Characterization of biofilm bacterial communities and cast iron corrosion in bench-scale reactors with chloraminated drinking water

Biofilm bacterial communities and cast iron corrosion were studied in bench-scale reactors with chloraminated drinking water. Before 6 d, α-FeOOH was predominant in corrosion scales, and the main bacterial genera were Acidovorax and Aquabacterium with higher iron corrosion and release. After this point, Fe3O4 was formed, and Azospira and Dechloromonas became the main bacterial genera with lower iron corrosion and release. Principal component analysis (PCA) showed good correlation among the bacterial genera, corrosion rate, and the content of α-FeOOH and Fe3O4 in corrosion scales. Moreover, most probable number (MPN) enumerations indicated that the main nitrate-reducing bacteria (NRB), iron-oxidizing bacteria (IOB) and iron-reducing bacteria (IRB), could induce oxidation of Fe(II) and reduction of Fe(III) inside the corrosion scales. It was also verified that the process of Fe redox possibly induced by these microorganism respiration, could drive the transformation of α-FeOOH to Fe3O4. This resulted in higher inhibition of iron corrosion and release in chloraminated drinking water than that in sterile water.