Browsing by Author "Haley, John"

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    How bioaugmentation for pesticide removal influences the microbial community in biologically active sand filters
    (Elsevier, 2024-07-30) Pickering, Laura; Castro-Gutierrez, Victor; Holden, Barrie; Haley, John; Jarvis, Peter; Campo, Pablo; Hassard, Francis
    Removing pesticides from biological drinking water filters is challenging due to the difficulty in activating pesticide-degrading bacteria within the filters. Bioaugmented bacteria can alter the filter's microbiome, affecting its performance either positively or negatively, depending on the bacteria used and their interaction with native microbes. We demonstrate that adding specific bacteria strains can effectively remove recalcitrant pesticides, like metaldehyde, yielding compliance to regulatory standards for an extended period. Our experiments revealed that the Sphingobium CMET-H strain was particularly effective, consistently reducing metaldehyde concentrations to levels within regulatory compliance, significantly outperforming Acinetobacter calcoaceticus E1. This success is attributed to the superior acclimation and distribution of the Sphingobium strain within the filter bed, facilitating more efficient interactions with and degradation of the pesticide, even when present at lower population densities compared to Acinetobacter calcoaceticus E1. Furthermore, our study demonstrates that the addition of pesticide-degrading strains significantly impacts the filter's microbiome at various depths, despite these strains making up less than 1% of the total microbial community. The sequence in which these bacteria are introduced influences the system's ability to degrade pesticides effectively. This research shows the potential of carefully selected and dosed bioaugmented bacteria to improve the pesticide removal capabilities of water filtration systems, while also highlighting the dynamics between bioaugmented and native microbial communities. Further investigation into optimizing bioaugmentation strategies is suggested to enhance the resilience and efficiency of drinking water treatment systems against pesticide contamination.
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    Regrowth of microorganisms from treatment to tap in operational drinking water supply networks
    (MDPI, 2024-09-13) Carneiro, Isabel; Fish, Katherine; Jarvis, Peter; Haley, John; Webber, Fiona; Gaskin, Paul; Boxall, Joby
    This research provides new understanding of the (re)growth of microorganisms within drinking water distribution networks. Flow cytometry data quantifying total and intact cell counts from consumers’ taps are currently rare, and its value for aiding understanding of the growth of microorganisms is unknown. In this study, changes in microbial concentrations from the treatment works to customers’ taps were measured (using flow cytometry) in two UK drinking water distribution networks. Throughout each network, five locations were sampled for five consecutive days within a week, and to assess seasonal impacts, this was repeated twice in each network. Significant growth of microorganisms was observed in both networks during autumn, particularly at higher-water-age taps. These results give novel emphasis to the active impact of the distribution system on microbiological growth by using flow cytometry data collected in a systematic way from treatment through to customers’ taps. Such understanding is essential to achieving the delivery of safe and aesthetically pleasing drinking water to customers.