<p>Rapid industrialization has led to the concentration of heavily polluting industries, such as coatings, in industrial parks, resulting in significant volumes of hazardous wastewater. Effective inflow management and process monitoring are essential for the stable operation of wastewater treatment plants. This study collected samples from a coating industrial park and its treatment plant to analyze water quality. Fluorescence spectra were analyzed using parallel factor analysis (PARAFAC) to identify specific components. A fluorescence peak at Ex/Em = 350/425 nm was detected, indicating the presence of aromatic hydrocarbons. Conventional treatment, which primarily includes physical and chemical methods such as coagulation, flocculation, and activated sludge processes, was ineffective in removing these substances, while Fenton precipitation successfully degraded them. UV₂₅₄ showed significant correlations with the biological index (BIX) (<i>r</i> =  − 0.52) and fluorescence component C1 (<i>r</i> = 0.85), suggesting its potential as a pollutant marker. Component C4, identified as lignin-like, is characteristic of coating industry materials. These findings highlight the potential of fluorescence spectroscopy and PARAFAC for tracing wastewater sources and monitoring pollutant degradation in industrial treatment plants.</p>