Gang Wen

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.

Efficient nutrient reduction at the sediment–water interface under mixed aeration combined with Limnodrilus hoffmeisteri was achieved by benthic bioturbation optimizing sediment microenvironment and regulating nitrogen and phosphorus transformation.

Efficiently removing organoarsenic contaminants like p-Aminophenylarsonic acid (pASA) with their toxic inorganic byproducts remains a major challenge. Ferrate [Fe(VI)] can oxidize organoarsenic and immobilize inorganic arsenic, but the molecular mechanisms linking these functions are unclear. Here, using theoretical computational spectroscopy and stopped-flow analysis, we identified a critical pathway mediated by Fe(V/IV)–O-As(III) intermediates (INTs) that bridges oxidative degradation and heterogeneous sequestration. X-band EPR further confirmed the INTs (g-factors = 2.006, 1.928, 1.712), with rhombic peaks and quadruple hyperfine splitting. These INTs form barrierlessly between Fe(VI/V) and ·As(III)O(OH)2 released upon C–As bond cleavage in pASA. The thus-formed INTs exhibit superior reactivity to Fe(VI/V/IV), enabling more effective organoarsenic degradation and As(III) oxidation via outer-sphere electron transfer. Additionally, these INTs facilitate highly efficient inner-sphere electron transfer, forming Fe(III/II)–O-As(V) complexes that directly evolve into As-bearing Fe nanoparticles via Fe–O–As bond formation, a process with a lower energy barrier. The abundance of INTs during pASA degradation can be regulated by modulating Fe(VI) decomposition kinetics using common reagents: H2O2 accelerates and NaClO delays Fe(VI) decomposition. The Fe(VI)/NaClO system achieved 88% total As removal, higher than the 72% for Fe(VI)/H2O2 and 78% for Fe(VI) alone, and exhibited enhanced As–Fe coordination, indicating improved sequestration. Overall, this work reveals a pivotal mechanistic bridge in metalloid contaminant removal, offering new insights for designing oxidation-sequestration synergy in environmental remediation.

Anthropogenic organophosphorus compounds (OPCs) are water contaminants of concern because of their ecotoxicity and contribution to phosphorus loading. We investigated the quantitative reaction chemistry and phosphorus fate of 17 OPCs during ferrate(VI) treatment. Second-order rate constants ranged from 12.2 to 353.1 M–1 s–1 at pH 7.0, with phosphonates generally reacting faster than organophosphate esters. A speciation-based kinetic model identified HFeVIO4– and partially deprotonated OPCs as kinetically relevant reactants. Direct Fe(VI) accounted for 83.7–98.9% of their transformation, whereas Fe(V)/Fe(IV) and •OH made minor contributions. Product identification and theoretical analyses revealed oxidative dephosphorylation as an important transformation pathway. C–P bond cleavage predominated for glyphosate (GLY), converting 92.9% of its phosphorus to orthophosphate at an Fe(VI)-to-GLY ratio of 20:1 and pH 7.0. Even for less reactive chlorpyrifos and trichlorfon, phosphate yields could approach 18.6% and 20.4%, respectively. Ferrate-derived Fe(III) nanoparticles captured the released phosphate, achieving 71.5% total phosphorus and 67.2% total organic carbon removal. A quantitative structure–activity relationship model, independently evaluated with five additional OPCs (R2 = 0.807), identified oxidation potential, molecular complexity, phosphorus functional-group identity, and phosphorus-centered steric hindrance as reactivity determinants. These findings deepen mechanistic understanding of ferrate reactions with OPCs and inform rational ferrate application for organophosphorus pollution control.