Decomposition process of cefotaxime sodium from antibiotic wastewater by Up-flow Blanket Filter (UBF) reactor: Reactor performance, sludge characteristics and microbial community structure analysis

Highlights: • The concentration of chemical oxygen demand (COD) positively associated with cefotaxime sodium in simulated wastewater. • The Oxidation-Reduction Potential (ORP) was affected by volatile fatty acids (VFA) in UBF reactor. • The anaerobic decomposition processes of cefotaxime sodium in line with the three-stage methanogens process. • Variation on microbial community along with the operation of reactor and Pseudomonas became one of the dominant bacteria. In this study, a novel Up-flow Blanket Filter (UBF) reactor was applied to the degradation of antibiotic wastewater. The experiments showed that when the hydraulic retention time (HRT) was 24 h and the ratio of volatile fatty acids (VFA) to alkalinity (ALK) was 0.3, the best removal efficiency was achieved in the combined packing UBF reactor, and the COD removal efficiency reached 80.1%–84.6%, exhibiting a significant difference in reaction performance from the other two reactors (P < 0.05) and a good efficiency of cefotaxime sodium removal. Moreover, the microstructure and surface characteristics of the reactor fillers were studied through scanning electron microscope (SEM) analysis, which showed that three fillers all had biofilm adhesion, but the combined packing gave best performance. Energy dispersive spectrometer (EDS) tests indicated abundant element components in the combined packing. The particle size distribution of sludge was also considered in the experiment, and the result showed the particle size of sludge increased with the operation of the reactor. In addition, microbial community structures of sludge and biofilm with the combined packing were analyzed. High-throughput sequencing confirmed the existence of Pseudomonas, which had good adaptability to antibiotic wastewater and became the dominant bacteria. Decomposition process of cefotaxime sodium after hydrolysis and anaerobic treatment was analyzed through Fourier transform infrared spectroscopy (FTIR). The reactor, which is economical, exhibited favorable performance in degrading the pollutions in the antibiotic wastewater.