Exploring the role of microbial communities in the removal of taste and odour compounds in drinking water treatment works

Smith, Holly-Anne 2024. Exploring the role of microbial communities in the removal of taste and odour compounds in drinking water treatment works. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Geosmin and 2-methylisoborneol (MIB) are the two most common ‘taste and odour’ (T&O) compounds, frequently causing seasonal spikes in T&O influent (raw) water and presenting significant challenges for the drinking water treatment industry. Sand rapid gravity filtration (RGF) has been proposed as a solution to this problem, as the biofilms in the filters have been suggested to biologically remove influent T&O compounds, without the need for intervention. This project explored the microbial communities in drinking water treatment works, with a focus on sand RGFs for their association with the removal of T&O compounds. Samples were collected during the summer and autumn from three operational water treatment works (WTWs) with varying histories of T&O concentrations and removal efficiencies without intervention. WTW1 is highly efficient at removing geosmin despite high influent concentrations, WTW2 has moderate removal capability, and WTW3 shows no biological removal of geosmin or MIB, with higher influent levels of MIB than geosmin. Samples of raw water (RW), dissolved air flotation (DAF) sludge, post-DAF (clarified) water (CW), rapid gravity filtration (RGF) sand, and post-filtration (filtered) water were taken from all three WTWs. DNA metabarcoding and metagenomic approaches were used to analyse the microbial community composition within the WTW ecosystems, complemented by statistical analysis of taxa, metagenome-assembled genome (MAG) classifications, and phylogenomics. RGF samples were used in batch microcosm experiments to assess geosmin removal efficiencies by the three WTW sand RGF communities. The microcosm study showed that WTW1-RGF had the most efficient geosmin removal, followed by WTW2-RGF and WTW3-RGF, indicating that geosmin degraders are more enriched in WTW1 and WTW2 RGF microbial communities. However, the results also indicated some adaptation to geosmin degradation through enrichment. Analysis of the operational WTWs revealed differences in the microbial communities within the different treatment stages (habitats) of WTWs. Bacteria were much more abundant than Archaea or Eukaryotes and bacterial communities were dominated by Pseudomonadota, with other prevalent phyla including Acidobacteriota, Bacillota, Cyanobacteriota, Chloroflexota, and Verrucomicrobiota. RGF sand microbial communities were highly diverse and uniquely distinct from other stages. Metagenomic analysis indicated an enrichment of Bradyrhizobium, Rhizobium, Mesorhizobium, Sphingomonas, Sphingopyxis, and Sphingobium in the RGF filters of WTW1 and WTW2

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Biosciences
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	3 October 2024
Last Modified:	11 Oct 2024 14:31
URI:	https://orca.cardiff.ac.uk/id/eprint/172591

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