| Summary: | © 2016 Dr. Benjamin Lewis Freidman In-situ remediation is the most ecologically and cost effective method for the clean-up of petroleum hydrocarbon contaminated sites, particularly in cold regions. In-situ remediation can accelerate the natural biodegradation rates through engineered modification and optimisation of environmental conditions. Permeable reactive barriers are one technology that can remove migrating petroleum hydrocarbons. The reactive materials can enhance biofilm formation and biodegradation over that which occurs in soils. Establishing the appropriate soil water conditions for biofilm formation can result in the development of bio-reactive materials. This thesis assessed the performance of bio-reactive materials for application to permeable reactive barriers at petroleum hydrocarbon contaminated sites in low nutrient, cold environments. Batch and continuous flow studies demonstrated that nutrient amended zeolites were preferable as bio-reactive materials, when compared with encapsulated fertilisers (chapter 4). This assessment was based on the stability and longevity of nutrient release from the materials. In laboratory flow cells across 432 bed volumes passing, ammonium exchanged zeolite was shown to enhance biofilm formation as well as the biodegradation of Antarctic diesel in low nutrient soil water (chapter 5). Biodegradation indices confirmed that Antarctic diesel was readily accessible to biofilm colonising the surface of the ammonium exchanged zeolite. While biofilm formation and biodegradation was also observed on natural zeolite, the biodegradation of Antarctic diesel was significantly lower in the soil water and demonstrates the importance of ammonium delivery to the development of bio-reactive materials. Sequenced materials within laboratory flow cells, containing ammonium exchanged zeolite and activated carbon, demonstrated that microbial cells had limited access to Antarctic diesel compounds adsorbed onto activated carbon (chapter 6). Saturation of the activated carbon with Antarctic diesel resulted in partial desorption of the diesel compounds, facilitating microbial growth via a biofilm induced concentration gradient. The sequenced bed design, encompassing adsorption and biodegradation phenomena, can effectively manage the risk posed by migrating petroleum hydrocarbon spills in cold regions. The translation of laboratory studies to field scale was assessed through permeable reactive barrier installation at sub-Antarctic Macquarie Island and biological activated carbon analysis from central Victorian drinking water treatment plants (chapter 7). These two case studies demonstrated the importance of informed bio-reactive material selection for municipal and remote water treatment applications.
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