Total fluorescence as a surrogate for organic carbon measurement: Implications for rapid water and wastewater quality...

This study investigates total fluorescence (TF) as a surrogate for measuring total organic carbon (TOC) and dissolved organic carbon (DOC) in water samples. Three analytical instruments - TOC analyzer, size-exclusion chromatography with organic carbon detector (SEC-OCD), and three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy - are used to analyze samples from various wastewater sources. The research establishes correlations among these methods for determining organic matter concentrations. Results indicate a robust linear relationship between TF and DOC, with a correlation coefficient (R²) of 0.997 for DOC concentrations exceeding 0.5 mg/L. However, at concentrations below this threshold, TF tends to underestimate DOC due to sensitivity limitations, which restricts its direct application in ultra-pure or reverse osmosis-treated waters unless appropriately calibrated. Clustering analysis of fluorescence data revealed distinct groupings of samples based on organic content, further supporting the use of TF as an indicator of water quality and treatment efficiency. Rapid fluorescence measurements enable high-throughput analysis with minimal delays, streamlining water quality assessments. Historical data from engineering-scale, demonstration-scale, and full-scale treatment facilities support TF's usefulness as a surrogate for TOC/DOC measurement. The proposed fluorescence method demonstrated greater sensitivity than traditional DOC measurements at specific sites, with a minimum detection limit of approximately 0.05 mg/L for DOC in certain water matrices. For broader applications involving different water sources, TF provides a general indication of organic concentrations, while calibration is needed for high-sensitivity requirements, such as trace organic carbon detection. These findings suggest that TF holds promise for expedited evaluation of water quality, pollution levels, and treatment effectiveness across diverse treatment trains, offering a new tool in water and wastewater treatment practices and enhancing environmental quality management.