Role Of Wastewater Treatment Plants Research Articles

The Role of Wastewater Treatment Plants in Dissemination of Antibiotic Resistance: Source, Measurement, Removal and Risk Assessment.

Antibiotic Resistance Genes (ARGs) are contaminants of emerging concern with marked potential to impact public and environmental health. This review focusses on factors that influence the presence, abundance, and dissemination of ARGs within Wastewater Treatment Plants (WWTPs) and associated effluents. Antibiotic-Resistant Bacteria (ARB) and ARGs have been detected in the influent and the effluent of WWTPs worldwide. Different levels of wastewater treatment (primary, secondary, and tertiary) show different degrees of removal efficiency of ARGs, with further differences being observed when ARGs are captured as intracellular or extracellular forms. Furthermore, routinely used molecular methodologies such as quantitative polymerase chain reaction or whole genome sequencing may also vary in resistome identification and in quantifying ARG removal efficiencies from WWTP effluents. Additionally, we provide an overview of the One Health risk assessment framework, as well as future strategies on how WWTPs can be assessed for environmental and public health impact.

Quorum sensing bacteria improve microbial networks stability and complexity in wastewater treatment plants

Quorum-sensing bacteria (QSB) are crucial factors for microbial communication, yet their ecological role in wastewater treatment plants (WWTPs) remains unclear. Here, we developed a method to identify QSB by comparing 16S rRNA gene sequences. QSB in 388 activated sludge samples collected from 130 WWTPs across China primarily were identified as rare taxa and conditionally rare taxa. A co-occurrence network shared by all sludge communities revealed that QSB exhibited higher average clustering coefficient (0.46) than non-QSB (0.15). Individual sludge networks demonstrated that quorum sensing microbiomes were positively correlated with network robustness and network complexity, including average clustering coefficient and link density. We confirmed that QSB keystones and QSB nodes have a positive impact on network complexity by influencing network modularity through a structural equation model. Meanwhile, QSB communities directly contributed to maintaining network robustness (r = 0.29, P < 0.05). Hence, QSB play an important role in promoting network complexity and stability. Furthermore, QSB communities were positively associated with the functional composition of activated sludge communities (r = 0.33, P < 0.01), especially the denitrification capacity (r = 0.45, P < 0.001). Overall, we elucidated the ecological significance of QSB and provided support for QS-based regulation of activated sludge microbial communities.

The environmental occurrence, fate, and risks of 25 endocrine disruptors in Slovenian waters

Natural hormones, synthetic steroids and bisphenols are among the most active endocrine disruptors (EDs) in the aquatic environment, with great potential for causing adverse effects in aquatic organisms and humans. In this study, a focused group of 25 potent estrogenic and other ED compounds were simultaneously measured in wastewaters (WWs) and receiving surface waters (SWs) before and after wastewater treatment plants (WWTPs), where their removal efficiency was also estimated. Up to 16 of 25 EDs were successfully quantified in SWs and WWs, with bisphenols BPS, BPA, and BPF together with estriol and chlormadinone being the most prevalent with the highest measured concentrations of up to 35 μg/L in WWs and 400 ng/L in SWs. High load and insufficient removal of these substances by WWTPs lead to a significant increase in their concentrations in the receiving SWs downstream, while other sources could be responsible for an important portion of river contamination with EDs. Removal efficiency was very good for most EDs, although only from 0 to 44 % for E2, which shows a need for the improvement of current removal techniques. E2 and EE2 contribute the most to the alarmingly high risks of the total ED estrogenic potential, with the value increased by 36 % in SWs downstream from WWTPs, and the RQ value for the total estrogenic potential in individual SW samples being three orders of magnitude higher than that representing high risk. An additional comprehensive multi-parameter risk assessment determined high risk quotient and priority index values for BPA, E2, BPS and E1 with values of up to 450 in SWs. Our results show a focused insight into the risks associated with an important group of EDs and the role of WWTPs, while further highlighting the importance of regular monitoring of the environmental occurrence and risks of a focused range of EDs.

