Characterization of bacterial community and iron corrosion in drinking water distribution systems with O₃-biological...

Bacterial community structure and iron corrosion were investigated for simulated drinking water distribution systems (DWDSs) composed of annular reactors incorporating three different treatments: ozone, biologically activated carbon and chlorination (O₃-BAC-Cl₂); ozone and chlorination (O₃-Cl₂); or chlorination alone (Cl₂). The lowest corrosion rate and iron release, along with more Fe₃O₄ formation, occurred in DWDSs with O₃-BAC-Cl₂ compared to those without a BAC filter. It was verified that O₃-BAC influenced the bacterial community greatly to promote the relative advantage of nitrate-reducing bacteria (NRB) in DWDSs. Moreover, the advantaged NRB induced active Fe(III) reduction coupled to Fe(II) oxidation, enhancing Fe₃O₄ formation and inhibiting corrosion. In addition, O₃-BAC pretreatment could reduce high-molecular-weight fractions of dissolved organic carbon effectively to promote iron particle aggregation and inhibit further iron release. Our findings indicated that the O₃-BAC treatment, besides removing organic pollutants in water, was also a good approach for controlling cast iron corrosion and iron release in DWDSs.