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Advanced oxidation processes based on persulfate activation by biochar have been widely used to remove antibiotics and antibiotic resistance genes (ARGs) from wastewater. In this study, we used a common continuous fixed-bed reactor based on a biochar/persulfate system to treat wastewater. The average apparent ARG-removal efficiency was 82.38% in the biochar/persulfate reactor. The results of continuous reactor activity suggested the presence of ARG residues in the biochar (the abundance of ARG in the biochar increased 103-fold) and unstable removal of extracellular ARGs, raising concerns about a potential environmental burden. Kinetic experiments showed that the absolute abundance of intracellular ARGs (iARGs) rapidly decreased 98.3% within 30 min, but extracellular ARGs (eARGs) correspondingly increased 15-fold, suggesting that persulfate broke bacterial cells open and quickly released iARGs as eARGs. Moreover, the proportions of the three types of ARGs showed that ARG removal was attributed to about 70% degradation and 30% adsorption by the biochar/persulfate reactor. Further analysis revealed that biochar acts as a special shelter for ARGs. Release experiment of used biochar indicated that nearly half of absorbed ARGs could be released into new environment and causing potential risk. Overall, our findings provide a fundamental understanding of the fate of ARGs during treatment of antibiotic-contaminated wastewater and new insights into the multiple roles of biochar, which can potentially represent an additional burden on ecosystems and human health. [Display omitted] • Biochar/persulfate (BC/PS) treatment was used to remove ARGs from wastewater. • BC/PS showed very high efficiency in removing ARGs from wastewater. • ARG adsorption by biochar poses a threat due to later release into the environment. [ABSTRACT FROM AUTHOR]

Degradation of antibiotic resistance genes (ARGs) in water chlorination can be influenced by bromide (Br - ), a common component in water matrices; however, detailed kinetic information on this process is limited. This study investigated the degradation kinetics tetA and bla TEM-1 genes, contained within the plasmid pWH1266, when exposed to bromine, chlorine, and chlorine with varying concentrations of Br - across a pH range of 7.0-8.5. The degradation of four ARG amplicons, measured using quantitative polymerase chain reaction, was observed to pursue second-order kinetics with bromine, exhibiting k of 4.0 × 10 2 - 1.6 × 10 3  M -1  s -1 at pH 7.0 and 2.6 × 10 2 - 9.6 × 10 2  M -1  s -1 at pH 8.5. These k values increased linearly with the length of the ARG sequences (209-1136 bps), yielding sequence-independent k of 1.2 and 7.4 × 10 -1 (M AT + GC) -1  s -1  at pH 7.0 and 8.5, respectively. The degradation rate of ARGs during chlorination increased with rising Br - concentration due to the bromine formation through the reaction between chlorine with Br - , which subsequently degrades ARGs more rapidly than chlorine. This behavior was successfully simulated using a kinetic model derived from the reaction kinetics of bromine and chlorine reactions with ARGs. The existence of dissolved organic matter extracts only marginally decreased the enhanced degradation of ARGs with Br - , while ammonia significantly inhibited this process during chlorination, both with and without Br - , due to the low reactivity of NH 2 Cl and NH 2 Br toward ARGs. These findings highlight the importance of Br - in ARG degradation during water chlorination and the need for further studies in diverse water matrices., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Abstract The feasibility of thermophilic anaerobic digestion (AD) for the attenuation of antibiotic resistance genes (ARGs) in biomass wastes under high antibiotic concentrations remains unclear. In this study, a thermophilic completely stirred digester (55 °C) was fed with municipal excess sludge spiked with increasing concentrations of oxytetracycline (OTC) (0–1000 mg/L) over a period of 280 days. Results showed that thermophilic AD could maintain stable methane production (338.40 ± 26.26 mL/d/gVS) even at an OTC dose of 1000 mg/L with the sludge phase OTC concentration reaching around 24,000 mg/kg. More important, the abundance of resistome detected by high-throughput quantitative PCR in the substrate was reduced (p < 0.01) by 55.54%–86.27% by thermophilic AD over the whole period. Partial canonical correspondence and network analyses showed that the reduction of ARGs was achieved mainly through two ways: eliminating the original hosts of ARGs in the substrate (from 41.74% ± 2.60% in the substrate to 12.08% ± 1.02% in digested sludge), and blocking the horizontal proliferation of ARGs in the digested sludge by reducing the abundance of mobile genetic elements and restricting their horizontal exchange within a small number of thermophilic genera. This study showed that thermophilic AD is feasible for the attenuation of ARGs in biomass even containing high level of OTC. Graphical abstract Image 1 Highlights • Thermophilic AD could maintain stable methane production under high OTC stress. • Resistome in the substrate was reduced by thermophilic AD under high OTC stress. • Original hosts of ARGs in the substrate were eliminated by thermophilic AD. • HGT of ARGs in thermophilic digested sludge was blocked even under high OTC stress. [ABSTRACT FROM AUTHOR]

