Rehabilitation of sulfide tailings through designed Technosol and microbial-inoculant

Abstract

The implementation of pastures or herbaceous intercropped with non-food autochthonous plants to extract high-added value compounds is a promising option for improving both the environmental and the economic sustainability of the active mining areas. The continuous generation of acid mine drainage and the physico-chemical characteristics of sulfide tailings make impossible the germination and development of plant covers, and therefore, an essential step in the environmental rehabilitation is the physico-chemical improvement of these materials. This study assessed, in a batch assay, the acid neutralization capacity of a designed Technosol applied to sulfide tailings at differentes applications rates. The best proportion was used subsequently in microcosm assay under greenhouse conditions, where herbaceous species were sown. Three treatments were established: sulfide tailings with a microbial inoculant (MI); Technosol+sulfide tailing with and without MI. The MI included a micorrhizal fungi +Trichoderma. In sulfide tailings with the MI no germination occurred. Significant improvement of physico-chemical properties of the sulfide tailing and their leachates were obtained with Technosol application (e.g. increase of fertility and pH, decrease of the contaminants available fraction). The Technosol also allowed the develpoment of a vigourous herbaceous cover without visual phytotoxic symptoms that can valorize the mining areas through a new land use. The production of herbaceous biomass was similar designed Technosol with or without MI.