Application of biosensor for determination of biochemical oxygen demand and heavy metal toxicity in urban canal water

Global attention has been increasingly paid to the use of biosensor in water quality monitoring, particularly for on-site determination of biochemical oxygen demand and heavy metal toxicity. However, there have not been many publications that show a practical application of biosensor. In this study, canal water in Ho Chi Minh City was collected to evaluate the potential application of biosensor, which measures respiratory activity of immobilized microorganisms on plastic biochips and calcium alginate beads, for the fast determination of biochemical oxygen demand and heavy metal toxicity. The total amount of aerobic bacteria immobilized on the plastic biochips was 35.6 times higher than that on calcium alginate beads, which, in turn, leads to an increased sensitivity of the biosensor based on the plastic biochips in measurement of biochemical oxygen demand. Additionally, the one-way analysis of variance coupled with Turkey Honestly Significant Difference test at a significant level of 0.05 showed no statistical difference between the values of biochemical oxygen demand in samples at various locations determined by 5-day standard method and biosensor. The biosensor also demonstrated its capability in detection of toxicity of Cu(II), Pb(II), Cr(III), Ni(II), and Cr(VI) at concentrations of 2 mg/L, 0.5 mg/L, 1 mg/L, 0.5 mg/L, and 0.1 mg/L, which are the allowable maximum concentration for industrial wastewater discharged into receiving water, respectively.