Degradation of emerging contaminants from water under natural sunlight: The effect of season, pH, humic acids and nitrate and identification of photodegradation by-products

Occurrence and environmental fate of anti-influenza drugs in a subcatchment of the Yodo River Basin, Japan

Understanding the current situation and risk of environmental contamination by anti-influenza drugs in aquatic environments is key to prevent the unexpected emergence and spread of drug-resistant viruses. However, few reports have been focused on newer drugs that have recently been introduced in clinical settings. In this study, the behaviour of the prodrug baloxavir marboxil (BALM)-the active ingredient of Xofluza, an increasingly popular anti-influenza drug-and its pharmacologically active metabolite baloxavir (BAL) in the aquatic environment was evaluated. Additionally, their presence in urban rivers and a wastewater treatment plant (WWTP) in the Yodo River basin was investigated and compared with those of the major anti-influenza drugs used to date (favipiravir (FAV), peramivir (PER), laninamivir (LAN), and its active metabolite, laninamivir octanoate (LANO), oseltamivir (OSE), and its active metabolite, oseltamivir carboxylate (OSEC), and zanamivir (ZAN)) to comprehensively assess their environmental fate in the aquatic environment. The results clearly showed that BALM, FAV, and BAL were rapidly degraded through photolysis (2-h, 0.6-h, and 0.4-h half-lives, respectively), followed by LAN, which was gradually biodegraded (7-h half-life). In addition, BALM and BAL decreased by up to 47 % after 4 days and 34 % after 2 days of biodegradation in river water. However, the remaining conventional drugs, except for LANO (<1 % after 10 days), were persistent, being transported from the upstream to downstream sites. The LogKd values for the rates of sorption of BALM (0.5-1.6) and BAL (1.8-3.1) on river sediment were higher than those of conventional drugs (-0.5 to 1.7). Notably, all anti-influenza drugs were effectively removed by ozonation (>90-99.9 % removal) after biological treatment at a WWTP. Thus, these findings suggest the importance of introducing ozonation to reduce pollution loads in rivers and the environmental risks associated with drug-resistant viruses in aquatic environments, thereby promoting safe river environments.

Introducing a prediction method for the photodegradation of p-cresol, a phenolic contaminant of emerging concern, in wastewater effluent

Despite extensive efforts to understand the photodegradation of phenolic contaminants of emerging concern (PhCECs) in aquatic systems, prediction methods, especially in waters containing effluent organic matter (EfOM), remain underdeveloped. This study introduces a prediction method for p-cresol, a representative PhCECs, based on correlations between EfOM optical parameters and p-cresol kinetic parameters. We examined p-cresol photodegradation in various EfOM samples, characterized by their optical properties, and used the reaction rate coefficient between EfOM and p-cresol, α3EfOM⁎, to quantify and predict p-cresol degradation in different wastewater effluent samples. Results showed significant correlations between p-cresol's photodegradation rate constant (0.144 to 0.441 h-1) and EfOM characteristics, with α3EfOM⁎ values ranging from 4 × 1011 to 10 × 1011 M-1 s-1. The method was validated with p-cresol at concentrations ranging from 25 to 100 μM and multiple EfOM samples. The method's applicability was further evaluated using propranolol, a pharmaceutical contaminant of emerging concern, demonstrating its versatility for predicting the degradation behavior of other contaminants in different wastewater samples. The method accurately predicted p-cresol and propranolol degradation across diverse wastewater samples, suggesting its potential for expansion to other classes of contaminants, aiding in water quality management, improving wastewater treatment processes, and enhancing environmental risk assessments.

