Development of a real-time fDOM-based coagulant dosing system: Beta-testing and model implementation in drinking water treatment plants

The potential of fluorescent dissolved organic matter (fDOM) signal for online coagulant dose control at drinking water treatment plants (DWTPs) was investigated. This included (1) development of an fDOM signal-based model for coagulant dose prediction, (2) model assessment and beta testing trials at six DWTPs, and (3) assessment of real-world deployment of the new model at a DWTP. Jar test experiments were conducted using water from 15 water sources across Australia to generate a dataset for development of the model. Model assigned enhanced alum doses (EnD) removed about 85 % of the coagulable fraction, or ~ 53 % of the total DOM, measured as fDOM. These jar test results served as a foundation for developing an fDOM signal-based model applicable to a wide range of raw water sources with varying DOM concentrations and characteristics. The fDOM model predictions for EnD were benchmarked against the jar test results and a previously established model using offline UV–Vis-based input data. Beta testing and field deployment trials demonstrated an average correlation coefficient of 0.98 between the online fDOM and offline mEnCo model predictions at six study sites. The fDOM model's application demonstrated potential for rapidly adjusting coagulant dosing in response to sudden, significant changes in water quality. This may enable improved cost-efficiencies in coagulant use and provision of consistent high quality treated waters where raw waters are variable in quality, potentially reducing health related risks. The findings of this study underscore the potential of the fDOM signal-based model for real-time coagulant dosing control at DWTPs.