Removal of antibiotics and antibiotic resistance genes from domestic sewage by constructed wetlands: Effect of flow configuration and plant species. - Related Documents




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775701.0000Removal of antibiotics and antibiotic resistance genes from domestic sewage by constructed wetlands: Effect of flow configuration and plant species. This study aims to investigate the removal of antibiotics and antibiotic resistance genes (ARGs) in raw domestic wastewater by various mesocosm-scale constructed wetlands (CWs) with different flow configurations or plant species including the constructed wetland with or without plant. Six mesocosm-scale CWs with three flow types (surface flow, horizontal subsurface flow and vertical subsurface flow) and two plant species (Thaliadealbata Fraser and Iris tectorum Maxim) were set up in the outdoor. 8 antibiotics including erythromycin-H2O (ETM-H2O), monensin (MON), clarithromycin (CTM), leucomycin (LCM), sulfamethoxazole (SMX), trimethoprim (TMP), sulfamethazine (SMZ) and sulfapyridine (SPD) and 12 genes including three sulfonamide resistance genes (sul1, sul2 and sul3), four tetracycline resistance genes (tetG, tetM, tetO and tetX), two macrolide resistance genes (ermB and ermC), two chloramphenicol resistance genes (cmlA and floR) and 16S rRNA (bacteria) were determined in different matrices (water, particle, substrate and plant phases) from the mesocosm-scale systems. The aqueous removal efficiencies of total antibiotics ranged from 75.8 to 98.6%, while those of total ARGs varied between 63.9 and 84.0% by the mesocosm-scale CWs. The presence of plants was beneficial to the removal of pollutants, and the subsurface flow CWs had higher pollutant removal than the surface flow CWs, especially for antibiotics. According to the mass balance analysis, the masses of all detected antibiotics during the operation period were 247,000, 4920-10,600, 0.05-0.41 and 3500-60,000μg in influent, substrate, plant and effluent of the mesocosm-scale CWs. In the CWs, biodegradation, substrate adsorption and plant uptake all played certain roles in reducing the loadings of nutrients, antibiotics and ARGs, but biodegradation was the most important process in the removal of these pollutants.201627443461
776110.9996Fate and removal of bacteria and antibiotic resistance genes in horizontal subsurface constructed wetlands: Effect of mixed vegetation and substrate type. This study aimed to investigate the influence of cropping method and substrate type on the fate and the removal of bacterial and antibiotic resistance genes (ARGs) indicators from primary wastewater by constructed wetlands (CWs) during startup and maturation stages. Four small-scale CWs differing in their plantation pattern (monoculture vs. polyculture) and substrate type were constructed and operated under field conditions. While for bacteria, the greatest impact of the cropping method and substrate type on removal was during the startup stage rather than the maturation stage, for ARGs, such impact was significant at both stages. During startup, the removal efficiencies of heterotrophic bacteria, fecal coliforms, E. coli, 16S rRNA genes and lacZ increased with the operation time. At maturation, the removal efficiencies were constant and were within the range of 89.2-99.4%, 93.7-98.9%, 89-98.8%, 94.1-99.6% and 92.9-98.7%, respectively. The removal efficiencies of intl1, tetM, intl1, sul1, ermB and total ARGs were also increased with the operation time. However, they were ARG type and configuration-dependent; at maturation they ranged between 50.7%-89.4%, 85.9%-97%, 49.6%-92.9%, 58.2%-96.7% and 79.9-94.3%, respectively. The tuff-filled serially planted CW was also the only one capable of removing these genes at similar high efficiency. Metagenomic analysis showed that none of the ARGs was among the most common ARGs in water and biofilm samples; rather most ARGs belonged to bacterial efflux transporter superfamilies. Although ARGs were removed, they were still detected in substrate biofilm and their relative concentrations were increased in the effluents. While the removal of both bacteria and ARGs was higher during summer compared to winter, the season had no effect on the removal pattern of ARGs. Hence, combination of the serial plantation with substrate having high surface area is a potential strategy that can be used to improve the performance of CWs.202133338689
