Discharge of three benzotriazole corrosion inhibitors with municipal wastewater and improvements by membrane bioreactor treatment and ozonation

Occurrence, removal, and prioritization of organic micropollutants in four full-scale wastewater treatment plants in Korea

This study investigated the occurrence, removal rate, and potential risks of 43 organic micropollutants (OMPs) in four municipal wastewater treatment plants (WWTPs) in Korea. Results from two-year intensive monitoring confirmed the presence of various OMPs in the influents, including pharmaceuticals such as acetaminophen (pain relief), caffeine (stimulants), cimetidine (H2-blockers), ibuprofen (non-steroidal anti-inflammatory drugs- NSAIDs), metformin (antidiabetics), and naproxen (NSAIDs) with median concentrations of >1 μg/L. Some pharmaceuticals (carbamazepine-anticonvulsants, diclofenac-NSAIDs, propranolol-β-blockers), corrosion inhibitors (1H-benzotriazole-BTR, 4-methyl-1H-benzotriazole-4-TTR), and perfluorinated compounds (PFCs) were negligibly removed during WWTP treatment. The OMP concentrations in the influents and effluents were mostly lower in August than those of other months (p-value <0.05) possibly due to wastewater dilution by high precipitation or enhanced biodegradation under high-temperature conditions. The anaerobic-anoxic-oxic process (A2O) with a membrane bioreactor exhibited higher OMP removal than other processes, such as A2O with sedimentation or the conventional activated sludge process (p-value <0.05). Pesticides (DEET and atrazine), corrosion inhibitors (4-TTR and BTR), and metformin were selected as priority OMPs in toxicity-driven prioritization, whereas PFCs were determined as priority OMPs given their persistence and bioaccumulation properties. Overall, our results contribute to an important database on the occurrence, removal, and potential risks of OMPs in Korean WWTPs.

Contamination of ultraviolet absorbers in food: toxicity, analytical methods, occurrence and risk assessments

Ultraviolet (UV) absorbers are chemical substances that are widely used as defenses against the damaging effects of solar radiations. UV absorbers, despite their benefits, are categorized as emerging pollutants because they have been demonstrated to be mutagenic, toxic, pseudo-persistent, bio-accumulative, and to have strong estrogenic effects. Because of their common use in personal care products, they continue to enter the environment. Several food samples, particularly those derived from aquatic sources, have been found to be contaminated with these compounds. Toxic effects on aquatic life, such as metabolic imbalance and developmental toxicity, result from the continued presence of UV absorbers in aquatic bodies. In addition, the degree of exposure to these pollutants in foods should be examined because there are certain risks associated with their consumption by humans. Therefore, this review focuses on the toxicity, analytical techniques, occurrence, and risk assessments of UV absorbers found in food.

Key constructed wetland design features for maximized micropollutant removal from treated municipal wastewater: A literature study based on 16 indicator micropollutants

The removal of micropollutants from wastewater by constructed wetlands (CWs) has been extensively studied and reviewed over the past years. However, most studies do not specifically focus on the removal of micropollutants from the effluent of conventional wastewater treatment plants (WWTP) that still contains micropollutants, but on the removal of micropollutants from raw wastewater. Raw wastewater has a significantly different composition compared to WWTP effluent, which positively or negatively affects micropollutant removal mechanisms. To determine the optimal CW design for post-treatment of WWTP effluent to achieve additional micropollutant removal, this review analyzes the removal of 16 Dutch indicator micropollutants for post-treatment technology evaluation from WWTP effluent by different types of CWs. It was concluded that CW systems with organic enhanced adsorption substrates reach the highest micropollutant removal efficiency as a result of adsorption, but that the longevity of the enhanced adsorption effect is not known in the systems studied until now. Aerobic biodegradation and photodegradation are other relevant removal mechanisms for the studied micropollutants. However, a current knowledge gap is whether active aeration to stimulate the aerobic micropollutant biodegradation results in an increased micropollutant removal from WWTP effluent. Further knowledge gaps that impede the wider application of CW systems for micropollutant removal from WWTP effluent and allow a fair comparison with other post-treatment technologies for enhanced micropollutant removal, such as ozonation and activated carbon adsorption, relate to i) saturation of enhanced adsorption substrate; ii) the analysis of transformation products and biological effects; iii) insights in the relationship between microbial community composition and micropollutant biodegradation; iv) plant uptake and in-plant degradation of micropollutants; v) establishing design rules for appropriate hydraulic loading rates and/or hydraulic retention times for CWs dedicated to micropollutant removal from WWTP effluent; and vi) the energy- and carbon footprint of different CW systems. This review finishes with detailed suggestions for future research directions that provide answers to these knowledge gaps.

Comparative toxicogenomics of benzotriazole ultraviolet stabilizers at environmental concentrations in Asian clam (Corbicula fluminea): Insight into molecular networks and behavior

Benzotriazole ultraviolet stabilizers (BUVSs) are widespread emerging pollutants, which can pose exposure risks to benthic organisms. However, the toxicity and mechanisms of BUVSs congeners in benthic clams are far from elucidated. In this study, Asian clams (Corbicula fluminea) were exposed to one of UV-234, UV-326, UV-329, or UV-P at environmentally relevant levels (0.1, 1, and 10 μg/L) for 21 days. Filtration rate (FR) was increased in clams exposed to all BUVSs and there were notable histopathologic changes, including irregular digestive lumen, lipid droplet vacuolation, and degraded epithelial cells. To determine the molecular underpinnings following BUVSs exposure, the transcriptome responses in digestive glands were compared. Differentially expressed genes shared among BUVSs treatments were associated with focal adhesion, TNF-α/NF-κB proinflammatory pathways, and apoptosis. Following this, biochemical analysis of biomarkers related to apoptosis were conducted to further validate response. Exposure to BUVSs inhibited anti-oxidant enzyme activity and induced oxidative stress. Heat shock proteins were also triggered with exposure, and there was an induction of caspase-3 and caspase-9 activity. Molecular responses were not identical in the digestive gland of C. fluminea when comparing responses to BUVSs; nevertheless conserved mechanism (impairment of the oxidative defense system, immune system disruption, and induction of apoptosis) among BUVSs congeners was noted. This study provides novel insight into the toxicity and hazards of BUVSs in benthic organisms.

Exposure to high-performance benzotriazole ultraviolet stabilizers: Advance in toxicological effects, environmental behaviors and remediation mechanism using in-silica methods

Benzotriazole ultraviolet stabilizers (BUVSs), as light stabilizers, have attracted widespread attention because of their easy migration in the environment and their acute toxicity and biological toxicity effects, such as immunotoxicity and hepatotoxicity. Accordingly, the treatment and remediation mechanisms of high-performance, environmentally friendly, and low human health risk BUVS substitutes were analyzed. Firstly, the weights and the comprehensive effect (CE) values of migration and toxicity of BUVSs were determined by Topsis assisted by the coefficient of variation (CV) method. From this, a three-dimensional quantitative structure activity relationship (3D-QSAR) model based on the CE values of the 13 BUVSs was constructed. Secondly, EPI software was used to predict the functionality and environmental friendliness of BUVS substitutes, and a partial least squares regression machine learning (ML-PLSR) model was used to analyze the mechanism. Then, ADMET (absorption, distribution, metabolism, excretion, toxicity), TOPKAT, and exposure dose models were used to evaluate the ecological and human health risks of BUVSs and their substitutes. Finally, the key charge information affecting the UV-326 substitutes was deduced by time dependent density functional theory (TDDFT). Using UV-326 as an example, 15 UV-326 substitutes with reduced CE values were designed (reductions of 2.61%-23.18%). Compared with ML-PLSR models of acute toxicity, immunotoxicity, and hepatotoxicity, it was found that the decrease of DM and Q_yy values and the increase of Q_zz value could further decrease the toxicity of the UV-326 substitutes. Ecological and human health risk assessment showed that the exposure risks of the six UV-326 substitutes were within acceptable limits. TDDFT showed that the change of electron distribution and electron excitation type were the key factors affecting the performance of the UV-326 substitutes, and a charge transfer excitation type was more conducive to obtaining high-performance, environmentally friendly UV-326 substitutes. This study aims to alleviate the toxic damage to the ecological environment and human health caused by BUVS exposure.

