Suspect and Nontarget Screening Reveal the Underestimated Risks of Antibiotic Transformation Products in Wastewater Treatment Plant Effluents

Source orientation, environmental fate, and risks of antibiotics in the surface water of the largest sediment-laden river

Antibiotics present a more complex pollution profile in large rivers, particularly in suspended sediment-laden flows. This study quantified 25 antibiotics in surface water samples from the whole sediment-laden Yellow River. A new comprehensive prioritization index (CPI) was developed to identify priority risk control regions. The concentrations of the detected antibiotics ranged from 0.670 to 232 ng/L (mean: 9.62 ng/L), with the highest mean concentration observed for tetracyclines (TCs) at 20.2 ng/L. The most prominent antibiotic pollution was observed in the midstream region, with mean concentrations reaching 251 ng/L. Three SEMs were constructed for three antibiotic categories, with 75.6 % of the variation explained for SAs and CAs. Suspended particulate matter (SPM) significantly influences the environmental fate of antibiotics directly, negatively affecting TCs and QNs (λ = -0.302) but positively impacting SAs and CAs (λ = 0.475). Source apportionment precisely revealed that human sources in the midstream region and animal sources downstream contributed 80.75 % and 71.55 %, respectively. Although more than 85 % of the risk values were less than 0.1, the midstream region was identified as the priority control region (CPITOX >0.01). In particular, OFL, CTC, and ENO from human sources were the main contributors in the midstream region. This study elucidates antibiotic fate and risks in the whole sediment-laden Yellow River, providing a scientific basis for assessing pollution in other large rivers.

Identifying and prioritizing organic toxicants in treated flowback and produced water from shale gas exploitation sites using an integrative effect-directed analysis and nontarget screening method

The use of hydraulic fracturing in shale gas exploitation has generated substantial amount of flowback and produced water (FPW), and ecological risk of these highly complex chemical mixtures has raised worldwide concern. Herein, an integrative effect-directed analysis (EDA) and nontarget screening (NTS) workflow was developed to identify and prioritize main toxicants in the treated FPW (T-FPW). The workflow included sample extraction and fractionation, zebrafish embryo toxicity tests, target and nontarget chemical analyses, and toxicity prioritization and confirmation using toxicological priority index (ToxPi). Results showed that less hydrophobic compounds (log Kow < 3.7) which were used in fracturing fluid and their degradation products were the potentially high-risk toxicants in T-FPW. Thirty-nine target compounds identified in toxic fraction explained 4.82% of the mortality. Additional 584 nontarget contaminants were annotated by NTS. Risk prioritization was achieved for 470 identified contaminants with ecotoxicity data available using a ToxPi method. Six nontarget toxicants were identified with higher ecological risks than all target contaminants, and their presence in FPW were confirmed using reference standards. A principal component analysis of NTS features revealed that EDA fractionation reduced mixture complexity and focused toxicant screening, which significantly improved NTS efficiency, highlighting advantages of integrative EDA and NTS for mixture risk assessment.

Unveiling the mechanism and driving factors of pharmaceutical and personal care product (PPCP) removal in wastewater treatment plants

Wastewater treatment plants (WWTPs) are primary point sources of pharmaceuticals and personal care products (PPCPs) entering the environment; however, few studies have systematically elucidated the PPCP removal mechanism in WWTPs. In this study, we conducted two composite sampling campaigns, collecting water and sludge samples from each treatment stage of four secondary or tertiary WWTPs with various processes. Our goal was to identify the mechanisms and driving factors behind the removal of 30 common PPCPs. The average removal efficiency of all PPCPs was 62.57 %, with significant variations (-308.03 %-91.03 %) among individual PPCPs. The contribution of sludge adsorption, biodegradation and chemical degradation to the removal of 30 PPCPs was quantified. The average biodegradation efficiency of sulfonamides was 44.90 %, but reconversion of chelate products to the sulfonamides after chemical treatment (UV) was the main reason for their low removal efficiency (about 30 %). Base dissociation constant (pKb) and logKow were used to evaluate the contribution of charge interactions and hydrophobic partitioning to the adsorption capacity of PPCPs for the first time. For PPCPs that could ionize into cations, higher pKb increased adsorption capacity, whereas for other PPCPs logKd (distribution coefficient) and logKow showed a significant positive correlation. The biodegradation of sulfonamides was positively correlated with their solubility. The presence of hydroxyl and carboxyl groups promoted microbial degradation of non-antibiotic compounds. This study reveals the universal mechanisms and driving factors behind PPCP removal in WWTPs, providing insights to guide the targeted optimization of treatment processes for PPCP removal.

A nature-inspired metal-free electrocatalyst towards efficient electron transfer and robust cascade oxygen reduction for wastewater treatment

The pressing demand for removing high-risk emerging contaminants from wastewater calls for tailored treatment strategies, for which heterogeneous electrocatalysis induced by cascade oxygen reduction reaction (ORR) holds considerable potential. This process, however, suffers from poor interfacial electron transfer and discounted performance in non-acidic conditions. Inspired by the electron respiration chain of cells, a metal-free, quinone-based catalyst (PBth-BQ) was innovatively designed and synthesized. With excellent redox reversibility over 50 cycles and no risk of metal leaching, it boosted the direct electron transfer by 110 % compared to the bare graphite substrate and facilitated cascade ORR to generate ·OH for effective contaminant abatement in the pH range of 3-13. Among them, pH 8 demonstrated the best performance, which is suitable for wastewater treatment. In particular, PBth-BQ performed well as both anodic and cathodic electrodes in azithromycin mineralization with different oxygen donors, verified by the in-situ mass spectrum. Considering the abundance of quinone-like structures in oxidized carbon materials, this biomimetic design may inspire the further exploration of cheap and efficient electrocatalysts for wastewater treatment.

