RESUMEN
Organic pollutants can alter the physicochemical properties and microbial communities of water bodies. In water contaminated with organic pollutants, the unique extracellular electron transfer mechanisms that promote sulfamethoxazole (SMX) degradation in tri-electrode microbial electrochemical systems (TE-MES) may be impacted. To simulate biodegradable organic matter contamination, glucose (GLU) was added. Metagenomics and metabolomics were used to analyze changes in microbial community structure, metabolism, and function on the electrodes. GLU addition accelerated water quality deterioration, and enhanced SMX degradation. Microbial taxa on the electrodes experienced selective enrichment. Notably, methanogens and SMX-degrading bacteria were enriched, while denitrifying bacteria and antibiotic-resistant bacteria were suppressed. Enriched metabolites were linked to 15 metabolic pathways and other functions like microbial signaling and genetics. Non-redundant genes also clustered in metabolic pathways, aligning with metabolite enrichment results. Additional pathways involved life cycle processes and protein interactions. Enzymes related to carbon metabolism, particularly glycoside hydrolases, increased significantly, indicating a shift in carbon metabolism on microbial electrodes after GLU addition. The abundance of intracellular electron transfer enzymes rose, while outer membrane proteins decreased. This contrasts with the typical TE-MES mechanism where outer membrane proteins facilitate SMX degradation. The presence of organic pollution may shift SMX degradation from an extracellular electrochemical process to an intracellular metabolic process, possibly involving co-metabolism with simple organic compounds. This study provides mechanistic insights and theoretical guidance for using TE-MES with embedded microbial electrodes to treat antibiotic-contaminated water affected by organic pollution.
RESUMEN
Anaerobic Membrane Bioreactors (AnMBR) offer numerous advantages in wastewater treatment, yet they are prone to membrane fouling after extended operation, impeding their long-term efficiency and stability. In this study, a coupled system was developed using modified conductive membranes as the filtration membrane for the AnMBR and as the anodic conductive membrane in the microbial electrochemical system, with a total volume of approximately 2.57 L. The research focused on understanding the membrane fouling characteristics of the AnMBR when treating wastewater containing sodium ion (Na+) and magnesium ion (Mg2+). When the system was treating wastewater containing Na+, organic pollutants such as proteins and polysaccharides were identified as the primary causes of membrane fouling. Three experimental groups generating different electric currents exhibited extended operational times compared to the open-circuit control group, with extensions of 30, 24, and 15 days, respectively. Conversely, when treating wastewater with Mg2+, organic-inorganic composite fouling, primarily driven by Mg2+ bridging, emerged as the key challenge, with the experimental groups showing operational extensions of 5, 8, and 23 days, respectively, in comparison to the control group. Analysis of proteins and polysaccharides indicated that electric current played a crucial role in reducing organic fouling in the sludge cake layer. When treating wastewater containing Na+, the effectiveness of membrane fouling control was directly proportional to the electric current, while when treating wastewater containing Mg2+, it was directly proportional to the voltage.