Role of wastewater treatment plants in pollution reduction - evaluated by grey water footprint indicator

The study assesses the pollution discharged from 251 wastewater treatment plants (WWTPs) throughout the Odra river basin in the Czech Republic. The development of pollution production over a period of 15 years (2004–2018) together with a number of WWTPs in the Odra river basin were analyzed. The grey water footprint (GWF) of discharged pollution was determined both in terms of individual size categories of WWTPs and in terms of the parameter that most affects the level of pollution. The share of the small WWTPs size categories (up to 2,000 PE) on the total GWF value of discharged pollution is only 8%, although these are the most numerous. The share of the WWTPs of the size category &gt; 10,000 PE on the total GWF value of discharged pollution is 82%. Total phosphorus (at large WWTPs) and ammonium nitrogen (at small WWTPs) were identified as the key pollutants that most determine the value of the grey water footprint of discharged pollution.

Increased Antimicrobial and Multidrug Resistance Downstream of Wastewater Treatment Plants in an Urban Watershed.

Development and spread of antimicrobial resistance (AMR) and multidrug resistance (MDR) through propagation of antibiotic resistance genes (ARG) in various environments is a global emerging public health concern. The role of wastewater treatment plants (WWTPs) as hot spots for the dissemination of AMR and MDR has been widely pointed out by the scientific community. In this study, we collected surface water samples from sites upstream and downstream of two WWTP discharge points in an urban watershed in the Bryan-College Station (BCS), Texas area, over a period of nine months. E. coli isolates were tested for resistance to ampicillin, tetracycline, sulfamethoxazole, ciprofloxacin, cephalothin, cefoperazone, gentamycin, and imipenem using the Kirby-Bauer disc diffusion method. Antimicrobial resistant heterotrophic bacteria were cultured on R2A media amended with ampicillin, ciprofloxacin, tetracycline, and sulfamethoxazole for analyzing heterotrophic bacteria capable of growth on antibiotic-containing media. In addition, quantitative real-time polymerase chain reaction (qPCR) method was used to measure eight ARG – tetA, tetW, aacA, ampC, mecA, ermA, blaTEM, and intI1 in the surface water collected at each time point. Significant associations (p < 0.05) were observed between the locations of sampling sites relative to WWTP discharge points and the rate of E. coli isolate resistance to tetracycline, ampicillin, cefoperazone, ciprofloxacin, and sulfamethoxazole together with an increased rate of isolate MDR. The abundance of antibiotic-resistant heterotrophs was significantly greater (p < 0.05) downstream of WWTPs compared to upstream locations for all tested antibiotics. Consistent with the results from the culture-based methods, the concentrations of all ARG were substantially higher in the downstream sites compared to the upstream sites, particularly in the site immediately downstream of the WWTP effluent discharges (except mecA). In addition, the Class I integron (intI1) genes were detected in high amounts at all sites and all sampling points, and were about ∼20 times higher in the downstream sites (2.5 × 107 copies/100 mL surface water) compared to the upstream sites (1.2 × 106 copies/100 mL surface water). Results suggest that the treated WWTP effluent discharges into surface waters can potentially contribute to the occurrence and prevalence of AMR in urban watersheds. In addition to detecting increased ARG in the downstream sites by qPCR, findings from this study also report an increase in viable AMR (HPC) and MDR (E. coli) in these sites. This data will benefit establishment of improved environmental regulations and practices to help manage AMR/MDR and ARG discharges into the environment, and to develop mitigation strategies and effective treatment of wastewater.

One water – evolving roles of our precious resource and critical challenges

AbstractThis article presents the evolving challenges and roles of our water resources in this contemporary world. First, water quality issues surrounding water supplies are discussed. Potential pathways to address the water quality challenges are presented, which include technological approaches for minimizing waste and enhancing resource recovery. Focused discussions on emerging global pollutants such as microplastics and PFAS (per- and poly-fluoro alkyl substances) and treatment alternatives are included. Next, the roles of used water (wastewater) in the wake of circular economy and recent outbreaks are discussed. The potential for energy and resource recovery possibilities and the critical role of wastewater treatment plants in controlling the spread of outbreaks are discussed in detail. Finally, perspectives on some of the key developments essential for transforming our water infrastructure, addressing water-centered socio-economic issues and the critical needs of digitalization in water sector operations are presented.