Abstract The increasing finding of pathogens and antibiotic resistance genes (ARGs) in drinking water has become one of the most challenging global health threats worldwide. However, conventional disinfection strategies in drinking water treatment plants (DWTPs) require further optimization in combating the antibiotic resistome. Here, we show that antimicrobial resins with quaternary ammonium salts (AMRs-QAS) exhibit great potentials in diminishing specific potential pathogens that relatively resist chlorine or UV disinfection in DWTPs, and comprehensive analyses using microscopy and fluorescence techniques revealed that the antimicrobial capacity of AMRs-QAS mainly proceed via the bacterial adsorption and cell membrane dissociation. Moreover, a total of 15 among 30 selected ARGs, as well as 4 selected potential pathogens including Pseudomonas aeruginosa, Bacillus subtili s, Escherichia coli and Staphylococcus aureus were all detected in the source water. Coupling the AMRs-QAS with 0.2 mg/L chlorine resulted in higher removal efficiencies than chlorination (2 mg/L) or UV disinfection (400 mJ cm−2) for all the detected pathogens and ARGs in drinking water and significantly decreased the relative abundances of Pseudomonas aeruginosa, Bacillus subtili s, Escherichia coli , as well as all the detected ARGs (p < 0.05). Co-occurrences of pathogens and ARGs were revealed by a correlation network and possibly accounts for the ARGs removal. This coupled disinfection strategy overcomes the limitations of individual disinfection methods, i.e. the enrichment of specific pathogens and ARGs among bacterial populations, and provides an alternative for minimizing health risks induced by the antibiotic resistome in DWTPs. Graphical abstract Image 1 Highlights • AMRs-QAS show potential in diminishing pathogens that resist disinfectant in DWTPs. • Coupling AMRs-QAS with low-dose chlorine effectively combats antibiotic resistome. • Co-occurrences of pathogens and ARGs account for the ARGs removal by AMRs-QAS. • AMRs-QAS can assist to the chlorine or UV disinfection in DWTPs. [ABSTRACT FROM AUTHOR]