Unveiling the overlooked silent threat: High-throughput suspect screening of antibiotics and multidimensional heterogeneity in aquatic ecosystems of megacity

The environmental and health impacts of antibiotics (ABx) have garnered global attention. However, the issue of ABx contamination in aquatic ecosystems of densely populated megacities remains largely overlooked. Significant research gaps persist, particularly in understanding the full-chain pollution characteristics that span from urban aquatic environments to edible aquatic organisms, due in part to the lack of systematic monitoring data to support comprehensive assessments. To address this gap, this study conducts the first comprehensive screening of ABx in the aquatic ecosystems of a megacity, offering quantitative evaluations of ABx complexity and multidimensional heterogeneity. Over a one-year period, 406 samples were collected from four rivers and three lakes, and large-scale analyses identified 37 ABx compounds, with the overall detection rate of 30.05 %, with Sulfonamides (SAs), Quinolones (QNs), and Macrolides (MLs) being the most prevalent. Surface water samples contained the greatest number of ABx types, while amphibians exhibited the highest detection rate and concentrations. A pronounced increase in detections during the dry season (spring and winter) highlighted substantial spatio-temporal variation. Source-sink analysis revealed hospital effluents and wastewater treatment plants as primary pollution sources. Among the detected compounds, Nalidixic acid (NCA), Sulfamethazine (SMTZ), Flumequine (FQ), and Tylosin (TLS) posed the most significant ecological risks, with NCA identified as a priority for targeted control. This study establishes a novel framework for the high-throughput suspect screening, occurrence pattern analysis, and risk assessment of ABx in megacities worldwide.

Integrating machine learning, suspect and nontarget screening reveal the interpretable fates of micropollutants and their transformation products in sludge

Activated sludge enriches vast amounts of micropollutants (MPs) when wastewater is treated, posing potential environmental risks. While standard methods typically focus on target analysis of known compounds, the identity, structure, and concentration of transformation products (TPs) of MPs remain less understood. Here, we employed a novel approach that integrates machine learning for the quantification of nontarget TPs with advanced target, suspect, and nontarget screening strategies. 39 parent chemicals and 286 TPs were identified, with the majority being pharmaceuticals, followed by phthalate acid ester and alkylphenols. To quantify TPs without reference standards, we applied machine learning to forecast the relative response factors (RRFs) relied on their physicochemical characteristics. The random forest regression model showed great performance, with prediction errors of RRFs ranging from 0.03 to 0.35. The mean concentrations for parents and TPs were 1.32 -19.83 and 6.35 -9.94 μg/g dw, respectively. Further risk-based prioritization integrating environmental exposure and ToxPi scoring ranked the identified 182 compounds, with three parents and one TP recognized as high priorities for management. N-demethylation and N-oxidated TPs are generally less toxic than their parents. These findings are expected to facilitate MPs and their TPs investigations for reliable environmental monitoring and risk assessment across different sludge treatment processes.

Antibiotics in the global river system arising from human consumption

The presence of antibiotics in surface waters poses risks to aquatic ecosystems and human health due to their toxicity and influence on antimicrobial resistance. After human consumption and partial metabolism, antibiotic residues are excreted and undergo complex accumulation and decay processes along their pathway from wastewater to natural river systems. Here, we use a global contaminant fate model to estimate that of the annual human consumption of the 40 most used antibiotics (29,200 tonnes), 8,500 tonnes (29%) are released into the river system and 3,300 tonnes (11%) reach the world's oceans or inland sinks. Even when only domestic sources are considered (i.e. not including veterinary or industrial sources), we estimate that 6 million km of rivers worldwide are subject to total antibiotic concentrations in excess of thresholds that are protective of ecosystems and resistance promotion during low streamflow conditions, with the dominant contributors being amoxicillin, ceftriaxone, and cefixime. Therefore, it is of concern that human consumption alone represents a significant risk for rivers across all continents, with the largest extents found in Southeast Asia. Global antibiotic consumption has grown rapidly over the last 15 years and continues to increase, particularly in low- and middle-income countries, requiring new strategies to safeguard water quality and protect human and ecosystem health.

Unraveling the Composition Profile and Ecological Risk of Triazine Herbicides and Their Transformation Products in Urban Sewage Discharge

Triazine herbicides (THs) are used globally to control weeds in urban environments, but their transformation products (TPs) are rarely considered due to the lack of reference standards. In this study, a total of 41 TPs were found in wastewater influents and effluents of 28 municipal wastewater treatment plants (MWWTPs) from six cities in China by integrating suspect screening (36 TPs), molecular networking (9 TPs), and diagnostic fragment searching (12 TPs). Among these, 36 TPs were detected for the first time in urban aquatic environments, and 28 TPs were first reported in aquatic environments. Polar THs and their TPs were only partially removed from the aqueous phase in the wastewater treatment process. Concentrations of THs and their TPs present in wastewater effluents ranged from 107 to 435 ng/L. Thus, THs and their TPs discharged from wastewater effluents pose a medium risk to freshwater algae in the receiving waters. Moreover, 4 THs (ametryne, atrazine, terbutryn, and prometryne) and 3 TPs (atrazine-desisopropyl, TP247, and TP258) pose significant risks in several effluents. Considering the persistent and mobile properties and ecological risk of THs and their TPs, these contaminants should be specifically considered in further environmental monitoring and included in the regulation.