Environmental risk assessment of low molecule benzotriazoles in urban road rainwaters in Poland

This study aimed to identify and quantify benzotriazoles (BTRs) emissions from road traffic and paved areas in an urban environment. Heterocyclic organic compounds BTRs are an emerging threat, under-recognized and under-analyzed in most environmental and water legislation. They are hazardous, potentially mutagenic, and carcinogenic micropollutants, not susceptible to effective biodegradation, and they move easily through the trophic chain, contaminating the environment and water resources. Traffic activities are a common source of BTR emissions in the urban environment, directly polluting human habitats through the different routes and numerous vehicles circulating in the cities. Using twelve heterogeneous locations scattered over a metropolitan area in Poland as a case study, this research analyzed the presence of BTRs in water samples from runoff produced from rainwater and snowmelt. 1H-BTR, 4Me-BTR, 5Me-BTR and 5Cl-BTR were detected in the tested runoff water. 5Cl-BTR was present in all samples and in the highest concentrations reaching 47,000 ng/L. Risk quotients calculated on the basis of the determined concentrations indicate that the highest environmental risk is associated with the presence of 5Cl-BTR and the sum of 4Me-BTR and 5Me-BTR, and the most sensitive organisms are bacteria and invertebrates. The results indicate that it is possible to associate the occurrence of these contaminants with the type of cover, traffic intensity, and vehicle type.

Degradation of Benzotriazole UV-stabilizers in the presence of organic photosensitizers and visible light: A time-resolved mechanistic study

Benzotriazole UV-stabilizers (BUVSs) are commonly used in industry as solar filters, due to their strong UV light absorption. Because of their extended usage, environmental contamination of waters due to BUVSs constitutes a growing concern. Direct photodegradation of BUVSs is not efficient due to their intrinsic thermal pathways to release the absorbed light. Nevertheless, their abatement in natural environments could be assisted by chromophoric dissolved organic matter. Among the BUVSs, three representative candidates were selected, UV-326, UV-327 and UV-328, to demonstrate the potential of Riboflavin (RF) as a natural visible-light absorbing photocatalyst for the abatement of these recalcitrant pollutants under reductive conditions. The use of visible light and DABCO, as a model sacrificial electron donor, generates the radical anion RFTA^.-. This key species reacts with the solar filters, achieving their reductive abatement from the medium. Moreover, the participation of every potential reactive species has been investigated by photophysical techniques, together with determination of the quenching rate constant for every reaction pathway. Consequently, evidence supported the main role of the reductive photodegradation pathway, being RFTA^.- the key species in the abatement of BUVSs.

Pollution characteristics, exposure assessment and potential cardiotoxicities of PM2.5-bound benzotriazole and its derivatives in typical Chinese cities

Benzotriazole and its derivatives (BTRs), classified as high-volume production chemicals, have been widely detected in various environmental media, including the atmosphere, water, soil and dust, as well as organisms. However, studies on the pollution characteristics and health impact of PM_2.5 related BTRs are so far limited. This study is the first to demonstrate the regional scale distribution of PM_2.5-bound BTRs and their potential cardiotoxicities. Optimized methods of extraction, purification and GC-EI-MS/MS were applied to characterize and analyze PM_2.5-bound BTRs from three cities in China during the winter of 2018. The concentration of ∑BTRs in Taiyuan (6.28 ng·m^-3) was more than three times that in Shanghai (1.53 ng·m^-3) and Guangzhou (1.99 ng·m^-3). Benzotriazole (BTR) and 5-methyl-1H-benzotriazole (5TTR) contributed more than 80% of ∑BTRs concentration as the major pollutants among three cities. The correlation analysis indicated that there was a positive correlation between temperature and concentration of BTR and a negative correlation between temperature and concentration of 5TTR. In addition, the risk of BTRs exposure to toddlers should be paid more attention in Taiyuan by the human exposure assessment. Furthermore, toxicity screening by experimental methods indicated that 4-methyl-1H-benzotriazole (4TTR) was the most harmful to cardiomyocytes. The western blot assay showed a ROS-mediated mitochondrial apoptosis signaling pathway was activated after exposure to 4TTR in neonatal rat cardiomyocytes (NRCMs). On the other hand, metabolomics revealed that exposure of 4TTR to NRCMs disturbed mitochondrial energy metabolism by disturbing pantothenate and coenzyme A synthesis pathway. Our study not only clarifies the contamination profiles of PM_2.5-bound BTRs in typical Chinese cities but also reveals their cardiotoxicities associated with mitochondrial dysfunction.

Layered double hydroxides loaded sludge biochar composite for adsorptive removal of benzotriazole and Pb(II) from aqueous solution

In this work, a novel sludge biochar/Zn-Al layered double hydroxide composite (SL) was synthesized in a facile co-precipitation method, and it was used to simultaneously remove benzotriazole (BTA) and lead ion (Pb(II)). Batch adsorption experiments demonstrated that composites with sludge content of 1.0 g (SL-1.0) had a great adsorption performance for BTA and Pb(II). The maximum adsorption capacities of SL-1.0 for BTA and Pb(II) were 239.6 and 226.1 mg g^-1, respectively. There was preferential adsorption of BTA in BTA and Pb(II) binary system. The adsorption mechanism analysis indicated that the BTA and Pb(II) adsorption involved electrostatic attraction and chemical bonding with surface functional groups on SL-1.0. Specifically, hydrogen bonding and π-π interaction were mainly ascribed to BTA adsorption, while complexation with surface function groups dominated Pb(II) adsorption. With the advantages of facile synthesis and excellent adsorption capacity, SL-1.0 possesses great potential for simultaneously removing of BTA and Pb(II) from wastewaters.

Linking plant-root exudate changes to micropollutant exposure in aquatic plants (Lemna minor and Salvinia natans). A prospective metabolomic study

Recent findings indicate that plant-root exudates can stimulate plant-associated microorganisms to enhance the biodegradation of contaminants in constructed wetlands. To understand this process, we studied the root-exudation changes of two aquatic plants (Lemna minor and Salvinia natans) upon micropollutants exposure (10, 100 and 1000 μg/L mixes containing naproxen, diclofenac, carbamazepine, and benzotriazole). After a 2-day exposure, plant exudates were collected, extracted and non-target analysis was performed with a gas chromatography-high resolution Orbitrap mass-spectrometer. Plants didn't show morphological or growth differences between the control and spiked reactors, but exudation changes were observed in both plants at all concentration levels. Partial least squares discriminant analysis showed that, for Lemna minor, the increase of micropollutants exposure was linked to the reduction of sugar and fatty acid exudation. This may trigger changes in the microbial community living on complex carbon forms. Instead, in Salvinia natans, micropollutants exposure was linked to the release of long-chain compounds such as cuticular waxes and sesquiterpenoids, which might be related to stress signaling. These results demonstrate that plant micropollutant-exposure at environmentally relevant concentration levels triggers changes in root exudates. This may help to design new strategies to enhance micropollutants degradation in nature based solutions such as in constructed wetlands.

Aerobic biodegradation of emerging azole contaminants by return activated sludge and enrichment cultures

Azoles are an emerging class of contaminants with a growing ubiquitous presence in the environment. This study investigates the aerobic microbial degradation of four azoles, pyrazole (PA), 1,2,4-triazole (TA), benzotriazole (BTA) and 5-methylbenzotriazole (5-MBTA), with return activated sludge and microbial enrichment cultures. Slow degradation of PA was observed in the presence of glucose and NH₄⁺ with a peak degradation rate of 0.5 mg d^-1 gVSS^-1. TA was found to be highly persistent, with no significant degradation observed in 6-8 months under any incubation condition. In contrast, the benzotriazoles were readily degraded at faster rates in all incubation conditions. The degradation rates observed for BTA and 5-MBTA, when provided as the sole substrates, were 8.1 and 16.5 mg d^-1 gVSS^-1, respectively. Two enrichment cultures, one degrading BTA and the other degrading 5-MBTA, were developed from the activated sludge. Mass balance studies revealed complete mineralization of 5-MBTA and partial breakdown of BTA by the enrichment cultures. Nocardioides sp. and Pandoraea pnomenusa were the most abundant bacteria in the BTA and 5-MBTA degrading enrichment cultures, respectively. The research shows large differences in the biodegradability of various azoles, ranging from complete mineralization of 5-MBTA to complete persistence for TA.

