Wastewater Treatment Plant Effluent Samples Research Articles

Digital One-Step Competitive Detection of a Small Molecule in Synthetic and Environmental Waters.

Optical methods for single-molecule analysis hold the promise of accurate, sensitive, and rapid detection of target molecules. Here, we demonstrate the efficiency of such an approach for the competitive detection of small molecules in water. Our biosensing method is based on a combination of a single-DNA biochip for the parallelization of tethered particle motion real-time measurements with antibodies and modified targets as molecular competitors. The antibodies are coupled to the particles tethered to the surface by a long DNA bearing in its middle the molecular competitor bound to the antibodies. Competitive target binding leads to a detectable conformational change of the DNA tethers from looped to unlooped in proportions related to the target concentration. We thus managed to detect fluorescein, chosen as a model of a target molecule, in freshwater of various qualities, from solutions prepared with ultrapure water to more complex matrices such as river water and wastewater treatment plant effluent samples. Similar dose-response curves were obtained under these various conditions in a wide range of concentrations from nanomolar to micromolar with a limit of detection around 2 nM.

Improving sample preparation by biochar-coated sampling tubes: proof-of-concept extraction of sex hormones from real waters

This work showcases a novel application of biochar for analytical sample treatment. The carbonaceous material, obtained by pyrolysis of orange peel waste (550°C) without any post-synthesis treatment or functionalization, was thoroughly characterized and easily immobilized on the inner wall of sampling tubes in order to perform a sort of “in-vial” solid-phase extraction (SPE). The as-obtained device was tested for the extraction of seven sexual steroids, as probe water pollutants, from tap, lake, river water and wastewater treatment plant effluent samples spiked with 0.2-5 µg L−1 of each compound. The sorption kinetics profiles showed quantitative uptake from the sample (25 mL) in 20 min contact time, followed by complete elution in pure ethanol (2 mL, 15 min), thanks to the proper balance between sorption affinity and ease of elution. Under the selected conditions, recovery was in the range 60-123 %, with good inter-day precision (RSD 10-18 %, n=3). As evidence of the excellent reproducibility, an overall RSD below 15 % was observed from inter-day inter-batch recovery tests on three individually prepared sampling tubes. The procedure, carried out on a roller mixer, allows 10 samples to be extracted simultaneously, improving the sample throughput. Moreover, reusability tests showed that the same device maintains its efficiency for 10 consecutive sorption/desorption cycles. The greenness assessment, carried out by two dedicated software, further supported the sustainability of this biochar-based sample preparation as an alternative SPE.

Long term study on the fate and environmental risks of favipiravir in wastewater treatment plants and comparison with COVID-19 cases

In recent years especially during COVID-19, the increased usage of antiviral drugs has led to increased interest in monitoring their presence in wastewater worldwide. In this study, it was examined the occurrence, fate and environmental risks of favipiravir which is used for COVID-19 treatment in two wastewater treatment plants (WWTPs) with different treatment processes in Istanbul, Turkey. Favipiravir was measured in WWTPs influent samples, effluent samples and sludge samples with maximum concentrations of 97 μg/L, 64.11 μg/L and 182.47 μg/g, respectively. Favipiravir had removal efficiency below 55 % for both WWTPs. Mass balance analysis showed that favipiravir removal in WWTPs mainly attributed to biodegradation/biotransformation. Statistical analysis revealed a significant correlation between favipiravir concentration and COVID-19 incidence in Istanbul. The microbial distribution analysis indicated that comparison of collected COVID-19 pandemic sludge and post-pandemic period sludge samples, a noteworthy reduction in the Chloroflexi and Actinobacteriota phyla at the phylum level was observed. Environmental risk assessment using risk quotients ranged from 168 to 704, indicating that the presence of this antiviral drug posed significant ecological risks to aquatic organisms. The study concluded that WWTPs were releasing antiviral drugs into the environment, thereby posing risks to both the aquatic ecosystem and public health. The results of this study demonstrate the persistence of favipiravir in WWTPs and offer crucial supporting data for further research into the advancement of wastewater treatment technology. Also, this study shows wastewater based monitoring is supplementary and early warning system for determining the occurrence of antiviral drugs.

