Regulation methods and enhanced mechanism on the efficient degradation of aromatics in biochemical treatment system of coal chemical wastewater

In order to address the problems of poor treatment effect of coal chemical wastewater (CCW) biochemical treatment system resulting in non-compliance with effluent standards and unstable operation, a combination regulation method of co-substrate metabolism and predominant flora enhancement was constructed, and the performance and mechanism of enhanced degradation of aromatics in CCW was also investigated in this study. The results showed that when the influent concentration of chemical oxygen demand (COD) and aromatics was less than 600 mg/L and 180 mg/L respectively, there was no significant effect of the combined regulation method on the enhanced treatment of aromatics, the removal rate of total organic carbon (TOC) in the system could all more than 73%; while when the influent concentration of COD increased to 800 mg/L and the aromatics concentration increased to more than 240 mg/L, the ordinary activated sludge system had collapsed. Compared with the regulation method of co-substrate metabolism alone, the combination regulation method increased the removal rate of TOC by 21%. The analysis of antioxidant enzyme activity showed that under the combination regulation method, the antioxidant enzyme activity of microorganisms was higher and their resistance to adverse environments was stronger. EPS and dehydrogenase analysis indicated that the combination regulation method was more conducive to microbial degradation of aromatics. Meanwhile, the analysis of microbial community structure showed that the aromatics degradation bacteria genera Rhodococcus, Luteococcus, etc. were enriched under the combination regulation method. The study provides a theoretical basis and technical guidance for solving the problems of unstable operation of CCW biochemical treatment systems and non-compliance with effluent standards.