Photodegradation of the novel herbicide pyraclonil in aqueous solution: Kinetics, identification of photoproducts, mechanism, and toxicity assessment

Pyraclonil is a new type of pyrazole herbicide, whose photochemical fate in aqueous solution has not been reported yet. In this study, effects on the photolysis rate such as light source, pH, NO3-, Fe3+, fulvic acid (FA) and riboflavin (RF) were investigated. Pyraclonil photodegraded in pure water under both UV and simulated sunlight with half-lives of 32.29 min and 42.52 h, respectively. Under UV, the degradation rate of pyraclonil in pH 4 solution (0.0299 ± 0.0033 min-1) was about twice higher than that in pH 9 (0.0160 ± 0.0063 min-1). Under simulated sunlight, low concentration (0.1-1 mg/L) of FA, NO3-, Fe3+ and RF noticeably promoted the photodegradation of pyraclonil. Then, with the combination of experimental UPLC-Q-TOF/MS and computational calculation of density functional theory (DFT), fourteen transformation products (TPs) of pyraclonil were identified with possible mechanism of C-N bond cleavage, photorearrangement, demethylation, hydroxylation and oxidation. Additionally, acute toxicity assessment was conducted through ECOSAR prediction and laboratory bioassays. The prediction results indicated that toxicity of TP157 to daphnid and green algae was 1.3 and 1.4 times higher than that of the parent, respectively. The bioassay results indicated that toxicities of TP157 and TP263 to C. vulgaris were about 1.6 and 5.9 times higher than that of the parent, respectively. The results provided a reference for elucidating the potential hazards of pyraclonil to non-target organisms and promoting its rational use.

Comparative study of emerging pollutants of interest in the groundwater of the volcanic islands of La Palma and El Hierro (Canary Islands)

Emerging pollutants (EPs) include a wide array of chemical compounds, as well as some microorganisms, which presence was unknown or unmeasurable until recently, or have recently started to be considered a threat towards the environment or animal and human health. No clear or homogeneous regulations exist for their measurement or control, and efforts should be made to assess their presence and offer solutions for their safe management, as well as to achieve an optimal protection of water resources. A previous study performed by our research group thoroughly studied a wide profile of EPs in El Hierro Island (Canary Islands) for the first time. Now, we present the study of the same panel of 70 EPs in La Palma Island (Canary Islands). 14 samples were collected in 2021, at different locations in La Palma island, representing seven municipalities (Los Llanos de Aridane, Santa Cruz de la Palma, El Paso, Breña Baja, Tazacorte, Barlovento and Fuencaliente) and four installation types (Piezometers/Wells, Wastewater Treatment Plant (WWTP), Water Gallery and Water Springs). High performance liquid chromatography-mass spectrometry (HPLC-MS) was performed to analyse the EP array, which included five chemical families: UV filters, UV blockers/stabilizers, parabens, Pharmaceutical Active Compounds (PhACs) and pesticides. Subsequently, a comprehensive descriptive and statistical analysis, including different tests was performed on the data obtained. Heterogeneous concentration levels of the EPs studied were found based on municipality and installation type among the island, with some of the PhACs and UV blockers/stabilizers showing very high levels, especially at Breña Baja and wastewater treatment plants (WWTPs). It is worth noting that some of the samples comprised within the WWTPs category were collected outside the treatment plant, after water has been treated, so they should not bear dangerous concentrations of any hazardous compound. The high presence of two pesticides, imidacloprid (ranging from 68.7 to 24,896.5 ng⋅L-1) and acetamiprid (ranging from 1010.7 to 5168.1 ng⋅L-1) was worth highlighting too. In addition, three EP concentration clusters were found to virtually divide the island based on mathematical percentiles of EP mean concentrations, which can help gain more insight into the contamination status of the island and measures that could be taken for their management. Finally, a comparison between La Palma results and the profile observed at El Hierro by our research group was presented. Altogether, the study performed calls for a need to take actions towards avoiding entrance of EPs in the water cycle, and not just focusing on remediation strategies once they have reached the groundwater, freshwater or soil.

Hypochlorite-mediated degradation and detoxification of sulfathiazole in aqueous solution and soil slurry