Occurrence of multidrug-resistant Escherichia coli and antibiotic resistance genes in a wastewater treatment plant and its associated river water in Harare, Zimbabwe

Wastewater treatment plants (WWTPs) have been identified as point sources of antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARG). Due to variations in antibiotic use and prescribing patterns in different countries, it is imperative to establish the presence of ARB and ARGs in water environments on a country-by-country basis. This study investigated the occurrence of 11 antibiotic-resistance genes (QNRB, DFR14, CTX-M, KPC, Sul1, QNRA, Sul2, ERMB, ERMA, SHV, NDM), and antibiotic-resistant Escherichia coli in a WWTP and its associated river water in Harare, Zimbabwe. 24 water samples were collected across 3 sites: upstream and downstream of the WWTP; final effluent of the WWTP. The samples were collected weekly for 8 weeks. Pure cultures of the E. coli isolates were obtained by membrane filtration (0.45 µm) and repeated streaking on Tryptone Bile X-glucuronide followed by biochemical tests (indole test; citrate test; motility, indole, and ornithine). Antibiotic resistance profiling was done for 12 antibiotics using the disc diffusion method. Total genomic DNA was extracted from the 21 water samples and the occurrence of 11 antibiotic-resistant genes investigated using conventional PCR. 86 E. coli isolates were obtained from the sampled sites: 28 from the upstream site, 26 from the WWTP effluent, and 32 from the downstream site. The results from chi-squared analysis showed a significant association (p < 0.05) between the sampling site and the percentage of antibiotic-resistant E. coli for all 12 antibiotics investigated. The percentage of E. coli isolates resistant to the tested antibiotics varied from 29% (ertapenem) to 80.2% (ciprofloxacin). 81 (94.2%) E. coli isolates were resistant to antibiotics from ≥3 classes. Eight (8/11, 72.7%) ARGs were detected in the WWTP effluent and river water samples. Results indicate that the investigated WWTP and associated river water are reservoirs of ARGs and antibiotic-resistant E. coli, which is a public health concern.

Ecotoxicological mixture risk assessment of 35 pharmaceuticals in wastewater effluents following post-treatment with ozone and/or granulated activated carbon

Reducing the risk posed by mixtures of pharmaceuticals is a goal of current initiatives such as the European Green Deal to reduce anthropological environmental impacts. Wastewater effluent typically contains large numbers of active pharmaceutical ingredients (APIs). For some APIs, existing technology such as conventional activated sludge (CAS) wastewater treatment plants (WWTPs) have removal rates below 20 %, thus the WWTP discharges are adding to the toxic burden of receiving waters.We present an environmental risk assessment of mixtures of 35 APIs in effluent samples from 82 Northern European WWTPs using the concentration addition model, and identify the respective risk-driving APIs. This is then compared to a corresponding mixture risk assessment of effluent samples from the Danish Hillerød WWTP subjected to post-treatment with varying specific ozone doses (0.15–1.05 mgO3/mgDOC) and/or granulated activated carbon (GAC).All 82 WWTP effluent samples exceeded risk thresholds by at least a factor of 30, with a median RQSUM of 92.9, highlighting the need for effluent post-treatment and/or a substantial dilution in the recipient waters. Antibiotics, analgesics and anti-depressants were among the top risk drivers with 99 % of the average mixture risk attributable to azithromycin, diclofenac, venlafaxine, clarithromycin and mycophenolic acid. Effluent mixture risk was reduced by ozonation in a concentration-dependent manner, decreasing below threshold levels to a median RQSUM of 0.83 following treatment with 0.65 mgO3/mg DOC. Fresh GAC was also effective at reducing the mixture risk both alone and with ozone treatment, with median RQSUM of 0.04 and 0.07 respectively.To our knowledge, this is the first study to present a risk assessment of pharmaceutical mixtures in effluent comparing “conventional” WWTP processes with additional post-treatment with ozone and/or GAC for reducing the joint risks of pharmaceutical mixtures for recipient waters. We demonstrate the need for additional WWTP treatment technologies, and the efficacy of GAC and ozonation in decreasing the risk to the aquatic environment from pharmaceutical mixtures to below acceptable threshold limits.

