that we impose such as disinfection. Biofilms are generally thought of as being detrimental in drinking water distribution systems; they can harbour pathogens that intermittently emerge at the tap and they can affect the aesthetics of drinking water. The formation and dissolution of biofilms are intricately linked with the flow conditions and therefore, if we are to manage biofilms in drinking water systems, then it is imperative that we understand the crucial role that hydrodynamics play. Thus, my thesis focuses on the growth of biofilms in drinking water under three distinct flow regimes: turbulent, transition and laminar, and under stagnant conditions, and reveals the role that hydrodynamics play in shaping biofilms in drinking water distribution systems.
Not all bacteria are merely passive tracers in flow whose fate is governed by the physical flow alone. This thesis presents evidence that there might be key bacteria in aggregation in drinking water, whose biology acts to enhance the formation of multi-species biofilms. I explored that by testing the role that the Methylobacterium strain DSM 18358 played in the formation of biofilms on surfaces that starts with the formation of aggregates in the bulk water. I also explored whether the ability of this Methylobacterium strain to form aggregates was influenced by the flow regime. Ultimately, this research reveals whether the formation and structure of those aggregates in drinking water is influenced by the subtle interplay between biological and physical processes.
Given that they are bacteria that can degrade various dangerous chlorine disinfection by-products I explored the role of the Methylobacterium strain DSM 18358 in the concentration of trihalomethanes in drinking water as these chlorine disinfection by-products can cause serious problems to human health when they occur at high concentrations in drinking water. Overall, I identified whether the presence of this Methylobacterium strain in drinking water can actually deliver a service that contributes to better drinking water quality.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Supported by funding from the James Watt 2013 Scholarship.
• Keywords: biofilms, drinking water, reactor, flow regimes, Methylobacterium, trihalomethanes, aggregation.
• Subjects: T Technology > T Technology (General)
• Colleges/Schools: College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Funder's Name: Engineering and Physical Sciences Research Council (EPSRC)
• Supervisor's Name: Sloan, Professor William T.
• Date of Award: 2017
• Depositing User: Erifyli Tsagkari
• Unique ID: glathesis:2017-8557
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 30 Oct 2017 15:47
• Last Modified: 17 Nov 2017 13:08
• URI: https://theses.gla.ac.uk/id/eprint/8557