Biodegradation of the sulfonamide antibiotic sulfamethoxazole by sulfamethoxazole acclimatized cultures in microbial fuel cells

Highlights: • SMX acclimatized sludge was applied for efficient SMX removal in MFCs. • SMX concentrations up to 0.20 mM showed little negative effect on voltage generation. • Control experiments showed that biodegradation was dominant over sorption. • Large microbial community shifts were observed after SMX acclimatization. • Aromatic-degrading Thauera (56.4%) was most dominant genus at the bioanode. Microbial fuel cells (MFCs) are known for their ability to enhance the removal rate of toxins while generating power. This research presents a performance assessment of MFCs for power generation and sulfamethoxazole (SMX) degradation using SMX acclimatized cultures. Experiments were performed in MFC batch mode using different SMX concentrations in synthetic wastewater. The experimental results showed that voltage generation was >400 mV up to the SMX concentration of 0.20 mM (at 400 Ω external resistance). Control experiments supported the inference that biodegradation was the main process for SMX removal compared to sorption by SMX acclimatized cultures and that the process results in efficient removal of SMX in MFC mode. The specific removal rates of SMX in MFC with SMX acclimatized sludge were 0.67, 1.37, 3.43, 7.32, and 13.36 μm/h at initial SMX concentrations of 0.04, 0.08, 0.20, 0.39, and 0.79 mM, respectively. Moreover, the MFC was able to remove >90% of the TOC from the wastewater up to SMX concentrations of 0.08 mM. However, this TOC removal produces negative effects at higher SMX concentrations due to toxic intermediates. Microbial community analysis revealed large changes in bacterial communities at the phylum, class, and genus levels after SMX acclimatization and MFC operation. Thauera, a well-known aromatic-degrading bacteria, was the most dominant genus present in post-acclimatized conditions. In summary, this study showed that acclimatized sludge can play an important role in the biodegradation of SMX in MFCs.