Scenario-specific in situ remediation strategies and multi-technology collaborative model optimization for acid mine drainage in closed coal mines

Abstract

Groundwater rebound and the re-establishment of groundwater flow systems following coal mine closure can intensify the sustained generation and migration of acid mine drainage (AMD), imposing dual hydraulic and contaminant loads. This situation underscores the urgent need for long-term and cost-effective integrated in situ remediation strategies. This review focuses on AMD in closed coal mines and critically synthesizes its formation and temporal evolution, site-characterization approaches, in situ remediation technologies, scenario-specific integrated remediation strategies, and model-driven optimization methods. Integrated in situ remediation of AMD in closed coal mines should be founded on the systematic characterization of source zones, migration pathways, and reactive processes. On this basis, remediation strategies can be tailored to specific contamination scenarios by combining source control, grouting, permeable reactive barriers, and bioremediation to achieve source-load reduction, pathway control, and reaction enhancement. This review aims to advance AMD management in closed coal mines from end-of-pipe treatment and isolated technology deployment toward an integrated in situ remediation framework supported by site characterization, scenario matching, and model-based optimization, thereby providing a theoretical framework and decision support for the long-term remediation of groundwater contamination in complex post-mining environments.