Simultaneous determination of low molecule benzotriazoles and benzotriazole UV stabilizers in wastewater by ultrasound-assisted emulsification microextraction followed by GC-MS detection

A rapid, sensitive, economically and ecologically friendly method based on one-step ultrasound-assisted emulsification microextraction and in situ derivatization followed by gas chromatography-mass spectrometry for simultaneous determination of low molecular benzotriazoles and benzotriazole-based ultraviolet filters was developed. The optimized method allows quantification of benzotriazole, 4-methylbenzotriazole, 5-methylbenzotriazole; 5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzortriazole and 2-(2'-hydroxy-5'-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole in municipal and industrial (dairy) wastewater. The method was validated using real influent and effluent wastewater and samples at various stages of the purification process. Relative recoveries obtained using wastewater as sample matrix were between 77 and 137%, method limits of detection from 0.001 to 0.035 µg/L, method limits of quantification from 0.003 to 0.116 µg/L, the repeatability expressed by the coefficient of variation did not exceed 12%. The use of the method for the determination of tested compounds in municipal and industrial wastewater showed their presence in most of the tested samples, in concentrations from LoD to 6.110 µg/L. The conducted studies of samples from municipal wastewater treatment plant located in north-east Poland showed that the effectiveness of benzotriazole removal by this plant wasfrom 29 to 84%. The load of tested compounds released into the environment by this facility ranges from 2 to 269 mg/day/1000 inhabitants.

UV/chlorine process for degradation of benzothiazole and benzotriazole in water: Efficiency, mechanism and toxicity evaluation

Benzothiazole (BZA) and benzotriazole (BTZ) as emerging contaminants were found persistent in aquatic environments and toxic to aquatic organisms. The degradation of BZA and BTZ by UV/chlorine was systematically investigated in this study, and the results showed that BZA and BTZ can be remarkably removed by UV/chlorine compared with UV alone and dark chlorination. The radical quenching tests showed that degradation of BZA and BTZ by UV/chlorine involved the participation of reactive chlorine species (RCS), hydroxyl radical (HO·), and UV photolysis. HO· dominated BZA degradation at neutral and alkalinity, while RCS dominated BTZ degradation. The second-rate order constants for ClO· and BZA and BTZ were 2.22 × 10⁸ M^-1 s^-1, and 2.40 × 10⁸ M^-1 s^-1, respectively. Besides, the second-order rate constants for HO· and BZA and BTZ were also determined at pH 5.0, 7.0, and 9.0, respectively. The degradation efficiency of BZA by UV/chlorine was substantially promoted at acidic conditions, while the degradation efficiency of BTZ was promoted at both acidic and specific alkaline range mainly due to the reactivity of radical species and deprotonated form. The influence of Cl^- was negligible, but the suppression effect of humic acid was slight during the BZA and BZT degradation by UV/chlorine. The transformation products were detected and the possible pathways were proposed. Seven disinfection by-products (DBPs) were identified both in BZA and BTZ degradation and trichloromethane was the main DBP. The toxicity assessment performed by luminescent bacteria and ECOSAR analysis indicated that the detoxification of BZA could be achieved by UV/chlorine, whereas the toxicity of BTZ was increased mainly due to the formation of intermediates. The findings from this study demonstrated UV/chlorine is likewise efficient for BZA and BTZ removal but the toxicity should be considered in the BTZ degradation.

Photo transformation of 5-methylbenzotriazole and 5-chlorobenzotriazole by UV irradiation: Influences of pH, salinity, metal species and humic acid

5-methylbenzotriazole (5-TTri) and 5-chlorobenzotriazole (CBT) are two benzotriazole derivatives widely used in various industrial and domestic applications. This paper reports on the photochemical behaviour of 5-TTri and CBT in aqueous solutions under UV radiation at 254 nm and the influences of pH, salinity, metal species and humic acid (HA) on their photo-transformation processes. The photolysis of 5-TTri and CBT under the exposure to UV light were found to follow the first-order reaction kinetic in all cases with half-lives ranging from 7.1 h to 24.3 h for 5-TTri and 5.1 h-20.5 h for CBT in various aqueous solutions containing metal ions and HA. The photolysis rates for both 5-TTri and CBT were strongly dependent on the solution pH value, and decreased with increasing solution pH. Salinity, metal species Cu²⁺ and Fe³⁺, and especially HA had inhibitory effects on the photolysis of 5-TTri and CBT under UV light irradiation at 254 nm. We proposed the tentative photo transformation schemes for both 5-TTri and CBT, which involved two photoproducts (4-methylaniline and N, N-diethylaniline- p-toluidine) and three photoproducts (4-chloroaniline, Aniline and 2,6-diethylaniline), respectively, via N-N and N-NH bond scission and dechlorination process.

Degradation of benzotriazole by sulfate radical-based advanced oxidation process

Benzotriazole (BTA) is a recalcitrant contaminant that is widely distributed in aquatic environments. This study explored the effectiveness of sulfate radical-based advanced oxidation process in degrading BTA (SR-AOP). The sulfate radical was generated by heat activation of persulfate (PS). Our results show alkaline pH promoted the BTA degradation. The solution pH also affected the speciation of total radicals. Sulfate radical ( S O 4 ⋅ - ) predominated at acidic pH while hydroxyl radical (HO^•) predominated at basic pH. High temperature, high PS concentration and low BTA concentration promoted the BTA degradation. Influence of water matrix constituents on the reaction kinetics was assessed. We found that ≤10 mM of Cl^- promoted the reaction, but 100 mM Cl^- inhibited it. H C O 3 - was similar to Cl^-. Br^- and C O 3 2 - inhibited the reaction while S O 4 2 - did not affect the reaction. N O 3 - of ≤10 mM did not affect the reaction, but 100 mM of N O 3 - inhibited it. Eleven degradation intermediates were identified using ultra-high solution Orbitrap mass spectrometry. Based on the intermediates identified, possible reaction pathways were proposed. Overall, SR-AOP can effectively mineralize BTA, but water matrix constituents greatly influenced the reaction kinetics and thus should be carefully considered for its practical application. Abbreviations: BTA, benzotriazole; PS, persulfate; PMS, peroxymonosulfate; SPC, sodium percarbonate; AOP, advanced oxidation process; PS-AOP, persulfate-based advanced oxidation process; SR-AOP, sulfate radical-based advanced oxidation process; TAP, thermally activated persulfate; TOC, total organic carbon; TBA, tert-butyl alcohol.

Photocatalytic Transformations of 1H-Benzotriazole and Benzotriazole Derivates

Benzotriazoles are a new class of organic emerging pollutants ubiquitously found in the environment. The increase of their concentration to detectable values is the consequence of the inability of the Conventional Waste Water Plants (CWWPs) to abate these products. We subjected 1H-benzotriazole (BTz), tolyltriazole (TTz), and Tinuvin P (TP, a common UV plastic stabilizer) to photocatalytic degradation under UV-irradiated TiO2 in different conditions. The principal photoformed intermediates, the relationship between the degradation rate and the pH, the degree of mineralization, and the fate of the organic nitrogen were investigated. Under the adopted experimental conditions, all the studied substrates were rapidly photocatalytically transformed (the maximum degradation rates for BTz and TTz were (3.88 ± 0.05) × 10-2 and (2.11 ± 0.09) × 10-2 mM min-1, respectively) and mineralized (the mineralization rate for BTz and TTz was 4.0 × 10-3 mM C min-1 for both substrates). Different from the 1,2,4-triazole rings that are not completely mineralized under photocatalytic conditions, 1H-benzotriazole and tolyltriazole were completely mineralized with a mechanism that involved a partial conversion of organic nitrogen to N2. The photocatalytic process activated by UV-irradiated TiO2 is an efficient tool to abate 1H-benzotriazole and its derivatives, avoiding their release in the environment.