718020.9995Removal of antibiotic residues, antibiotic resistant bacteria and antibiotic resistance genes in municipal wastewater by membrane bioreactor systems. Antibiotic residues, antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are considered new classes of water contaminants due to their potential adverse effects on aquatic ecosystems and human health. This paper provides comprehensive data on the occurrences of 19 antibiotics, bacteria resistant to 10 antibiotics, and 15 ARGs in raw influent and different treatment stages of conventional activated sludge (CAS) and membrane bioreactor (MBR) systems. Seventeen out of the 19 target antibiotics were detected in raw influent with concentrations of up to ten micrograms per liter. Concentrations of antibiotics measured in the secondary effluent were much lower compared to those in the raw influent. Among the antibiotics, amoxicillin, azithromycin, ciprofloxacin, chloramphenicol, meropenem, minocycline, oxytetracycline, sulfamethazine and vancomycin had highest removal by CAS or MBR systems with median removal efficiency (RE) > 70%, while trimethoprim and lincomycin were recalcitrant in the CAS system with median RE <50%. Similarly, the target ARB and ARGs were omnipresent in the raw influent samples with average concentrations as high as 2.6 × 10(6) CFU/mL and 2.0 × 10(7) gene copies/mL, respectively. The concentrations of ARB in secondary effluent of the CAS system declined relative to the raw influent (i.e. lower than raw influent by 2-3 orders of magnitude) and no ARB were detected in the MF permeate of the MBR system. For ARGs, their concentrations in secondary effluent/MF permeate ranged from below method quantification limit (201830193193
717930.9995Prevalence and proliferation of antibiotic resistance genes in two municipal wastewater treatment plants. The propagation of antibiotic resistance genes (ARGs) is an emerging health concern worldwide. Thus, it is important to understand and mitigate their occurrence in different systems. In this study, 30 ARGs that confer resistance to tetracyclines, sulfonamides, quinolones or macrolides were detected in two activated sludge wastewater treatment plants (WWTPs) in northern China. Bacteria harboring ARGs persisted through all treatment units, and survived disinfection by chlorination in greater percentages than total Bacteria (assessed by 16S rRNA genes). Although the absolute abundances of ARGs were reduced from the raw influent to the effluent by 89.0%-99.8%, considerable ARG levels [(1.0 ± 0.2) × 10(3) to (9.5 ± 1.8) × 10(5) copies/mL)] were found in WWTP effluent samples. ARGs were concentrated in the waste sludge (through settling of bacteria and sludge dewatering) at (1.5 ± 2.3) × 10(9) to (2.2 ± 2.8) × 10(11) copies/g dry weight. Twelve ARGs (tetA, tetB, tetE, tetG, tetH, tetS, tetT, tetX, sul1, sul2, qnrB, ermC) were discharged through the dewatered sludge and plant effluent at higher rates than influent values, indicating overall proliferation of resistant bacteria. Significant antibiotic concentrations (2%-50% of raw influent concentrations) remained throughout all treatment units. This apparently contributed selective pressure for ARG replication since the relative abundance of resistant bacteria (assessed by ARG/16S rRNA gene ratios) was significantly correlated to the corresponding effluent antibiotic concentrations. Similarly, the concentrations of various heavy metals (which induce a similar bacterial resistance mechanism as antibiotics - efflux pumps) were also correlated to the enrichment of some ARGs. Thus, curtailing the release of antibiotics and heavy metals to sewage systems (or enhancing their removal in pre-treatment units) may alleviate their selective pressure and mitigate ARG proliferation in WWTPs.201526372743
775840.9995Removal efficiency of antibiotic residues, antibiotic resistant bacteria, and genes across parallel secondary settling tank and membrane bioreactor treatment trains in a water reclamation plant. Antimicrobial resistance is recognized as a potent threat to human health. Wastewater treatment facilities are viewed as hotspots for the spread of antimicrobial resistance. This study provides comprehensive data on the occurrences of 3 different antibiotic resistant opportunistic pathogens (with resistance to up to 5 antibiotics), 13 antibiotic resistant genes and intI1, and 22 different antimicrobial residues in a large water reclamation plant (176 million gallons per day) that runs a