The researchers studied how different types of wetlands can clean up acid mine drainage, which is polluted water from mining activities. They found that using hydrogen gas along with plants in wetlands helps remove sulphate and heavy metals effectively. Wetlands with plants had higher removal rates than those without. The best results were seen in wetlands with gravel and Phragmites australis plants. Adding hydrogen gas increased the removal efficiency of sulphate and metals. This study shows that using hydrogen gas and measuring certain factors can help improve the cleaning process in wetlands.