ASPECTS OF THE OCCURRENCE AND BEHAVIOR OF IRON BACTERIA IN BOREHOLES AND AQUIFERS

Iron bacteria are well known to borehore operators as the cause of iro n biofouling--the build-up of orange-coloured slimes and encrustations on casing, pump and pipe surfaces. In addition to biofouling, these n uisance organisms play a part in: enhancing the corrosion of borehole, pump and pipe components; influencing the chemistry of polluting acid ic mine drainage waters; and promoting the accumulation of soluble iro n in groundwaters. This paper highlights the diversity of organisms wh ich may be classed as iron bacteria, briefly describes the behaviour o f iron bacteria in boreholes and aquifers and outlines the deleterious effects that their activity can have on the efficient functioning of groundwater abstraction systems. However, it would be wrong to classif y iron bacteria only as a nuisance. There is potential for harnessing the activities of these organisms in a positive way and particular ref erence is made here to the benefits of biological removal of iron and arsenic from groundwaters.