Iron pipe corrosion enhanced the transformation of iopamidol, a precursor of iodinated disinfection byproducts: The role of sulfate-reducing bacteria.

Long-term use of iron pipes leads to inevitable corrosion due to chemical and biological processes, with sulfate-reducing bacteria (SRB) playing a significant role. The corrosion products generated will affect the transformation of micropollutants in pipe networks. This study investigated the effect of SRB-influenced corrosion (SIC) on the transformation of iodine-containing micropollutants, using iopamidol (IPM) as a model compound. The degradation rate of IPM in the presence of Febio (with SIC) was 2.3 times higher than that with Feabio (without SIC). This enhancement was primarily attributed to accelerated and selective electron transfer facilitated by FeSx formation in the SIC process. The enhancement was more pronounced in presence of an appropriate amount of SO42 (120 mg L-1), or under a weakly acidic condition (pH 6). The enhancement was further validated in real water, where the released iodide was converted into iodinated disinfection by-products (I-DBPs) and/or iodate (IO3-), depending on the disinfectant used. This study offers an insight into the interplay between SRB-driven iron corrosion and iodine-containing pollutant transformation, contributing to a deeper understanding of micropollutant fate in corroded iron pipe networks.