Effect of earthworms in reduction and fate of antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs) during clinical laboratory wastewater treatment by vermifiltration

In the recent decades, the role of wastewater treatment plants has been entrenched for the dissemination of antibiotic resistant bacteria into the environment. The present study explores the dynamics of earthworms-microorganisms interactions involved in the high treatment efficacy of vermifiltration technology along with reduction of antibiotic resistant bacteria (ARB). This study is the first of its kind to investigate the performance efficacy of vermifilter (VF) for clinical laboratory wastewater treatment. The results of the study showed that earthworms and VF associated microbial community had a significant effect on Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) reduction (78–85%), coliforms and pathogen removal (>99.9%) and caused a significant shift in the prevalence pattern of ARB. Molecular profiling of resistance causing genes such as ESBL (blaSHV, blaTEM and blaCTX-M), MRSA (mec-A) and Colistin (mcr-1) confirmed the probable mechanisms behind the resistance pattern. The microbial community diversity in the influent, earthworm's coelomic fluid and gut and filter media layers associated with the VF assists in the formation of biofilm, which helps in the removal of pathogens from the wastewater. This biofilm formation further results in a paradigm shift in the resistance profile of ARB and ARG, specifically most effective against drugs, targeting cell wall and protein synthesis inhibition such as Ampicillin, Ticarcillin, Gentamicin and Chloramphenicol. These findings further validate vermifiltration technology as a sustainable and natural treatment technology for clinical laboratory wastewater, specifically for the removal of pathogens and antibiotic resistance.

Microfibers from synthetic textiles as a major source of microplastics in the environment: A review

Microplastic fibers, also known as microfibers, are the most abundant microplastic forms found in the environment. Microfibers are released in massive numbers from textile garments during home laundering via sewage effluents and/or sludge. This review presents and discusses the importance of synthetic textile-based microfibers as a source of microplastics. Studies focused on their release during laundering were reviewed, and factors affecting microfiber release from textiles and the putative role of wastewater treatment plants (WWTPs) as a pathway of their release in the environment were examined and discussed. Moreover, potential adverse effects of microfibers on marine and aquatic biota and human health were briefly reviewed. Studies show that thousands of microfibers are released from textile garments during laundering. Different factors, such as fabric type and detergent, impact the release of microfibers. However, a relatively smaller number of available studies and often conflicting findings among studies make it harder to establish definitive trends related to important factors contributing to the release of microfibers. Even though current WWTPs are highly effective in capturing microfibers, due to the presence of a massive number of microfibers in the influent, up to billions of fibers per day are released through effluent into the environment. There is a need to establish standardized protocols and procedures that can allow meaningful comparisons among studies to be performed.

Role of different wastewater treatment plants in antibiotic resistance spreading

Abstract The global action plan on antimicrobial resistance reports the necessity to develop standards and guidance for the presence of antimicrobial agents in the environment, especially in wastewater, highlighting its possible role in the antibiotic resistance spreading. In addition, the New European One Health Action Plan against Antimicrobial Resistance underlines the need to support research into knowledge gaps on the release of resistant microorganisms into the environment and their dissemination. The aim of this study was to evaluate the presence of Antibiotic Resistance Bacteria (ARB) and Antibiotic Resistance Genes (ARG) in wastewater treatment plants (WWTPs). At this scope, untreated sewage and treated effluents of three different WWTPs (A, B and C) were sampled for one year. Sample dilutions were plated on R2Agar added/not-added with 4 different antibiotics (ampicillin 32mg/L; tetracycline 16 mg/L; chloramphenicol 32 mg/L; sulfamethoxazole 50,4 mg/L) to evaluate the percentage of antibiotic resistant bacteria and their WWTPs removal rate (%). DNA extraction on the filter used to concentrate the wastewater samples was performed to reveal the ARG presence; subsequently specific PCRs for ARG (blaTEM, tetA, sul II, sul III) were carried out. ARB were detected in all samples analysed. The highest antibiotic resistance percentage was revealed in the sewage (mean 21,7%±4,8) and effluent (mean 21,1%±3,0) of the three wastewater treatment plants for sulfamethoxazole. Moreover, sul II was the most present gene in the samples (81% of all samples, 89 % of sewages and 72% of effluents). The lower WWTPs removal was recovered in the plant B for the tetracycline (95, 7%). The results obtained underlines the need to monitor WWTP as critical hot spot for the antibiotic resistance spreading also considering the One Health approach. Furthermore, the results obtained could suggest interventions to reduce the spread of the antibiotic resistance in the integrated urban water cycle. Key messages The information obtained could provide usefulness information about the role of wastewater treatment plant in the antibiotic resistance spreading. The results could contribute to suggest the interventions targeted to reduce the antibiotic resistance phenomenon in the integrated urban water cycle.