Manganese ore substrate up-flow microbial fuel cell constructed wetland (UCW-MFC(Mn)) as an innovative wastewater treatment technology for purifying antibiotics and electricity generation with few antibiotic resistance genes (ARGs) generation has attracted attention. However, antibiotic purifying effects should be further enhanced. In this study, a biofilm electrode reactor (BER) that needs direct current driving was powered by a Mn ore anode (UCW-MFC(Mn)) to form a coupled system without requiring direct-current source. Removal efficiencies of sulfadiazine (SDZ), ciprofloxacin (CIP) and the corresponding ARGs in the coupled system were compared with composite (BER was powered by direct-current source) and anaerobic systems (both of BER and UCW-MFC were in open circuit mode). The result showed that higher antibiotic removal efficiency (94% for SDZ and 99.1% for CIP) in the coupled system was achieved than the anaerobic system (88.5% for SDZ and 98.2% for CIP). Moreover, electrical stimulation reduced antibiotic selective pressure and horizontal gene transfer potential in BER, and UCW-MFC further reduced ARG abundances by strengthening the electro-adsorption of ARG hosts determined by Network analysis. Bacterial community diversity continuously decreased in BER while it increased in UCW-MFC, indicating that BER mitigated the toxicity of antibiotic. Degree of modularity, some functional bacteria (antibiotic degrading bacteria, fermentative bacteria and EAB), and P450 enzyme related to antibiotic and xenobiotics biodegradation genes were enriched in electric field existing UCW-MFC, accounting for the higher degradation efficiency. In conclusion, this study provided an effective strategy for removing antibiotics and ARGs in wastewater by operating a BER-UCW-MFC coupled system. [Display omitted] • BER decreased antibiotic selective pressure and horizontal gene transfer potential. • Electric field strengthened antibiotic and resistance gene removal in the coupled system. • UCW-MFC has higher adsorption ability for antibiotic resistance gene than BER. • Cooperation between fermentative and electrochemically active bacteria was observed. • The bacterial community composition and function was impacted by electric field. [ABSTRACT FROM AUTHOR]

Wastewater treatment systems are considered as hotspots for release of antibiotic resistance genes (ARGs) into the environment. Anaerobic-aerobic sequential (AAS) bioreactors now are intensively used for wastewater treatment worldwide. However, the occurrence of ARGs in wastewater treatment systems exposed to low-level (i.e., sub-inhibitory) antibiotic is poorly known. Here, we studied the distribution patterns of seven tetracycline resistance genes ( tet genes) including tet (A), tet (C), tet (G), tet (X), tet (M), tet (O), and tet (W), as well as one mobile element [class 1 integron ( intI1 )] in AAS bioreactors under exposure to tetracycline from 50 μg/L to 500 μg/L. Additionally, effect on the removal performance of nutrients and tetracycline in both anaerobic and aerobic units was also investigated. A tetracycline concentration gradient selected for bacterial resistance in the anaerobic reactor, with the exception of tet (A) and tet (W), and the tetracycline removal deteriorated by 47%. However, the abundance of tet and intI1 genes reduced in the subsequent aerobic unit, and the removal of tetracycline, soluble COD, and NH 4 + -N maintained at average efficiencies of 91%, 90%, and 93%, respectively. The level of tet (X) was largely unaffected by AAS treatment. It is notable that intI1 genes probably played a crucial role on the horizontal dissemination of tet genes. The tetracycline levels and intI1 genes appear to be the primary factors influencing the occurrence of tet genes in AAS bioreactors. Nonetheless, AAS treatments still show promise for reducing antibiotics, ARGs and mobile elements without affecting nutrient removal, and need further research for practical applications. [ABSTRACT FROM AUTHOR]

The fate of antibiotic-resistant bacteria (ARB) and associated antibiotic-resistant gene (ARG) expression under electrolytic stimulation in bio-electrochemical reactors (BERs) was unknown. In this study, sulfadiazine resistant bacteria ( Klebsiella spp.), which were isolated from a BER, were subjected to constant direct current (DC) stimulation in a simulated BER. With an increase of the current from 7 to 28 mA, it was found that lactic dehydrogenase (LDH) showed a 1.03-, 1.21-, 1.34-, and 1.46-fold value compared with the control at 48 h, indicating that the cell membrane permeability had increased. Since the adenosine triphosphate (ATP) concentration increased with the current, the specific growth rate of Klebsiella spp. increased ( R  = 0.98). The viable count of Klebsiella spp. reached a maximum at 19 mA and then decreased. The percentage of ARB lethality, which was reflected by flow cytometry analysis, increased from 18% (7 mA) to 37.8% (28 mA) at 48 h. Reactive oxygen species (ROS) produced from the electrolysis of water were greater with the increasing current ( R  = 0.94), which may be responsible for the high lethality rate of Klebsiella spp.. Scanning electronic microscope results showed that electrolytic stimulation changed the cell surface morphology with some cell disruption. An upregulation of sulII and int1 expression was observed. A significant correlation between int1 and the current ( R  = 0.97) were observed. Taken together, BERs possess potential risks in accelerating ARB multiplication and promoting ARG expression. [ABSTRACT FROM AUTHOR]

