Rust-Triggered Malodors: Molecular Insights into Corrosion Product-Amplified Algal Odor Generation in Water Distribution Networks

Drinking water odor pollution and pipeline corrosion seriously threaten drinking water safety. Odor-producing algae can penetrate conventional water treatment processes and enter drinking water distribution networks, causing prominent water quality risks. Taking Microcystis aeruginosa as the target alga, this study investigated the effects and underlying mechanisms of pipeline corrosion products (CPs) on the formation of algal odorants under chlorination conditions. The results show that the coexisting system of CPs and chlorine significantly promotes the release of β-cyclocitral from M. aeruginosa while reducing the rupture rate of algal cells. The underlying reason is that CPs consume chlorine in the system, lowering the actual chlorine exposure dose and alleviating oxidative damage to algal cells. Meanwhile, the coexistence of CPs and chlorine may induce oxidative stress in algal cells, potentially further affecting the synthesis and release of β-cyclocitral by M. aeruginosa. Transcriptomic analysis reveals that, in the coexistence system of chlorine and CPs, M. aeruginosa upregulates the expression of genes related to the biosynthesis of the precursor β-carotene, further driving β-cyclocitral production. This study first confirms the synergistic effect between pipeline corrosion and chlorination, which aggravates algal odor pollution. The elucidated underlying mechanism provides a new theoretical basis for the precise control of odor risks in drinking water distribution networks.