The development of small-scale, low-cost biofilm treatment systems for the control of pathogens in fresh water

Steven, Joshua

Abstract

Water that is contaminated with pathogenic microorganisms, can cause disease. Despite advances in the provision of safe drinking water, an estimated 580 million people lack consistent access to safe water whilst the consumption of biologically contaminated water leads to approximately 485,000 deaths each year. Well understood chemical and/or physical treatment regimes are commonplace in high income countries but are often not possible or suitable in remote or challenging communities where infrastructure is lacking and where drinking water is collected and managed at source. There is a need for sustainable, scalable, low cost, low energy systems that can be widely distributed and adopted for the provision of safer drinking water.
The aim of this research was to develop biofilm treatment systems (BTS) for the control and/or removal of freshwater contaminants, including but not limited to, common pathogenic bacteria. Laboratory scale and upscaled BTS were designed, developed, and investigated. The BTS utilise naturally occurring microorganisms that attach and form biofilms upon expanded ceramic filter media used in this research. The initial start-up (maturation) and development of the microbial community was investigated using single gene-based sequencing. These BTS were then applied for the control freshwater contaminants including Escherichia coli, Enterococcus faecalis and Pseudomonas aeruginosa.

The single gene-based community analysis demonstrates that under controlled conditions, the formation of an environmental biofilm is reproducible at scale from a singular seed source of environmental microorganisms. Moreover, such BTS operating within a recirculation configuration are able to achieve significant reductions of indicator species within fresh water; E. coli (99%), E. faecalis (99%), and P. aeruginosa (92%) after 24 h, which can be successfully applied in an upscaled configuration. The single gene-based community analysis identified potential antimicrobial producing species of bacteria within the biofilm of the BTS that is the hypothesised method by which the BTS was able to significantly reduce the number of viable pathogens from a source water.

The main findings of this study are that the viability of planktonic bacterial pathogens in fresh water are significantly reduced by functional characteristics inherent to mature environmental biofilms. Through competition sensing, biofilm communities may up-regulate defence mechanisms such as the production of antibiotics, biosurfactants and bactericidal toxins. This has important implications for the control and use of BTS within fresh water that is reproducible at scale. Moreover, this indicates, under controlled conditions, the environmental biofilm community was reproducible at scale; indicating that there is a potential to control biofilm growth within treatment systems based on the operational parameters of a treatment system.

Citation

Steven, J. The development of small-scale, low-cost biofilm treatment systems for the control of pathogens in fresh water. (Thesis). University of the West of England. Retrieved from https://uwe-repository.worktribe.com/output/10274632

• Thesis Type: Thesis
• Deposit Date: Jan 4, 2023
• Publicly Available Date: Oct 26, 2023
• Public URL: https://uwe-repository.worktribe.com/output/10274632
• Award Date: Oct 26, 2023