Treatment of acid coal gangue leaching wastewater with constructed wetland based on ceramsite substrate

This study investigates the use of constructed wetlands (CWs) with ceramsite derived from surplus sludge pyrolysis ash for acid mine drainage (AMD) remediation. The system, incorporating ceramsite, limestone, and gravel, used soybean wastewater as a microbial carbon source. Results showed that the ceramsite-based system effectively raised pH from 3.5 to 8.0, achieving removal rates of 99.96% for Fe, 96.53% for Mn, 94.84% for Cu, 99.26% for Zn, and 96.02% for total phosphorus. Metal ion removal was primarily through ceramsite adsorption, with minor plant-mediated adsorption. Microbial analysis revealed that pH and metal concentrations influenced bacterial composition, with dominant genera including Trichococcus, Clostridium_Sensu_Stricto_1, and Citrobacter. Sulfate-reducing bacteria such as Desulfovibrio and Desulfobulbus played crucial roles in sulfate reduction. This study demonstrates a sustainable AMD treatment method that not only improves metal ion removal but also addresses sludge disposal challenges, highlighting the environmental benefits of using waste-derived materials for pollution control and resource recovery.