Although various activated sodium hypochlorite (NaClO) systems were proven to be promising strategies for recalcitrant organics treatment, the direct interaction between NaClO and pollutants without explicit activation is quite limited. In this work, a revolutionary approach to degrade sulfathiazole (STZ) in aqueous and soil slurry by single NaClO without any activator was proposed. The results demonstrated that 100% and 94.11% of STZ could be degraded by 0.025 mM and 5 mM NaClO in water and soil slurry, respectively. The elimination of STZ was shown to involve superoxide anion (O2•-), chlorine oxygen radical (ClO•), and hydroxyl radical (•OH), according to quenching experiments and the analysis of electron paramagnetic resonance. The addition of Cl-, HCO3-, SO42-, and humic acid (HA) marginally impeded the decomposition of STZ, while NO3-, Fe3+, and Mn2+ facilitated the process. The NaClO process exhibited significant removal effectiveness at a neutral initial pH. Moreover, the NaClO facilitated application in various soil samples and water matrices, and the procedure was also successful in effectively eliminating a range of sulfonamides. The suggested NaClO degradation mechanism of STZ was based on the observed intermediates, and the majority of the products exhibited lower ecotoxicity than STZ. Besides, the experiment results by using X-ray diffraction (XRD) and a fourier transform infrared spectrometer (FTIR) indicated the negligible effects on the composition and structure of soil by the treatment of NaClO. Simultaneously, the experimental results also illustrated that the bioavailability of heavy metals and the physiochemical characteristics of the soil before and after the remediation did not change to a significant extent. Following the remediation of NaClO, the phytotoxicity tests showed reduced toxicity to wheat and cucumber seeds. As a result, treating soil and water contaminated with STZ by using NaClO was a reasonably practical and eco-friendly method.

Synthesis and characterization of TiO2-based supported materials for industrial application and recovery in a pilot photocatalytic plant using chemometric approach

In this contribution, the performance of powdered titanium dioxide (TiO2)-based photocatalysts was evaluated in a pilot photocatalytic plant for the degradation of different dyes, with an investigated volume of 1 L and solar simulated light as irradiation source. Five different samples, synthesized in our laboratories, were tested in the pilot plant, each consisting of TiO2 nanoparticles (NPs) coupled with a different material (persistent luminescent material and semiconductor material) and treated in different thermal conditions. All synthesized samples have been subjected to X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller analysis (BET), and transmission electron microscopy (TEM) characterization, to shed light on the influence of introducing other materials on titania characteristics. To study and evaluate the significance of the parameters affecting the process in the pilot plant, a chemometric approach was applied, by selecting a mathematical model (D-Optimal) to simultaneously monitor a large number of variables (i.e., 7), both qualitative and quantitative, over a wide range of levels. At the same time, the recovery of the synthesized photocatalysts was studied following a novel promising recuperation method, i.e., annulling the surface charge of the suspended samples by reaching the isoelectric point (pHPZC) of each sample, for the quantitative precipitation of TiO2 nanoparticles.

Advances in identifying and managing emerging contaminants in aquatic ecosystems: Analytical approaches, toxicity assessment, transformation pathways, environmental fate, and remediation strategies

Emerging contaminants (ECs) are increasingly recognized as threats to human health and ecosystems. This review evaluates advanced analytical methods, particularly mass spectrometry, for detecting ECs and understanding their toxicity, transformation pathways, and environmental distribution. Our findings underscore the reliability of current techniques and the potential of upcoming methods. The adverse effects of ECs on aquatic life necessitate both in vitro and in vivo toxicity assessments. Evaluating the distribution and degradation of ECs reveals that they undergo physical, chemical, and biological transformations. Remediation strategies such as advanced oxidation, adsorption, and membrane bioreactors effectively treat EC-contaminated waters, with combinations of these techniques showing the highest efficacy. To minimize the impact of ECs, a proactive approach involving monitoring, regulations, and public education is vital. Future research should prioritize the refining of detection methods and formulation of robust policies for EC management.

Cobalt doped nitrogen-vacancies-rich C3N5 with optimizing local electron distribution boosts peroxymonsulfate activation for tetracycline degradation: Multiple electron transfer mechanisms

Heterogeneous photocatalysis coupled with peroxymonosulfate (PMS) activation is considered as an advanced water purification technology for emerging contaminates degradation. In this study, Cobalt (Co) doped nitrogen-vacancies-rich C3N5 photocatalysts (Co/Nv-C3N5) were designed to activate PMS for tetracycline removal. The photo-chemical oxidation system displayed superior advantage, in which the observed rate constant of tetracycline degradation (0.1488 min-1) was 10.86 and 1.82 times higher than that of photo-oxidation and chemical-oxidation systems. Density functional theory calculation results verified the reconstruction of local charge distribution during PMS activation, indicating Co doping and nitrogen-vacancy engineering not only promoted photoelectrons capture, but also boosted electron transfer from the C-N framework to PMS and the generation of active species. Furthermore, several unique multiple electron transfer mechanisms were found in nonradicals (h+, 1O2 and Co(IV)) pathways. Additionally, three possible tetracycline degradation pathways were proposed and the toxicity of the intermediates was evaluated. Overall, the findings from this study provided a novel strategy for developing high-efficient photocatalyst for the rapid degradation of organic pollutants.