conventional Modified Ludzack-Ettinger (MLE) reactor followed by a secondary settling tank (SST) and membrane bioreactor (MBR) in parallel. All the antibiotic resistant bacteria and most of the antibiotic resistance genes were present in the raw influent, ranging from 2.5 × 10(2)-3.7 × 10(6) CFU/mL and 1.2× 10(-1)-6.5 × 10(10) GCN/mL, respectively. MBR outperformed the SST system in terms of ARB removal as the ARB targets were largely undetected in MBR effluent, with log removals ranging from 2.7 to 6.8, while SST only had log removals ranging from 0.27 to 4.6. Most of the ARG concentrations were found to have significantly higher in SST effluent than MBR permeate, and MBR had significantly higher removal efficiency for most targets (p < 0.05) except for sul1, sul2, bla(OXA48), intI1 and 16S rRNA genes (p > 0.05). As for the antibiotic residues (AR), there was no significant removal from the start to the end of the treatment process, although MBR had higher removal efficiencies for azithromycin, chloramphenicol, erythromycin, erythromycin-H(2)O, lincomycin, sulfamethoxazole and triclosan, compared to the SST system. In conclusion, MBR outperformed SST in terms of ARB and ARGs removal. However low removal efficiencies of most AR targets were apparent.202438492595
776250.9994Lateral flow sand filters are effective for removal of antibiotic resistance genes from domestic wastewater. The ability of lateral flow sand filters, used as on-site wastewater treatment systems (OWTS), to remove antibiotic resistance genes (ARGs), antibiotic resistant bacteria (ARB), and other relevant genetic markers (HF183, 16S rRNA, and int1) was assessed. Municipal wastewater was settled in a septic tank prior to loading into six pilot-scale lateral flow sand filters comprised of three different sand media types, at 5 and 30% slopes. The sand filters were sampled bi-weekly for: 9 ARGs and 3 other complimentary gene markers (sul1, sul2, qnrS, tetO, ermB, bla(TEM), bla(CTX-M), mecA, vanA, int1, HF183, 16S rRNA), and conventional microbial and water quality indicators, from July to November in 2017, and four times in the summer of 2018. The sand filters were observed to attenuate 7 of the ARGs to mostly below 2 log gene copies per mL. Log reductions ranging from 2.9 to 5.4 log were observed for the removal of absolute abundances of ARGs from septic tank effluent in 5 of the 6 sand filters. The fine-grained filter on the 5% slope did not perform as well for ARG attenuation due to hydraulic failure. The apportionment of cell-associated versus cell-free DNA was determined for the gene markers and this indicated that the genes were primarily carried intracellularly. Average log reductions of ARB with resistance to either sulfamethoxazole, erythromycin, or tetracycline were approximately 2.3 log CFU per mL within the filters compared to the septic tank effluent. This field study provides in-depth insights into the attenuation of ARB, ARGs, and their genetic compartmentalization in variably saturated sand OWTS. Overall, this type of OWTS was found to pose little risk of antimicrobial resistance contamination spread into surrounding environments when proper hydraulic function was maintained.201931306951
804860.9994Ecological risks of sulfonamides and quinolones degradation intermediates: Toxicity, microbial community, and antibiotic resistance genes. The ecological risks posed by incompletely degraded antibiotic intermediates in aquatic environments warrant significant attention. This study investigated the degradation mechanisms of sulfonamides (sulfadiazine, sulfamethoxazole) and quinolones (ciprofloxacin, norfloxacin) during thermally activated persulfate (TAP) treatment. The main degradation mechanisms for sulfonamides involved S-N bond cleavage and -NH(2) oxidation mediated by sulfate and hydroxyl radicals, whereas quinolone degradation occurred primarily through piperazine ring cleavage facilitated by a single linear oxygen. Toxic degradation intermediates were found to be enriched with bacteria in real water samples, including Aeromonas (SDZ-50, 9.61%), Acinetobacter (SMZ-50, 21.91%), unclassified Archaea (CIP-50, 19.32%), and Herbaspirillum (NOR-50, 17.36%). Meanwhile, the abundance of sulfonamide-associated antibiotic resistance genes (ARGs) (sul1 and sul2) and quinolone-associated ARGs (mfpA, emrA, and lfrA) significantly increased, with SMZ-50 and NOR-50 reaching 659.34 and 2009.98 RPKM, respectively. Correlation analysis revealed differences in host diversity and composition driven by the same classes of antibiotics and their intermediates.202539662843
