Cumulative effects and metabolic characteristics of aromatic compounds in microbial cells during the biochemical treatment process of coal chemical wastewater

This study aimed to investigate the effectiveness of a biochemical treatment system for coal chemical wastewater (CCW) in degrading aromatic compounds. The study examined the degradation sequence of different compounds, including benzene series (BTEX), phenols, polycyclic aromatic hydrocarbons (PAHs), and nitrogen heterocyclic compounds (NHCs), in the system. The study also analyzed the metabolic characteristics of accumulated aromatic organic compounds in the cells of microorganisms. The results showed that the aromatic compounds were first adsorbed from water by extracellular polymers (EPS) before entering the cells. The removal rates of COD and TOC in CCW reached 95% after system operation for 8 h. BTEX and NHCs were completely degraded outside the cells within 2 h, whereas PAHs and some phenols accumulated inside the cells. The metabolic characteristics of the accumulated compounds were analyzed and found to be gradually degraded through the action of catechol dioxygenase. The study findings not only demonstrate the potential for achieving efficient biodegradation of aromatic compounds in CCW but also provide the essential theoretical underpinning for the regulation and environmentally benign treatment of such wastewater within a biochemical treatment system.