Occurrence, distribution, and ecological risk assessment of artificial sweeteners in surface and ground waters of the middle and lower reaches of the Yellow River (Henan section, China)

As a new class of water contaminants, artificial sweeteners (ASs) have attracted much attention due to their environmental persistence and potential adverse effects to human and the environment. This study systematically investigated the occurrence and distribution of four commonly used ASs in the effluent of wastewater treatment plants (WWTPs), surface water and groundwater in the middle and lower reaches of the Yellow River (Henan section). Sucralose (SUC) was dominant in WWTP effluents and had the highest mass loading. Acesulfame (ACE), cyclamate (CYC), saccharin (SAC), and SUC were consistently detected in surface water at concentrations ranging from 1.364 ng/L (CYC) to 7786 ng/L (ACE). Spatial analysis showed that the pollution level of ASs in the trunk stream was lower than that in most tributaries. The total concentrations of ASs detected in surface water ranged between 308.7 and 10,498 ng/L, while in groundwater, the total concentration of ASs detected was between ND-4863 ng/L. ACE and SUC are the main pollutants in surface water and groundwater within this survey area. The risk assessment showed that the risks of the four target ASs to aquatic organisms were negligible (risk quotient (RQ) values < 0.1), and the maximum risk quotient of the mixtures (MRQ) values of all rivers were all much less than 0.1.

Photodegradation of organic micropollutants in aquatic environment: Importance, factors and processes

Photochemical reactions widely occur in the aquatic environment and play fundamental roles in aquatic ecosystems. In particular, solar-induced photodegradation is efficient for many organic micropollutants (OMPs), especially those that cannot undergo hydrolysis or biodegradation, and thus can mitigate chemical pollution. Recent reports indicate that photodegradation may play a more important role than biodegradation in many OMP transformations in the aquatic environment. Photodegradation can be influenced by the water matrix such as pH, inorganic ions, and dissolved organic matter (DOM). The effect of the water matrix such as DOM on photodegradation is complex, and new insights concerning the disparate effects of DOM have recently been reported. In addition, the photodegradation process is also influenced by physical factors such as latitude, water depth, and temporal variations in sunlight as these factors determine the light conditions. However, it remains challenging to gain an overview of the importance of photodegradation in the aquatic environment because the reactions involved are diverse and complex. Therefore, this review provides a concise summary of the importance of photodegradation and the major processes related to the photodegradation of OMPs, with particular attention given to recent progress on the major reactions of DOM. In addition, major knowledge gaps in this field of environmental photochemistry are highlighted.

Insights into the formation of environmentally persistent free radicals during photocatalytic degradation processes of ceftriaxone sodium by ZnO/ZnIn2S4

At present, the researches on photocatalysis were mainly focused on the design, improvement and development of catalysts, and less attention was paid to the existing characteristics of environmentally persistent free radicals (EPFRs) during the process of photocatalytic oxidation. In this study, A flower-like Z-type heterojunction ZnO/ZnIn₂S₄ (ZnO/ZIS) and typical antibiotic ceftriaxone sodium (CS) were taken as study objects, concentrating on the generation characteristics of EPFRs during the degradation of CS by ZnO/ZIS, and clarifying the degradation mechanism of CS in which EPFRs participated. The results showed that the degradation efficiency of 10 mg/L CS by 0.40 g/L ZnO/ZIS reached 85.3% in 150 min under the irradiation of 500 W xenon lamp. It was clear that ·O₂^- and h⁺ play major roles in CS degradation by ZnO/ZIS under visible light, and ·OH plays an auxiliary role. Furthermore, the formation mechanism of EPFRs during photocatalytic degradation processes of CS by ZnO/ZIS were first investigated thoroughly via experimental analysis and density functional theory (DFT) calculations. The concentration level of EPFRs centered on oxygen atoms is 10¹¹ spin/mm³, which were generated in the process of degradation of CS by ZnO/ZIS under visible light. The production of EPFRs chiefly includes two procedures: chemical adsorption and transfer of electrons. The adsorption energy of precursor P8 on ZnIn₂S₄ side is -1.91 eV, the electrons transferred from precursor P8 and P11 to ZnO/ZnIn₂S₄ heterojunction. Surprisingly, EPFRs have little negative effects on the degradation process of CS by ZnO/ZIS. The study was not only a key field in the development of photocatalysis technology, but also a new way to study the removal mechanism of antibiotics.