Suspect Screening of Pharmaceuticals and Their Transformation Products (TPs) in Wastewater during COVID-19 Infection Peak: Identification of New TPs and Elevated Risks

Pharmaceuticals and their transformation products (TPs) in wastewater are emerging contaminants that pose risks to ecosystems and human health. Here, a typical period marked by the easing of the "zero-COVID" policy in December 2022, resulting in unprecedented infections in China, was chosen to illustrate the environmental impact of pharmaceutical usage during the COVID-19 pandemic. A suspect screening workflow was developed to identify pharmaceuticals and transformation products (TPs) in wastewater influent and effluent from a wastewater treatment plant (WWTP) during the peak and postpeak periods of COVID-19, integrating medication recommendations and TPs' prediction. A total of 114 pharmaceuticals and TPs were identified (13 TPs were detected for the first time in WWTP) by using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS). Wastewater-based epidemiology analysis showed that the most predominant pharmaceuticals were nonsteroidal anti-inflammatory drugs. Interestingly, the consumption of propafenone increased after the infection peak, possibly linked to long COVID-19 symptoms. Risks were further evaluated based on concentration, detection frequency, and PMT (persistence, mobility, and toxicity) properties, revealing that TPs of aminopyrine, acetaminophen, etc. showed even greater ToxPi scores than their parent compounds. This study highlights the elevated risks posed by pharmaceutical discharge during epidemics and the necessity for TPs' monitoring.

Entropy Similarity-Driven Transformation Reaction Molecular Networking Reveals Transformation Pathways and Potential Risks of Emerging Contaminants in Wastewater: The Example of Sartans

The transformation pathways and risks of emerging contaminants (ECs) in wastewater remain unclear due to the limited throughput of nontarget screening. In this study, an improved method called entropy similarity-driven transformation reaction molecular networking (ESTRMN) was developed to identify transformation products (TPs) in wastewater. In detail, entropy similarity was the most effective algorithm for identifying parent-product spectrum pairs and a threshold of 0.5 for it was determined with the guarantee of high specificity. Additionally, a TP structure database predicted according to known structures and reactions was established to assist in identification. Sartan is one of the most commonly used angiotensin II receptor blocker antihypertensive drugs. Take sartans as an example, 69 TPs of sartans with confidence levels above 3 were identified by ESTRMN, 43 of which were newly discovered. The most common reactions included hydroxylation, hydrolysis, and oxidation, resulting in the majority of sartan TPs exhibiting higher persistence, mobility, and toxicity (PMT) than their parents. The concentration of 75% sartans and TPs increased after treatment in a WWTP, and the overall risk has not been effectively mitigated. This study emphasizes the role of ESTRMN in incorporating TPs of ECs into environmental monitoring protocols and risk assessment frameworks for wastewater management.

Antibiotics in ambient fine particulate matter from two metropolitan cities in China: Characterization, source apportionment, and health risk assessment

Excessive production and widespread application of antibiotic has led to residues in environmental matrices worldwide. There is limited knowledge of the concentrations of antibiotics bound to ambient fine particulate matter (PM2.5) and their health risks. We investigated the occurrence, sources, environmental driving factors, and health risks of antibiotics in PM2.5 samples collected from Beijing and Shijiazhuang, China, during periods of high air pollution. Using ultra-high performance liquid chromatography-tandem mass spectrometry, 25 antibiotics were detected in PM2.5 at concentrations ranging from undetectable to 774.7 pg/m3. These compounds were predominantly tetracyclines and macrolides. The positive matrix factorization model was used to pinpoint the main sources of these antibiotics as pharmaceutical and medical waste, sewage treatment plants, and livestock emissions, with contributions of 39.1 %, 31.7 %, and 29.2 % respectively, to the total concentrations. Crucial environmental driving factors were determined using a linear mixed-effects model and random forest model. Most antibiotics showed a positive correlation with gaseous pollutants and a negative correlation with meteorological factors. PM2.5, PM10, and CO had the highest influence. The estimated daily intake and hazard quotient (HQ) were calculated to assess the human inhalation exposure risks for these antibiotics, and children aged 0-6 years had the highest intake of 102.8 pg/kg/day. Although the calculated health risk of antibiotic inhalation was low (HQ < 1), considering that exposure to antibiotics via inhalation occurs over long periods and these compounds accumulate, further attention should be given to health risks associated with this exposure. Our results provide valuable insight for environmental planning and policymaking concerning antibiotic pollution and its associated health risks.

Contribution of Coal Tar Sources to Polycyclic Aromatic Compounds and Associated Ecological Risk in Lake Ontario Sediments: Inference from a Novel Marker

Coal tar-related products as a source of polycyclic aromatic compounds (PACs) are particularly concerning due to high PAC concentrations and inadequate source management. Benzo[b]carbazole, a benzocarbazole isomer exclusively found in coal tar-derived products, acts as an ideal marker to distinguish coal tar sources from others, enabling more robust quantification of coal tar contributions to PACs. To evaluate the historical and recent contributions of coal tar-related sources to the levels of PACs in Lake Ontario and associated ecological risk, we analyzed 31 PACs and 3 BCBz isomers in surface sediments and a sediment core. In the surface sediments, summed concentrations of the PACs ranged from 170 to 11,000 ng/g, dry weight, 63-90% of which were attributed to the 16 EPA polycyclic aromatic hydrocarbons (PAHs). Our results suggest the contribution by coal tar-related sources to PAC contamination has increased over the past decades and reached over 40% in Lake Ontario surface sediments. Employing the toxicological-priority-index scheme for the field data, high molecular weight EPA PAHs were identified as priority PACs. Cumulative PAC risk assessments indicate that with the exception of Mimico Creek, all other sampling sites exhibited elevated risk values.

Identification, annotation and toxicity estimation of organic pollutants in human serum via non-target analysis

Environmental organic pollution causes a threat to the ecological environment, constrains social development and can also potentially harm human health. We applied non-target analysis to screen organic pollutants from the serum of 89 individuals, identifying 67 pollutants in the categories of industrial intermediates, plasticizers, surfactants, pharmaceuticals, pesticides, and exogenous pollutant metabolites. The detection rate of chemicals for industrial use (50.3%; 95% CI: 39.7, 60.8) was higher, reflecting the environmental exposure characteristics of the surrounding functional areas. In addition, 1168 potential pollutant features were annotated to 10 superclasses. Exposure levels of identified pollutants were semi-quantified by predicting response factors via machine learning model. Highly exposed pollutants involved various categories, especially pharmaceuticals due to their property of being easily absorbed by human body cross biological barriers. Toxicity of developmental toxicity, bioconcentration, mutagenicity and oral rat median lethal dose (LD50) were predicted with the occurrence rates of 62.7%, 10.4%, 11.9% and 11.9% of the identified pollutants respectively. 4-[3-(Trifluoromethyl)benzyl]piperidine (industrial intermediate), risperidone (pharmaceutical), and aminocarb (insecticide) were predicted to have multiple toxic effects, which deserved attention and further hazard assessment. This study provides a comprehensive pattern of human exposure to organic pollutants, contributing to evaluate the health risks caused by pollutants to the population, thus providing data support for the monitoring and management of pollutants.

