A cost-effective strategy using an amperometric biosensor with Escherichia coli that provides a rapid toxicity determination
of wastewaters is described. This Cellsense biosensor system comprises a biological component (E. coli) immobilized in
intimate contact with a transducer which converts the biochemical signal into a quantifiable electrical signal. The electrical
signal can subsequently be amplified, stored and displayed. This work using a whole bacterial biosensor system studied the E.
coli responses to commonly detected compounds in textile and tannery wastewaters, such as phenolic compounds, non-ionic
surfactants, and benzene sulfonate compounds. Chemical analysis was performed by sequential solid-phase extraction (SSPE)
followed by liquid chromatography–mass spectrometry (LC–MS). The 50% effective concentrations (EC50) values were
determined for every standard substance and were converted to toxicity units (TU). The Cellsense system was applied to
real-world environmental samples of influent and effluent wastewater treatment works (WWTW) in Catalonia (Spain), with
one WWTW receiving industrial tannery wastes, and untreated textile wastewater from Porto (Portugal). The toxicity units
were also calculated for the samples giving positive responses to the toxicity to the Cellsense system and permitted to establish
the pollutants responsible of the observed toxicity.