Spatial and seasonal variations of organic corrosion inhibitors in the Pearl River, South China: Contributions of sewage discharge and urban rainfall runoff

While organic corrosion inhibitors are ubiquitous in aquatic environments, knowledge on their occurrence, sources and transport in urban surface water is still scarce. In this study, the spatial and seasonal variations of organic corrosion inhibitors and their potential sources were investigated in the Pearl River Delta (PRD), one of the most highly urbanized watersheds in China. A total of 8 compounds belonging to benzothiazole (BTH) and benzotriazole (BTR) groups respectively, were identified in the Pearl River. In addition, there were clear spatial and temporal differentiations in the concentration profiles. The dry season provided higher concentrations of BTH (213-1082 ng L^-1) and BTR (112-1279 ng L^-1) compared to the wet season (30-574 ng L^-1 for BTH and 23-482 ng L^-1for BTR), indicating a dominant process of dilution. Remarkably higher concentrations and similar composition features of targets were observed in the effluent samples from two sewage treatment plants (STPs). Our study indicated that rainfall runoff from urban traffic roads during wet season may also be an important contributor to the Pearl River water environment. The annual total mass loading of corrosion inhibitors from the main channel of the Pearl River is 53.2 tons and exhibited strong seasonal variation. Effluents discharge from STPs and urban rainfall runoff from traffic roads are main sources of corrosion inhibitors to the Pearl River.

Oxidative removal of benzotriazole using peroxymonosulfate/ozone/ultrasound: Synergy, optimization, degradation intermediates and utilizing for real wastewater

This study investigated the degradation efficiency of BTA using combination of ultrasound (US), peroxymonosulfate (PMS), and ozone. The effects of different operational parameters were investigated to optimize the process performance. The results showed that the highest removal efficiency was reached at neutral pH, ozone = 6.8 mg/L, PMS = 1.5 mM and US power = 200 W. Under these conditions, 40 mg/L of BTA was completely degraded within 60 min leading to the almost 85% of chemical oxygen demand removal, 75% of total organic carbon removal and 73.3% of organic nitrogen removal. Based on the scavenging tests, it was found that hydroxyl radical was the main oxidizing agent in the oxidation of BTA by PMS/ozone/US process. The inhibitive effect of anions on BTA removal was under this order NO₂^- > HCO₃^- > Cl^- > NO₃^- > SO₄^2-. Degradation intermediates of BTA were identified and oxidation pathway was proposed. Finally, real samples of saline water, petrochemical wastewater and secondary effluent matrices were investigated for the performance of PMS/ozone/US process and it was found that 54%, 72.3% and 94.6% BTA removal efficiency were reached, respectively. PMS/ozone/US process was compared to US/peroxone (ozone + H₂O₂) and the results showed importance of US irradiation in both systems. Accordingly, PMS/ozone/US process could be considered as an efficient and promising process for BTA degradation in various wastewaters.

Integration of target analyses, non-target screening and effect-based monitoring to assess OMP related water quality changes in drinking water treatment

The ever-increasing production and use of chemicals lead to the occurrence of organic micro-pollutants (OMPs) in drinking water sources, and consequently the need for their removal during drinking water treatment. Due to the sheer number of OMPs, monitoring using targeted chemical analyses alone is not sufficient to assess drinking water quality as well as changes thereof during treatment. High-resolution mass spectrometry (HRMS) based non-target screening (NTS) as well as effect-based monitoring using bioassays are promising monitoring tools for a more complete assessment of water quality and treatment performance. Here, we developed a strategy that integrates data from chemical target analyses, NTS and bioassays. We applied it to the assessment of OMP related water quality changes at three drinking water treatment pilot installations. These installations included advanced oxidation processes, ultrafiltration in combination with reverse osmosis, and granular activated carbon filtration. OMPs relevant for the drinking water sector were spiked into the water treated in these installations. Target analyses, NTS and bioassays were performed on samples from all three installations. The NTS data was screened for predicted and known transformation products of the spike-in compounds. In parallel, trend profiles of NTS features were evaluated using multivariate analysis methods. Through integration of the chemical data with the biological effect-based results potential toxicity was accounted for during prioritization. Together, the synergy of the three analytical methods allowed the monitoring of OMPs and transformation products, as well as the integrative biological effects of the mixture of chemicals. Through efficient analysis, visualization and interpretation of complex data, the developed strategy enabled to assess water quality and the impact of water treatment from multiple perspectives. Such information could not be obtained by any of the three methods alone. The developed strategy thereby provides drinking water companies with an integrative tool for comprehensive water quality assessment.

Diazole and triazole inhibition of nitrification process in return activated sludge

Azoles are emerging contaminants that are resistant to biodegradation during wastewater treatment. Their presence has been widely reported in wastewater effluents and receiving waters. In this work, the potential inhibition of nitrification process by six different azole compounds in wastewater treatment plants was investigated in batch bioassays. The azoles studied included three diazoles: pyrazole (Pz); 1-methylpyrazole (MePz); 3,5-dimethylpyrazole (DMePz); and three triazoles: 1,2,4-triazole (Tz); benzotriazole (BTz); and 5-methyl benzotriazole (MeBTz). The concentration of azoles causing 50% inhibition (IC₅₀) increased (azoles became less inhibitory) in the following order (mg L^-1): BTz (1.99) < MeBTz (2.18) < Pz (2.69) < Tz (3.53) < DMePz (17.3) < MePz (49.6). No clear structure-inhibitory relationships were found using Log P and pKa as structural properties. The toxicity of any given azole may be related to the role of substituent groups on disabling/enabling binding to the active sites of metallo-enzymes in nitrifying microorganisms. This is exemplified by the low toxicity of MePz, which has a cyclic N blocked by a methyl group. The observed inhibition caused to nitrifying bacteria is more severe than their cytotoxicity to other target organisms (e.g., methanogens and heterotrophic bacteria), suggesting a specific inhibition to the copper-containing enzyme, ammonium monooxygenase, in ammonia oxidizing nitrifying microorganisms.

Resilience to multiple stressors in an aquatic plant and its microbiome

PREMISE

Outcomes of species interactions, especially mutualisms, are notoriously dependent on environmental context, and environments are changing rapidly. Studies have investigated how mutualisms respond to or ameliorate anthropogenic environmental changes, but most have focused on nutrient pollution or climate change and tested stressors one at a time. Relatively little is known about how mutualisms may be altered by or buffer the effects of multiple chemical contaminants, which differ fundamentally from nutrient or climate stressors and are especially widespread in aquatic habitats.

METHODS

We investigated the impacts of two contaminants on interactions between the duckweed Lemna minor and its microbiome. Sodium chloride (salt) and benzotriazole (a corrosion inhibitor) often co-occur in runoff to water bodies where duckweeds reside. We tested three L. minor genotypes with and without the culturable portion of their microbiome across field-realistic gradients of salt (3 levels) and benzotriazole (4 levels) in a fully factorial experiment (24 treatments, tested on each genotype) and measured plant and microbial growth.

RESULTS

Stressors had conditional effects. Salt decreased both plant and microbial growth and decreased plant survival more as benzotriazole concentrations increased. In contrast, benzotriazole did not affect microbial abundance and even benefited plants when salt and microbes were absent, perhaps due to biotransformation into growth-promoting compounds. Microbes did not ameliorate duckweed stressors; microbial inoculation increased plant growth, but not at high salt concentrations.

CONCLUSIONS

Our results suggest that multiple stressors matter when predicting responses of mutualisms to global change and that beneficial microbes may not always buffer hosts against stress.