Regional disparities in PPCPs contamination of urban wastewater treatment plants: Unveiling influential factors and ecological effects

This study investigates the discharge of pharmaceuticals and personal care products (PPCPs) from wastewater treatment plants (WWTPs) into natural waters, highlighting a significant correlation with regional human activities. Despite the complexity of assessing factors influencing PPCPs sources, it remains underexplored. By conducting an extensive literature review of seven categories of PPCPs in WWTPs across five typical regions of China, the study reveals both similarities and disparities in PPCPs composition. Correlation analysis and four machine learning algorithms are employed to identify affecting factors for PPCPs emissions. The findings reveal that regional differences in per capita load are affected by treatment scale and population served by WWTPs. Economic indicators, wastewater treatment efficiency, and population age structure correlate with specific PPCPs. The RF algorithms demonstrated reliable predictive capabilities for PPCPs concentrations, identifying significant influencing factors such as service population, treatment capacity, and economic development. Ecological risk assessments indicate that certain PPCPs, such as norfloxacin (NOR) and ofloxacin (OFL), pose high risks to algae. These findings underscore the necessity for region-specific strategies to address PPCPs challenges, considering factors like economic development, urbanization, and demographic characteristics, and provide valuable insights into PPCPs presence and ecological risks.

Incorporating Transformation Products for an Integrated Assessment of Antibiotic Pollution and Risks in Surface Water

The widespread presence of antibiotics in aquatic ecosystems is a global challenge, yet the occurrence and risks associated with their transformation products (TPs) remain poorly understood. This study investigated the occurrence and potential risks of antibiotics and their TPs in water along the Chaobai River in Beijing. We used high-resolution mass spectrometry and an integrated target, suspect, and nontarget screening approach to identify 21 parent antibiotics and 78 TPs among 90 water samples, with the majority from macrolides and sulfonamides. Notably, target quantification and machine-learning-assisted semiquantification revealed that the cumulative concentrations of TPs were higher than the cumulative concentrations of parent compounds, with average contributions of TPs ranging between 50.7 and 63.7%. Most downstream water samples were largely influenced by domestic sewage, as indicated by the significantly higher concentrations and proportions of TPs, as well as the greater diversity in their composition profiles compared to upstream and reservoir samples. Moreover, of the 78 TPs, 26.9, 67.9, and 6.4% exhibited greater persistence, mobility, or toxicity than their parent antibiotics, respectively. Sixteen macrolide TPs presented both greater ecological risks to aquatic organisms and higher resistance selection risks than their parent antibiotics. TPs contributed substantially to the overall antibiotic-related risks by an average of between 31.2 and 54.1%. This study highlights the occurrence of antibiotic TPs in river water, underscoring the need to consider TPs in comprehensive risk assessments of antibiotics.

A Database on Antibiotics and Antibiotic Resistance in Wastewater and Solid Waste from Pharmaceutical Industry Based on a Systematic Review

Residual antimicrobial agents in wastewater and solid waste from antimicrobial manufacturing facilities can potentially contaminate environments. The World Health Organization has established technical guidelines for managing antimicrobial resistance (AMR) in pharmaceutical wastewater and solid waste. However, the scarcity of publicly available data on antimicrobial manufacturing processes impedes the development of effective mitigation strategies. To address this knowledge gap, we developed a comprehensive database documenting antibiotics and antibiotic resistance genes (ARGs) in actual wastewater and solid waste samples, primarily fermentation residues. Through systematic review methodology, we compiled data from extensive searches of English-language article databases, including Web of Science and PubMed. The database contains data from 270 distinct samples collected across 45 fermentation residue treatment systems and 46 wastewater treatment systems, derived from 70 published English-language articles spanning 2008 to 2024. In operational pharmaceutical facilities, antibiotic concentrations ranged from 82 to 1,663 mg/L in raw wastewater and from 1,000 to 10,182 mg/kg dry matter (DM) in antibiotic fermentation residues. Various treatment technologies demonstrated significant reductions in both antibiotic concentrations and ARG levels within wastes. This database provides the first global perspective on antibiotic and ARG contamination from antibiotic production processes, supporting AMR management initiatives. It establishes a dynamic, continuously updated platform accessible to researchers and industry stakeholders via the link: https://dash.drwater.net/antiboard/.

Profiling metabolites and exploring metabolism of parabens in human urine using non-target screening and molecular networking

Parabens are widely used as preservatives in food, pharmaceuticals, and cosmetics due to their excellent antimicrobial activities, cost-effectiveness, and stability. Previous studies have demonstrated their harmful potential and ubiquity in the environment and human tissues. This study revealed profiles of parabens and their metabolites in urine samples from a general population of different ages in China using non-target screening. Metabolism of parabens in human bodies was further explored through the identified metabolites in combination of molecular networking. A total of 34 paraben compounds were screened in the urine samples. In addition to 3 identified confidence level 1 (CL1) parent parabens, 3 CL2 compounds were also identified, namely 4-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, and ethylparaben sulfate. Furthermore, 6 CL3 compounds were tentatively identified, five of which were sulfonated and sulfated metabolites of parabens. The remaining 22 were CL4 features without certain chemical structures. Hazardousness assessment suggested toxic potential of the identified metabolites. Distribution of the parabens and metabolites in the urines showed age-dependent differences. Sulfonation and sulfation were potentially significant metabolic pathways of the parabens in human bodies. This study provides a new insight into understanding metabolism of parabens in human bodies and potential risks of human exposure to parabens.