Microplastic Monitoring at Different Stages in a Wastewater Treatment Plant Using Reflectance Micro-FTIR Imaging

While the presence of microplastics has been reported in aquatic habitats across the globe, the pathways through which they enter the environment are still poorly understood. Studies investigating the fate of microplastics in wastewater are gaining attention but are still scarce, despite the urgent need to understand the role of wastewater treatment plants (WWTP) as point sources of aquatic microplastic pollution. A likely reason for the limited number of WWTP-associated studies is that working with a biogenic organic matter (BOM)-rich sample matrix like wastewater is challenging. Here, we investigated the presence of microplastics (MP) throughout several stages of a wastewater treatment plant (WWTP) at multiple depths, employing Fenton’s reagent and focal plane array-based reflectance micro-Fourier-transform infrared spectroscopic (FPA-based reflectance micro-FTIR) imaging, a protocol that allows the automated detection and identification of microplastics in complex samples with high organic matter content, without the need for previous visual sorting, or reducing considerably the thickness of the sample, or the use of IR-transparent transmission windows. It was found that the number of microplastic fragments detected at downstream stages of the WWTP notably decreased following the primary settlement stage, with primary settlement stage samples responsible for 76.9% of total microplastics detected. Despite the marked reduction in the number of microplastic particles following the primary settlement stage, an average total of 1.5 MP L-1 were identified in the final effluent of the WWTP.

Spectroscopic analysis of microplastic contaminants in an urban wastewater treatment plant from Seoul, South Korea

In this study, a systematic multi-spectroscopic analysis of microplastics (MPs) sampled from a metropolitan area of Seoul was undertaken to elevate understanding of the role of wastewater treatment plants (WWTPs) in eliminating suspended contaminants including MPs before releasing the effluent water into the environment. We analyzed pollutants in influent and effluent samples from a WWTP in Seoul, South Korea. Spectroscopic and microscopic methods were used to analyze MPs. Fourier-transform infrared (FT-IR) spectroscopy in the wavenumber region between 4000 and 715 cm−1 was employed to estimate the abundance of MPs in wastewater. Stereomicroscope images and Nile red staining were used to facilely identify MPs in both influents and effluents to compare the results with those of FT-IR data. Hyperspectral imaging could identify MPs in the influent sample with the reflection method at 400–900 nm. Our preliminary results indicate that the most observed MPs after the wastewater were filtered by a 45 μm stainless steel mesh filter were polyethylene (PE) and polypropylene (PP). The total number of the prevalent MPs in influent samples decreased significantly. Nanostructure particles could be found by field-emission scanning electron microscopy (FE-SEM). Our combined multi-spectroscopic study should be helpful to provide a guideline for the rapid spectroscopic analysis of freshwater in the Han River, Seoul, South Korea.

The Possible Roles of Wastewater Treatment Plants in Sector Coupling

The development of a power system based on high shares of renewable energy sources puts high demands on power grids and the remaining controllable power generation plants, load management and the storage of energy. To reach climate protection goals and a significant reduction of CO2, surplus energies from fluctuating renewables have to be used to defossilize not only the power production sector but the mobility, heat and industry sectors as well, which is called sector coupling. In this article, the role of wastewater treatment plants by means of sector coupling is pictured, discussed and evaluated. The results show significant synergies—for example, using electrical surplus energy to produce hydrogen and oxygen with an electrolyzer to use them for long-term storage and enhancing purification processes on the wastewater treatment plant (WWTP). Furthermore, biofuels and storable methane gas can be produced or integrate the WWTP into a local heating network. An interconnection in many fields of different research sectors are given and show that a practical utilization is possible and reasonable for WWTPs to contribute with sustainable energy concepts to defossilization.

