Trends in Micropollutant Biotransformation along a Solids Retention Time Gradient

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For many polar organic micropollutants, biotransformation by activated sludge microorganisms is a major removal process during wastewater treatment. However, our current understanding of how wastewater treatment operations influence microbial communities and their micropollutant biotransformation potential is limited, leaving major parts of observed variability in biotransformation rates across treatment facilities unexplained. Here, we present biotransformation rate constants for 42 micropollutants belonging to different chemical classes along a gradient of solids retention time (SRT). The geometric mean of biomass-normalized first-order rate constants shows a clear increase between 3 and 15 d SRT by 160% and 87%, respectively, in two experiments. However, individual micropollutants show a variety of trends. Rate constants of oxidative biotransformation reactions mostly increased with SRT. Yet, nitrifying activity could be excluded as primary driver. For substances undergoing other than oxidative reactions, i.e., mostly substitution-type reactions, more diverse dependencies on SRT were observed. Most remarkably, characteristic trends were observed for groups of substances undergoing similar types of initial transformation reaction, suggesting that shared enzymes or enzyme systems that are conjointly regulated catalyze biotransformation reactions within such groups. These findings open up opportunities for correlating rate constants with measures of enzyme abundance such as genes or gene products, which in turn should help to identify enzymes associated with the respective biotransformation reactions.


  • Stefan Achermann
  • Per Falås
  • Adriano Joss
  • Cresten B. Mansfeldt
  • Yujie Men
  • Bernadette Vogler
  • Kathrin Fenner
Enheter & grupper
Externa organisationer
  • Swiss Federal Institute of Aquatic Science and Technology
  • ETH Zürich
  • University of Illinois at Urbana-Champaign
  • University of Zurich

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Vattenbehandling
Sidor (från-till)11601–11611
TidskriftEnvironmental Science and Technology
Utgåva nummer20
StatusPublished - 2018
Peer review utfördJa