Decreasing bioaccessible antibiotics, heavy metals, and antibiotic resistance genes (ARGs) in soil by adsorption is an attractive, but unrealized, approach for ARG risk reduction. This approach has the potential to reduce the (co)selection pressure from antibiotics and heavy metals on bacteria and ARG horizontal gene transformation to pathogens. Here, a wet-state silicon-rich biochar/ferrihydrite composite (SiC–Fe(W)) synthesized by loading ferrihydrite onto rice straw-derived biochar was examined for i) adsorption of oxytetracycline and Cu2+ to reduce (co)selection pressure and ii) adsorption of extracellular antibiotic resistance plasmid pBR322 (containing tet A and bla TEM-1) to inhibit ARG transformation. SiC–Fe(W) gained the adsorption priority of biochar (for Cu2+) and wet-state ferrihydrite (for oxytetracycline and pBR322) and showed adsorptive enhancement (for Cu2+ and oxytetracycline) from a more wrinkled and exposed surface from biochar silica-dispersed ferrihydrite and a more negatively charged biochar, and the adsorption capacity for SiC–Fe(W) was 17–135 times that of soil. Correspondingly, 10 g/kg SiC–Fe(W) amendment increased the soil adsorption coefficient K d by 31%–1417% and reduced the selection pressure from dissolved oxytetracycline, co-selection pressure from dissolved Cu2+, and transformation frequency of pBR322 (assessed with Escherichia coli). The development of Fe–O–Si bonds on silicon-rich biochar in alkaline enhanced ferrihydrite stability and adsorption capacity (for oxytetracycline), presenting a new potential strategy of biochar/ferrihydrite composite synthesis for adsorptive inhibition of ARG proliferation and transformation in ARG pollution control. [Display omitted] • SiC–Fe(W) containing silica-stabilized and high-surface ferrihydrite and sichar was synthesized. • SiC–Fe(W) held adsorption capacity exceeding biochar and wet-state ferrihydrite for Cu2+ and oxytetracycline. • Adsorptive inhibition of ARG proliferation and transmission in soil was realized by SiC–Fe(W). • SiC–Fe(W) promoted the persistence of soil sorption enhancement towards oxytetracycline and ARG in dry-wet cycle. [ABSTRACT FROM AUTHOR]

Domestic wastewater treatment plants as a reservoir of antibiotic resistance genes (ARGs) have received much attention, but the effect of dyes on the propagation of ARGs has rarely been investigated. In this study, we investigated the differences in distributions of ARGs and microbial communities using high-throughput qPCR and 16S rRNA gene sequencing, respectively, between mixed (dyeing and domestic) wastewater and domestic sewage. The relative abundance of ARGs in inflows of mixed wastewater (IW2 and IW3) was higher than that of domestic wastewater (IW1). The relative abundance of mobile genetic elements in the inflow of textile dyeing wastewater (IDW3) was 3- to 13-fold higher than that in other samples. Moreover, in IDW3, some distinct high abundance ARGs, particularly operons encoding efflux pumps (such as acrR-01 , acrB-01 and acrF ), were significantly correlated with Streptococcus of the Firmicutes. To explore why the abundance of ARGs was relatively high in mixed wastewater, six representative types of organic compounds in textile dyeing wastewater were used to test the effect on plasmid-based conjugative transfer from E. coli HB101 to E. coli NK5449. These six compounds all facilitated the transfer of resistance-carrying RP4 plasmid, and the highest transfer frequency (approximately 10 −5 -10 −3 ) was over 4- to 200-fold higher than that in the control group (approximately 10 −6 -10 −5 ). These results illustrated that the six common residual compounds, particularly low-dose substances in IDW3, could facilitate the dissemination of ARGs in aquatic environments. More importantly, this study revealed for the first time that dyeing contaminants influenced horizontal gene transfer (HGT) of ARGs. [ABSTRACT FROM AUTHOR]