Removal of micropollutants and ecotoxicity during combined biological activated carbon and ozone (BO3) treatment

Ozonation is a viable option to improve the removal of micropollutants (MPs) in wastewater treatment plants (WWTPs). Nevertheless, the application of ozonation is hindered by its high energy requirements and by the uncertainties regarding the formation of toxic transformation products in the process. Energy requirements of ozonation can be reduced with a pre-ozone treatment, such as a biological activated carbon (BAC) filter, that removes part of the effluent organic matter before ozonation. This study investigated a combination of BAC filtration followed by ozonation (the BO3 process) to remove MPs at low ozone doses and low energy input, and focused on the formation of toxic organic and inorganic products during ozonation. Effluent from a WWTP was collected, spiked with MPs (approximately 1 µg/L) and treated with the BO3 process. Different flowrates (0.25–4 L/h) and specific ozone doses (0.2–0.6 g O3/g TOC) were tested and MPs, ecotoxicity and bromate were analyzed. For ecotoxicity assessment, three in vivo (daphnia, algae and bacteria) and six in vitro CALUX assays (Era, GR, PAH, P53, PR, andNrf2 CALUX) were used.Results show that the combination of BAC filtration and ozonation has higher MP removal and higher ecotoxicity removal than only BAC filtration and only ozonation. The in vivo assays show a low ecotoxicity in the initial WWTP effluent samples and no clear trend with increasing ozone doses, while most of the in vitro assays show a decrease in ecotoxicity with increasing ozone dose. This suggests that for the tested bioassays, feed water and ozone doses, the overall ecotoxicity of the formed transformation products during ozonation was lower than the overall ecotoxicity of the parent compounds. In the experiments with bromide spiking, relevant formation of bromate was observed above specific ozone doses of approximately 0.4 O3/g TOC and more bromate was formed for the samples with BAC pre-treatment. This indirectly indicates the effectivity of the pre-treatment in removing organic matter and making ozone more available to react with other compounds (such as MPs, but also bromide), but also underlines the importance of controlling the ozone dose to be below the threshold to avoid formation of bromate. It was concluded that treatment of the tested WWTP effluent in the BO3 process at a specific ozone dose of 0.2 g O3/g TOC, results in high MP removal at limited energy input while no increase in ecotoxicity, nor formation of bromate was observed under this condition. This indicates that the hybrid BO3 process can be implemented to remove MPs and improve the ecological quality of this WWTP effluent with a lower energy demand than conventional MP removal processes such as standalone ozonation.

Sucralose and Predicted De Facto Wastewater Reuse Levels Correlate with PFAS Levels in Surface Waters

Per- and polyfluoroalkyl substances (PFAS) pose risks to human health and ecosystems and are commonly found in wastewater treatment plant (WWTP) effluents discharged into surface waters. WWTPs continuously discharging PFAS into surface waters are hypothesized to lead to pervasive PFAS for downstream drinking water treatment plant (DWTP) intakes. To investigate the impact of this unplanned (de facto) wastewater reuse, we analyzed river water and WWTP effluent samples for 19 target PFAS and a surrogate chemical (sucralose) in a large watershed, with >165 WWTP discharges and multiple DWTP surface water intakes. The ∑PFAS concentrations of WWTP effluents (50–200 ng/L) were higher than that of the river water, with the same relative distributions of individual PFAS found in both samples. Surface water samples showed a direct and linear relationship between ∑PFAS and sucralose concentrations [∑PFAS (ng/L) = 0.0014 × (sucralose (ng/L)) + 19; R2 = 0.92] or predicted de facto reuse levels. Unplanned wastewater reuse could be a widespread source of PFAS for thousands of DWTPs. This study provides valuable guidance for future initiatives aimed at identifying sources of PFAS through de facto reuse modeling and chemical surrogate sampling.

