In-situ Bioremediation and Molecular Microbiological Monitoring of Ammonia Contaminated Groundwater

Joyce, Evelyn (2022) In-situ Bioremediation and Molecular Microbiological Monitoring of Ammonia Contaminated Groundwater. Doctoral thesis, SETU Waterford.

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To reduce ammonia contamination in groundwater, two Permeable Reactive Barriers (PRBs) were installed in a closed landfill site in Ennis, Co. Clare to act as a sustainable in-situ bioremediation solution. The PRBs were designed to reduce ammonia (NH4-N) contamination in the groundwater by cycling ammonia through the nitrogen cycle to dinitrogen gas thereby reducing contamination of the receiving surface water bodies. The PRBs were designed to promote the first (aerobic) stage of the nitrogen cycle in PRB1, i.e., nitrification and the second (anaerobic) stage of the nitrogen cycle in PRB2 i.e., denitrification. Monitoring wells were installed upstream of the PRBs, within the PRBs, between the PRBs and downstream of the PRBs, resulting in five monitoring wells. These five monitoring wells (S1- S5) were monitored onsite for pH, DO, temperature, and electrical conductivity. Water samples were analysed to determine concentrations of ammoniacal nitrogen, nitrite, nitrate, and total organic carbon. eDNA was extracted from water collected from the monitoring wells and analysed to determine abundance of nitrogen cycling functional genes (i.e., bacterial, and archaeal amoA as well as nirK, nirS and nosZ). eDNA from both PRBs at six monthly intervals was used to investigate the microbial communities present. The results showed that PRB1 significantly reduced the NH4-N contamination in the groundwater and that PRB2 significantly reduced the concentrations of the resulting nitrification by-products nitrite (NO2) and nitrate (NO3) thereby signalling bioremediation. Concentrations of target contaminant, NH4-N, were significantly lower in downstream monitoring S5 compared to all other monitoring wells. The molecular analysis confirmed that nitrogen cycling microbes were present on the site and suggested that the PRBs were functioning as a bioremediation solution for ammonia contamination.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: In-situ Bioremediation, Molecular Microbiological Monitoring, Ammonia Contaminated Groundwater
Departments or Groups: *NONE OF THESE*
Divisions: School of Science > Department of Chemical and Life Sciences
Depositing User: Derek Langford
Date Deposited: 15 Sep 2022 10:40
Last Modified: 15 Sep 2022 10:40

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