Evaluating the behavior and environmental risks of carbamazepine and its metabolites in soil aquifer treatment: Insights from deconjugation dynamics and toxicity assessment

The presence of pharmaceuticals in the environment has been a growing concern. Recent studies highlight the ecological risks of pharmaceuticals, but most risk assessments focus on the parent drug, neglecting metabolites. This study examines the behavior and environmental risks of carbamazepine (CBZ) and its metabolites in soil aquifer treatment (SAT) for wastewater reclamation. Findings indicate that CBZ metabolites' total concentration exceeds that of CBZ. Notably, carbamazepine-N-glucuronide (CBZ-N-Glu) concentration decreased from 48.12 ng/L to undetectable levels during SAT, while CBZ concentration increased from 64.87 to 95 ng/L, suggesting possible deconjugation of CBZ-N-Glu. Batch and column experiments confirmed the hypothesis, showing a gradual disappearance of CBZ-Glu and a corresponding rise in CBZ concentration when CBZ-N-Glu was spiked into a recirculated SAT system. Quantitative structure-activity relationships (QSAR) analysis revealed that CBZ exhibits higher acute and chronic toxicity, with metabolites showing varying levels of developmental toxicity. The study also evaluates the persistence, mobility, and toxicity (PMT) characteristics of CBZ and its metabolites, highlighting CBZ-N-Glu's particularly adverse PMT characteristics compared to CBZ. In summary, the residual pharmaceuticals in the reclaimed water process should be evaluated systematically, considering both the parent compounds and their metabolites.

First insight into the environmental fate of N-acetylated sulfonamides from wastewater disinfection to solar-irradiated receiving waters

The worldwide detection of emerging transformation products of organic micropollutants has raised accumulating concerns owing to their unknown environmental fate and undesired toxicity. This work first explored the reaction kinetics and mechanisms of the prevalent N-acetylated sulfonamides (N4-AcSAs, the typical sulfonamide metabolites) from wastewater disinfection to solar-irradiated receiving waters. The transformation scenarios included chlorination/bromination, photodegradation, and solar/chlorine treatment. The halogenations of two N4-AcSAs (N4-acetylated sulfadiazine, N4-AcSDZ; N4-acetylated sulfamethoxazole, N4-AcSMX) were pH-dependent at pH 5.0-8.0, and the reactions between the neutral forms of oxidants and anionic N4-AcSAs dominated the process. Furthermore, solar-based photolysis significantly eliminated N4-AcSAs in small water bodies with low dissolved organic carbon levels, while the indirect photolysis mediated by hydroxyl radicals and carbonate radicals contributed the most. The presence of chlorine residues in solar-irradiated wastewater effluents promoted the decay of N4-AcSAs, in which the generated hydroxyl radicals and ozone played a major role. Product analysis suggested the main transformation patterns of N4-AcSAs during the above scenarios included electrophilic attack, bond cleavage, SO2 extrusion, hydroxylation, and rearrangement. Multiple secondary products maintained higher persistence, mobility, and toxicity to aquatic organisms than N4-AcSAs. Overall, the natural and engineered transformations of such micropollutants underlined the necessity of including their degradation products in future chemical management and risk assessment.

Chemical profiling of organic contaminants in rural surface waters combining target and non-target LC-HRMS/MS analysis

The pollution of natural waters by contaminants of emerging concern (CECs) is one of the pressing problems due to their global distribution and potential negative effects on the environment and human health. In rural areas with lower population density and limited industrial development, less contamination is expected. However, the lack of wastewater treatment plants (WWTPs) or their poor removal efficiency can lead to significant input of pollutants. In this context, 11 streams of rural areas in the Guadalquivir River basin, southeast of Spain, were studied over two years to obtain an overview of the origin and distribution of contaminants. A target method using solid-phase extraction and liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) was developed for the analysis of 316 compounds in surface waters. A total of 78 target analytes were detected, comprising pesticides, pharmaceuticals, personal care products (PCPs), transformation products (TPs), and industrial chemicals. The flame retardant tributyl phosphate (16-3572 ng L-1) was detected in all samples, followed by caffeine (30-8090 ng L-1) and the analgesic tramadol (3-1493 ng L-1). The target approach was combined with a non-target analysis (NTA) strategy to obtain an overall perspective of the chemical profile of unexpected or unknown compounds in the samples. Up to 79 contaminants were tentatively identified, and 12 of them were finally confirmed with standards. Most of the contaminants determined by NTA were pharmaceuticals and their TPs. The results indicated that most of CECs have an urban origin despite traditional agriculture is the main economic activity in this region. Moreover, the absence of WWTPs in small towns is significant, as contamination levels at these sites were comparable to or higher than those in larger populations with sewage treatments.

Microbiome regulation for sustainable wastewater treatment

Sustainable wastewater treatment is essential for attaining clean water and sanitation, aligning with UN Sustainable Development Goals. Wastewater treatment plants (WWTPs) have utilized environmental microbiomes in biological treatment processes in this effort for over a century. However, the inherent complexity and redundancy of microbial communities, and emerging chemical and biological contaminants, challenge the biotechnology applications. Over the past decades, understanding and utilization of microbial energy metabolism and interaction relationships have revolutionized the biological system. In this review, we discuss how microbiome regulation strategies are being used to generate actionable performance for low-carbon pollutant removal and resource recovery in WWTPs. The engineering application cases also highlight the real feasibility and promising prospects of the microbiome regulation approaches. In conclusion, we recommend identifying environmental risks associated with chemical and biological contaminants transformation as a prerequisite. We propose the integration of gene editing and enzyme design to precisely regulate microbiomes for the synergistic control of both chemical and biological risks. Additionally, the development of integrated technologies and engineering equipment is crucial in addressing the ongoing water crisis. This review advocates for the innovation of conventional wastewater treatment biotechnology to ensure sustainable wastewater treatment.