Four typical personal care products in a municipal wastewater treatment plant in China: Occurrence, removal efficiency, mass loading and emission

The occurrence, removal efficiency, mass loading and environmental emission of four categories (benzotriazoles; parabens; antimicrobials; benzophenones) of personal care products were simultaneously determined along the whole process line through an integrated approach (involving both dissolved and adsorbed phase) at a typical wastewater treatment plant in Hunan Province, Southern China. The results showed the prevalence of 13 and 11 target compounds in wastewater and suspended particulate matter, respectively. Twelve substances were detected in the sludge with the mean concentrations ranging from 0.12 to 591.23 ng/g dry weight. Benzotriazoles were the dominant compounds existing in water and antimicrobials were readily being absorbed onto suspended particulate matter and sludge. The overall removal efficiencies of compounds in the total treatment were -84.06%-98.53%. Mass balance results revealed that 85.17%-98.73% of the parabens and benzophenones were removed by degradation, while antimicrobials were removed by being adsorbed onto sludge. However, benzotriazoles could not be efficiently removed and the mass loss was lower than 61.03%. Although ultraviolet radiation played a limited role in removing most target compounds, it still had an impact on removing antimicrobials, 5,6-dimethyl-1H-benzotriazole and 2-hydroxy-4-methoxybenzophenone. The total mass loading and emission of personal care products were 506.35 mg/d/1000 people and 357.56 mg/d/1000 people, respectively. This work would help understand the removal approaches and real pollution of personal care products in the water environment.

Characterization and quantification of methyl-benzotriazoles and chloromethyl-benzotriazoles produced from disinfection processes in wastewater treatment

Wastewater treatment plants (WWTPs) are one of the major sources of contaminants of emerging concern (CECs) in the environment. Benzotriazole corrosion inhibitors are a class of CECs that are resistant to biodegradation and have been reported in waters varying from WWTP effluent to groundwater and drinking water. This study examined wastewater influent and effluent grab samples over three years using Comprehensive Two-Dimensional Gas Chromatography (GC × GC) to discover six target benzotriazoles, four of which have never been properly characterized in water prior to this work. The six benzotriazoles were two methyl isomers (4-methyl-1H-benzotriazole and 5-methyl-1H-benzotriazole) as well as four chloromethyl isomers (previously unidentified). Using targeted analysis, the benzotriazoles were quantified and semi-quantified in the wastewater. In all seasons sampled but one, the concentration of three of the four chloromethyl-benzotriazoles increased from the influent to effluent waters. For the first time, it was observed that the 4 and 5-methyl-benzotriazoles interact with the sodium hypochlorite in the tertiary treatment step of the WWTP leading to the formation of the four chloromethyl-benzotriazoles. This was confirmed with lab scale synthesis of the reaction where the products were chromatographically analyzed and matched mass spectral and retention time data of the water samples. Assisted by the mass spectral fragmentation information, the four chloromethyl-benzotriazole isomers were tentatively identified as 4-chloromethyl-2H-benzotriazole, 5-chloromethyl-1H-benzotriazole, 4-chloromethyl-1H-benzotriazole, and 5-chloromethyl-2H-benzotriazole, in order of elution. No analytical standards are available for the chloromethyl-benzotriazole compounds and this is the first attempted identification of them in waters. The yearly mass loadings of total benzotriazoles were estimated to average between 148.86 and 394.64 kg/year at this particular facility. The WWTP studied reuses all effluent water for irrigation of crop and forested land so this high value of benzotriazoles entering the environment is concerning and the impacts need to be further studied.

Identification of mutagenic and endocrine disrupting compounds in surface water and wastewater treatment plant effluents using high-resolution effect-directed analysis

Effect-directed analysis (EDA) has shown its added value for the detection and identification of compounds with varying toxicological properties in water quality research. However, for routine toxicity assessment of multiple toxicological endpoints, current EDA is considered labor intensive and time consuming. To achieve faster EDA and identification, a high-throughput (HT) EDA platform, coupling a downscaled luminescent Ames and cell-based reporter gene assays with a high-resolution fraction collector and UPLC-QTOF MS, was developed. The applicability of the HT-EDA platform in the analysis of aquatic samples was demonstrated by analysis of extracts from WWTP influent, effluent and surface water. Downscaled assays allowed detection of mutagenicity and androgen, estrogen and glucocorticoid agonism following high-resolution fractionation in 228 fractions. From 8 masses tentatively identified through non-target analysis, 2 masses were further investigated and chemically and biologically confirmed as the mutagen 1,2,3-benzotriazole and the androgen androstenedione. The compatibility of the high-throughput EDA platform with analysis of water samples and the incorporation of mutagenic and endocrine disruption endpoints allow for future application in routine monitoring in drinking water quality control and improved identification of (emerging) mutagens and endocrine disruptors.

Unravelling the role of vegetation in the attenuation of contaminants of emerging concern from wetland systems: Preliminary results from column studies

Water pollution with contaminants of emerging concern (CECs) is widespread in water bodies due to the low effectiveness of industrial and urban wastewater treatment systems. In recent decades, the implementation of vegetation-based wastewater treatment systems such as wetlands has been observed to help solve this issue. However, there is a lack of knowledge regarding the removal percentage attributable to plants and how plants affect this removal improvement. In this study, we monitored planted (Phragmites australis) and unplanted sand columns to assess the effect of vegetation on the attenuation of 5 well-known CECs (benzotriazole, sulfamethoxazole, carbamazepine, bisphenol A, and diclofenac) and link it to the presence of different root exudates. The columns were operated in a continuous feeding mode for more than 6 months at 3 hydraulic loading rates (HLRs) (70, 140, and 280 mm d^-1). We found that the presence of vegetation increased CEC attenuation from no effect to more than 200% compared to the unplanted columns. The highest effect was observed for carbamazepine (94-200%), followed by diclofenac (22-171%), benzotriazole (48-127%), and sulfamethoxazole (no effect to 43%), depending on the tested HLR. Furthermore, the greater CEC attenuation in planted columns was linked to the release of certain root exudates that may shape the root microbiome. We expect our assay to be a starting point for exploring the role of root exudates in enhancing CEC removal efficiency in wastewater.

Elimination of Micropollutants in Activated Sludge Reactors with a Special Focus on the Effect of Biomass Concentration

This study aimed to investigate the effects of sludge retention time (SRT), hydraulic retention time (HRT), and biomass concentration (CTSS) in activated sludge systems on removal of various micropollutants (MPs), covering a wide spectrum of biodegradability. The influence of biomass concentration on the classical pseudo-first-order rate constant was verified. Results showed that the removal rate constants were affected by both the HRT and SRT. The enhancement of the SRT increased the removal of all the MPs except for two macrolide antibiotics. Application of a higher HRT also improved MP removal, as was expected from the measured removal rate constants. More interesting, our results indicated that, logically, the increase of biomass concentration (expressed as total suspended solids CTSS) from 3 to 5 gTSS L−1 significantly enhanced the removal rate of the highly and moderately degradable compounds. Conversely, a further increase to 8 gTSS L−1 produced only an unexpected moderate effect, showing that the rate was not proportional to biomass concentration, contrary to what is generally postulated. Therefore, the use of classical kinetic models is questionable, since they do not cover the entire range of boundary conditions in activated sludge systems. This work opens new research paths and suggests potential improvements to processes.