799870.9994Seasonal variation and removal efficiency of antibiotic resistance genes during wastewater treatment of swine farms. The seasonal variation and removal efficiency of antibiotic resistance genes (ARGs), including tetracycline resistance genes (tetG, tetM, and tetX) and macrolide (ermB, ermF, ereA, and mefA), were investigated in two typical swine wastewater treatment systems in both winter and summer. ARGs, class 1 integron gene, and 16S rRNA gene were quantified using real-time polymerase chain reaction assays. There was a 0.31-3.52 log variation in ARGs in raw swine wastewater, and the abundance of ARGs in winter was higher than in summer. tetM, tetX, ermB, ermF, and mefA were highly abundant. The abundance of ARGs was effectively reduced by most individual treatment process and the removal efficiencies of ARGs were higher in winter than in summer. However, when examining relative abundance, the fate of ARGs was quite variable. Anaerobic digestion reduced the relative abundance of tetX, ermB, ermF, and mefA, while lagoon treatment decreased tetM, ermB, ermF, and mefA. Sequencing batch reactor (SBR) decreased tetM, ermB, and ermF, but biofilters and wetlands did not display consistent removal efficiency on ARGs in two sampling seasons. As far as the entire treatment system is concerned, ermB and mefA were effectively reduced in both winter and summer in both total and relative abundance. The relative abundances of tetG and ereA were significantly correlated with intI1 (p < 0.01), and both tetG and ereA increased after wastewater treatment. This may pose a great threat to public health.201726715413
800880.9994Reductions of bacterial antibiotic resistance through five biological treatment processes treated municipal wastewater. Wastewater treatment plants are hot spots for antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs). However, limited studies have been conducted to compare the reductions of ARB and ARGs by various biological treatment processes. The study explored the reductions of heterotrophic bacteria resistant to six groups of antibiotics (vancomycin, gentamicin, erythromycin, cephalexin, tetracycline, and sulfadiazine) and corresponding resistance genes (vanA, aacC1, ereA, ampC, tetA, and sulI) by five bench-scale biological reactors. Results demonstrated that membrane bioreactor (MBR) and sequencing batch reactor (SBR) significantly reduced ARB abundances in the ranges of 2.80∼3.54 log and 2.70∼3.13 log, respectively, followed by activated sludge (AS). Biological filter (BF) and anaerobic (upflow anaerobic sludge blanket, UASB) techniques led to relatively low reductions. In contrast, ARGs were not equally reduced as ARB. AS and SBR also showed significant potentials on ARGs reduction, whilst MBR and UASB could not reduce ARGs effectively. Redundancy analysis implied that the purification of wastewater quality parameters (COD, NH4 (+)-N, and turbidity) performed a positive correlation to ARB and ARGs reductions.201627384166
351390.9994Tetracyclines, sulfonamides and quinolones and their corresponding resistance genes in the Three Gorges Reservoir, China. The Three Gorges Project significantly impacted water quality and ecological balance in this area. The special engineered aquatic environment could be an important reservoir for antibiotic resistance genes (ARGs). Fifteen ARGs corresponding to three groups of antibiotics (tetracyclines, sulfonamides and quinolones) were determined in surface water, soil and sediment in this study. Total concentrations of antibiotics ranged from 21.55 to 536.86ng/L, 3.69 to 438.76ng/g, 15.78 to 213.84ng/g in water, soil and sediment, respectively. Polymerase chain reaction (PCR) of ARGs revealed the presence of two sulfonamide resistance genes (sul1, sul2), five tetracycline resistance genes (tetA, tetB, tetM, tetQ, tetG) and class 1 integron gene (intI1) in all samples. And the relative abundance of sulfonamide resistance genes was generally higher than tetracycline resistance genes in three matrices. Significant correlations (p<0.05) were found between the concentrations of intI1 and ARGs (tetA, tetB, tetM, tetQ, tetG, sul1, sul2), indicating intI1 may facilitate the proliferation and propagation of these genes. Redundancy analysis (RDA) showed distribution of ARGs was related to the certain antibiotics residues, which may exert selective pressure on bacteria and thus enrich the abundance of ARGs. The results of this study could provide useful information for both better understanding and management of the contamination caused by ARGs and related antibiotics in engineered aquatic environments.201829727994