Tracing contaminants of emerging concern and their transformations in the whole treatment process of a municipal wastewater treatment plant using nontarget screening and molecular networking strategies

This study employed nontarget screening with high-resolution mass spectrometry and molecular network strategy to characterize the occurrence and tranformation of contaminants of emerging concern (CECs) through a wastewater treatment plant in Guangzhou. We detected 70,631 compounds in positive mode and 14,423 in negative mode in influent, from which 94.5 % of these compounds were successfully eliminated after treatment. Among them, 510 chemicals were identified, with pharmaceuticals being the largest category excluding natural products, accounting for 146 compounds. And 29 CECs were semiquantified with concentrations ranging from 2.80 ng/L (Fluconazole) to 10,351 ng/L (Nicotine). The removal efficiency varied: 60 compounds were easily removable (>90 % removal), 17 were partially removable (40-90 % removal), and 44 were non-degradable (<40 % removal). Additionally, we tentatively identified transformation products (TPs) of CECs using a molecular network analysis, revealing over 20,000 compound pairs sharing common fragments, with 191 compounds potentially linked to 47 level 1 compounds, suggesting their role as TPs of CECs. These findings illuminated the actual treatment efficiency of wastewater treatment plants for CECs and the potential TPs, offering valuable insights for future improvements in wastewater management practices.

Enhancing Internal Electric Field of Metal-Free Donor-Acceptor Conjugated Photocatalysts for Efficient Photocatalytic Degradation of Tetracycline and CO2 Reduction

Constructing alternating donor-acceptor (D-A) units within g-C3N4 represents an effective strategy for enhancing photocatalytic performance through improved charge carrier separation while concurrently addressing energy shortages and facilitating wastewater remediation. Here, a series of D-A-type conjugated photocatalysts (CNBTC-X) are prepared using g-C3N4 as an acceptor unit and different masses of 5-bromo-2-thiophenecarboxaldehyde (BTC) as a donor unit by a one-step thermal polymerization. CNBTC-50 presents higher photocatalytic properties for CO2 reduction coupled with tetracycline (TC) removal than those of g-C3N4, CNBTC-10, CNBTC-30, and CNBTC-70. The introduction of the unique electron-donor-acceptor structure effectively drives the separation and transfer of photoinduced carriers while reducing the internal carrier transfer hindrance. Photocatalytic experiments reveal that the CNBTC-50 photocatalyst achieves up to 94.6% TC removal under visible light irradiation conditions. Compared with that of the pristine g-C3N4, the photocatalytic degradation reaction rate constant of CNBTC-50 is significantly increased by about 3.87 times. The study examines the influence of various reaction parameters on degradation activity, including catalyst concentration, pH, and TC concentration. Additionally, LC-MS is utilized to perform a comprehensive analysis of the intermediates and pathways involved in TC degradation. Furthermore, CNBTC-50 demonstrates remarkable photocatalytic CO2 reduction activity, achieving rates of 20.83 μmol g-1 h-1 (CO) and 9.36 μmol g-1 h-1 (CH4), which are 10.68 and 5.98 times more efficient than those of g-C3N4, respectively. This work aims to offer valuable guidance for the rational design of nonmetal D-A-structured catalysts and effectively integrates reaction systems to couple CO2 reduction with antibiotic removal.

Antibiotic biotransformation potential of biofilms in streams receiving treated wastewater effluent: Biodegradation mechanism and bacterial community structure

Antibiotics are a widely distributed and effective antibacterial agents. Human medical treatment and livestock aquaculture are major sources of antibiotics in aquatic ecosystems, potentially damaging the biofilms that are the foundation of stream food webs. In this study, we conducted antibiotic biotransformation experiments using biofilms cultured in streams upstream and downstream of a wastewater treatment plant outlet to distinguish different fate processes of antibiotics in biofilms. It was found that stream biofilms have biotransformation potential mainly for specific sulfonamide antibiotics. Flavobacterium and Dyadobacter were identified to be associated with biofilm biotransformation of antibiotics by 16S rDNA sequencing. Besides, microorganisms released from treated wastewater integrated into downstream biofilm communities, thereby enhancing the biotransformation potential of downstream biofilm communities compared to upstream biofilm. These findings enriched the understanding of the biotransformation of micropollutants by stream biofilms, and to thus promote the development of biofilm-based monitoring technologies.

Pore modulation of single atomic Fe sites for ultrafast Fenton-like chemistry with amplified electron migration oxidation

The limited interaction between pollutants, oxidants, and the surface catalytic sites of single atom catalysts (SACs) restricts the water decontamination effectiveness. Confining catalytic sites within porous structures enables the localized enrichment of reactants for optimized reaction kinetics, while the specific regulatory mechanisms remain unclear. Herein, SACs with porous modification significantly improves the utilization of peroxymonosulfate (PMS) and pollutant degradation activity. Confining catalytic sites in porous structure effectively reduces the mass transfer distance between radicals (SO4•- and •OH) and pollutants, thereby improving reaction performance. Pore modulation changes the surface electronic structure, leading to a significant improvement in the electron migration process. The system shows significant potential in effectively oxidizing various common emerging pollutants, and exhibits robust resistance to interference from environmental matrices. Moreover, a quantitative evaluation using life cycle assessment (LCA) indicates that the pFe-SAC/PMS system showcases superior environmental importance and practicality.

