British Columbia Mine Reclamation Symposium

A non-biological option for Se removal by photocatalytic reduction of selenate in mine-impacted water containing high concentrations of sulfate and nitrate Holmes, A.; Giesinger, K.; Ye, J.; Milan, E.; Ngan, A.; Gu, F.


Mine-impacted water (MIW) rich in selenium (Se) results from natural sources of water drainage, such as rain and snowmelt, infiltrating into waste rock piles and tailings on operating or abandoned mines. Dissolved Se is commonly found in its fully oxidized form, selenate, a highly bioavailable and mobile compound in the environment. The removal of selenate from MIW is desired, given its potential toxicity in aquatic ecosystems. MIW can contain varying concentrations of dissolved species, thus selective reduction of selenate is desired. In this study, we present the photocatalytic reduction of selenate over titanium dioxide (TiO₂) as a promising non-biological technique for selenate removal from mine-impacted water in order to remove Se from more than 600 μg L-¹ to below concentrations of 1 μg L-¹. For MIW treatment, the development of a process capable of removing selenate prior to biological denitrification process is desired, due to the numerous advantages achieved through removing Se from the biological process. This work sheds light on the mechanisms of selenate photocatalytic reduction and highlights the main drivers impacting the electron transfer process; information which can be used to build predictive models and engineer specialized solutions to achieve selective Se reduction under variable conditions.

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