Enantioselective hydrolysis and photolysis of mandipropamid in different aquatic environments - evaluation of influencing factors

The hydrolysis and photolysis of the chiral fungicide mandipropamid were investigated, and the potential enantioselectivity of mandipropamid in solutions was further assessed. The aqueous solutions were filtered and directly injected into the liquid chromatography with tandem mass spectrometry. In the hydrolysis experiments, mandipropamid enantiomers hydrolyzed slowly in aquatic solutions with half-lives > 200 days; nevertheless, rise of the pH and incubation temperature could increase the hydrolysis rates more than 1.1 times (half-lives decreased from 495.1 to 216.6 days). Compared with the hydrolysis results, photolysis was found to be the main degradation pathway for mandipropamid in different solutions (half-lives < 14 h, except in pH = 5.05 buffer solution). Organic solvents were able to accelerate the photolysis of mandipropamid, but acidic solutions and the addition of flavonoids or inorganic salts significantly inhibited the photolysis of mandipropamid. During the hydrolysis and photolysis processes, the configuration of mandipropamid enantiomers was stable and five possible transformation products were identified by high resolution mass spectrometry. Due to the enantiomeric fraction values > 0.5, the hydrolysis and photolysis of mandipropamid were enantioselective, and S-( +)-mandipropamid preferentially disspated in certain aqueous solutions. The systematic evaluation of the hydrolysis and photolysis of mandipropamid enantiomers may provide more accurate data for better assessment of environmental and ecological risks in aquatic ecosystems.

Kinetics of the photolysis of pyridaben and its main photoproduct in aqueous environments under simulated solar irradiation

The photolytic fate of pyridaben and its main photolysis product was investigated in different aqueous solutions. Results showed that the photolysis of pyridaben followed pseudo first-order kinetics or the hockey-stick model. In buffer solutions, the half-life of pyridaben was the shortest at pH 4, while the degradation rate within 24 h was the highest at pH 9. Humic acids (HA) at concentrations of 1-20 mg L^-1 favored the photolysis of pyridaben while fulvic acids (FA) did not have a significant effect. Nitrate at low concentrations (0.01 mM) accelerated the photolysis and Fe(iii) at high concentrations (0.01 and 0.1 mM) significantly inhibited the photolysis. The photolysis rate of pyridaben in rainwater, tap water, and river water was significantly higher than that in distilled water. The half-lives in distilled water, rainwater, tap water, river water, and pond water were 2.36, 1.36, 1.61, 1.77, and 2.68 h, respectively. Ultra-high-performance liquid chromatography/high-resolution mass spectrometry identified M328 as a photolysis product. The degradation of M328 followed pseudo first-order kinetics in distilled water, buffer solutions and aqueous solutions fortified with HA. The half-lives of M328 were in the range of 7.07-13.95 h. These results are essential for further environmental risk assessment of pyridaben.

