Proposal to optimize ecotoxicological evaluation of wastewater treated by conventional biological and ozonation processes

Environ Sci Pollut Res Int. 2016 Feb;23(4):3008-17. doi: 10.1007/s11356-015-5419-1. Epub 2015 Sep 24.


A mixture of urban and hospital effluents (50% v/v) was evaluated for ecotoxicity with an advanced bioassay battery. Mixed effluents were tested before any treatment, after biological treatment alone, and after biological treatment followed by a tertiary ozonation (15 mg O3/L). Laying a high value on the continuance of organisms' fitness, essential to preserve a healthy receiving ecosystem, the main objective of this study was to combine normalized bioassays with newly developed in vivo and in vitro tests in order to assess alteration of embryo development, growth and reproduction, as well as genotoxic effects in aquatic organisms exposed to complex wastewater effluents. Comparison of the bioassays sensitivity was considered. Contrary to the lack of toxicity observed with normalized ecotoxicity tests, endpoints measured on zebrafish embryos such as developmental abnormalities and genotoxicity demonstrated a residual toxicity in wastewater both after a biological treatment followed or not by a tertiary O3 treatment. However, the ozonation step allowed to alleviate the residual endocrine disrupting potential measure in the biologically treated effluent. This study shows that normalized bioassays are not sensitive enough for the ecotoxicological evaluation of wastewaters and that there is a great need for the development of suitable sensitive bioassays in order to characterize properly the possible residual toxicity of treated effluents.

Keywords: Bioassay; Ecotoxicity; Fish embryo test; Genotoxicity; Micropollutant; Ozonation; Wastewater.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biodegradation, Environmental
  • Biological Assay / methods
  • Cell Line
  • Crustacea / drug effects
  • Crustacea / growth & development
  • Ecotoxicology*
  • Embryo, Nonmammalian / drug effects
  • Endocrine Disruptors / analysis*
  • Endocrine Disruptors / toxicity
  • Humans
  • Ozone / chemistry*
  • Pilot Projects
  • Receptors, Estrogen / metabolism
  • Rotifera / drug effects
  • Rotifera / growth & development
  • Toxicity Tests / methods
  • Waste Water* / chemistry
  • Waste Water* / microbiology
  • Water Pollutants, Chemical / analysis*
  • Water Pollutants, Chemical / toxicity
  • Water Purification / methods*
  • Zebrafish / growth & development


  • Endocrine Disruptors
  • Receptors, Estrogen
  • Waste Water
  • Water Pollutants, Chemical
  • Ozone