Enhanced metals precipitation in acid mine drainage by thermal activation magnesite-pine shavings dispersed alkaline substrate

The acid mine drainage (AMD) is characterized by its highly acidic nature and elevated concentrations of metal ions, thereby exerting significant impacts on both human health and the environment. This study employed a dispersed alkaline substrate (DAS) consisting of thermal activation magnesite and pine shavings for the treatment of AMD. The investigation focused on determining the optimal thermal activation conditions of magnesite, evaluating the effectiveness of the DAS in regulating acidity and removing metal ions from AMD, identifying critical factors influencing treatment efficiency, and conducting toxicity assessment on the effluent. Results indicated that calcination at 700 °C for 60 min was determined to be the optimal thermal activation condition for magnesite. Under the optimal operating conditions of the DAS (flow rate: 0.4 mL/min, filling mass ratio: thermal activation magnesite to pine shavings = 1:1), the system achieved complete removal (100%) of metal ions within 396 h while maintaining a pH above 7.0. Moreover, it significantly minimized operating costs and sludge generation. Toxicity assessment experiments conducted using <i>Chlorella proteolytica</i> demonstrated a significant reduction in biotoxicity after treatment with this system. These findings suggest that a DAS based on thermal activation magnesite holds promise as an effective solution for treating AMD.