The electro-peroxone (EP) process is an electricity-based oxidation process enabled by electrochemically generating hydrogen peroxide (H 2 O 2) from cathodic oxygen (O 2) reduction during ozonation. In this study, the removal of antibiotic resistant bacteria (ARB) and plasmid-encoded antibiotic resistance genes (ARGs) during groundwater treatment by ozonation alone and the EP process was compared. Owing to the H 2 O 2 -promoted ozone (O 3) conversion to hydroxyl radicals (•OH), higher •OH exposures, but lower O 3 exposures were obtained during the EP process than ozonation alone. This opposite change of O 3 and •OH exposures decreases the efficiency of ARB inactivation and ARG degradation moderately during the EP process compared with ozonation alone. These results suggest that regarding ARB inactivation and ARG degradation, the reduction of O 3 exposures may not be fully counterbalanced by the rise of •OH exposures when changing ozonation to the EP process. However, due to the rise of •OH exposure, plasmid DNA was more effectively cleaved to shorter fragments during the EP process than ozonation alone, which may decrease the risks of natural transformation of ARGs. These findings highlight that the influence of the EP process on ARB and ARG inactivation needs to be considered when implementing this process in water treatment. [Display omitted] • AntiBiotic resistant bacteria (ARB) can be effectively inactivated by ozonation and electro-peroxone. • Higher O 3 doses are needed for antibiotic resistant gene (ARG) degradation than disinfection. • The change of ozonation to electro-peroxone may slightly decrease ARG degradation efficiency. • Plasmid DNA is more thoroughly cleaved to shorter fragments by electro-peroxone than ozonation. [ABSTRACT FROM AUTHOR]

The emergence of plasmid-mediated tigecycline-resistant genes [ tet (X3)to tet (X6)] in animals and humans has raised serious concerns over their possible cross-environmental dissemination. However, behavior of these emerging mobile tet (X)-variant genes in manure treatment processes, particularly for different composting treatments, has not yet been studied. Here, we explored the environmental behavior of mobile tet (X)-variant genes in two typical manure composting treatments and amended soils based on a large-scale molecular investigation across eight provinces in China. Results showed that tet (X4) was the predominant mobile tet (X)-variant gene in fresh manure, natural and thermophilic composting products with both the highest detection frequency (82.5% ± 14.7%), and absolute abundance of tet (X4)[4.26 ± 0.09) × 1010] copies/g dry weight, followed by tet (X3), tet (X6), and tet (X5). The occurrence of all mobile tet (X)-variant genes, particularly tet(X4) , in receiving soil following composting fertilizer application indicated their transmission from manure to soil. Paired-sampling strategy revealed no significant reduction in mobile tet (X)-variant genes by natural composting, while thermophilic composting exhibited clear efficacy in removing tet (X)-variant genes. After thermophilic composting, tet(X4) exhibited the lowest reduction (94.1%) compared with other mobile tet (X)-variant genes (96.9%–99.9%), which may be attributable to its significant correlation with IS CR2 (P < 0.05) facilitating its transfer to various hosts including persisted thermotolerant bacteria. Thus, tet(X4) showed better persistence in livestock-related environments. Collectively, this study highlights the importance of controlling the environmental dissemination of clinically relevant mobile tet (X)-variant genes by establishing a sound process and operational strategy. [Display omitted] • Emerging mobile tet (X) variants in different composting treatments were explored. • Thermophilic composting exhibited clear efficacy in removing total tet (X) variants. • Tet (X4) showed lower reduction than other variants after thermophilic composting. • IS CR2 facilitated the transfer of highly-prevalent tet (X4) during composting. [ABSTRACT FROM AUTHOR]