Role of wastewater treatment plants in distribution of antibiotic resistance genes

Role of wastewater treatment plants in distribution of antibiotic resistance genes

Circular Economy in Wastewater Treatment Plant

Abstract Wastewater treatment plants are becoming an important part of circular economy. In addition to the classic role of wastewater treatment plants, they are gaining a new important mission to fulfil. According to the Nutrients-Energy-Water (N-E-W) paradigm, wastewater treatment plants should also focus on energy production and resource recovery. Intensification of biogas production is an important element in improving the energy efficiency of wastewater treatment plants. This can be achieved by introducing sewage sludge co-digestion with organic substrate, thermal hydrolysis and disintegration of the sludge. Water renewal, which includes a number of processes to restore the water features of the wastewater, is also becoming an important objective. Intensive research is being carried out on the production of bioplastics by bacteria inhabiting municipal and industrial sewage. Technologies for recovery of nutrients (nitrogen and phosphorus) from sewage and sludge are also advanced. The paper presents current trends in the development of sewage treatment plants based on the assumptions of circular economy and current policy of the European Green Deal.

Study on Propellers Distribution and Flow Field in the Oxidation Ditch Based on Two-Phase CFD Model

The oxidation ditch (OD) plays an important role in wastewater treatment plants. With increasing demand and production costs, the energy consumption and sludge deposition occurring in the OD must be diminished to enhance its development. In this paper, a two-phase computational fluid dynamics (CFD) model of water and activated sludge examined the flow field characteristics of an OD, consisting of two side-by-side propellers. The system was studied under five configurations, where the spacing between the propellers was set equal to −0.2, −0.1, 0, 0.1, 0.2 times the length of the OD. The viscosity and settling rate of activated sludge was imported in the numerical simulation through a user defined function (UDF). The optimal scheme of the propeller’s power consumption, velocity distribution, and sludge concentration distribution was obtained. The result shows that sludge concentrations are linked with dead zone velocity but not necessarily with low velocities. Experiments confirmed the validity of the velocity flow field simulated by the two-phase CFD model. Overall, these findings form the basis for the propellers distribution optimization and allow a deeper insight into the flow field of OD systems.

Role of wastewater treatment plants on environmental abundance of Antimicrobial Resistance Genes in Chilean rivers.

Point sources such as wastewater treatment plants (WWTPs) commonly discharge their effluent into rivers. Their waste may include antibiotic residues, disinfectants, antibiotic resistant bacteria (ARB), and Antimicrobial Resistance Genes (ARG). There is evidence that ARG can be found in the natural environment, but attribution to specific point sources is lacking. The goal of this study was to assess the release and dissemination of ARG from three WWTPs in southern Chile via two pathways: through the river systems, and through wild birds. A longitudinal study was conducted, collecting river sediment samples at different distances both upstream and downstream from each WWTP. Wild birds were sampled from around one of the WWTPs once a month for 13 months. A microfluidic q-PCR approach was used to quantify 48 genes covering different molecular mechanisms of resistance, and data was analyzed using ordination methods and linear mixed regression models. There was a statistically significant increase downstream from the WWTPs (p < 0.05) for 17 ARG, but the downstream dissemination through the rivers was not clear. Beta-lactamase genes blaKPC, blaTEM, and blaSHV were the most abundant in birds, with higher abundance of blaSHV in migratory species compared to resident species (p < 0.05). The gene profile was more similar between the migratory and resident bird groups compared to the WWTP gene profile. While results from this study indicate an influence of WWTPs on ARG abundance in the rivers, the biological significance of this increase and the extent of the WWTPs influence are unclear. In addition, wild birds were found to play a role in disseminating ARG, although association to the specific WWTP could not be ascertained.

Prevalence and characterization of Staphylococcus aureus in wastewater treatment plants by whole genomic sequencing

Infections with Staphylococcus aureus are being spread through contact with the community environment, but the role of wastewater treatment plants in the transmission routes is not defined. This study investigated the prevalence, types, genetic elements, and potential for transmission of S.aureus by these engineered systems. Synchronized sampling events at two wastewater treatment plants were conducted with isolates of S.aureus obtained by a selective enrichment method using acriflavine that suppressed Staphylococcus epidermidis growth. DNA was extracted from a subset of the S.aureus isolates, checked by PCR to assure the absence of S.epidermidis, and sequenced to determine the multilocus sequence type, spa type, and carriage of the methicillin resistance and Panton-Valentine leukocidin genetic elements. Sequences were analyzed for single nucleotide polymorphism differences in pairwise comparison of isolates. There were two dominant S.aureus clonal complexes identified in the isolates, one commonly identified as hospital-related (CC5) and one community-related (CC8). Both types of isolates were found at both treatment facilities, even though only one facility had significant hospital sewage inputs. The presence of S.aureus persisted through treatment, with some isolates recovered from the final processes showing genetic diversity. The presence of the Panton-Valentine leukocidin genetic element was greater than the 1-5% expected from global reports. Our results suggest that treatment provides an opportunity for genetic shift, while the persistence and release of evolved strains of S.aureus may provide an environmentally relevant pathway to new hosts in the environment.

