Abstract:A combined treatment process, consisting of modified iron–carbon micro-electrolysis coupled with hydrolytic acidification and followed by an anoxic/oxic biological system, was developed and evaluated to address the complex composition and low biodegradability of textile dyeing wastewater. Granular iron–carbon micro-electrolysis media were prepared using zero-valent iron (ZVI), activated carbon, and kaolin as the main raw materials. In an aqueous environment, the media formed a relatively stable micro-electrolysis system, in which ZVI acted as the anodic material, while activated carbon served as the cathodic material and adsorption carrier. Through the synergistic effects of electrochemical reactions and adsorption, the transformation and degradation of refractory organic pollutants were enhanced, thereby improving the pretreatment performance during the hydrolytic acidification stage. The incorporation of activated carbon and kaolin effectively mitigated the aggregation and surface passivation of ZVI during operation and contributed to improved structural stability of the micro-electrolysis media. On this basis, the iron-carbon micro-electrolysis media were further modified with metallic manganese and applied in the hydrolytic acidification reactor to regulate microbial metabolic processes and carbon conversion pathways. Continuous-flow experiments were conducted to investigate organic matter transformation characteristics, volatile fatty acid production, and greenhouse gas emissions during the hydrolytic acidification stage. The results showed that the introduction of manganese did not reduce the pollutant degradation efficiency, while a decrease in greenhouse gas emissions from the hydrolytic acidification stage was observed. When the modified micro-electrolysis media were employed, the concentration of volatile fatty acids in the hydrolytic acidification effluent reached 348.34 mg COD/L, providing a readily biodegradable carbon source for subsequent biological treatment. Under the same operating conditions, the methane emission flux from the hydrolytic acidification reactor was measured at 21.32 g/(m2·d). During long-term continuous operation of the combined micro-electrolysis–hydrolytic acidification–anoxic–oxic process, the system exhibited stable performance and effective pollutant removal. The removal efficiencies for COD and -N reached 93.3% and 74.4%, respectively, while the color removal efficiency was 65%. These results indicate that the combined process can effectively enhance dyeing wastewater treatment performance and reduce greenhouse gas emissions during the anaerobic pretreatment stage. However, certain limitations should be considered for practical engineering applications. In this study, simulated dyeing wastewater was used, whereas actual dyeing wastewater typically exhibits substantial fluctuations in water quality, which may affect pollutant removal efficiency and operational stability. In addition, the potential release of Mn2+ from manganese-modified micro-electrolysis media during long-term operation of the hydrolytic acidification reactor has not been fully clarified, and its possible impact on process performance requires further investigation. These issues need to be examined under more complex influent conditions and extended operational periods. Close-