Efficient biodegradation and decolorization of azo dyes using peroxidase/chitosan-based enzyme-assisted coagulation

This study presents a novel enzyme-assisted coagulation (EAC) system as a low-carbon, energy-free strategy for the efficient treatment of azo dyes in textile wastewater. The EAC system integrates enzymatic oxidation with natural polymer-based coagulation and operates effectively under mild conditions without external energy input. Using horseradish peroxidase (HRP) and chitosan as model components, the system was applied to three representative azo dyes—Allura Red, Eriochrome Black, and Sunset Yellow—achieving decolorization efficiencies exceeding 98 %. Analytical techniques, including UV–Vis spectroscopy, FTIR, HPLC, and GC–MS, confirmed effective dye degradation and the stable aggregation of byproducts. The EAC mechanism involves the dual functionality of chitosan, which initially acts as an adsorbent and flocculant to enhance enzyme accessibility and subsequently serves as a stabilizing matrix that immobilizes and facilitates the removal of degradation products. This synergistic interaction between HRP and chitosan offers an efficient, biodegradable, and environmentally friendly approach for sustainable dye wastewater treatment.