Removal Efficiency and Transformation Mechanism of Refractory Organic Matter in Food Industry Wastewater Treated by the UV/H2O2 System

Abstract To address the unclear removal efficiency and transformation mechanism of refractory organic matter in food industry wastewater (FIW), this study employed the UV / H 2 O 2 system to conduct deep treatment on the biological effluent from dairy, meat, edible oil, and hot pot base processing enterprises, as well as from their associated industrial park wastewater treatment plants. The applicability of ultraviolet–visible (UV–Vis) and three-dimensional excitation-emission matrix (3D–EEM) spectroscopy for performance evaluation and mechanistic elucidation was also investigated. The results showed that under the initial pH = 3, [ H 2 O 2 ] = 1 mM , UV = 14 W , and t = 60 min conditions, the removal efficiencies of UV 254 and total organic carbon in the FIW by this system reached 71.53%–90.57% and 54.13%–80.20%, respectively. During the reaction process, the HO • generated by UV irradiation of H 2 O 2 attacked the conjugated systems (such as benzene rings and carbonyl groups) and C–C bonds, thereby gradually reducing humic acid-like substances, lowering the aromaticity, hydrophobicity, apparent molecular weight, and benzene ring content of organic compounds, andately achieving mineralization. Correlation analysis confirmed the feasibility and effectiveness of using UV–Vis and 3D–EEM spectral analysis for performance evaluation and mechanism interpretation. Typical pollutant experiments further suggested that the ecological risks of the UV / H 2 O 2 -treated effluent warrant attention. This study provides a technical reference for the efficient treatment of FIW and demonstrates the value of spectral techniques for performance and mechanistic research in this field.