Industrial effluents boosted antibiotic resistome risk in coastal environments

Wastewater treatment plants (WWTPs) have been regarded as an important source of antibiotic resistance genes (ARGs) in environment, but out of municipal domestic WWTPs, few evidences show how environment is affected by industrial WWTPs. Here we chose Hangzhou Bay (HZB), China as our study area, where land-based municipal and industrial WWTPs discharged their effluent into the bay for decades. We adopted high-throughput metagenomic sequencing to examine the antibiotic resistome of the WWTP effluent and coastal sediment samples. And we proposed a conceptual framework for the assessment of antibiotic resistome risk, and a new bioinformatic pipeline for the evaluation of the potential horizontal gene transfer (HGT) frequency. Our results revealed that the diversity and abundance of ARGs in the WWTP’s effluent were significantly higher than those in the sediment. Furthermore, the antibiotic resistome in the effluent-receiving area (ERA) showed significant difference from that in HZB. For the first time, we identified that industrial WWTP effluent boosted antibiotic resistome risk in coastal sediment. The crucial evidences included: 1) the proportion of ARGs derived from WWTP activated sludge (WA) was higher (14.3 %) and two high-risky polymyxin resistance genes (mcr-4 and mcr-5) were enriched in the industrial effluent receiving area; 2) the HGT potential was higher between resistant microbiome of the industrial effluent and its ERA sediment; and 3) the highest resistome risk was determined in the industrial effluent, and some biocide resistance genes located on high-risky contigs were related to long-term stress of industrial chemicals. These findings highlight the important effects of industrial activities on the development of environmental antimicrobial resistance.

Utility of a non-target screening method to explore the chlorination of similar sulfonamide antibiotics: Pathways and N[sbnd]Cl intermediates

Sulfonamides (SAs) are ubiquitous antibiotics that are increasingly detected in aquatic environments and can react with free available chlorine to produce transformation products (TPs) during disinfection. However, the TPs generated during chlorination remains poorly understood. Here, a non-target screening method based on the PyHRMS program was used to assess the transformation pathways of five SAs, particularly the transient NCl intermediates, during a simulated chlorination process. We observed 210 TPs during SA chlorination using a non-target screening method based on high-resolution mass spectrometry, and the reaction mechanisms mainly included chlorine substitution, desulfonation, and hydroxylation. Among the TPs, 87 were tentatively proposed to be NCl intermediates as they instantly disappeared after quenching with Na2S2O3. The MS2 spectra of 13 of these potential NCl intermediates were obtained, and all displayed an [M-Cl]+ fragment. A diagnostic fragment ion (DFI) strategy was applied to explore the structural relationship between parent compounds and TPs. Based on the result, five SAs and 101 TPs (if their MS2 spectra were available) could be connected through the same fragments, and this method was also proved effective in a real wastewater treatment plant effluent sample. We believe this novel method can help explore the TPs of organic compounds during chlorination in drinking water plants.

Removing per- and polyfluoroalkyl substances (PFAS) in water by foam fractionation

Treatment of large volumes of waters contaminated by per- and polyfluoroalkyl substances (PFAS) remains a challenge. This work presented a systematic study on PFAS removal by foam fractionation (FF). Experiments were conducted on both laboratory-spiked and environmental water samples containing PFASs. It is found that higher air flow, greater ionic strength, and addition of thickener boosted PFAS removal in the defoamed bottom solutions and intensified enrichment in the collected foam. FF treatments of a landfill leachate, a groundwater contaminated by aqueous film-forming foams, and a wastewater treatment plant effluent sample were evaluated. The removal reached above 70% for most monitored PFASs, except the ones of short alkyl chains. PFAS concentrations in the final collected foams were up to over 30 × than that in the original samples. Analysis using high-resolution mass spectrometry revealed enrichment of non-target PFASs by FF. The results of this study demonstrate great effectiveness of FF in removing most PFASs from waters, producing low-volume, highly concentrated solutions of PFASs in all tested environmental samples.

Endocrine disrupting chemicals entering European rivers: Occurrence and adverse mixture effects in treated wastewater

