Characteristics of Aniline Aerofloat Biodegradation in Mineral Processing Wastewater and Energy Recovery by Single-Chamber Bioelectrochemical System: Strategies for Efficiency Improvement and Microbial Mechanisms

Aniline aerofloat (AAF) is a typical refractory organic regent residual in mineral processing wastewater (MPW). Microbial fuel cells (MFCs) have been proven highly effective in degrading organic contaminants and resource recovering in wastewater treatment processes. However, AAF biodegradation potential and the related mechanisms in MFC systems remain poorly understood. In this study, the degradation of AAF, electricity generation performance and microbial mechanisms in the single-chamber MFC (sMFC) were confirmed. Affecting factors including AAF concentration, operation resistor, and pH were analyzed. The results indicated that under initial sodium acetate/AAF concentration of 300/100 mg/L, pH 7.0 and an operation resistor of 200 Ω, the AAF removal efficiency achieved 72.7 ± 1.6% with an output voltage of approximately 232 mV. The existence of AAF increased the relative abundance of electroactive bacteria, especially <i>Comamonas</i> and <i>Geobacter</i>. Functional prediction analysis showed that carbohydrate metabolism pathways was the dominant process. The relative abundance of N-respiration and S-respiration functional groups significantly increased, thereby improving COD and AAF removal. This study demonstrated that the MFC anode was beneficial to AAF degradation and provided an alternative route for the biodegradation of organic mineral processing reagents. To our knowledge, this is the first study evaluating AAF biodegradation performance in the MFC system.