The optimal pH range for the treatment of acid mine drainage AMD to prevent the release of toxic heavy metals into the environment is typically between 6 and 9. In this pH range, most heavy metals, such as iron, aluminum, and manganese, will precipitate as hydroxides or other insoluble forms, reducing their mobility and potential for environmental contamination.However, it is important to note that the specific pH range for effective treatment may vary depending on the composition of the AMD and the presence of specific heavy metals. In some cases, a more precise pH target may be necessary to ensure the effective precipitation of all toxic metals present. Additionally, other treatment methods, such as the use of adsorbents or biological processes, may be employed in conjunction with pH adjustment to further enhance the removal of heavy metals from AMD.