Source, fate, transport and modelling of selected emerging contaminants in the aquatic environment: Current status and future perspectives

The occurrence of emerging contaminants (ECs), such as pharmaceuticals and personal care products (PPCPs), perfluoroalkyl and polyfluoroalkyl substances (PFASs) and endocrine-disrupting chemicals (EDCs) in aquatic environments represent a major threat to water resources due to their potential risks to the ecosystem and humans even at trace levels. Mathematical modelling can be a useful tool as a comprehensive approach to study their fate and transport in natural waters. However, modelling studies of the occurrence, fate and transport of ECs in aquatic environments have generally received far less attention than the more widespread field and laboratory studies. In this study, we reviewed the current status of modelling ECs based on selected representative ECs, including their sources, fate and various mechanisms as well as their interactions with the surrounding environments in aquatic ecosystems, and explore future development and perspectives in this area. Most importantly, the principles, mathematical derivations, ongoing development and applications of various ECs models in different geographical regions are critically reviewed and discussed. The recommendations for improving data quality, monitoring planning, model development and applications were also suggested. The outcomes of this review can lay down a future framework in developing a comprehensive ECs modelling approach to help researchers and policymakers effectively manage water resources impacted by rising levels of ECs.

A Systematic Review of Photolysis and Hydrolysis Degradation Modes, Degradation Mechanisms, and Identification Methods of Pesticides

The degradation modes and characteristics of different pesticides were introduced. In addition, this paper also describes the degradation mechanism of different pesticides, classifies, and summarizes the methods of degradation products identification. For the sake of human life health and better biological environment, we should have a familiar knowledge of the natural degradation of pesticides and understand the photo-hydrolysis and its influencing factors (temperature, pH, light, etc.). Through the degradation mechanism and influencing factors, the degradation time could be accelerated and it also provides a theoretical basis and basic support for the treatment of pesticide residues in the future.

Occurrence, sources and environmental risk assessment of pharmaceuticals in the Sea of Marmara, Turkey

In the present study, the occurrence and spatial distribution of selected eleven pharmaceuticals were investigated in the Sea of Marmara, Turkey. Samples were collected from different depths of the nine stations in April and October 2019. Pharmaceuticals were analyzed using liquid-liquid and solid-phase extraction (SPE) methods followed by high-performance liquid chromatography (HPLC). All target pharmaceutical compounds were detected at least once in the study area. Gemfibrozil, which belongs to the lipid regulatory group, was the most frequently detected in seawater at high concentrations (<0.016-9.71 μg/L). Ibuprofen (<0.015-2.13 μg/L) and 17α-ethynylestradiol (<0.010-3.55 μg/L) were identified as the other frequently detected pharmaceuticals. In addition, the presence of these selected compounds in April was higher than in October. According to the risk assessment results, naproxen, diclofenac, clofibric acid, gemfibrozil, 17β-estradiol, and 17α-ethynylestradiol represent a high risk to aquatic organisms in the Sea of Marmara. These findings underline the importance of continued monitoring of these compounds as relevant organic contaminants in the study area to take appropriate measures to protect the ecosystem and, ultimately, human health.

The environmental distribution and removal of emerging pollutants, highlighting the importance of using microbes as a potential degrader: A review

Emerging pollutants (EPs) create a worldwide concern owing to their low concentration and severe toxicity to the receptors. The prominent emerging pollutants categories as pharmaceutical and personal care product, plasticizer, surfactants, and persistent organic pollutants. Typically, EPs are widely disseminated in the aquatic ecosystem and capable of perturbing the physiology of water bodies as well as humans. The primary sources of EPs in the environment include anthropogenic release, atmospheric deposition, untreated or substandard treated wastewater, and extreme weather events. Intensive research has been done covering the environmental distribution, ecological disturbance, fate, and removal of EPs in the past decades. However, a systematic review on the distribution of EPs in the engineered and natural aquatic environment and the degradation of different EPs by using anaerobic sludge, aerobic bacteria, and isolated strains are limited. This review article aims to highlight the importance, application, and future perceptions of using different microbes to degrade EPs. Overall, this review article illustrates the superiority of using non-cultivable and cultivable microbes to degrade the EPs as an eco-friendly approach. Practically, the outcomes of this review paper will build up the knowledge base solutions to remove EPs from the wastewater.

Humic-Like Substances as Auxiliaries to Enhance Advanced Oxidation Processes

The application of humic-like substances (HLSs) in advanced oxidation processes for wastewater treatment is summarized in this work. HLSs share important characteristics with humic substances, and they can be isolated from different wastes using procedures that are related with their pH-dependent solubility. They are able to generate, upon irradiation, reactive species such as hydroxyl radicals and singlet oxygen or triplet excited states. Although photochemical removal of pollutants can be reached by HLSs, in general, irradiation times are very long. HLSs are good metal-complexing agents, and the Fe-HLS complex is able to participate in (photo)-Fenton-like processes at mild pH, preventing iron deactivation. Finally, novel hybrid materials with environmental applications have been synthesized using HLSs; in some cases, they also contain iron oxides, which allow a better separation but also the ability to drive heterogeneous (photo)-Fenton processes.

