Effect of chlorination and ozone pre-oxidation on the photobacteria acute toxicity for dissolved organic matter from sewage treatment plants

Abstract

The effect of chlorination and ozone pre-oxidation on the photobacteria acute toxicity for dissolved organic matter (DOM) from sewage treatment plants was investigated in this study. The results show that ozone pre-oxidation enhanced the photobacteria acute toxicity of the water samples. DOM before and after ozone pre-oxidation was fractionated by resins into six kinds of hydrophobic and hydrophilic organics. The six fractions were chlorinated individually and the photobacteria acute toxicity before and after chlorination was tested. It was found that the percentage of hydrophilic organics in DOM significantly increased after ozone pre-oxidation and hydrophilic organics exhibited remarkably higher acute toxicity than hydrophobic organics. In view of potentiometric titration and fourier transform infrared (FTIR) analysis, the hydrophilic organics showed a rather higher content of ph-OH structures than hydrophobic organics.