Source identification and characteristics of dissolved organic matter and disinfection by-product formation potential using EEM-PARAFAC in the Manas River, China

Abstract

Dissolved organic matter (DOM) is ubiquitous in natural water and reacts with disinfectants to form disinfection by-products (DBPs). The analysis of DOM in raw water is helpful in evaluating the formation potential of DBPs. However, there is relatively little research on the DOM identification of raw water in northern China. In this study, the sources and characteristics of DOM were investigated in the samples collected from the Manas River. Dissolved organic carbon (DOC), UV₂₅₄, specific ultraviolet absorbance, and fluorescence indices (fluorescence index, humification index, and biological index) were measured to characterize the DOM, and trihalomethanes (THMs) were quantified following formation potential tests with free chlorine. The maximum amount of total trihalomethane formation potential (THMsFP) was 225.57 μg L⁻¹. The DOM of the Manas River consisted of microorganisms and soil resources. The excitation–emission matrix combined with parallel factor analysis (EEM-PARAFAC) identified microbial humus (C1, 54%) and tryptophan-like protein (C2, 46%). PARAFAC components were evaluated as the precursor surrogate parameters of THMsFP. Additionally, the linear THMsFP correlation was stronger with C1 + C2 (r = 0.529, p < 0.01) than with C1 (r = 0.485, p < 0.01). Thus, C1 + C2 is an accurate THMsFP precursor surrogate parameter for the Manas River, and the use of fluorescence spectroscopy may be a robust alternative for predicting DOC removal.