“…Neutralization with lime or other reagents (e.g., limestone, sodium hydroxide, and sodium carbonate) is a frequently used method for treating large volume of AMD, particularly those from small mines, because of its simplicity. 10,11 However, there are several limitations for this method. On one hand, the conversion of ferrous ions (Fe 2+ ) into ferrous hydroxides occurs at pH > 9, indicating that a large amount of alkalinity is needed to increase the pH of AMD from 2-4 to >9.…”