Acute biotoxicity assessment of heavy metals in sewage sludge based on the glucose consumption of Escherichia coli

As a simple and feasible method for acute biotoxicity assessment, personal glucose meter (PGM) can be successfully applied in the early warning of environmental pollutants in sewage. In this paper, the acute biotoxicity of single and joint heavy metals in sewage and real sludge samples was systematically described based on the glucose metabolism of Escherichia coli (E. coli). Results indicated that the biotoxicity order of five single heavy metals in sewage was Hg(2+) > As(3+) > Cu(2+) > Zn(2+) > Cd(2+). The joint heavy metals of Cu(2+) + Zn(2+), Cu(2+) + Cd(2+), and Cu(2+) + Hg(2+) produced synergistic effects, while Cu(2+) + As(3+) and Cd(2+) + Zn(2+) possessed antagonistic effects for the combined biotoxicity. In spiked sludge, Cd(2+) and Zn(2+) owned higher biotoxicity than Cu(2+) and As(3+). Notably, the electroplate factory and housing estate sludge respectively showed the highest and lowest inhibition rates as 57.4% and 17.7% under the real sludge biotoxicity assessment. These results demonstrated that PGM was a sensitive and portable method, which could be widely used for acute biotoxicity assessment of heavy metals in sewage sludge.