wcm.02.2025.257.268

Acid Mine Drainage (AMD) generated from coal mining activities typically exhibits low pH levels (3.75) and high metal concentrations, posing significant threats to aquatic ecosystems. Conventional treatment methods are often costly and less effective in the long term. This study investigates the application of a passive open limestone channel system, utilizing local materials (fly ash, zeolite, limestone, and silica sand) to neutralize AMD. The experimental setup employed three treatment combinations (A, B, and C) tested in an 8-compartment channel system with varying slopes (5°, 7°, and 9°). Combination A used fresh materials, B reused materials from A, and C utilized unwashed materials from B. Effectiveness was evaluated based on pH improvement and operational efficiency. Results showed that Combination A achieved an average pH of 7.51 (76% efficiency), with optimal neutralization occurring in compartment 8. Combination B reached a pH of 7.39 (62% efficiency) but neutralized AMD more rapidly in compartments 5–6. Combination C achieved a pH of 7.15 (73% efficiency). The pH decline in the final compartments was attributed to CO₂ accumulation, gypsum residue formation, and material clogging. Although Combination A had the highest chemical efficiency, Combination B was deemed the most technically optimal due to its balanced pH improvement (7.39), faster neutralization rate, and material efficiency. The study recommends integrating chemical and technical aspects in AMD treatment system design to ensure environmental and economic sustainability.