Leanyer Sanderson Waste Stabilisation Pond Microbiology

  • Alea Marie Rose

    Student thesis: Doctor of Philosophy (PhD) - CDU

    Abstract

    The Leanyer Sanderson Wastewater Stabilisation Ponds were built in 1972
    and are the largest in Northern Australia. Before this study, the knowledge of
    pond bacteria was limited to the culturable Escherichia coli and enterococci.
    Unfortunately, a focus on these bacteria misses the majority of resident pond
    bacteria, their responses to the tropical environment, and the dynamics of
    important bacteria like nitrogen cyclers.

    My primary research objectives were to (1) identify the microbial community
    composition in the ponds; (2) identify the genes and microbes responsible for
    pond nitrogen cycling; and (3) investigate how the microbial community
    responds to desludging. To address objectives (1) and (2), 288 wastewater
    samples were collected at the inlet, middle and outlet of Sanderson Ponds 1,
    2 and 5 in the morning (6 am) and afternoon (1 pm) during the early wet and
    dry seasons. For objective (3), 96 samples were collected in a similar manner
    from Leanyer Pond 2 before desludging and then one week, six months, and
    12-months after. Measurements included both in situ physico-chemistry and
    microbial DNA (or RNA). I used 16S rRNA gene sequencing to determine the
    bacterial community composition and Functional Gene Array to determine the
    activity of nitrogen cycling genes.

    I found that bacteria typically associated with the human gut are replaced by
    environmental bacteria as effluent progresses through the ponds and that IV
    desludging improves the removal of faecal bacteria and nitrogen. The study
    determined where and how nitrogen is removed from the pond system. For
    each pond, I identified a unique fingerprint of faecal and environmental
    bacteria-indicators that can be used for pond management and for developing
    new tests for human faecal pollution in the environment. Thus, I demonstrated
    that DNA-based detection methods can provide powerful and cost-effective
    monitoring tools that can be used both by wastewater managers and
    environmental regulators.

    Date of Award2021
    Original languageEnglish
    SupervisorKaren Gibb (Supervisor), Keith Christian (Supervisor), Karen Gibb (Supervisor) & Anna Padovan (Supervisor)

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