In this study, the response of antibiotic resistance genes (ARGs), mobile gene elements (intI 1), and human bacterial pathogens (HBPs) to addition of manure biochar (1–10 g/L) was studied in anaerobic digestion (AD) at 20–55 °C for treating dairy manure. Twelve ARGs comprising five tetracycline resistance genes, two sulfonamide resistance genes, two macrolide resistance genes, three β-lactam antibiotic resistance genes, and intI 1 were analyzed by quantitative PCR. High-throughput sequencing data were matched against a database of putative 538 HBPs. Significant removal of ARGs (except for tet O and erm B) and intI 1 was observed in all the samples. Manure biochar resulted in significant removal of ARGs and HBPs; however, negative effects were also observed in some conditions. This is the first study to provide to explore the fates of ARGs and HBPs by adding manure biochar to AD. [Display omitted] • Manure biochar was added to anaerobic digestion (20–55 C) of dairy manure. • Fate of antibiotic resistance genes and human bacterial pathogens was investigated. • Significant removal of antibiotic resistance genes was achieved. • Significant removal of human bacterial pathogens observed by adding manure biochar. [ABSTRACT FROM AUTHOR]

Urbanization is a process of ecosystem evolution mediated by human activities. One of the main consequences is the alteration of antibiotic resistome and microbiome in aquatic environment, which may transfer from water to sediments and exert a long-term health concern to aquatic animals and even humans. However, the role of urbanization in shaping resistome and microbiome in water and sediments is largely unknown. Here, a typical watershed with a significant gradient of urbanization was selected, and the resistome and microbiome in both water and sediments were profiled. In water, the relative abundance of ARGs and bacterial diversity increased gradually along the urbanization, but were relatively stable in sediments. The abundance of potential multidrug-resistant bacteria in peri-urban and urban water were significantly higher than rural water, while in sediments, unique potential multidrug-resistant bacteria were detected at different urbanization levels. Population size was identified as the key factor shaping the ARGs profiles. Finally, environmental risk assessment based on the projection pursuit regression model suggested that the water in urban region had higher potential environmental risk of antibiotic resistance, in contrary to the sediments in rural and peri-urban regions. Our findings revealed distinct responses of water and sediment to urbanization in terms of antibiotic resistome and microbiome. This work provides important guide for hierarchically controlling ARGs dissemination in watershed. [Display omitted] • ARGs abundance and bacterial diversity in water increased with urbanization. • Population size was the key factor driving the succession of ARGs. • Water had higher environmental risk of antibiotic resistance in urban region. • Sediment had higher environment risks in rural and peri-urban regions. [ABSTRACT FROM AUTHOR]

Iron (Fe) has been widely applied to treat arsenic (As)-contaminated water, and Fe could influence bioavailability and toxicity of As. However, little is known about the impact of As and/or Fe on gut microbiota, which plays important roles in host health. In this study, high-throughput sequencing and quantitative real time PCR were applied to analyze the impact of As and Fe on mouse gut microbiota. Co-exposure of As and Fe mitigated effects on microbial community to a certain extent. Correlation analysis showed the shifts in gut microbiota caused by As and/or Fe exposure might be important reason of changes in metabolic profiles of mouse. For antibiotic resistance genes (ARGs), co-exposure of As and Fe increased types and abundance of ARGs. But for high abundance ARGs, such as tetQ, tetO and tetM, co-exposure of As and Fe mitigated effects on their abundances compared to exposure to As and Fe alone. No obvious relationship between ARGs and mobile genetic elements were found. The changes in ARGs caused by metal exposure might be due to the alteration of gut microbial diversity. Our results show that changes of gut microbial community caused by As and/or Fe can influence host metabolisms and abundances of ARGs in gut, indicating that changes of gut microbiota should be considered during the risk assessment of As and/or Fe. [ABSTRACT FROM AUTHOR]

