Impact of physicochemical and microbial drivers on the formation of disinfection by-products in drinking water distribution systems: A multivariate Bayesian network modeling approach.

The formation of disinfection byproducts (DBPs) in drinking water distribution systems (DWDS) is significantly affected by numerous factors, including physicochemical water properties, microbial community composition and structure, and the characteristics of organic DBP precursors. However, the codependence of various factors remains unclear, particularly the contribution of microbial-derived organics to DBP formation, which has been inadequately explored. Herein, we present a Bayesian network modeling framework incorporating a Bayesian-based microbial source tracking method and excitation-emission fluorescence spectroscopy-parallel factor analysis to capture the critical drivers influencing DBP formation and explore their interactions. The results showed that the planktonic and suspended particle-associated bacteria in tap water mainly originated from bacteria in the treated water. Protein- and tryptophan-like fluorescence components were identified, illustrating their contribution to DBP formation cannot be ignored. The microbial abundance of Actinobacteria, Bacilli, and Bacteroidia is significantly related to the formation of trihalomethanes, haloacetic acids, and N-nitrosamines. These findings highlight the necessity for prioritizing management policies to control biofilm formation and minimize DBP formation in DWDSs.