In the present study on endocrine disrupting chemicals (EDCs) in treated wastewater, we used chemical and effect-based tools to analyse 56 wastewater treatment plant (WWTP) effluents from 15 European countries. The main objectives were (i) to compare three different receptor-based estrogenicity assays (ERα-GeneBLAzer, p-YES, ERα-CALUX®), and (ii) to investigate a combined approach of chemical target analysis and receptor-based testing for estrogenicity, glucocorticogenic activity, androgenicity and progestagenic activity (ERα-, GR-, AR- and PR-GeneBLAzer assays, respectively) in treated wastewater. A total of 56 steroids and phenols were detected at concentrations ranging from 25 pg/L (estriol, E3) up to 2.4 μg/L (cortisone). WWTP effluents, which passed an advanced treatment via ozonation or via activated carbon, were found to be less contaminated, in terms of lower or no detection of steroids and phenols, as well as hormone receptor-mediated effects. This result was confirmed by the effect screening, including the three ERα-bioassays. In the GeneBLAzer assays, ERα-activity was detected in 82 %, and GR-activity in 73 % of the samples, while AR- and PR-activity were only measured in 14 % and 21 % of the samples, respectively. 17β-estradiol was confirmed as the estrogen dominating the observed estrogenic mixture effect and triamcinolone acetonide was the dominant driver of glucocorticogenic activity. The comparison of bioanalytical equivalent concentrations (BEQ) predicted from the detected concentrations and the relative effect potency (BEQchem) with measured BEQ (BEQbio) demonstrated good correlations of chemical target analysis and receptor-based testing results with deviations mostly within a factor of 10. Bioassay-specific effect-based trigger values (EBTs) from the literature, but also newly calculated EBTs based on previously proposed derivation options, were applied and allowed a preliminary assessment of the water quality of the tested WWTP effluent samples. Overall, this study demonstrates the high potential of linking chemical with effect-based analysis in water quality assessment with regard to EDC contamination.

Bioaccumulation potential of the tricyclic antidepressant amitriptyline in a marine Polychaete, Nereis virens

The continual discharge of pharmaceuticals from wastewater treatment plants (WWTPs) into the marine environment, even at concentrations as low as ng/L, can exceed levels that induce sublethal effects to aquatic organisms. Amitriptyline, a tricyclic antidepressant, is the most prescribed antidepressant in Norway, though the presence, potential for transport, and uptake by aquatic biota have not been assessed. To better understand the release and bioaccumulative capacity of amitriptyline, laboratory exposure studies were carried out with field-collected sediments. Influent and effluent composite samples from the WWTP of Stavanger (the 4th largest city in Norway) were taken, and sediment samples were collected in three sites in the proximity of this WWTP discharge at sea (WWTP discharge (IVAR), Boknafjord, and Kvitsøy (reference)). Polychaetes (Nereis virens) were exposed to field-collected sediments, as well as to Kvitsøy sediment spiked with 3 and 30 μg/g amitriptyline for 28 days. The WWTP influent and effluent samples had concentrations of amitriptyline of 4.93 ± 1.40 and 6.24 ± 1.39 ng/L, respectively. Sediment samples collected from IVAR, Boknafjord, and Kvitsøy had concentrations of 6.5 ± 3.9, 15.6 ± 12.7, and 12.7 ± 8.0 ng/g, respectively. Concentrations of amitriptyline were below the limit of detection in polychaetes exposed to sediment collected from Kvitsøy and IVAR, and 5.2 ± 2.8 ng/g in those exposed to Boknafjord sediment. Sediment spiked with 3 and 30 μg/g amitriptyline had measured values of 423.83 ± 33.1 and 763.2 ± 180.5 ng/g, respectively. Concentrations in worms exposed to the amended sediments were 9.5 ± 0.2 and 56.6 ± 2.2 ng/g, respectively. This is the first known study to detect measurable concentrations of amitriptyline in WWTP discharge in Norway and accumulation in polychaetes treated with field-collected sediments, suggesting that amitriptyline has the potential for trophic transfer in marine systems.

Pharmaceutical and Antibiotic Pollutant Levels in Wastewater and the Waters of the Zarqa River, Jordan

