Effects of iron and manganese on the formation of HAAs upon chlorinating Chlorella vulgaris

Abstract

The major objective of the present study was to investigate the role of iron and manganese on the formation of haloacetic acids (HAAs) when algae are chlorinated at different pHs. The results showed that both iron and manganese can reduce the yields of dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) on chlorinating green alga Chlorella vulgaris (C. vulgaris) at a pH range of 6.0-9.0, and the decline of DCAA and TCAA was shown to be more significant at the low pH range. At pH 6.0, DCAA and TCAA yields decreased by 44.5% and 57.3%, respectively with the addition of 0.5 mg L(-1) iron, and decreased 39.5% and 49.4%, respectively with the addition of 0.5 mg L(-1) manganese. The main reason for decreasing the yields of HAAs as shown by scanning electron microscope (SEM) is that Fe(OH)(3(am)) or MnO(2(am)) coat the algal cells, which then improves their agglomeration of algal cells which is also revealed by the laser particle size analysis (LPSA).