Removal and transformation pathways of benzothiazole and benzotriazole in membrane bioreactors treating synthetic municipal wastewater

Lab-scale membrane bioreactors (MBRs), with aerated activated sludge and internal microfiltration module, were used for the treatment of municipal wastewater containing high, yet environmentally relevant, concentrations of benzothiazole (BT) and benzotriazole (BTA). These high production volume compounds are commonly used in the industry and households, and therefore occur ubiquitously in municipal wastewater and the aquatic environment. The aim of this study was to assess the removal of BT and BTA from synthetic municipal wastewater in MBRs and to estimate the contribution of elimination processes and to identify potential biotransformation products. The overall removal of BT and BTA was high, and after the adaptation period, it reached 99.8% and 97.2%, respectively, but recurring periods of unstable BTA removal occurred. The removal due to biotransformation was 88% for BT and 84% for BTA and the disposal with waste sludge accounted for only <1% of the removed load. The remaining fraction of the removed load of BT and BTA was attributed to be retained by phenomena associated with membrane fouling. The adaptation process was reflected in multifold increase in biodegradation kinetic coefficient (k_biol) for BT (reported for the first time) and BTA. Biodegradation was attributed to catabolic mechanism rather than to cometabolism. Hydroxylation was observed to be the main transformation reaction for BT, whereas for BTA hydroxylation, methylation and cleavage of benzene ring were noted. This study has shown the feasibility of treating municipal wastewater with high concentrations of BT and BTA in MBRs and identified potential challenges for the removal of BTA.

Occurrence, toxicity and transformation of six typical benzotriazoles in the environment: A review

Benzotriazoles (BTs) are a group of heterocyclic compounds which have been widely applied in industrial activities and domestic life mainly as corrosive inhibitors. BTs have been ubiquitously detected in receiving environments and cause potential toxicity to non-target organisms. This paper reviews the occurrence and fate of six selected benzotriazole compounds in different environmental and biological matrices, as well as the transformation and toxicity. Due to their high hydrophilicity and insufficient removal in wastewater treatment plants (WWTPs), these compounds were widely detected in aquatic environments with concentrations mainly from tens ng/L to tens μg/L. Considerable residual levels of BTs in plant, fish, air, tap water and human urine have implied the potential risks to various organsims. The reported acute toxicity of BTs are generally low (EC₅₀ in mg/L level). Some observed sublethal effects including endocrine disrupting effects, hepatotoxicity and neurotoxicity, as well as the ability to promote the development of endometrial carcinoma still raise a concern. BTs are found often more recalcitrant to biodegradation compared to photolysis and ozonation. Environmental factors including pH, temperature, irradiation wavelength, redox condition as well as components of matrix are proved crucial to the removal of BTs. Further studies are needed to explore the precise environment fate and toxicity mechanism of BTs, and develop advanced treatment technologies to reduce the potential ecological risks of BTs.

Simultaneous removal of pollutants from water using nanoparticles: A shift from single pollutant control to multiple pollutant control

The steady increase in population, coupled with the rapid utilization of resources and continuous development of industry and agriculture has led to excess amounts of wastewater with changes in its composition, texture, complexity and toxicity due to the diverse range of pollutants being present in wastewater. The challenges faced by wastewater treatment today are mainly with the complexity of the wastewater as it complicates treatment processes by requiring a combination of technologies, thus resulting in longer treatment times and higher operational costs. Nanotechnology opens up a novel platform that is free from secondary pollution, inexpensive and an effective way to simultaneously remove multiple pollutants from wastewater. Currently, there are a number of studies that have presented a myriad of multi-purpose/multifunctional nanoparticles that simultaneously remove multiple pollutants in water. However, these studies have not been collated to review the direction that nanoparticle assisted wastewater treatment is heading towards. Hence, this critical review explores the feasibility and efficiency of simultaneous removal of co-existing/multiple pollutants in water using nanomaterials. The discussion begins with an introduction of different classes of pollutants and their toxicity followed by an overview and highlights of current research on multipollutant control in water using different nanomaterials as adsorbents, photocatalysts, disinfectants and microbicides. The analysis is concluded with a look at the current attempts being made towards commercialization of multipollutant control/multifunctional nanotechnology inventions. The review presents evidence of simultaneous removal of pathogenic microorganisms, inorganic and organic compound chemical pollutants using nanoparticles. Accordingly, not only is nanotechnology showcased as a promising and an environmentally-friendly way to solve the limitations of current and conventional centralised water and wastewater treatment facilities but is also presented as a good substitute or supplement in areas without those facilities.

Fate of pharmaceuticals and personal care products in a wastewater treatment plant with parallel secondary wastewater treatment train

Seasonal variations in the concentrations and fate of 20 selected pharmaceuticals and personal care products (PPCPs) were investigated over one year in a wastewater treatment plant in New Zealand, which relies on a membrane bioreactor (MBR) and Bardenpho as parallel processes for its secondary treatment. Results showed that all of the monitored PPCPs were detected in the wastewater influent. Nonsteroidal anti-inflammatory drugs (NSAIDS) and caffeine were predominant in the influent, whereas in the effluent, β-blockers and benzotriazole were present at significant concentrations. Total PPCPs' concentration in the influent was found to be 130 μg/L. Average removal efficiency was found to be ≥ 99% for acetaminophen, caffeine, TCEP, naproxen, and ibuprofen, whereas <50% of trimethoprim, metoprolol, and benzotriazole were removed. Contrary to the existing literature, no significant differences were found in the removal of PPCPs through MBR and Bardenpho processes, hinting that optimally operated Bardenpho can be equally effective in the removal of emerging contaminants as MBR. The occurrence and removal efficiencies of PPCPs were found to exhibit significant seasonal variations, with the highest influent concentrations of PPCPs reported in autumn and winter. Heavy rainfall had an insignificant impact on PPCPs' removal efficiencies although it resulted in much-diluted concentrations of PPCPs in the influent. Spearman's correlation analysis showed significant correlations between PPCPs' mass loads in the influent, wastewater quality parameters, and environmental factors. It was also found that, except sulfamethoxazole, ecotoxicity risks were minimal for the rest of the monitored PPCPs in wastewater effluent.

Effect of full-scale ozonation and pilot-scale granular activated carbon on the removal of biocides, antimycotics and antibiotics in a sewage treatment plant

Several micropollutants show low removal efficiencies in conventional sewage treatment plants, and therefore enter the aquatic environment. To reduce the levels of micropollutants in sewage effluent, and thereby the effects on biota, a number of extra treatment steps are currently being evaluated. Two such techniques are ozonation and adsorption onto activated carbon. In this study, we investigated the efficiency of Sweden's first full-scale ozonation treatment plant at removing a number of antibiotics, antimycotics and biocides. The effect of adding granular activated carbon (GAC) on a pilot scale and pilot-scale ozonation were also evaluated. The conventional treatment (13,000 PE) with the add-on of full-scale ozonation (0.55 g O₃/g Total organic carbon (TOC)) was able to remove most of the studied compounds (>90%), except for benzotriazoles and fluconazole (<50%). Adsorption on GAC on a pilot scale showed a higher removal efficiency than ozonation (>80% for all studied compounds). Three types of GAC were evaluated and shown to have different removal efficiencies. In particular, the GAC with the smallest particle sizes exhibited the highest removal efficiency. The results demonstrate that it is important to select an appropriate type of carbon to achieve the removal goal for specific target compounds.

Dynamics of emerging organic contaminant removal in conventional and intensified subsurface flow treatment wetlands

Six pilot-scale treatment wetlands treating municipal wastewater were monitored for classical wastewater parameters and selected Emerging Organic Compounds (EOCs): caffeine (CAF), ibuprofen (IBU), naproxen (NPX), benzotriazole (BTZ), diclofenac (DCL), acesulfame (ACE) and carbamazepine (CBZ) on a weekly basis over the course of one year. Treatment efficacy of the wetland systems was compared to that of a municipal wastewater treatment plant adjacent to the research site (activated sludge technology). The aerated wetlands VAp and HAp, and the two-stage vertical flow system VGp + VSp showed the highest treatment efficacy (>70% removal on a mass basis) and comparable treatment efficacy to the conventional WWTP for removal of CAF, IBU, NPX, BTZ, and DCL. Annual mass removal of ACE in the WWTP was 50% and varied in the wetlands (depending on system design) from zero to 62%. On a mean monthly basis, ACE removal in the treatment wetlands VGp + VSp, VAp, HAp, R was high (> 90%) for six months of the year. Monthly mean mass removal of CBZ was negligible for the WWTP and all treatment wetland systems except H50p, which showed up to 49% mass removal in June. Monthly mean mass removals of classical wastewater parameters and readily biodegradable EOCs (represented by CAF, IBU, NPX) were most stable in the intensified wetland designs VAp, HAp, and R. A statistical analysis confirms that system complexity, aerobic conditions, and temperature have the highest correlation to overall pollutant removal in the treatment wetland systems, including EOCs of high to moderate biodegradability. First-order removal rate coefficents and temperature correction factors for EOCs are reported for the first time in the treatment wetland literature. Limitations on the use of these values in engineering design are discussed.

