Exploring the role of carbon source types in trace-level sulfamethoxazole removal and greenhouse gas emissions in AnMBRs

Abstract

The efficient removal of trace-level sulfamethoxazole (SMX) from wastewater remains a significant challenge. Different carbon sources can enrich distinct microbiomes, leading to variations in the functional capacity of the community. This makes it possible to select appropriate carbon sources that are conducive to enhancing SMX removal, thereby improving the overall SMX removal efficiency in WWTPs. In this study, acetate, citrate, and glucose were tested as carbon sources in anaerobic membrane bioreactors (AnMBRs) to investigate their effects on trace-level SMX removal. Glucose, as a carbon source, achieved the highest SMX removal efficiency, reduced the risk of resistance gene transmission, and maintained stable nutrient removal performance. The higher abundance of SMX-degrading bacteria and the higher content of extracellular polymeric substances in glucose-fed cultures are the reasons for the higher SMX removal rate. Additionally, GHG emissions, primarily methane, increase with the increase of SMX concentration within the range of 10–250 μg L⁻¹. Methane production is predominantly driven by the acetate-to-methane pathway (M00357 KEGG). Higher SMX concentrations led to an increase in the abundance of SMX-resistant bacteria, causing a large amount of CH₄ emissions. These findings provide valuable insights into optimizing carbon source selection and deepen our understanding of the relationship between trace-level SMX removal and GHG emissions in wastewater treatment processes.