<![CDATA[Acid Mine Drainage (AMD) from sulfide-mineral oxidation poses an urgent threat to receiving water bodies due to its low pH and dissolved-metal load, making efficient, sustainable neutralization a priority for small- to medium-scale mines. This study comparatively evaluated active treatment (Ca(OH)₂), passive treatment (goat manure as an SRB substrate), and a hybrid combination for AMD neutralization and Fe–Mn removal, using a 15-day laboratory batch experiment monitoring pH, TSS, Fe, and Mn against an untreated control, analyzed via effectiveness calculations and Two-Way ANOVA. All treatments raised pH toward neutral, with passive treatment achieving the highest effectiveness (75% pH improvement, 52% Fe removal, 67% Mn removal); pH improvement plateaued near this level once added alkalinity reached equilibrium with residual acidity from ongoing pyrite oxidation. TSS rose in all treatments most in the hybrid system because effective metal removal itself generates suspended Fe/Mn-hydroxide flocs and SRB biomass, though values stayed within the regulatory limit (400 mg/L). These results position goat manure-based passive and hybrid treatments as low-cost, mechanistically distinct alternatives for net-acid, low-metal AMD management. Given the single-reactor, non-replicated design, further research with biological replicates, controlled temperature/DO/ORP monitoring, and field-scale validation is recommended, particularly to optimize passive-system design for TSS mitigation.]]>
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