Département Chimie de l’environnement

CyanO3: cyano-métabolites de la source au robinet

Source: Valentin Rougé, Eawag
Occurrence des peptides cyanobactériens et leur abatement pendant le traitment de l’eau potable

Les cyanobactéries prolifèrent dans les eaux douces à travers le monde et peuvent produire des cyanotoxines. Les microcystines, une famille de peptides cyanobactériens, ont été largement étudiées et la quantité d’évidences concernant leur toxicité a conduit à leur inclusion dans les lignes directrices sur la qualité de l’eau potable de l’OMS. Toutefois, les cyanobactéries produisent de nombreuses autres familles de peptides cyanobactériens. La question de l’impact de ces autres peptides cyanobactériens sur l’environnement et sur la santé humaine se pose.

Nous travaillons sur ces peptides cyanobactériens « de la source au robinet » en collaboration avec le service des eaux de Zürich (Wasserversorgung Zürich, WVZ). Nous posons la question de savoir si ces peptides peuvent atteindre les stations de traitement d’eau potable, et si celles-ci sont bien conçues pour empêcher ces peptides d’atteindre nos robinets.

Objectifs de ce projet:

  • Etudier les profiles saisonniers des peptides cyanobactériens dans la source d’eau et à l’entrée de la station de traitement d’eau potable
  • Evaluer l’abattement de ces peptides aux différentes étapes du traitement de l’eau
  • Déterminer les constantes de vitesse de réaction de deuxième ordre entre ces peptides et l’ozone avec une nouvelle méthode de mesure simultanée de multiples constantes.
  • Evaluer la toxicité potentielle des produits d’oxydation

L’ozone est fréquemment utilisé en Suisse contre les agents pathogènes, les composés organoleptiques et les micropolluants. L’ozone peut aussi dégrader efficacement les cyanotoxines connues, telles que les microcystines, ce qui en fait une addition parfois nécessaire dans les stations d’eau potable affectées par la prolifération de cyanobactéries. L’efficacité de l’ozone sur d’autres classes de peptides cyanobactériens est en revanche largement inconnue. Ce projet vise à combler le manque d’information sur la reactivité d’un grand nombre de peptides, sur leur produits d’oxydation et sur l’évolution de la toxicité due à ces peptides pendant l’ozonation. Mieux comprendre ces trois aspects aidera notre capacité à prédire leur devenir pendant le traitement de l’eau et évaluer les risques potentiels dus à la prolifération des cyanobactéries.

Publications

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      originalId => protected33024 (integer)
      authors => protected'Rougé, V.; von Gunten, U.; Janssen, E. M. L.' (70 chars)
      title => protected'Reactivity of cyanobacteria metabolites with ozone: multicompound competitio
         n kinetics' (86 chars)
      journal => protected'Environmental Science and Technology' (36 chars)
      year => protected2024 (integer)
      volume => protected58 (integer)
      issue => protected'26' (2 chars)
      startpage => protected'11802' (5 chars)
      otherpage => protected'11811' (5 chars)
      categories => protected'cyanopeptides; planktothrix; microcystis; micropollutant; ozonation; toxins;
          microcystin' (88 chars)
      description => protected'Cyanobacterial blooms occur at increasing frequency and intensity, notably i
         n freshwater. This leads to the introduction of complex mixtures of their pr
         oducts, i.e., cyano-metabolites, to drinking water treatment plants. To asse
         ss the fate of cyano-metabolite mixtures during ozonation, a novel multicomp
         ound ozone (O<sub>3</sub>) competition kinetics method was developed. Sixtee
         n competitors with known second-order rate constants for their reaction with
         
         
         . The apparent second-order rate constants (<em>k</em><sub>app,O3</sub>) at 
         pH 7 were simultaneously determined for 31 cyano-metabolites. <em>k</em><sub
         >app,O3</sub> for olefin- and phenol-containing cyano-metabolites were consi
         stent with their expected reactivity (0.4–1.7 × 10<sup>6</sup> M<sup>–1
         </sup> s<sup>–1</sup>) while <em>k</em><sub>app,O3</sub> for tryptophan- a
         nd thioether-containing cyano-metabolites were significantly higher than exp
         ected (3.4–7.3 × 10<sup>7</sup> M<sup>–1</sup> s<sup>–1</sup>). Cyano
         -metabolites containing these moieties are predicted to be well abated durin
         g ozonation. For cyano-metabolites containing heterocycles, <em>k</em><sub>a
         
         
         tivity of this class of compounds. Due to lower O<sub>3</sub> reactivities, 
         heterocycle- and aliphatic amine-containing cyano-metabolites may be only pa
         rtially degraded by a direct O<sub>3</sub> reaction near circumneutral pH. H
         ydroxyl radicals, which are formed during ozonation, may be more important f
         or their abatement. This novel multicompound kinetic method allows a high-th
         roughput screening of ozonation kinetics.' (1865 chars)
      serialnumber => protected'0013-936X' (9 chars)
      doi => protected'10.1021/acs.est.4c02242' (23 chars)
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Reactivity of cyanobacteria metabolites with ozone: multicompound competition kinetics

Cyanobacterial blooms occur at increasing frequency and intensity, notably in freshwater. This leads to the introduction of complex mixtures of their products, i.e., cyano-metabolites, to drinking water treatment plants. To assess the fate of cyano-metabolite mixtures during ozonation, a novel multicompound ozone (O3) competition kinetics method was developed. Sixteen competitors with known second-order rate constants for their reaction with O3 ranging between 1 and 108 M–1 s–1 were applied to cover a wide range of the O3 reactivity. The apparent second-order rate constants (kapp,O3) at pH 7 were simultaneously determined for 31 cyano-metabolites. kapp,O3 for olefin- and phenol-containing cyano-metabolites were consistent with their expected reactivity (0.4–1.7 × 106 M–1 s–1) while kapp,O3 for tryptophan- and thioether-containing cyano-metabolites were significantly higher than expected (3.4–7.3 × 107 M–1 s–1). Cyano-metabolites containing these moieties are predicted to be well abated during ozonation. For cyano-metabolites containing heterocycles, kapp,O3 varied from <102 to 5.0 × 103 M–1 s–1, giving first insights into the O3 reactivity of this class of compounds. Due to lower O3 reactivities, heterocycle- and aliphatic amine-containing cyano-metabolites may be only partially degraded by a direct O3 reaction near circumneutral pH. Hydroxyl radicals, which are formed during ozonation, may be more important for their abatement. This novel multicompound kinetic method allows a high-throughput screening of ozonation kinetics.
Rougé, V.; von Gunten, U.; Janssen, E. M. L. (2024) Reactivity of cyanobacteria metabolites with ozone: multicompound competition kinetics, Environmental Science and Technology, 58(26), 11802-11811, doi:10.1021/acs.est.4c02242, Institutional Repository