Spatial distribution of pharmaceuticals within the particulate phases of a peri-urban stream

Pharmaceutical products (PPs) are consumed worldwide and are continuously released into hydrological environments, but are not efficiently removed by sewage treatment plants. Their occurrence within the dissolved phase has been extensively studied, but only a few articles concern solid matrices. The mechanisms and extent of sorption depend on the properties of both the molecules (degradability, charge, hydrophobicity) and the matrices (clay content, organic matter content), making the spatio-temporal distribution of PPs in natural environments complex and poorly elucidated. To improve our understanding of PP distribution at a catchment scale, this study investigated different groups of molecules with varying solubility and charges, in water, suspended particulate matter, bed-load and pond sediments. The Egoutier stream, which collects the sewage effluents from two health institutions sewage effluents, is a good candidate for this investigation. Results indicate that PP occurrences in the different particulate compartments were mainly regulated by their wastewater occurrences and charges. Particulate phases all along the Egoutier stream were characterized by a limited clay content (i.e. less than 1%) and significant organic carbon content (i.e. between 0.3% and 18.0%) favouring non-specific adsorption. Therefore, neutral PPs, exhibiting higher discharge rates, persistence and hydrophobicities in comparison with cationic and anionic molecules, were the most abundant PPs in the particulate phases of this catchment. In bed-load sediments, global PP spatial distributions reflected discharge sites and sedimentary accumulation zones, mostly that of organic matter. Spatial distributions of the more hydrophobic and persistent PP in the particulate phases thus followed the stream sedimentary dynamic.

Photolytic fate of (E)- and (Z)-endoxifen in water and treated wastewater exposed to sunlight

Endoxifen is the main active metabolite of a common cytostatic drug, tamoxifen. Endoxifen has been recently detected in the final effluent of municipal wastewater treatment plants. The antiestrogenic activity of endoxifen could bring negative effects to aquatic life if released to the water environment. This study elucidated the fate and susceptibility of (E)- and (Z)-endoxifen (2 μg mL^-1, 1:1 wt ratio between the two easily interchangeable isomers) in wastewater and receiving surface water to sunlight. Phototransformation by-products (PBPs) and their toxicity were determined. Sunlight reduced at least 83% of endoxifen concentration in wastewater samples, whereas in surface water samples, 60% of endoxifen was photodegraded after 180 min of the irradiation. In ultrapure water samples spiked with endoxifen, PBPs were mainly generated via con-rotatory 6π-photocyclization, followed by oxidative aromatization. These PBPs underwent secondary reactions leading to a series of PBPs with different molecular weights. Eight PBPs were identified and the toxicity analysis via the Toxicity Estimation Software Tool revealed that seven of these PBPs are more toxic than endoxifen itself. This is likely due to the formation of poly-aromatic core in the PBPs due to exposure to sunlight. Therefore, highly toxic PBPs may be generated if endoxifen is present in water and wastewater exposed to sunlight. The presence, fates and activities of these PBPs in surface water especially at locations close to treated wastewater discharge points should be investigated.