Profiles, drivers, and prioritization of antibiotics in China's major rivers

Through a systematic review of literature references from 2007 to 2022, we compiled a comprehensive national dataset comprising over 67,000 records and covering information on 129 antibiotics detected in the surface water and sediments of China's major rivers. Our analysis revealed notably high antibiotic concentrations in the Liaohe and Yellow Rivers. Among the antibiotics examined, sulfonamides, quinolones, and tetracyclines exhibited relatively high median concentrations in river water. Regional distribution analysis highlighted increased antibiotic levels in Shandong and Tianjin compared to other areas. Partial least squares path modeling revealed that animal production and pollution discharge positively influenced antibiotic levels in river water, whereas natural and socioeconomic factors had negative impacts. Based on the ecological risk assessment, we formulated a prioritized national list of antibiotics, with sulfonamides having the largest number of entries, followed by quinolones. Importantly, our analysis revealed a declining trend in antibiotic concentrations and the associated risk levels across China during the study period. This study not only enhances our understanding of antibiotic distribution in China's water systems, but also contributes to the development of a scientifically sound approach for prioritizing antibiotics. Ultimately, these findings will inform targeted antibiotic management and control strategies. ENVIRONMENTAL IMPLICATION: Antibiotics, posing threats to ecosystems and human health, exhibit pseudo-persistence in the environment. we compiled a national dataset of over 67,000 records on antibiotics, our study scrutinized antibiotic distribution in China's major river water and sediment. Through this analysis, we identified key factors influencing distribution patterns and crafted a national priority ranking for antibiotics. These findings deepen our understanding of antibiotic presence and contribute to the development of targeted management strategies aimed at minimizing environmental impact.

Micro-nano H2 bubbles enhanced hydrodehalogenation of 3-chloro-4-fluoroaniline: Mass transfer and action mechanism

3-chloro-4-fluoraniline (FCA) is an important intermediate for the synthesis of antibiotics, herbicides and insecticides, and has significant environmental health hazards. Catalytic hydrogenation technology is widely used in pretreatment of halogenated organics due to its simple process and excellent performance. However, compared with the research of high activity hydrogenation catalyst, the research of efficient utilization of hydrogen source under mild conditions is not sufficient. In this work, micro-nano H2 bubbles are produced in situ by electrolytic water and active metal replacement, and their apparent properties are studied. The result show that the H2 bubbles have a size distribution in the range of 150-900 nm, which can rapidly reduce the REDOX potential of the water and maintain it in a hydrogen-rich state for a long time. Under the action of Pd/C catalyst, atomic hydrogen (H•) produced by dissociative adsorption can sequentially hydrogenate FCA to aniline. The H• utilization ratios of the above two hydrogen supply pathways reach 6.20% and 4.94% respectively, and H2 consumption is reduced by tens of times (≥50 → ≈1.0 mL/min). The research provides technical support for the efficient removal of halogenated refractory pollutants in water and the development of hydrogen economy.

Mechanisms linking triclocarban biotransformation to functional response and antimicrobial resistome evolution in wastewater treatment systems

Evaluating the role of antimicrobials biotransformation in the regulation of metabolic functions and antimicrobial resistance evolution in wastewater biotreatment systems is crucial to ensuring water security. However, the associated mechanisms remain poorly understood. Here, we investigate triclocarban (TCC, one of the typical antimicrobials) biotransformation mechanisms and the dynamic evolution of systemic function disturbance and antimicrobial resistance risk in a complex anaerobic hydrolytic acidification (HA)-anoxic (ANO)/oxic (O) process. We mined key functional genes involved in the TCC upstream (reductive dechlorination and amide bonds hydrolysis) and downstream (chloroanilines catabolism) biotransformation pathways by metagenomic sequencing. Acute and chronic stress of TCC inhibit the production of volatile fatty acids (VFAs), NH4+ assimilation, and nitrification. The biotransformation of TCC via a single pathway cannot effectively relieve the inhibition of metabolic functions (e.g., carbon and nitrogen transformation and cycling) and enrichment of antimicrobial resistance genes (ARGs). Importantly, the coexistence of TCC reductive dechlorination and hydrolysis pathways and subsequent ring-opening catabolism play a critical role for stabilization of systemic metabolic functions and partial control of antimicrobial resistance risk. This study provides new insights into the mechanisms linking TCC biotransformation to the dynamic evolution of systemic functions and risks, and highlights critical regulatory information for enhanced control of TCC risks in complex biotreatment systems.

Accumulation of antibiotics in the environment: Have appropriate measures been taken to protect Canadian human and ecological health?

In Canada, every day, contaminants of emerging concern (CEC) are discharged from waste treatment facilities into freshwaters. CECs such as pharmaceutical active compounds (PhACs), personal care products (PCPs), per- and polyfluoroalkyl substances (PFAS), and microplastics are legally discharged from sewage treatment plants (STPs), water reclamation plants (WRPs), hospital wastewater treatment plants (HWWTPs), or other forms of wastewater treatment facilities (WWTFs). In 2006, the Government of Canada established the Chemicals Management Plan (CMP) to classify chemicals based on a risk-priority assessment, which ranked many CECs such as PhACs as being of low urgency, therefore permitting these substances to continue being released into the environment at unmonitored rates. The problem with ranking PhACs as a low priority is that CMP's risk management assessment overlooks the long-term environmental and synergistic effects of PhAC accumulation, such as the long-term risk of antibiotic CEC accumulation in the spread of antibiotic resistance genes. The goal of this review is to specifically investigate antibiotic CEC accumulation and associated environmental risks to human and environmental health, as well as to determine whether appropriate legislative strategies are in place within Canada's governance framework. In this research, secondary data on antibiotic CEC levels in Canadian and international wastewaters, their potential to promote antibiotic-resistant residues, associated environmental short- and long-term risks, and synergistic effects were all considered. Unlike similar past reviews, this review employed an interdisciplinary approach to propose new strategies from the perspectives of science, engineering, and law.

