Effects of microbial cycling of Fe(II)/Fe(III) and Fe/N on cast iron corrosion in simulated drinking water distribution systems

Effects of microbial cycling of Fe(II)/Fe(III) and Fe/N, as driven by the bacterium Dechloromonas hortensis, on iron corrosion were studied in simulated drinking water distribution systems (DWDSs) with different nitrate concentrations. Fe/N redox cycling accelerated Fe(II) oxidation and α-FeOOH formation in DWDSs with 22.0 mg/L initial NO3−-N. The greatest amount of Fe3O4 was formed through Fe(II)/Fe(III) redox cycling in DWDSs with 2.2 mg/L initial NO3−-N. This resulted in the lowest corrosion rate and iron release. Therefore, the redox cycling of Fe(II)/Fe(III) driven by D. hortensis was favourable to the formation of more stable corrosion scales in DWDSs.