The effect of coagulation on the removal of algogenic organic matter and the optical parameters for predicting disinfection byproducts

Algae-derived disinfection byproducts (DBPs) are receiving increasing attention. Coagulation is the first water treatment section in removing algogenic organic matter (AOM). However, there is a significant knowledge gap in the effects of coagulation on DBPs produced from AOM. In this study, in view of the multi-component AOM, several analysis methods were combined to investigate the changes in AOM of Microcystic aeruginosa during the coagulation treatment, including ultraviolet–visible absorbance, multi-peaks Gaussian fitting method based on differential absorption spectroscopy, Excitation-emission matrix, and Fourier transform infrared spectroscopic analysis. To identify the characteristic parameters that could indicate the formation of DBPs, the yields of twenty-one DBP species produced from the residual AOM after the coagulation treatment were investigated. The correlations between DBPs and the spectral parameters were also analyzed. The results showed that aluminum salt coagulant could significantly remove protein-like compounds, chlorophyll, and phycocyanin in AOM, but it had a limited ability to precipitate AOM. With the increase of aluminum sulfate coagulant, the yields of DBPs produced from the residual extracellular organic matter decreased, while those produced from the residual intracellular organic matter decreased firstly and then gradually increased. The Pearson’s correlation results showed that the combination of fluorescent regions of protein-like and humic acid-like could be used as an optical surrogate for predicting the formation of DBPs.