Assamra wastewater treatment plant (WWTP) is the largest treatment facility in Jordan. Treated wastewater is discharged into the Zarqa River (ZR) and used to irrigate fodder and vegetables. ZR also includes surface runoff, stormwater, and raw wastewater illegally discharged into the river. This study examined pharmaceutically active compounds (PhAC) in water resources in the ZR basin. Samples of WWTP influent and effluent and river water from four sites along ZR were collected. Concentrations of 18 target antibiotics, one stimulant, and 15 other PhACs were determined in the samples. Five antibiotics were detected in WWTP influent (510–860 ng L−1 for ∑Antibiotics) and six in the effluent (2300–2600 ng L−1 for ∑Antibiotics). Concentrations in the effluent of all antibiotics except clarithromycin increased by 2- to 5-fold compared with those in influent, while clarithromycin concentration decreased by around 4- fold (from 308 to 82 ng L−1). WWTP influent and effluent samples contained 14 non-antibiotic PhACs, one simulant, and six antibiotics at detectable concentrations. The dominant PhACs were paracetamol (74% of ∑PhACs) in the influent and carbamazepine (78% of ∑PhACs) in the effluent. At ZR sampling sites, carbamazepine was the dominant PhAC in all cases (800–2700 ng L−1). The antibiotics detected in WWTP effluent were also detected at the ZR sites. In summary, water in ZR is contaminated with PhACs, including antibiotics, and wastewater discharge seems to be the main pathway for this contamination. The occurrence of antibiotics and other PhACs in the irrigated soil requires investigation to assess their fate.

Biochar – An efficient sorption material for the removal of pharmaceutically active compounds, DNA and RNA fragments from wastewater

Wastewaters are considered a remarkable source of micropollutants capable of influencing the environment both directly and indirectly. Here we tested porous ecological carbon (Biochar), an effective sorbent material for removing pharmaceuticals, drugs, and their metabolites found in wastewaters. The tested Biochar type was first characterised and used for adsorption experiments of selected micropollutants from a municipal WWTP (wastewater treatment plant) effluent sample. The sorption efficiency was studied on selected pharmaceuticals due to their common presence in aquatic ecosystems. The results show that the studied Biochar type removed the pharmaceuticals with high efficiency (above 90%), so this material can potentially be applied in wastewater treatment. We achieved greater than 99% efficiency in total RNA removal from wastewater. Wastewater might contain infectious RNA fragments of the SARS-CoV-2 virus. However, Biochar can be used as a sorbent in wastewater treatment to remove antibiotic resistance genes. We have also observed a total DNA removal ability of Biochar. On the other hand, the total number and antibiotic-resistant coliform bacteria and enterococci were not changed after Biochar wastewater treatment.

Target, suspect and non-target screening analysis from wastewater treatment plant effluents to drinking water using collision cross section values as additional identification criterion

The anthropogenic entry of organic micropollutants into the aquatic environment leads to a potential risk for drinking water resources and the drinking water itself. Therefore, sensitive screening analysis methods are needed to monitor the raw and drinking water quality continuously. Non-target screening analysis has been shown to allow for a more comprehensive investigation of drinking water processes compared to target analysis alone. However, non-target screening is challenging due to the many features that can be detected. Thus, data processing techniques to reduce the high number of features are necessary, and prioritization techniques are important to find the features of interest for identification, as identification of unknown substances is challenging as well. In this study, a drinking water production process, where drinking water is supplied by a water reservoir, was investigated. Since the water reservoir provides surface water, which is anthropogenically influenced by wastewater treatment plant (WWTP) effluents, substances originating from WWTP effluents and reaching the drinking water were investigated, because this indicates that they cannot be removed by the drinking water production process. For this purpose, ultra-performance liquid chromatography coupled with an ion-mobility high-resolution mass spectrometer (UPLC-IM-HRMS) was used in a combined approach including target, suspect and non-target screening analysis to identify known and unknown substances. Additionally, the role of ion-mobility-derived collision cross sections (CCS) in identification is discussed. To that end, six samples (two WWTP effluent samples, a surface water sample that received the effluents, a raw water sample from a downstream water reservoir, a process sample and the drinking water) were analyzed. Positive findings for a total of 60 substances in at least one sample were obtained through quantitative screening. Sixty-five percent (15 out of 23) of the identified substances in the drinking water sample were pharmaceuticals and transformation products of pharmaceuticals. Using suspect screening, further 33 substances were tentatively identified in one or more samples, where for 19 of these substances, CCS values could be compared with CCS values from the literature, which supported the tentative identification. Eight substances were identified by reference standards. In the non-target screening, a total of ten features detected in all six samples were prioritized, whereby metoprolol acid/atenolol acid (a transformation product of the two β-blockers metoprolol and atenolol) and 1,3-benzothiazol-2-sulfonic acid (a transformation product of the vulcanization accelerator 2-mercaptobenzothiazole) were identified with reference standards. Overall, this study demonstrates the added value of a comprehensive water monitoring approach based on UPLC-IM-HRMS analysis.Graphical abstract

Metagenomic analysis of urban wastewater resistome and mobilome: A support for antimicrobial resistance surveillance in an endemic country.

