Résumé - Abstract
The increasing exploitation of low-grade and refractory ores requires more aggressive separation conditions of valuable minerals and generates high flows and loads of mine impacted water. Available technologies for the removal of nitrogen-based contaminants (thiocyanate, cyanide, cyanate, ammonia nitrogen and nitrite) have often limited performance for such mine water. In the context of sustainable mining operations, the development of innovative water treatment technologies becomes mandatory. In this study, the performance of microbubbles ozonation for the removal of nitrogen-based contaminants in mine impacted water was evaluated at laboratory pilot scale on synthetic mine effluents, as well as four real mine effluents. Results showed that: (i) pH has high impact on the process efficiency, while temperature and hydraulic retention time have lower impact; (ii) removal rates of ozonation on thiocyanate and weak acid dissociable (WAD) cyanide were above 97% while removal rate for ammonia nitrogen and cyanate varied from 59 to 99%, and from 47 to 99% respectively; (iii) effluents that were non-acutely toxic to Daphnia magna were observed on three out of four real mine effluents trials.