INTRODUCTION

The microbiota present in the sulphur cycle have been studied since the end of the nineteenth century when the pioneering work of the famous microbiologists Winogradsky and Beijerinck took place. Sulphur conversions involve the metabolism of several different specific groups of bacteria, e.g. sulphate-reducing bacteria (SRB), phototrophic sulphur bacteria and thiobacilli, specialized to use these sulphur compounds in their different redox states (Lens and Kuenen, 2001). Many of these microorganisms possess unique metabolic and ecophysiological features, and to date there are still regular reports of novel microorganisms with extraordinary properties. Several of the microbial conversions of the sulphur cycle can be implemented for pollution control (Table 13.1). This chapter overviews the applications in environmental technology, which utilize the metabolism of SRB as the key process.

Technological utilization of SRB sounds at first somewhat controversial, as sulphate reduction has been considered unwanted for many years in anaerobic wastewater treatment (Hulshoff Pol et al., 1998). Emphasis of the research in the 1970s–1980s was mainly on the prevention or minimalization of sulphate reduction during methanogenic wastewater treatment (Colleran et al., 1995). From the 1990s onwards, interest has grown in applying sulphate reduction for the treatment of specific wastestreams, e.g. inorganic sulphate-rich wastewaters such as acid mine drainage, metal polluted groundwater and flue-gas scrubbing waters. Nowadays, sulphur-cycle-based technologies are not solely considered as “end-of-pipe” applications, but their potential for pollution prevention as well as for sulphur, metal or water recovery and re-use are now fully recognized.