In developing countries, where high levels of antimicrobial resistance are observed in hospitals, the surveillance of this phenomenon in wastewater treatment plants (WWTPs) and the environment is very limited, especially using cutting-edge culture-independent methods. In this study, the composition of bacterial communities, the resistome and mobilome (the pool of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs), respectively) at a WWTP were determined using shotgun metagenomics and culture-based approaches. Wastewater samples were collected at four sampling points of a WWTP in Antioquia, Colombia. A total of 24 metagenomes were analyzed. Specifically, there were marked differences in bacterial community composition, resistome, and mobilome, according to the WWTP sampling points. Bacterial families of clinical importance such as Moraxellaceae, Aeromonadaceae, and Enterobacteriaceae were mainly detected in the WWTP influent and effluent samples. Genes encoding resistance to macrolide-lincosamide-streptogramin, β-lactams, and those conferring multidrug resistance (e.g., acrB, adeG, and mexD) were the most abundant. Moreover, some clinically important ARGs such as blaKPC-2 and blaCTX-M, and others not reported locally, such as blaTEM-196, blaGES-23, blaOXA-10, mcr-3, and mcr-5 were frequently detected. Co-occurrence network analyses indicated a significant association of ARGs such as blaOXA-58 and blaKPC genes with Aeromonadaceae and Enterobacteriaceae. Among the markers of MGEs, intI1 and ISCR8 were the most frequently detected. Altogether, this work reveals the importance of shotgun metagenomics and culture-based approaches in antimicrobial resistance studies. The findings also support that WWTPs are hotspots for antimicrobial resistance, whose analysis constitutes a powerful tool to predict the impact of antimicrobial resistance in a population.

Naproxen removal by CWPO with Fe3O4/multi-walled carbon nanotubes in a fixed-bed reactor

The prepared Fe3O4/multiwalled carbon nanotubes (MWCNTs) in catalytic wet peroxide oxidation (CWPO) is an effective method of removing some pharmaceuticals from water matrices for environmental protection. Therefore, operating parameters (catalyst dose, H2O2 dose, flow rate, pH) of CWPO with the easy-prepared Fe3O4/MWCNT composite were evaluated for the effective NAP removal in an up-flow bed reactor (UFBR). The prepared catalyst was successfully synthesized by a facile coprecipitation method. The highest removals of TOC and NAP by continuous CWPO of NAP aqueous solution (10 mg L−1) were obtained in the experiments with ratios 0.4 g of catalyst load/double H2O2 stoichiometric ratio (78.4% for TOC and 83% for NAP), and 0.2 g of catalyst load/stoichiometric dose (39.1% for TOC and 73.1% for NAP). Both operated at 10 mg L−1 of NAP, 1.7 mL min−1, 50 °C and circumneutral pH. In addition, their high consumption H2O2 efficiency (> 59.6%) and a low concentration of leached iron dissolved (< 0.28 mg L−1) found at 450 min indicated the great catalyst stability. Furthermore, the application of CWPO for different aqueous matrices, the NAP removal from in a surface water sample was almost complete (90.5%) 1260 min TOS while whereas in the hospital wastewater and wastewater treatment plant effluent samples were 64.9% and 58.9%, respectively. Our results demonstrate that continuous CWPO with the easy-prepared Fe3O4/MWCNTs has the potential to be applied as an effective treatment for the rapid removal of NAP from different water matrices.

LED irradiated photo-Fenton for the removal of estrogenic activity and endocrine disruptors from wastewater treatment plant effluent.

