RESUMO
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.
RESUMO
The integration of anoxic filter and aerobic rotating biological contactor shows promise in treating rural domestic sewage. It offers high efficiency, low sludge production, and strong shock resistance. However, further optimization is needed for odor control, pollutant removal, and power consumption. In this study, the investigation on a one-pump-drive lab-scale device of retention anoxic filter (RAF) integrated with hydraulic rotating bio-contactor (HRBC) and its optimal operation mode were conducted. During the 50-day operation, optimal operation parameters were investigated. These parameters included a 175 % reflux ratio (RR), 5-h hydraulic retention time in the RAF (HRTRAF), and 2.5-h hydraulic retention time in the HRBC (HRTHRBC). Those conditions characterized a micro-aerobic environment (DO: 0.6-0.8 mg/L) in RAF, inducing improved deodorization (89.3 % sulfide removal) and denitrification (85.9 % nitrate removal) simultaneously. During the operation period, 84.79 ± 3.87 % COD, 82.71± 2.06 % NH4+-N, 74.83 ± 2.06 % TN, 91.68± 2.12 % S2-, and 89.04 ± 1.68 % TON were removed in RAF-HRBC. Based on large amount of operational data, organic loading rate curves of RAF-HRBC were validated and calibrated as a crucial reference to aid in full-scale designs and applications. The richness of microbial community was improved in both RAF and HRBC. In the RAF, the autotrophic sulfide-oxidizing nitrate-reducing bacteria (a-son) and heterotrophic sulfide-oxidizing nitrate-reducing bacteria (h-son) were selectively enriched, which intensified the sulfide removal and denitrification process. In the two-stage HRBC system, the 1st stage RBC was primarily composed of organics degraders, while the 2nd stage RBC consisted mainly of ammonium oxidizers. Overall, the integrated RAF-HRBC process holds significant potential for simultaneously improving pollutant removal and in-situ odor mitigation in decentralized domestic sewage treatment. This process specifically contributes to enhancing environmental sustainability and operational efficiency.