Apportioning sources of chemicals of emerging concern along an urban river with inverse modelling

Concentrations of chemicals in river water provide crucial information for assessing environmental exposure and risks from fertilisers, pesticides, heavy metals, illicit drugs, pathogens, pharmaceuticals, plastics and perfluorinated substances, among others. However, using concentrations measured along waterways (e.g., from grab samples) to identify sources of contaminants and understand their fate is complicated by mixing of chemicals downstream from diverse diffuse and point sources (e.g., agricultural runoff, wastewater treatment plants). To address this challenge, a novel inverse modelling approach is presented. Using waterway network topology, it quantifies locations and concentrations of contaminant sources upstream by inverting concentrations measured in water samples. It is computationally efficient and quantifies uncertainty. The approach is demonstrated for 13 contaminants of emerging concern (CECs) in an urban stream, the R. Wandle (London, UK). Mixing (the forward problem) was assumed to be conservative, and the location of sources and their concentrations were treated as unknowns to be identified. Calculated CEC source concentrations, which ranged from below detection limit (a few ng/L) up to 1μg/L, were used to predict concentrations of chemicals downstream. Using this approach, >90% of data were predicted within observational uncertainty. Principal component analysis of calculated source concentrations revealed signatures of two distinct chemical sources. First, pharmaceuticals and insecticides were associated with a subcatchment containing a known point source of treated effluent from a wastewater treatment plant. Second, illicit drugs and salicylic acid were associated with multiple sources, interpreted as input from untreated sewage including Combined Sewer Overflows (CSOs), misconnections, runoff and direct disposal throughout the catchment. Finally, a simple algorithmic approach that incorporates network topology was developed to design sampling campaigns to improve resolution of source apportionment. Inverse modelling of contaminant measurements can provide objective means to apportion sources in waterways from spot samples in catchments on a large scale.

Solid-liquid redistribution and degradation of antibiotics during hydrothermal treatment of sewage sludge: Interaction between biopolymers and antibiotics

Waste activated sludge serves an important reservoir for antibiotics within wastewater treatment plants, and understanding the occurrence and evolution of antibiotics during sludge treatment is crucial to mitigate the potential risks of subsequent resource utilization of sludge. This study explores the degradation and transformation mechanisms of three typical antibiotics, oxytetracycline (OTC), ofloxacin (OFL), and azithromycin (AZI) during sludge hydrothermal treatment (HT), and investigates the influence of biopolymers transformation on the fate of these antibiotics. The findings indicate that HT induces a shift of antibiotics from solid-phase adsorption to liquid-phase dissolution in the initial temperature range of 25-90 °C, underscoring this phase's critical role in preparing antibiotics for subsequent degradation phases. Proteins (PN) and humic acids emerge as crucial for antibiotic binding, facilitating their redistribution within sludge. Specifically, the binding capacity sequence of biopolymers to antibiotics is as follows: OFL>OTC>AZI, highlighting that OFL-biopolymers display stronger electrostatic attraction, more available adsorption sites, and more stable binding strength. Furthermore, antibiotic degradation mainly occurs above 90 °C, with AZI being the most temperature-sensitive, degrading 92.97% at 180 °C, followed by OTC (91.26%) and OFL (52.51%). Concurrently, the degradation products of biopolymers compete for active sites to form novel amino acid-antibiotic conjugates, which inhibits the further degradation of antibiotics. These findings illuminate the effects of biopolymers evolution on intricate dynamics of antibiotics fate in sludge HT and are helpful to optimize the sludge HT process for effective antibiotics abatement.

Vital role of CYP450 in the biodegradation of antidiabetic drugs in the aerobic activated sludge system and the mechanisms

The extensive use of antidiabetic drugs (ADDs) and their detection in high concentrations in the environment have been extensively documented. However, the mechanism of ADDs dissipation in aquatic environments is still not well understood. This study thoroughly investigates the dissipation behavior of ADDs and the underlying mechanisms in the aerobic activated sludge system. The results indicate that the removal efficiencies of ADDs range from 3.98% to 100% within 48 h, largely due to the biodegradation process. Additionally, the gene expression of cytochrome P450 (CYP450) is shown to be significantly upregulated in most ADDs-polluted samples (P < 0.05), indicating the vital role of CYP450 enzymes in the biodegradation of ADDs. Enzyme inhibition experiments validated this hypothesis. Moreover, molecular docking and simulation results indicate that a strong correlation between the biodegradation of ADDs and the interactions between ADDs and CYP450 (Ebinding). The differences in dissipation behavior among the tested ADDs are possibly due to their electrophilic characteristics. Overall, this study makes the initial contribution to a more profound comprehension of the crucial function of CYP450 enzymes in the dissipation behavior of ADDs in a typical aquatic environment.

Discovering Novel Organophosphorus Compounds in Wastewater Treatment Plant Effluents through Suspect Screening and Nontarget Analysis

Limited knowledge on the structure of emerging organophosphorus compounds (OPCs) hampers our comprehensive understanding of their environmental occurrence and potential risks. Through suspect and nontarget screening, combining data-dependent acquisition, data-independent acquisition, and parallel reaction monitoring modes, we identified 60 OPCs (17 traditional and 43 emerging compounds) in effluents of 14 wastewater treatment plants (WWTPs) in Beijing and Qinghai, China. These OPCs comprise 26 organophosphate triesters, 17 organophosphate diesters, 6 organophosphonates, 7 organothiophosphate esters, and 4 other OPCs. Notably, 14 suspect OPCs were newly identified in WWTP effluents, and 16 nontarget OPCs were newly discovered in environmental matrices. Specifically, the cyclic phosphonate, (5-ethyl-2-methyl-1,3,2-dioxaphosphorinan-5-yl)methyl dimethyl phosphonate P-oxide (PMMMPn), consistently appeared in all WWTP effluents, with semiquantitative concentrations ranging from 44.4 to 282 ng/L. Its analogue, di-PMMMPn, presented in 93% of wastewater samples. Compositional differences between the WWTP effluents of two cities were mainly attributed to emerging OPCs. Hazard and ecological risk assessment underscored the substantial contribution of chlorinated organophosphate esters and organothiophosphate esters to overall risks of OPCs in WWTP effluents. This study provides the most comprehensive OPC profiles in WWTP effluents to date, highlighting the need for further research on their occurrence, fate, and risks, particularly for chlorinated OPCs.