7778100.9994Distribution of antibiotic resistance in the effluents of ten municipal wastewater treatment plants in China and the effect of treatment processes. Municipal wastewater treatment plant (WWTP) effluents represent an important contamination source of antibiotic resistance, threatening the ecological safety of receiving environments. In this study, the release of antibiotic resistance to sulfonamides and tetracyclines in the effluents of ten WWTPs in China was investigated. Results indicate that the concentrations of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) ranged from 1.1 × 10(1) to 8.9 × 10(3) CFU mL(-1) and 3.6 × 10(1) (tetW) to 5.4 × 10(6) (tetX) copies mL(-1), respectively. There were insignificant correlations of the concentrations of ARB and ARGs with those of corresponding antibiotics. Strong correlations were observed between the total concentrations of tetracycline resistance genes and sulfonamide resistance genes, and both of which were significantly correlated with intI1 concentrations. Statistical analysis of the effluent ARG concentrations in different WWTPs revealed an important role of disinfection in eliminating antibiotic resistance. The release rates of ARB and ARGs through the effluents of ten WWTPs ranged from 5.9 × 10(12) to 4.8 × 10(15) CFU d(-1) and 6.4 × 10(12) (tetW) to 1.7 × 10(18) (sul1) copies d(-1), respectively. This study helps the effective assessment and scientific management of ecological risks induced by antibiotic resistance discharged from WWTPs.201728088530
7792110.9994Comparative removal of two antibiotic resistant bacteria and genes by the simultaneous use of chlorine and UV irradiation (UV/chlorine): Influence of free radicals on gene degradation. The research aimed to remove antibiotic resistance by the simultaneous use of UV irradiation and chlorine (UV/chlorine). The inactivations of tetracycline resistant bacteria (TRB) during chlorination, UV irradiation, and UV/chlorine was investigated and compared with those of amoxicillin resistant bacteria (AmRB). Similar examination was also conducted for comparing the removals of their resistant genes (i.e., tetM and blaTem). The removals of antibiotic resistance highly depended on chlorine doses and UV intensities. The sufficient chlorine dose (20 mg.L(-1)) in the chlorination and the UV/chlorine completely inactivated TRB and AmRB (>7.3 log), while the UV irradiation could not achieve the complete disinfection. Microorganisms resistant to different antibiotics exhibit different susceptibility to the disinfection processes. The removals of antibiotic resistant genes (i.e., tetM and blaTem) were more difficult than those of TRB and AmRB. The UV/chlorine was the greatest process for tetM and blaTem removals, followed by chlorination and UV irradiation, respectively. Chlorination decreased the tetM and blaTem by 0.40-1.45 log and 1.04-2.45 log, respectively. The blaTem gene was highly reactive to chlorine, compared with tetM. The UV irradiation caused the tetM and blaTem reductions by 0.32-0.91 log and 0.59-0.96 log, respectively. The UV/chlorine improved the tetM and blaTem removals by 0.98-3.20 log and 1.28-3.36 log, respectively. The •OH contributed to the fraction of tetM and blaTem removals by 48% and 19%, respectively. The effect of reactive chlorine species on the tetM and blaTem removals was minor. The pseudo 1st-order kinetic constants (k') for tetM and blaTem removals by the UV/chlorine were highest. The •OH enhanced the k' values by 120% and 20% for the tetM and blaTem removals, respectively. The study showed the potential use of UV/chlorine for controlling antibiotic resistance.202133059146
