Department Environmental Chemistry

Amine Biotransformation

Many down-the-drain chemicals, especially pharmaceuticals, contain an amine functional group. It is therefore important to understand what transformations may take place at the amine functional group during activated sludge treatment and whether stable or otherwise problematic transformation products might be formed.

In this SNF-funded project, we investigate the biotransformation pathways of a range of structurally diverse amine-containing compounds in activated sludge communities. We use high-resolution mass spectrometry and post-acquisition data processing workflows to search for suspected and unknown transformation products. We use this information to derive the metabolic logic of amine biotransformation, which will then inform the development of biotransformation pathway prediction engines (link to enviPath project).

Publications

Extbase Variable Dump
array(2 items)
   publications => '7847,7576' (9 chars)
   libraryUrl => '' (0 chars)
Extbase Variable Dump
array(2 items)
   0 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=7847, pid=124)
      originalId => protected7847 (integer)
      authors => protected'Gulde, R.; Helbling, D. E.; Scheidegger, A.; Fenner,&nbs
         p;K.' (80 chars)
      title => protected'pH-dependent biotransformation of ionizable organic micropollutants in activ
         ated sludge' (87 chars)
      journal => protected'Environmental Science and Technology' (36 chars)
      year => protected2014 (integer)
      volume => protected48 (integer)
      issue => protected'23' (2 chars)
      startpage => protected'13760' (5 chars)
      otherpage => protected'13768' (5 chars)
      categories => protected'' (0 chars)
      description => protected'Removal of micropollutants (MPs) during activated sludge treatment can mainl
         y be attributed to biotransformation and sorption to sludge flocs, whereby t
         he latter process is known to be of minor importance for polar organic micro
         pollutants. In this work, we investigated the influence of pH on the biotran
         sformation of MPs with cationic-neutral speciation in an activated sludge mi
         crobial community. We performed batch biotransformation, sorption control, a
         nd abiotic control experiments for 15 MPs with cationic-neutral speciation, 
         one control MP with neutral-anionic speciation, and two neutral MPs at pHs 6
         , 7, and 8. Biotransformation rate constants corrected for sorption and abio
         tic processes were estimated from measured concentration time series with Ba
         yesian inference. We found that biotransformation is pH-dependent and correl
         ates qualitatively with the neutral fraction of the ionizable MPs. However, 
         a simple speciation model based on the assumption that only the neutral spec
         ies is efficiently taken up and biotransformed by the cells tends to overpre
         dict the effect of speciation. Therefore, additional mechanisms such as upta
         ke of the ionic species and other more complex attenutation mechanisms are d
         iscussed. Finally, we observed that the sorption coefficients derived from o
         ur control experiments were small and showed no notable pH-dependence. From 
         this we conclude that pH-dependent removal of polar, ionizable organic MPs i
         n activated sludge systems is less likely an effect of pH-dependent sorption
          but rather of pH-dependent biotransformation. The latter has the potential 
         to cause marked differences in the removal of polar, ionizable MPs at differ
         ent operational pHs during activated sludge treatment.' (1726 chars)
      serialnumber => protected'0013-936X' (9 chars)
      doi => protected'10.1021/es5037139' (17 chars)
      uid => protected7847 (integer)
      _localizedUid => protected7847 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected7847 (integer)modified
      pid => protected124 (integer)
   1 => Snowflake\Publications\Domain\Model\Publicationprototypepersistent entity (uid=7576, pid=124)
      originalId => protected7576 (integer)
      authors => protected'Schymanski, E. L.; Jeon, J.; Gulde, R.; Fenner, K.;
          Ruff, M.; Singer, H. P.; Hollender, J.' (135 chars)
      title => protected'Identifying small molecules via high resolution mass spectrometry: communica
         ting confidence' (91 chars)
      journal => protected'Environmental Science and Technology' (36 chars)
      year => protected2014 (integer)
      volume => protected48 (integer)
      issue => protected'4' (1 chars)
      startpage => protected'2097' (4 chars)
      otherpage => protected'2098' (4 chars)
      categories => protected'' (0 chars)
      description => protected'' (0 chars)
      serialnumber => protected'0013-936X' (9 chars)
      doi => protected'10.1021/es5002105' (17 chars)
      uid => protected7576 (integer)
      _localizedUid => protected7576 (integer)modified
      _languageUid => protectedNULL
      _versionedUid => protected7576 (integer)modified
      pid => protected124 (integer)

pH-dependent biotransformation of ionizable organic micropollutants in activated sludge

Removal of micropollutants (MPs) during activated sludge treatment can mainly be attributed to biotransformation and sorption to sludge flocs, whereby the latter process is known to be of minor importance for polar organic micropollutants. In this work, we investigated the influence of pH on the biotransformation of MPs with cationic-neutral speciation in an activated sludge microbial community. We performed batch biotransformation, sorption control, and abiotic control experiments for 15 MPs with cationic-neutral speciation, one control MP with neutral-anionic speciation, and two neutral MPs at pHs 6, 7, and 8. Biotransformation rate constants corrected for sorption and abiotic processes were estimated from measured concentration time series with Bayesian inference. We found that biotransformation is pH-dependent and correlates qualitatively with the neutral fraction of the ionizable MPs. However, a simple speciation model based on the assumption that only the neutral species is efficiently taken up and biotransformed by the cells tends to overpredict the effect of speciation. Therefore, additional mechanisms such as uptake of the ionic species and other more complex attenutation mechanisms are discussed. Finally, we observed that the sorption coefficients derived from our control experiments were small and showed no notable pH-dependence. From this we conclude that pH-dependent removal of polar, ionizable organic MPs in activated sludge systems is less likely an effect of pH-dependent sorption but rather of pH-dependent biotransformation. The latter has the potential to cause marked differences in the removal of polar, ionizable MPs at different operational pHs during activated sludge treatment.
Gulde, R.; Helbling, D. E.; Scheidegger, A.; Fenner, K. (2014) pH-dependent biotransformation of ionizable organic micropollutants in activated sludge, Environmental Science and Technology, 48(23), 13760-13768, doi:10.1021/es5037139, Institutional Repository
Schymanski, E. L.; Jeon, J.; Gulde, R.; Fenner, K.; Ruff, M.; Singer, H. P.; Hollender, J. (2014) Identifying small molecules via high resolution mass spectrometry: communicating confidence, Environmental Science and Technology, 48(4), 2097-2098, doi:10.1021/es5002105, Institutional Repository