Towards a better control of the wastewater treatment process: excitation-emission matrix fluorescence spectroscopy of dissolved organic matter as a predictive tool of soluble BOD5 in influents of six Parisian wastewater treatment plants

Abstract

The online monitoring of dissolved organic matter (DOM) in raw sewage water is expected to better control wastewater treatment processes. Fluorescence spectroscopy offers one possibility for both the online and real-time monitoring of DOM, especially as regards the DOM biodegradability assessment. In this study, three-dimensional fluorescence spectroscopy combined with a parallel factor analysis (PARAFAC) has been investigated as a predictive tool of the soluble biological oxygen demand in 5 days (BOD₅) for raw sewage water. Six PARAFAC components were highlighted in 69 raw sewage water samples: C2, C5, and C6 related to humic-like compounds, along with C1, C3, and C4 related to protein-like compounds. Since the PARAFAC methodology is not available for online monitoring, a peak-picking approach based on maximum excitation-emission (Ex-Em) localization of the PARAFAC components identified in this study has been used. A good predictive model of soluble BOD₅ using fluorescence spectroscopy parameters was obtained (r² = 0.846, adjusted r² = 0.839, p < 0.0001). This model is quite straightforward, easy to automate, and applicable to the operational field of wastewater treatment for online monitoring purposes.

Keywords: 3D fluorescence spectroscopy; Biological oxygen demand; Dissolved organic matter; Monitoring; Parallel factor analysis; Wastewater quality monitoring.