Elucidation of the factors controlling the kinetics of manganese oxidation during the passive treatment of mine drainage water
To understand the biogeochemical behavior and treatment efficiency of Mn in passive mine water treatment systems, the factors controlling the oxidation kinetics must be identified.
Start: 01 October 2021
End: 01 October 2024
Supervisors :
Eric van Hullebusch, Fabienne BATTAGLIA-BRUNET
Status: Defended
Manganese is one of the elements frequently encountered in mine water at concentrations above the regulated discharge limit to the natural environment. Removal of Mn(+II) using passive water treatment systems is possible but difficult to control due to slow oxidation kinetics under the physico-chemical conditions reported in mine drainages. The oxidation rate of manganese at pH close to neutrality can be significantly improved by biological catalysis or in the presence of solid manganese oxides. However, the biogeochemical cycling of Mn in passive treatment systems is not well understood. Unraveling the chemical and biological mechanisms that regulate the manganese removal in construted wetlands represents a major challenge for the management of mining sites. The objective is to determine the factors limiting Mn(+II) oxidation kinetics in existing passive treatment systems, in order to propose strategies to improve their efficiency. Mineralogical, biological and geochemical data on real wetlands will be acquired and bioreactors will be set up in order to elucidate the microbiological (direct and/or indirect bio-catalysis) and chemical mechanisms controlling the immobilization kinetics of manganese in the form of precipitated oxides.