Catalyst-free oxidative N–N coupling for the synthesis of 1,2,3-triazole compounds with tBuONO

A catalyst-free oxidative N–N coupling with tBuONO has been developed for the synthesis of 1,2,3-triazole compounds.

Prospective environmental risk assessment of mixtures in wastewater treatment plant effluents - Theoretical considerations and experimental verification

The aquatic environment is continually exposed to a complex mixture of chemicals, whereby effluents of wastewater treatment plants (WWTPs) are one key source. The aim of the present study was to investigate whether environmental risk assessments (ERAs) addressing individual substances are sufficiently protective for such coincidental mixtures. Based on a literature review of chemicals reported to occur in municipal WWTP effluents and mode-of-action considerations, four different types of mixtures were composed containing human pharmaceuticals, pesticides, and chemicals regulated under REACH. The experimentally determined chronic aquatic toxicity of these mixtures towards primary producers and the invertebrate Daphnia magna could be adequately predicted by the concept of concentration addition, with up to 5-fold overestimation and less than 3-fold underestimation of mixture toxicity. Effluents of a municipal WWTP had no impact on the predictability of mixture toxicity and showed no adverse effects on the test organisms. Predictive ERAs for the individual mixture components based on here derived predicted no effect concentrations (PNECs) and median measured concentrations in WWTP effluents (MC_eff) indicated no unacceptable risk for any of the individual chemicals, while MC_eff/PNEC summation indicated a possible risk for multi-component mixtures. However, a refined mixture assessment based on the sum of toxic units at species level indicated no unacceptable risks, and allowed for a safety margin of more than factor 10, not taking into account any dilution of WWTP effluents by surface waters. Individual substances, namely climbazole, fenofibric acid and fluoxetine, were dominating the risks of the investigated mixtures, while added risk due to the mixture was found to be low with the risk quotient being increased by less than factor 2. Yet, uncertainty remains regarding chronic mixture toxicity in fish, which was not included in the present study. The number and identity of substances composing environmental mixtures such as WWTP effluents is typically unknown. Therefore, a mixture assessment factor is discussed as an option for a prospective ERA of mixtures of unknown composition.

The Disappearing Director: The Case of Directed N-Arylation via a Removable Hydroxyl Group

A facile and broadly applicable method for the regiospecific N-arylation of benzotriazoles is reported. Copper-mediated reactions of diverse 1-hydroxy-1H-benzotriazoles with aryl boronic acids lead to 1-aryl-1H-benzotriazole 3-oxides. A N1-OH → N3 prototropy in the 1-hydroxy-1H-benzotriazoles is plausibly the underlying basis, where the tautomer is captured by the boronic acid, leading to C-N (not C-O) bond formation. Because the N-O bond in amine N-oxides and 1-hydroxy-1H-benzotriazoles can be easily reduced by diboron reagents such as (pinB)2 and B2(OH)4, exposure of the 1-aryl-1H-benzotriazole 3-oxides to B2(OH)4 then leads to facile reduction of the N-O bond resulting in diverse, regiospecifically-arylated benzotriazoles. Thus, the N-hydroxyl group in 1-hydroxy-1H-benzotriazoles acts as a disposable arylation director.

Assessment of the Acute Toxicity, Uptake and Biotransformation Potential of Benzotriazoles in Zebrafish ( Danio rerio) Larvae Combining HILIC- with RPLC-HRMS for High-Throughput Identification

The current study reports on the toxicity, uptake, and biotransformation potential of zebrafish (embryos and larvae) exposed to benzotriazoles (BTs). Acute toxicity assays were conducted. Cardiac function abnormalities (pericardial edema and poor blood circulation) were observed from the phenotypic analysis of early life zebrafish embryos after BTs exposure. For the uptake and biotransformation experiment, extracts of whole body larvae were analyzed using liquid chromatography-high-resolution tandem mass spectrometry (UPLC-Q-TOF-HRMS/MS). The utility of hydrophilic interaction liquid chromatography (HILIC) as complementary technique to reversed phase liquid chromatography (RPLC) in the identification process was investigated. Through HILIC analyses, additional biotransformation products (bio-TPs) were detected, because of the enhanced sensitivity and better separation efficiency of isomers. Therefore, reduction of false negative results was accomplished. Both oxidative (hydroxylation) and conjugative (glucuronidation, sulfation) metabolic reactions were observed, while direct sulfation proved the dominant biotransformation pathway. Overall, 26 bio-TPs were identified through suspect and nontarget screening workflows, 22 of them reported for the first time. 4-Methyl-1- H-benzotriazole (4-MeBT) demonstrated the highest toxicity potential and was more extensively biotransformed, compared to 1- H-benzotriazole (BT) and 5-methyl-1- H-benzotriazole (5-MeBT). The extent of biotransformation proved particularly informative in the current study, to explain and better understand the different toxicity potentials of BTs.

The fate of benzotriazole pollutants in an urban oxic intergranular aquifer

Benzotriazoles (BTs) are considered as Contaminants of Emerging Concern (CECs); however, information about their fate in aquifers continues to be absent. This was the focus of the present study, which provides the first evidence for relevant BTs' degradation products (BTTPs) in urban aquifers that may impact the groundwater quality. The mechanisms and biotransformation pathways of BTs were investigated in an oxic intergranular medium. The BTs and BTTPs were identified and quantified by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) analytical techniques based on reference standards and internal materials. The major transformation products were identified as 2-methyl-2H-benzotriazole (2-MeBT) for the degradation of 1H-benzotriazole (BT) and as 2,4-dimethyl-2H-benzotriazole (2,4-dMeBT) and 1,4-dimethyl-1H-benzotriazole (1,4-dMeBT) for the degradation of 4-methyl-1H-benzotriazole (4-MeBT), and most probably also 5-methyl-1H-benzotriazole (5-MeBT). The leakage of wastewater pipelines is most probably the source of BTs. Sediments with a lower hydraulic conductivity give rise to perched aquifer conditions that lead to the temporal storage of leaking effluents and presumably the majority of BTs' transformation processes via methylation and tautomerization. The most stable BTTPs entered the saturated zone of the aquifer, where they prevailed. Concentrations up to 1500 ng L^-1 were measured for the 2,4-dMeBT, which suggest a contamination risk for groundwater that is or may be used as a source for drinking water in the case of a constant input of pollutant loads from sewer systems.

Methanol-dispersed of ternary Fe3O4@γ-APS/graphene oxide-based nanohybrid for novel removal of benzotriazole from aqueous solution

A novel nanohybrid: Fe₃O₄ coated with γ-APS polymer deposited on graphene oxide (F@γ-A/G), to remove an emergent heterocyclic contaminant benzotriazole (BTA) from solution. F@γ-A/G was synthesized in methanol-dispersion via aminosilanization under ultra-sonication. We newly found that F@γ-A/G crystallite lattice has a 2D triangular-network intersection with angle of 60° in three types of d₃₁₁, d₂₂₀ and d₁₁₁ planes with different interplanar spacings. Textural characteristics did not affect BTA adsorption, which was desired at high temperature (40 °C), neutral solution (pH = 6) and controlled by endothermic process. Considering the maximum BTA adsorption capacity of 312.5 mg/g, which was much higher than previously reported adsorbents, the plausible mechanism was attributed to hydrophobic, electrostatic and π-π interaction. Effects of pH and temperature are significant on BTA adsorption to F@γ-A/G. Methanol was the best solvent for multiple cycle regeneration with only 2% loss of BTA removal efficiency even after five cycles of F@γ-A/G.

