Biological Iron Removal and Recovery from Water and Wastewater.

Iron is a common contaminant in source water and wastewater. The mining and metallurgical industries in particular can produce and discharge large quantities of wastewater with high iron concentrations. Due to the harmful effects of iron on organisms and infrastructure, efficient technologies for iron removal from water and wastewater are needed. On the other hand, iron is a valuable commodity for a wide range of applications. Microorganisms can facilitate iron removal and recovery through aerobic and anaerobic processes. The most commonly utilized microbes include iron oxidizers that facilitate iron precipitation as jarosites, schwertmannite, ferrihydrite, goethite, and scorodite, and sulfate reducers which produce hydrogen sulfide that precipitates iron as sulfides. Biological iron removal has been explored in various suspended cell and biofilm-based bioreactors that can be configured in parallel or series and integrated with precipitation and settling units for an effective flow sheet. This chapter reviews principles for biological iron removal and recovery, the microorganisms involved, reactor types, patents and examples of laboratory- and pilot-scale studies, and full-scale implementations of the technology.