Georemediation of a spent potliner leachate contaminated aquifer using calcite and carbon dioxide

Research presented in this thesis relates to the geo-remediation of spent potliner leachate contaminated groundwater, a designated hazardous liquid waste, using calcite and carbon dioxide and is presented as a “thesis by publication”. It is based on eight interrelated articles taken from four journal articles, three international conference abstracts, and a peer reviewed conference paper. In all publications the author has made a significant contribution to both the research, manuscript preparation and writing. Most of the research was funded by the Australian Research Council Linkage Grant LP100200488 in conjunction with Hydro Aluminium Kurri Kurri, New South Wales, Australia. This thesis presents an extensive geo-environmental site characterisation including groundwater monitoring, aquifer hydraulic, and cone penetration testing in order to determine the extent of contamination and geological conditions at the Hydro Aluminium field site. In conjunction with the field site characterisation, laboratory testing of over 300 batch kinetics experiments investigating the removal of the main contaminant, fluoride, as a function of various parameters including temperature, stirring rate, particle size, and CO₂ partial pressure and the associated kinetic modelling are presented. Of significance Chapter 6 presents the Hill model, a new model never before used in the field of geochemistry, to accurately describe the sigmodal kinetic reactions that occur in the remediation of spent potliner contaminated groundwater. The findings of the laboratory kinetics tests were used to determine cost effective remediation methods for the field site. Finally, the field and laboratory research are brought together in a detailed conceptual 3D model to investigate historical contaminant transport, and future permeable reactive barrier remediation options using visual modflow and MT3DMS.