Characterization of bacterial community and iron corrosion in drinking water distribution systems with O 3 -biological activated carbon treatment.

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 Fe3 O4 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 Fe3 O4 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.