7777120.9994Fate of antibiotic resistant cultivable heterotrophic bacteria and antibiotic resistance genes in wastewater treatment processes. Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are emerging contaminants of environmental concern. Heterotrophic bacteria in activated sludge have an important role in wastewater treatment plants (WWTPs). However, the fate of cultivable heterotrophic ARB and ARGs in WWPTs process remains unclear. In the present study, we investigated the antibiotic-resistant phenotypes of cultivable heterotrophic bacteria from influent and effluent water of three WWTPs and analysed thirteen ARGs in ARB and in activated sludge from anoxic, anaerobic and aerobic compartments. From each influent or effluent sample of the three plants, 200 isolates were randomly tested for susceptibility to 12 antibiotics. In these samples, between 5% and 64% isolates showed resistance to >9 antibiotics and the proportion of >9-drug-resistant bacteria was lower in isolates from effluent than from influent. Eighteen genera were identified in 188 isolates from influent (n=94) and effluent (n=94) of one WWTP. Six genera (Aeromonas, Bacillus, Lysinibacillus, Microbacterium, Providencia, and Staphylococcus) were detected in both influent and effluent samples. Gram-negative and -positive isolates dominated in influent and effluent, respectively. The 13 tetracycline-, sulphonamide-, streptomycin- and β-lactam-resistance genes were detected at a higher frequency in ARB from influent than from effluent, except for sulA and CTX-M, while in general, the abundances of ARGs in activated sludge from two of the three plants were higher in aerobic compartments than in anoxic ones, indicating abundant ARGs exit in the excess sledges and/or in uncultivable bacteria. These findings may be useful for elucidating the effect of WWTP on ARB and ARGs.201525950407
7771130.9993Can chlorination co-select antibiotic-resistance genes? Selective pressures, such as chemical or heavy metal pollution, may co-select for bacterial antibiotic resistance in the environment. However, whether chlorination in water treatment can co-select antibiotic-resistant bacteria is controversial. In this study, high capacity quantitative polymerase chain reaction (qPCR) analysis was applied to target almost all known antibiotic-resistance genes (ARGs) (282 types) and 13 mobile genetic elements (MGEs) in bacteria detected in secondary effluents from a municipal wastewater treatment plant after chlorination. The results revealed that 125 unique ARGs were detected in non-chlorinated samples, and the number decreased (79-91 types) as the chlorine concentration was increased. Moreover, 7.49 × 10(4)-3.92 × 10(7) copies/100 ml water reduction of ARGs occurred with 4 mg Cl2/l. Considering the relative abundance of ARGs (i.e., ARG copies normalized to 16S rRNA gene copies), 119 ARGs decreased in response to chlorination, whereas only six ARGs, such as dfrA1, tetPB-03, tetPA, ampC-04, tetA-02, and erm(36), were potentially enriched by 10.90-, 10.06-, 8.63-, 6.86-, 3.77-, and 1.09-fold, respectively. Furthermore, the relative abundance of 12 detected MGEs was lower after chlorination. Therefore, chlorination was effective in reducing ARGs and MGEs rather than co-selecting them.201627192478
7770140.9993Mitigation of antibiotic resistance in a pilot-scale system treating wastewater from high-speed railway trains. Wastewater from high-speed railway trains represents a mobile reservoir of microorganisms with antibiotic resistance. It harbors abundant and diverse antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). This study investigated the removal of ARB and ARGs in a pilot-scale reactor, which consisted of an anaerobic/anoxic/oxic process, anaerobic/anoxic/aerobic process, and ozone-based disinfection to treat 1 m(3)/day wastewater from an electric multiple unit high-speed train. Further, the high prevalence of two mobile genetic elements (intI1 and Tn916/615) and five ARGs (tetA, tetG, qnrA, qnrS, bla(NDM-1), and ermF) was investigated using quantitative PCR. Significant positive correlations between ARGs (tetA, bla(NDM-1), and qnrA) and intI1 were identified (R(2) of 0.94, 0.85, and 0.70, respectively, P < 0.01). Biological treatment could significantly reduce Tn916/1545 (2.57 logs reduction) and Enterococci (2.56 logs reduction of colony forming unit (CFU)/mL), but the qnrS abundance increased (1.19 logs increase). Ozonation disinfection could further significantly decrease ARGs and Enterococci in wastewater, with a reduction of 1.67-2.49 logs and 3.16 logs CFU/mL, respectively. Moreover, food-related bacteria families which may contain opportunistic or parasitic pathogens (e.g., Moraxellaceae, Carnobacteriaceae, and Ruminococcaceae) were detected frequently. Enterococci filtered in this study shows multi-antibiotic resistance. Our study highlights the significance to mitigate antibiotic resistance from wastewater generated from high-speed railway trains, as a mobile source.202031864053
