| Abstract | The exposure of the post - mining waste - the rock or deposits, which valuable minerals are taken out - from sulfidic mine activities to water and air undergoes chemical and biological oxidation processes result a highly acidic leachate. This acidic leachate known as acid mine drainage (AMD), which contains low pH and high concentration of sulfate as well as toxic trace such as iron, copper, lead and zinc. There were a lot of mining waste in abandoned mine areas that can create AMD. Such kind of abandoned mines are present in several provinces of Thailand and these areas cannot be used for agriculture, and there are very few surviving living organisms. Active treatments, such as pump - and - treat techniques, are widely used in an attempt to control AMD but their operational costs are very high and they produce huge volume of potentially hazardous unstable sludge. One of the most promising passive treatment technologies for remediation of AMD from groundwater plumes is Permeable Reactive Barrier (PRB) due to its effectiveness and its low cost compared to other technologies. The purpose of this research is to select the appropriate organic materials used as electron donors for treating AMD, evaluate the suitable residence time in PRB, and investigate heavy metal removal efficiency. As the result, the appropriate organic materials for PRB were composted pig manure and rice husk with the suitable hydraulic retention time (HRT) 16 days. The percentage of sulfate removal was up to 98%, which the residue sulfate concentration was 14.5 mg/L. The rate constant (k) of rice & coconut, pig manure & coconut husk chip, pig manure & rice husk and pig manure, rice husk & coconut husk chip media were 0.121, 0.196, 0.277 and 0.206 respectively. The concentrations of iron reduced from 23.34 mg/L to around 2 mg/L. Copper and zinc concentrations decreased from 18.97 and 6.09 mg/L to below groundwater quality standards of Thailand. The percentages of iron, copper, zinc, and manganese removal were 93 %, 99 %, 88 %, and 96 % respectively. The column reactors, which added lime (0.15 g/L of the reactor) into the media, had more efficiency than the reactor that no lime in the media. |