Role of Microorganisms in Mining: Generation of Acid Rock Drainage and its Mitigation and Treatment

Natural oxidation of sulphide mineral wastes during their disposal and storage at the mining sites may result in generation of acid rock drainage (ARD) that may contain high acidity and high concentrations of dissolved metals and sulphates. Due to its chemical composition, ARD poses potential harm to the environment and significant challenges to many mining industries requiring development and application of effective ARD management plans to the mining sites during the operational and post-closure periods. If the generation of ARD cannot be prevented or controlled, it must be collected and treated to eliminate acidity and reduce the concentration of heavy metals and suspended solids before its release to the environment. As a group of microorganisms may contribute to the generation of ARD, different types of microorganisms may play a vital role in the development of microbiological prevention, control and treatment technologies. The role of microorganisms in the generation of ARD and their role in the methods used for prevention, control and treatment are discussed in this paper. Benefits, limitations and design criteria for passive biological processes are presented using examples of passive and biological treatment processes that have been developed recently and implemented to mine sites. © 2002 SDU. All rights reserved.