Ecological disposal of bauxite tailings and red mud: A sustainable strategy for bauxite industrial waste reuse

Abstract

Bauxite tailings and red mud are often piled as industrial waste with limited reuse potential. In this study, we demonstrate how these wastes can be effectively reused as a soil-like matrix (BRM) for ecological restoration in mining areas. Over the course of a three-year field experiment, two pioneer plants, Celosia argentea and Melilotus suaveolens, successfully established initial vegetation in the disposal area and promoted revegetation. Revegetation significantly increased microbial diversity and network stability in BRM (p < 0.05). In addition, the abundance of microbial carbon and nitrogen fixation genes in BRM also increased. Most notably, the Calvin cycle genes increased by 119 times. Annual increases in organic carbon, total nitrogen, and pore volume in BRM were observed, while salinity-alkalinity tended to that of natural soil. The three-dimensional pore structure showed that pores with diameters of 400–800 μm occur in the upper layer of BRM. These results reflect the capacity of BRM to support sustainable soil-like ecosystems. Furthermore, site leaching monitoring results indicate that the environmental risks associated with salt and toxic elements in BRM are manageable. Our results showcases the potential of transforming industrial waste into valuable soil resources and proposes a strategy for resource reuse and sustainable waste management of bauxite industrial waste.