Highly efficient removing polycyclic aromatic hydrocarbons in coking wastewater by bio-augmentation activated sludge with Nocardioides sp. JWJ-L0 through sodium acetate co-metabolism

Pyrene, a refractory substance in coking wastewater (CWW), is a high molecular weight polycyclic aromatic hydrocarbon (PAH) exhibiting teratogenicity, carcinogenicity, genetic toxicity, and bioaccumulation. Therefore, exploring the highly efficient biodegradation of pyrene in coking wastewater is of practical significance. With 20 mg·L−1 sodium acetate as the co-metabolic substrate, the degradation efficiency of Nocardioides sp. JWJ-L0 against 60 mg·L−1 pyrene reached 58.19 % in 5 days. The pyrene degradation mechanism involved surface adsorption and the pathway of phthalic acid metabolic. The results of cell growth kinetics indicated that the maximum specific growth rate (μmax) of 0.27 h−1 and substrate inhibition coefficient (Ki) of 521.54 mg·L−1 were higher than those of previous studies, indicating the bacteria ability with the quick growth and strong endurance to high concentrations of pyrene, respectively. Further, through adding the dominant bacteria Nocardioides sp. JWJ-L0 and sodium acetate to activated sludge, the pyrene and total organic carbon degradation efficiencies in CWW increased by 25.59 % and by 21.46 % compared to the results of activated sludge alone, in 72 h, respectively. High-throughput sequencing showed that the Nocardioides strain promoted the growth of the dominant phyla (Proteobacteria, Bacteroidetes, and Actinobacteria) and increased their relative abundance in the activated sludge system. These phyla possess the toxicity resistance and organic matter degradation ability. This is the first report of Nocardioides sp. use for pyrene degradation. The Nocardioides strain can be used for treating pyrene- or PAH-containing wastewater efficiently. This provides a new dominant bacterial bioremediation method for CWW.