Use of organic covers for acid mine drainage control

Organic covers may be used to prevent diffusion of oxygen into reactive sul phide wastes and subsequently to eliminate sulphide compounds oxidation and generation of acidic waters. The main advantages over other types of cover s are related with their low hydraulic permeability, high cation exchange c apacity and high alkalinity. In addition, the establishment of organic cove rs, which is considered as a low cost solution for the prevention of acid m ine drainage generation, does not disturb the natural environment, since th ey consist of industrial wastes rather than natural materials and allow the development of vegetation which improves the aesthetics of the reclaimed a reas. However, treatment of municipal sewage sludge is necessary prior to d ischarge, in order to minimize potential health and environmental risks, re sulting from the presence of toxic elements. In the present paper all processes associated with the function of an an or ganic cover are described and discussed, including potential health and env ironmental risks resulting from land application of municipal sewage sludge . In addition, preliminary laboratory data derived from the application of organic coves over reactive sulphidic concentrates are presented and discus sed, in order to evaluate the performance of the covers and to determine th e critical factors affecting their performance. The final aim of this resea rch work is the development of an experimental model, that predicts the per formance of an organic cover, by taking into account critical parameters su ch as annual rainfall rate, organic material height, initial moisture and m oisture under saturation conditions. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.