Systematic Review of Toxicity Removal by Advanced Wastewater Treatment Technologies via Ozonation and Activated Carbon

Upgrading
wastewater treatment plants (WWTPs) with advanced technologies
is one key strategy to reduce micropollutant emissions. Given the
complex chemical composition of wastewater, toxicity removal is an
integral parameter to assess the performance of WWTPs. Thus, the goal
of this systematic review is to evaluate how effectively ozonation
and activated carbon remove in vitro and in vivo toxicity. Out of
2464 publications, we extracted 46 relevant studies conducted at 22
pilot or full-scale WWTPs. We performed a quantitative and qualitative
evaluation of in vitro (100 assays) and in vivo data (20 species),
respectively. Data is more abundant on ozonation (573 data points)
than on an activated carbon treatment (162 data points), and certain
in vitro end points (especially estrogenicity) and in vivo models
(e.g., daphnids) dominate. The literature shows that while a conventional
treatment effectively reduces toxicity, residual effects in the effluents
may represent a risk to the receiving ecosystem on the basis of effect-based
trigger values. In general, an upgrade to ozonation or activated carbon
treatment will significantly increase toxicity removal with similar
performance. Nevertheless, ozonation generates toxic transformation
products that can be removed by a post-treatment. By assessing the
growing body of effect-based studies, we identify sensitive and underrepresented
end points and species and provide guidance for future research.