Direct toxicity assessment of copper (II) ions to activated sludge process using a p-benzoquinone-mediated amperometric biosensor

A simple, rapid and reliable amperometric mediated biosensor, which adopted activated sludge as biocomponent and p-benzoquinone as mediator, was developed successfully to determine the toxicity of heavy metal pollutants to the activated sludge environment. The obtained EC50 (30 min) for Cu(II) is 43.1 mg L−1, which had a good correlation to the EC50 values determined on the basis of COD (40.2 mg L−1) and NH4+-N (34.3 mg L−1) removal efficiencies of unacclimated activated sludge for 1.5 h incubation. The results showed that the activated sludge ToxTell biosensor, which was based on the reduction of the intra respiration activity of the whole system as a gross parameter for toxicity assessment, could be used as an effective tool for the protection of the activated sludge environment.