7208150.9993Occurrence and removal of antibiotics and the corresponding resistance genes in wastewater treatment plants: effluents' influence to downstream water environment. In this study, the occurrence of 8 antibiotics [3 tetracyclines (TCs), 4 sulfonamides, and 1 trimethoprim (TMP)], 12 antibiotic resistance genes (ARGs) (10 tet, 2 sul), 4 types of bacteria [no antibiotics, anti-TC, anti-sulfamethoxazole (SMX), and anti-double], and intI1 in two wastewater treatment plants (WWTPs) were assessed and their influences in downstream lake were investigated. Both WWTPs' effluent demonstrated some similarities, but the abundance and removal rate varied significantly. Results revealed that biological treatment mainly removed antibiotics and ARGs, whereas physical techniques were found to eliminate antibiotic resistance bacteria (ARBs) abundance (about 1 log for each one). UV disinfection did not significantly enhance the removal efficiency, and the release of the abundantly available target contaminants from the excess sludge may pose threats to human and the environment. Different antibiotics showed diverse influences on the downstream lake, and the concentrations of sulfamethazine (SM2) and SMX were observed to increase enormously. The total ARG abundance ascended about 0.1 log and some ARGs (e.g., tetC, intI1, tetA) increased due to the high input of the effluent. In addition, the abundance of ARB variation in the lake also changed, but the abundance of four types of bacteria remained stable in the downstream sampling sites.201626658782
7205160.9993Antibiotics and antibiotic resistance genes removal in biological aerated filter. Two laboratory-level biological aerated filters (BAF) were constructed to explore their treatment capacity for simulated antibiotic wastewater at high (1 - 16 mg/L) and low (0 - 0.5 mg/L) concentrations. Results showed that BAF was capable of removing both sulfonamides and tetracyclines with an efficiency of over 90 % at 16 mg/L. The main mechanism for removing antibiotics was found to be biodegradation followed by adsorption. Paenarthrobacter was identified as the key genus in sulfonamides degradation, while Hydrogenophaga played a crucial role in tetracyclines degradation. Antibiotics resistant genes such as intI1, sul1, sul2, tetA, tetW and tetX were frequently detected in the effluent, with interception rates ranging from 10(5) - 10(6) copies/mL. The dominated microorganisms obtained in the study could potentially be utilized to enhance the capacity of biological processes for treating antibiotics contaminated wastewater. These findings contribute to a better understanding of BAF treating wastewater containing antibiotics and resistant genes.202438301943
7209170.9993Role of a typical swine liquid manure treatment plant in reducing elements of antibiotic resistance. Biological treatment of swine liquid manure may be a favorable environment for the enrichment of bacteria carrying antibiotic resistance genes (ARGs), raising the alert about this public health problem. The present work sought to investigate the performance of a swine wastewater treatment plant (SWWTP), composed of a covered lagoon biodigester (CLB) followed by three facultative ponds, in the removal of usual pollutants, antibiotics, ARGs (blaTEM, ermB, qnrB, sul1, and tetA), and intI1. The SWWTP promoted a 70% of organic matter removal, mainly by the digester unit. The facultative ponds stood out in the solids' retention carried from the anaerobic stage and contributed to ammonia volatilization. The detected antibiotic in the raw wastewater was norfloxacin (< 0.79 to 60.55 μg L(-1)), and the SWWTP seems to equalize peaks of norfloxacin variation probably due to sludge adsorption. CLB reduced the absolute abundance of ARGs by up to 2.5 log, while the facultative stage does not seem to improve the quality of the final effluent in terms of resistance elements. Considering the relative abundances, the reduction rates of total and ARG-carrying bacteria appear to be similar. Finally, correlation tests also revealed that organic matter and solids control in liquid manure treatment systems could help reduce the spread of ARGs after the waste final disposal.202337477815
