Source-tracing of industrial and municipal wastewater effluent in river water via fluorescence fingerprinting

Fluorescence fingerprinting is a technique to uniquely characterize water samples based on their distinct composition of dissolved organic matter (DOM) measured via 3D fluorescence spectroscopy. It is an effective tool for monitoring the chemical composition of various water systems. This study examines a river affected by several municipal and industrial wastewater treatment plant (WWTP) effluents and aims to source-tracing them via fluorescence fingerprints based on parallel factor analysis (PARAFAC) components. Additional principal component analysis (PCA) clusters the WWTP effluents according to similarity. The results yield seven PARAFAC components characterizing the WWTP effluents. Considering the ratios among the components, these distinct fluorescence fingerprints are attributable to the studied industrial sectors: leather industry, meat processing, electronics industry, and municipal wastewater treatment. Furthermore, the fluorescence signal of the receiving river is examined by PCA and assessment of flow-weighted fluorescence intensities for source-tracing the fingerprints of the WWTP effluents. An analysis of the contribution of each WWTP effluent shows that during low flow, the fluorescence signal in the river is dominated by WWTP emissions. In contrast, during high flow events, the impact of WWTP emissions is masked by diffuse emissions. The techniques presented in this study have the potential to define generalizable fluorescence fingerprints for WWTP effluents of various industrial sectors and source-trace them in the receiving river. This approach represents a step closer to implementing complex fluorescence monitoring tools in rivers, tracing the impact of municipal and industrial WWTP effluents on riverine OM.