Application of Active and Passive Treatment of Acid Mine Drainage to Comply with the Threshold Parameter of Coal Mining Wastewater

Most of the coal mining in Indonesia that uses the open pit mining method faces serious problems, namely the treatment of acid mine drainage. This constitutes a relatively large volume of wastewater, especially in areas that have rainfall in the range of 2000–4000 mm yearly. Acid mine drainage as acidic wastewater formed during excavation cannot be avoided due to the oxidation process during overburden removal. The acidic wastewater that has formed must be managed strictly and appropriately prior to being released into public waters. There are two methods of treating acid mine wastewater, namely active and passive treatments. Active treatment is generally used more frequently during operations, considering the time, effort, and costs; however, when entering the mine closure period, natural processes must be used at lower costs. Undertaking passive treatment in this area has shown a reduction in the chemical materials used and has enabled a greater amount of wastewater to be managed. The purpose of this research is to describe the active and passive treatment processes in the management of acid mine drainage and to analyze the results of passive treatment in preparation for the mine closure stage. Development of passive treatment by swampy forest system can reduce cost of treatment, naturally process and more environment friendlier by reducing the quicklime materials.