Rapid Identification of Industrial Wastewater Discharges in Municipal Sewer Networks Based on Three-Dimensional Fluorescence Spectroscopy and Spectral Angle Mapping

• • The SAM algorithm exhibited a linear response (R² > 0.88) between spectral angle values and the volume ratio of enterprise wastewater in mixed samples, enabling quantitative estimation of pollution source contributions. • • Field monitoring over 12 hours revealed that enterprises D and F showed significant increases in SAM values (up to 1.04 and 1.13, respectively) during peak pollution periods, correlating with elevated DOC, TN, and UV254 levels, identifying them as primary contributors. • • Untreated industrial raw water samples showed low similarity (SAM values typically < 0.5) to municipal sewer water, indicating no direct discharge of raw wastewater, whereas treated effluents exhibited higher similarity (SAM values up to 1.13), confirming proper discharge pathways. • • The EEM+SAM technique provides a non-invasive, high-throughput method for real-time monitoring and source tracing, capable of distinguishing multiple pollution sources and quantifying their relative contributions, which is critical for proactive management of sewer networks.