Solid-state reduced sulfur compounds: Environmental aspects and bio-remediation

This article reviews major risks caused by microbial transformations of solid-state reduced sulfur compounds that are used or affected by anthropogenic activities. These materials, such as fossil fuels, ores, anaerobic sediments or solid waste, may undergo oxidative changes, resulting in a solubilization of sulfur from the solid phase. The risks are generally associated with acidification of the environment and the subsequent mobilization of toxic metals. In the second part of the article, current and perspective techniques applicable for the treatment of such materials are presented. Both methods that prevent solubilization and processes of microbial removal of reduced sulfur are discussed. Special interest is paid to techniques operating on long time scales, applicable for the treatment of large areas or highly voluminous wastes.