7238180.9993Prevalence of antibiotic resistance genes in different drinking water treatment processes in a northwest Chinese city. Antibiotic resistance genes (ARGs) are an emerging issue which are receiving increasing concerns in drinking water safety. However, the factors (e.g. treatment processes and water quality) affecting the removal efficiency of ARGs in the drinking water treatment plants (DWTPs) is still unclear. This work investigated the ARG profiles in each treatment process of two DWTPs located in a northwest Chinese city. The results showed that tetracycline and sulfonamide resistance genes were predominant among the 14 targeted ARGs. After the treatment, the Z water treatment plant which demonstrated a higher removal rate of ARGs (ranging from 50 to 80%), compared to the S plant (50-75%). And the average removal rate of tetracycline resistance genes (tetA, tetG, tetQ, tetX) was about 49.18% (S plant) and 67.50% (Z plant), as well as the removal rate of 64.2% and 72.9% for sulfonamide resistance (sul1 and sul2) at S and Z water plants, respectively. It was found that the relative abundance of main microbial communities (such as Bacteroidota, Actinobacteria, Verrucomicrobiota, Roseomonas), α-diversity index, as well as the abundance of pathogenic bacteria were all significantly reduced after different treatment processes. Network co-occurrence analysis revealed that Methylocystis possibly was the potential host for most ARGs, and sul1 was found across a broad spectrum of microorganisms in the drinking water environment. Adonis analysis showed that heavy metals and microbial communities explain solely 44.1% and 35.7% of variances of ARGs within DWTPs. This study provides insights into the contamination status and removal efficiencies of ARGs in DWTPs, offering valuable references for future studies on ARG removal, propagation, and diffusion patterns in drinking water treatment.202439316241
7181190.9993Effects of UVC doses on the removal of antimicrobial resistance elements from secondary treated sewage. Wastewater treatment plants (WWTPs) currently face major challenges toward the removal of microcontaminants and/or microbial matrices and consequently play an important role in the potential dissemination of biological resistance in freshwater. The ultraviolet (UV) system is a tertiary treatment strategy increasingly applied worldwide, although many studies have shown that disinfected effluent can still contain antibiotic-resistant bacteria and resistance genes. Therefore, to better understand the effects of UV radiation doses on the removal of all resistance elements (antibiotics, antibiotic-resistant bacteria, and antibiotic resistance genes), the present study was designed using a pilot-scale photoreactor. The UV doses could be varied to investigate whether there is an optimal UV dose capable of removing all resistance elements and also if the UV dose frequently applied in full-scale systems is able to reduce the resistance elements. The effect of different UV doses (A, 0-10 mJ/cm(2); B, 10-15 mJ/cm(2); and C, > 15 mJ/cm(2)) in a pilot-scale photoreactor on the removal of antibiotics, antibiotic-resistant bacteria, and genes from the effluent of a UASB reactor followed by a biological trickling filter system (UASB-TF) fed with real sanitary sewage was investigated. Samples of influent and effluent from the UVC photoreactor were collected, and the concentration levels of norfloxacin (NOR), ciprofloxacin (CIP), and levofloxacin (LEV) were assessed. The qnrB, sul1, ermB, integron-integrase (intI1), and 16S rRNA genes, total heterotrophic bacteria (THB), and bacterial resistance to azithromycin and sulfamethoxazole were also investigated. Results indicated that LEV and intI1 were found in the highest median concentrations in the photoreactor influent. Although most antibiotics (NOR and CIP) and ARGs (intI1, 16S rRNA, and qnrB) were apparently better removed with the highest UV dose (> 15 mJ/cm(2)) applied, except for LEV, sul1, and ermB genes, the Kruskal-Wallis test reported no significant difference between low and high doses. ARB removal (from 80 to 100%) was observed at all UV doses. Principal component analysis (PCA) suggested a clear pattern of pollutant groups, i.e., antibiotics, ARG, and ARB, which exhibited low (median of 8-16%), medium (37-96%), and high (> 97%) removal percentages, respectively. These results demonstrated that UVC photoreactors can be an alternative to complement biological treatment in sewage treatment plants at the dose normally applied in full-scale WWTPs (> 15 mJ/cm(2)). However, there was no optimal single dose capable of removing all the resistance elements investigated.202539873874