Analysis of emerging organic contaminants in water, fish and suspended particulate matter (SPM) in the Joint Danube Survey using solid-phase extraction followed by UHPLC-MS-MS and GC-MS analysis

In the third Joint Danube Survey (JDS3), emerging organic contaminants were analysed in the dissolved water phase of samples from the Danube River and its major tributaries. Analyses were performed using solid-phase extraction (SPE) followed by ultra-high-pressure liquid chromatography triple-quadrupole mass spectrometry (UHPLC-MS-MS) and gas chromatography-mass spectrometry (GC-MS). The polar organic compounds analysed by UHPLC-MS-MS were 1H-benzotriazole, methylbenzotriazoles, carbamazepine, 10,11-dihydro-10,11-dihydroxy-carbamazepine, diclofenac, sulfamethox-azole, 2,4-D (2,4-dichlorophenoxyacetic acid), MCPA (2-methyl-4-chlorophenoxyacetic acid), metolachlor, cybutryne (irgarol), terbutryn, DEET (N,N-diethyl-m-toluamide), and several perfluoroalkyl acids (C₆-C₉; C₈=perfluorooctanoic acid (PFOA)) and perfluorooctansulfonic acid (PFOS). In addition, several organophosphorus flame retardants were analysed by GC-MS. The most relevant compounds identified in the 71 water samples, in terms of highest median and maximum concentrations, were 1H-benzotriazole, tris(1-chloro-2-propyl)phosphate (TCPP), methylbenzotriazoles, carbama-zepine and its metabolite, DEET, sulfamethoxazole, tris(isobutyl)phosphate (TiBP), tris(2-chloroethyl)phosphate (TCEP), PFOA, PFOS and diclofenac. The concentrations of these compounds in the samples were generally below the environmental quality standard (EQS) threshold values, with the exception of PFOS, the concentration of which exceeded the annual average water EQS limit of 0.65ng/L along the whole river, and also exceeded the fish biota EQS of 9.1μg/kg. In addition, the proposed EQS for diclofenac, of 0.1μg/L, was exceeded in the Arges River in Romania (255ng/L).

Fungal treatment for the removal of endocrine disrupting compounds from reverse osmosis concentrate: Identification and monitoring of transformation products of benzotriazoles

The removal of 27 endocrine-disrupting compounds and related compounds (suspect effect) from a reverse osmosis concentrate using an alternative decontamination method based on a fungal treatment involving Trametes versicolor was assessed. In addition to chemical analysis, the toxicity of the treated water during the treatment was monitored using a bioluminescence inhibition test and estrogenic and anti-estrogenic tests. The compounds 1H-benzotriazole (BTZ) and two tolyltriazoles (TTZs), 4-methyl-1H-benzotriazole (4-MBTZ) and 5-methyl-1H-benzotriazole (5-MBTZ), were present in the reverse osmosis concentrate at the highest concentrations (7.4 and 12.8 μg L^-1, respectively) and were partially removed by the fungal treatment under sterile conditions (58% for BTZ and 92% for TTZs) and non-sterile conditions, although to lesser extents (32% for BTZ and 50% for TTZs). Individual biotransformation studies of BTZ and the TTZs by T. versicolor in a synthetic medium and further analysis via on-line turbulent flow chromatography coupled to an HRMS-Orbitrap allowed the tentative identification of the transformation products (TPs). Six TPs were postulated for BTZ, two TPs were postulated for 4-MBTZ, and four TPs were postulated for 5-MBTZ. Most of these TPs are suggested to have been generated by conjugation with some sugars and via the methylation of the triazole group. Only TP 148 A, postulated to be derived from the biotransformation of BTZ, was observed in the effluent of the bioreactor treating the reverse osmosis concentrate.

Occurrence and fate of benzotriazoles UV filters in a typical residential wastewater treatment plant in Harbin, China

Benzotriazoles (BTs) UV filters are widely used as ultraviolet absorbents for our daily products, which received increasing attention in the past decades. Residential wastewater treatment plant (WWTP) is both an important sink for wastewater and a key pollution source for receiving water for these chemicals. In this study, pretreatment and gas chromatography-tandem mass spectrometry analysis method were developed to determine the occurrence and fate of 9 BTs UV filters in wastewater and sludge from the WWTP with anaerobic-oxic treatment process (A/O) and biological aerated filter treatment process (BAF). Totally, 81 wastewater samples and 11 sludge samples were collected in four seasons. In wastewater, UV-326 and UV-329 were frequently detected, while the highest mean concentrations were detected for UV-234 and UV-329. The concentrations were in the range of <LOQs up to several hundred nanograms per liter. The removal efficiency of BTs UV filters was >85% in A/O process and 60-77% in BAF process except for UV-350, which was more difficult to remove with lower removal efficiencies of 33.3% for both A/O and BAF. All the target chemicals except for UV-320 were detected in sludge samples with the mean concentration ranging from 0.90 ng/g to 303.39 ng/g. There was no significant difference with concentrations and removal efficiency among different seasons. Higher detection frequency and concentration of BTs UV filters in downstream of the receiving water system indicated the contribution of effluent of the WWTP. Compared with other rivers, the lower concentrations in surface water in the Songhua River indicated light pollution status with of BTs UV filters.

A survey on trace organic chemicals in a German water protection area and the proposal of relevant indicators for anthropogenic influences

A comprehensive monitoring programme of trace organic chemicals (TOrC) was conducted for a German water protection area in karstic ground. The aim of this survey was to detect the potential anthropogenic influences of point sources such as wastewater treatment plants and diffuse pollution such as runoff water from roads on the raw water used for drinking water treatment. The programme comprised seven sampling campaigns within 2 years each with up to 20 sampling sites. In total, the programme included 84 anthropogenic compounds from pharmaceuticals, iodinated X-ray contrast media, sweeteners, industrial chemicals (benzotriazoles, melamines and benzothiazoles) and pesticide metabolites. Cyclamate occurred with the highest median concentration of 44 μg l^-1 in untreated wastewater and acesulfame occurred with a concentration of 20 μg l^-1 in treated wastewater. In runoff water from roads, the most relevant compounds were tolyltriazole with 2.3 μg l^-1 and the desphenyl-chloridazon with 1.2 μg l^-1. In the stream waters, the highest median concentrations were found for melamine and acesulfame both at 0.61 μg l^-1. High elimination during conventional wastewater treatment was observed for 5 out of 49 compounds. These are acetyl-sulfamethoxazole, aciclovir, cyclamate, ibuprofen and saccharin. Based on the survey results, we propose a set of nine compounds to be used as indicators for wastewater, untreated wastewater and runoff water from roads for an efficient surveillance. The indicators are intended to detect anthropogenic influences in surface, ground and drinking water.

Screening of biocides, metals and antibiotics in Swedish sewage sludge and wastewater

Incoming sewage water, treated effluent and digested sludge were collected from 11 Swedish sewage treatment plants (STPs) on 3 different days. Analytical protocols were established for a large number of compounds (47) with antimicrobial properties and the collected samples were then screened for the presence of these selected substances. Liquid chromatography tandem mass spectrometry (LC-MS/MS) and inductively coupled plasma mass spectrometry (ICP-MS) were used to analyse the samples. Thirty organic compounds and 10 metals were detected above their respective detection limit. Quaternary ammonium compounds were the most abundant substances in the particulate phases with levels up to 370 μg/g and benzotriazoles were the most common in the aqueous phases with levels up to 24 μg/L. Several compounds with no, or very limited, previously reported data were detected in this study, including chlorhexidine, hexadecylpyridinium chloride and 10-benzalkonium chloride. Some of these were both frequently detected (>60% detection frequency) and found in high levels (up to 19 μg/g d.w. sludge). This study gives a comprehensive overview of the presence in Swedish STPs of a number of antimicrobial substances, providing crucial information in designing relevant studies on potential microbial co- and cross resistance development between antibiotics, biocides, and metals in the sewage system.