Over a three-year field trial, the impacts of composted and raw gentamicin fermentation waste (GFW) application to land on residual soil gentamicin levels, physicochemical properties, bacterial community composition, and antibiotic resistance genes (ARGs) were assessed. In the saline-alkali soil tested, GFW application decreased electrical conductivity (EC) and pH. Importantly, there was no measurable long-term accumulation of gentamicin as a result of GFW addition. Changes in the abundance of Bacillus was primarily associated with degradation of gentamicin in soil, whereas wider (i.e. more general) shifts in bacterial communities over the treatments was linked to alteration of soil physicochemical properties, particularly pH, total nitrogen, dissolved organic carbon, EC, NO 3 −-N and NH 4 +-N. Compared with other treatments, soils receiving composted GFW harbored more types of ARGs and significantly higher (P < 0.05) abundances of mobile genes elements (MGEs) (especially IncQ and Int1) and aminoglycoside ARGs (especially aminoglycoside phosphotransferases genes, APH). Finally, the abundances of ARGs in soils receiving raw and composted GFW were 59.60% and 50.26% higher than that in soils only receiving chemical fertilizer, respectively. Specifically, the abundances of APH, especially strB , were significantly higher than other kinds of ARGs (P < 0.05). The results of linear regression and partial least squares path model showed that MGEs, including plasmids, integrons, and transposons, along with soil properties (EC and NH 4 +-N) were the main factors associated with change in ARGs. Furthermore, different MGEs were involved in different transfer mechanisms of specific ARGs. Our findings demonstrated the potential risks of using raw and composted GFW as fertilizer, and suggest potential solutions to this problem. [Display omitted] • Treatment with raw gentamicin fermentation waste affected soil bacterial composition. • Bacillus was related to the degradation of gentamicin in soil. • Using gentamicin fermentation waste caused spread of antibiotic resistance genes. • Mobile gene element and soil property affected shifts of antibiotic resistance genes. [ABSTRACT FROM AUTHOR]

Microbial fuel cell constructed wetlands (CW-MFCs) with different circuit operation conditions and hydraulic retention time (HRT) were constructed to evaluate their ability to remove and accumulate pharmaceutical and personal care products (PPCPs) (sulfadiazine (SDZ), carbamazepine (CBZ), naproxen (NPX) and ibuprofen (IBP)) during four months running process. The abundance level of corresponding sulfonamide antibiotic resistance genes (ARGs) was also investigated. The results showed that closed circuit operation of CW-MFC contributed to the decrease in mass loading of COD, NH 4 +-N, PPCPs, and wastewater toxicity in the effluent. Additionally, closed circuit operation with low HRT contributed to enhancing selected PPCP mass accumulation on electrodes by electro-adsorption, and thus the higher sulfonamide ARG abundance was detected in the electrodes and effluent. Moreover, the composition of bacteria was greatly influenced by the mass accumulation of PPCPs revealed by redundancy analysis results. Procrustes analysis results further demonstrated that bacterial community contributed greatly to the ARGs profiles. Therefore, ARGs with their host bacteria revealed by network analysis were partially deposited on electrode substrates, and thus ARGs were effectively accumulated on electrodes. Function analysis of the bacterial community from PICRUSt predicted metagenomes revealed that closed circuit mode enhanced the abundances of the function genes of metabolic and the multiple ARGs, suggesting that closed circuit operation exhibited positive effects on metabolic process and ARG accumulation in CW-MFC system. Image 1 • Enhanced PPCP removal and toxicity attenuation was observed in closed circuit CW-MFC. • Closed circuit operation of CW-MFC enhanced PPCP mass accumulation on anode. • Both closed circuit system and low HRT increased in the ecological risk of ARGs. • Abundances for metabolism related genes were higher in closed circuit CW-MFC. • Correlation between the ARGs, PPCP and bacterial genera on electrode was determined. [ABSTRACT FROM AUTHOR]