The goal of this work was to evaluate the performance of the LED irradiated photo-Fenton process on the removal of (i) estrogenic activity and (ii) seven endocrine disruptors (EDs) (4-octylphenol, 4-nonylphenol, bisphenol A, estrone, 17β-estradiol, 17α-ethinylestradiol, and estriol) from real wastewater treatment plant effluent (WWTPE). EDs are a group of contaminants of emerging concern present in WWTPE and which may be recognized by hormone receptors, thus harming animal and human health. The yeast estrogenic screen test (YES) was used to quantify estrogenic activity promoted by EDs in WWTPE samples before and after photo-Fenton treatment. Tests were performed following a factorial design with different iron (20, 40, and 60mgL-1) and hydrogen peroxide (100, 200, and 300mgL-1) concentrations in a laboratory scale LED photoreactor (λ = 455nm, 1.5L, 1.6 × 10-6 Einstein s-1). EDs were analyzed by gas chromatography coupled to a mass spectrometer. Control experiments consisted of Fenton process, iron only, LED irradiation only, and H2O2 only. Optimum experimental conditions for LED photo-Fenton resulted in 62% removal of estrogenic activity and 59% mineralization. In addition, treated WWTPE was not toxic to Aliivibrio fischeri and more than 80% of EDs were removed during LED irradiated photo-Fenton. Although Fenton process showed similar efficiency to that obtained by LED photo-Fenton, a higher volume of sludge was generated in the dark. Finally, results obtained in this study confirm the applicability of LED irradiated photo-Fenton process for improving the quality of WWTPE as an alternative to solar photo-Fenton in case solar radiation is not available, thus reducing hazards associated to WWTPE reuse or discharge.

Diphenylamine Antioxidants in wastewater influent, effluent, biosolids and landfill leachate: Contribution to environmental releases

Diphenylamine antioxidants (DPAs) are widely used industrial chemicals. Wastewater effluents and biosolids are important pathways for DPAs to enter the environment. Information on the fate of DPAs in wastewater treatment plants (WWTPs) and their environmental releases is limited. In this study, we characterized the occurrence, removal efficiencies, distribution, mass balance, and environmental releases of 17 DPAs in ten Canadian WWTPs and four landfill sites from 2013 to 2015. These WWTPs are different in sizes, and treatment technologies. Median concentrations of ΣDPAs were 78 ng/L in influent, 6.9 ng/L in effluent, 326 ng/L in leachate, and 445 ng/g in biosolids (dry weight), respectively. Diphenylamine (DPA) and ditertoctyl-diphenylamine (DTO-DPA) were the predominant congeners of DPAs in all the matrices. Residues of DPAs were not completely removed during wastewater treatment processes: most DPAs were detected in at least one sample of WWTP effluent with the highest concentration of 117 ng/L (DPA). Overall, high removal efficiencies (median > 90%) of most of the DPAs were observed in the secondary and advanced treatment, as well as in the facultative and aerated lagoons. In contrast, primary treatment exhibited a lower removal efficiency of the DPAs. Mass balance analysis shows that sorption to biosolids is the major removal pathway of DPAs in WWTPs. The results also highlight that environmental releases of DPAs via biosolid applications (70 mg/d/1000 people) can be over several times higher than that via wastewater effluent (2.5-36 mg/d/1000 people).

Removal of microplastics from secondary wastewater treatment plant effluent by coagulation/flocculation with iron, aluminum and polyamine-based chemicals

Microplastic (MP) removal by coagulation/flocculation followed by settling was studied in a secondary wastewater treatment plant (WWTP) effluent matrix. MP concentration in size range <10 µm in wastewater is currently unknown due to the exclusion of this size range in many studies and due to difficulties in MP quantification. WWTP effluent samples were spiked with a known amount of polystyrene spheres of two different sizes 1 µm and 6.3 µm. The samples were treated with inorganic and organic coagulants typically used in WWTPs, i.e., ferric chloride, polyaluminum chloride, and polyamine. The effect of pH was studied with ferric chloride by changing the pH from 7.3 to 6.5. In this study, MP removal was monitored using flow cytometry. The role of chemicals in MP removal at WWTPs has not been in the focus of previously reported MP studies. Our results showed that all tested coagulants enhanced the removal of MPs with dosages applicable to tertiary treatment. The highest removal efficiency obtained was 99.4%, and ferric chloride and polyaluminum chloride were more efficient than polyamine. Performances of ferric chloride and polyaluminum chloride were close to each other, with a statistically significant difference at a certain dosage range. Our findings suggest that chemical coagulation plays a key role in the removal of MPs, and the process can be optimized by selecting the right coagulant and pH.