Assessment of the Role of Wastewater Treatment Plant in Spread of Antibiotic Resistance and Bacterial Pathogens.

In current study, we performed a comparative study on bacterial load, total coliform counts and type of organisms present in pre- and post-treated wastewater samples from municipal wastewater treatment plant of Pune, India. In addition, we also studied the antibiotic resistance profiling and role of the selected treatment plant in spread of antibiotic resistance in the environment. Data showed that total 30 different bacterial species from 18-different genera were present in untreated wastewater while only 9 species from 6-different genera were present in post-treated effluent. Furthermore, pre-treated wastewater sample contains wide range of organisms with high levels of antibiotic resistance while bacterial load reduced drastically and pathogens were absent from post-treated effluent.

Occurrence of extended-spectrum β-lactamase (ESBL)/AmpC producing bacteria in wastewater treatment plant effluent

Extended-spectrum β-lactamase (ESBL)/AmpC producing bacteria are one of the critical priority resistant bacteria that contributes to treatment failure and increased death rates. In this work we aimed to study the role of wastewater treatment plants (WWTPs) as reservoirs of ESBL/AmpC producing faecal coliforms. The effluent samples were collected from two WWTPs and faecal coliforms were isolated from all samples using the membrane filtration method. Bacterial isolates were subjected to antimicrobial susceptibility testing toward cefotaxime and ceftazidime. The isolates that showed a resistance phenotype to these antibiotics were considered as putative ESBL/AmpC producing bacteria. These bacteria were subjected to the AmpC test using a protocol with phenylboronic acid. The AmpC negative strains in the AmpC test served as samples for multiplex PCR containing primers specific for blaTEM, blaSHV and blaCTX-M. In total, 498 faecal coliforms were isolated from WWTP effluent samples. For the antibiotic susceptibility testing 99 isolates were considered as ESBL/AmpC producing bacteria. Among them, 26 isolates were found to be positive in the AmpC test. The PCR results revealed that 49 isolates carried blaTEM, 6 bla SHV12, 1 blaCTX-M1 and 5 blaCTX-M15. The ESBL/AmpC producing faecal coliforms in WWTP effluent are discharged to the receiving water environment. These data need to be considered when analysing the risk of WWTP effluent to the environment and to human health, as many of the bacteria identified are not analysed in assessment of risk of pollution from WWTPs globally.

The Role of Wastewater Treatment Plants in the Environmental Dissemination of Antibiotic Resistant Bacteria (ARB) and Resistance Genes (ARG)

This study was conducted to evaluate the influence of wastewater treatment processes on the prevalence of antibiotic resistance fecal coliform (FC) and antibiotic resistance genes (ARGs) of FC. In addition, the occurrence of antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs) in surface waters receiving wastewater was evaluated. Greater resistance against penicillin (P), colisitin (CT) and ampicillin (AMP) were observed for FC isolated from effluent disinfected by chlorine (71%), than that disinfected by UV (45%). The greatest resistance against six antibiotics was recorded for FC isolates from effluent disinfected by chlorine. The prevalence of tetB and blaSHV was lowest in isolates from chlorine-disinfected effluents. The occurrence of ARG blaSHV was highest in FC isolated from effluent disinfected by UV. A significant correlation was recorded between FC levels in surface waters and the level of bacterial resistance to ampicillin (P SHV in effluents and in surface waters. TetA and tetC were highly prevalent in surface water compared to tetB. The results of the study demonstrate the widespread prevalence of ARB and ARG in wastewater and receiving water bodies. The result indicates that the source of ARB and ARG in surface waters originate from wastewater. Released ARB and ARG may serve as the source of ARG to pathogenic bacteria in surface waters. Disinfection processes may influence the selection of antibiotic resistant patterns of bacteria.