Hybrid Aluminum Electrocoagulation and Multi-Media Adsorption for Acid Mine Drainage Treatment

Acid mine drainage (AMD) is characterized by low pH, elevated dissolved metals, and high total dissolved solids (TDS), posing long-term risks to receiving waters and creating a need for robust yet practical treatment trains. This study evaluates a hybrid electrocoagulation–adsorption/filtration system for AMD treatment, combining rapid metal removal and pH correction in the electrocoagulation (EC) stage with downstream polishing by silica sand, activated carbon, and zeolite media. Electrocoagulation was carried out using aluminum electrodes at 1, 2, and 3 V with treatment times of 10–120 min. Effluent quality was assessed by Fe concentration, TDS, and pH to capture both metal removal and overall ionic strength reduction. The best overall performance was achieved at 3 V and 120 min, followed by filtration, reducing TDS from 2605 to 612 mg/L and Fe from 12.36 to 1.23 mg/L while increasing pH from 1.98 to 8.7. The EC step primarily destabilized and removed dissolved metals through hydroxide formation and sweep flocculation, whereas the filtration media provided additional adsorption sites for residual ions and colloids, yielding a clearer and more stable effluent. Overall, the hybrid system delivered substantial improvements in AMD quality using simple, low-energy unit operations and locally available media, indicating its potential as a scalable option for mine-impacted waters requiring simultaneous metal removal and pH normalization.