A bioelectronic tongue to estimate the toxicological intensity of pollutants in wastewater treatment plant

With 360 km³ of wastewater produced each year in Europe, the management and control of units responsible for their treatment appear as major challenges in preserving the environment. Nevertheless, these processes remain vulnerable to the presence of toxic compounds likely to compromise their performance. Although many toxicity tests exist to evaluate the impact of pollutants on the environment, these are generally not easily transferable to the monitoring of wastewater treatment processes (constraints of implementation, representativeness of the information provided). This innovative project leverages the concept of a "bioelectronic tongue" integrated into a biosensor to evaluate the toxic impact of pollutants on wastewater treatment plant (WWTP) microbiomes. This work presents a holistic approach, covering the entire process from the selection of representative microorganisms to in situ application. The strategy hinges on the synergistic implementation of 8 bioreporters, coupled with a data processing algorithm to generate relevant toxicity assessments. In parallel, a significant focus was placed on developing a biosensor optimized for in situ deployment of this innovative measurement strategy. The developed approach (TOXLAB) has been compared to reference methods currently used to assess the toxicological intensity of effluents. As expected, significant differences were highlighted between the standardized methods, particularly the method based on marine bioluminescent bacteria (lack of representativeness - 9 out of the 11 tested conditions could not be quantified with this method). However, the results provided by the TOXLAB approach show a certain adequacy with the toxicity data obtained on the urban WWTP microbiome. On the other hand, the results obtained on the industrial site (34 samples) are much more contrasted. Indeed, no correlation (r² = 0.033) could be established between the data from the TOXLAB approach and the effects induced on the autochthonous microbial community of the site. To explain these results, the work focused on the composition of these specific ecosystems, thus showing important differences between the microbiomes of WWTPs and the industrial site. Thus, in light of these results, the conclusion of the study shows the need to use a specific set of bioreporters, dedicated to each industrial site, in order to ensure a relative representativeness of the information provided.