Managed aquifer recharge implementation criteria to achieve water sustainability

Depletion of groundwater is accelerated due to an increase in water demand for applications in urbanized areas, agriculture sectors, and energy extraction, and dwindling surface water during changing climate. Managed aquifer recharge (MAR) is one of the several methods that can help achieve long-term water sustainability by increasing the natural recharge of groundwater reservoirs with water from non-traditional supplies such as excess surface water, stormwater, and treated wastewater. Despite the multiple benefits of MAR, the wide-scale implementation of MAR is lacking, partly because of challenges to select the location for MAR implementation and identify the MAR type based on site conditions and needs. In this review, we provide an overview of MAR types with a basic framework to select and implement specific MAR at a site based on water availability and quality, land use, source type, soil, and aquifer properties. Our analysis of 1127 MAR projects shows that MAR has been predominantly implemented in sites with sandy clay loam soil (soil group C) and with access to river water for recharge. Spatial analysis reveals that many regions with depleting water storage have opportunities to implement MAR projects. Analyzing data from 34 studies where stormwater was used for recharge, we show that MAR can remove dissolved organic carbon, most metals, E. coli but not efficient at removing most trace organics, and enterococci. Removal efficiency depends on the type of MAR. In the end, we highlight potential challenges for implementing MAR at a site and additional benefits such as minimizing land subsidence, flood risk, augmenting low dry-season flow, and minimizing salt-water intrusion. These results could help identify locations in the water-stressed regions to implement specific MAR for water sustainability.

Quantification of seasonal photo-induced formation of reactive intermediates in a municipal sewage lagoon upon sunlight exposure

Photochemically produced reactive oxygen species in wastewater lagoons upon sunlight exposure are important in the attenuation of emerging contaminants (ECs). The production of reactive radicals in wastewater lagoons depends on both environmental factors and the composition of effluent organic matter (EfOM) in the wastewater. Knowing the steady state concentrations of these reactive species produced in a particular lagoon wastewater is critical to the prediction of the persistence and attenuation of ECs in that sunlit wastewater treatment lagoon. This study quantified the formation of four photochemically produced reactive intermediates (PPRIs): hydroxyl radical, carbonate radical, singlet oxygen, and triplet excited state EfOM in 11 samples collected from a municipal wastewater lagoon over a full year. The temporal distribution of these key PPRIs in the lagoon under investigation was determined in relation to sunlight irradiance, wastewater composition and temperature. Greater sunlight intensity led to greater PPRI production over the year. Increasing wastewater temperature from 12 to 25 °C led to greater production of singlet oxygen, a moderate decrease in hydroxyl radical and increase in triplet excited state EfOM, and minimal impact on carbonate radical production. The optical properties of the lagoon wastewater of Napierian absorption coefficient (A₃₀₀) and E₂:E₃ ratio could be used as indicators of the formation of singlet oxygen (Pearson's r = 0.79) and triplet excited EfOM (Pearson's r = 0.76) produced upon solar irradiation. The concentration of carbonate radical formed was strongly correlated to the nitrate level in the wastewater (Pearson's r = 0.85). The findings could be used for modelling the seasonal sunlight-induced photolysis process of ECs during lagoon-based wastewater treatment, with a view to optimising the treatment process, predicting the efficacy of EC removal, and risk assessment of the treated water.

Exploring the phototransformation and assessing the in vitro and in silico toxicity of a mixture of pharmaceuticals susceptible to photolysis

The present study comprehensively investigates the phototransformation and ecotoxicity of a mixture of twelve pharmaceutically active compounds (PhACs) susceptible to photolysis. Namely, three antibiotics (ciprofloxacin, levofloxacin, moxifloxacin), three antidepressants (bupropion, duloxetine, olanzapine), three anti-inflammatory drugs (diclofenac, ketoprofen, nimesulide), two beta-blockers (propranolol, timolol) and the antihistamine ranitidine were treated under simulated solar irradiation in ultra-pure and river water. A total of 166 different transformation products (TPs) were identified by ultra-high performance liquid chromatography coupled with Orbitrap high resolution mass spectrometry (UHPLC-Orbitrap HRMS), revealing the formation of twelve novel TPs and forty-nine not previously described in photolytic studies. The kinetic profiles of the major TPs resulting from a series of chemical reactions involving hydroxylation, cleavage and oxidation, dehalogenation, decarboxylation, dealkylation and photo substitution have been investigated and the transformation pathways have been suggested. Additionally, an in vitro approach to the toxicity assessment of daphnids was contrasted with ecotoxicity data based on the Ecological Structure Activity Relationships (ECOSAR) software comprising the in silico tool to determine the adverse effects of the whole mixture of photolabile parent compounds and TPs. The results demonstrated that photolysis of the target mixture leads to a decrease of the observed toxicity.

Lignocellulose Biomass as a Multifunctional Tool for Sustainable Catalysis and Chemicals: An Overview

Today, the theme of environmental preservation plays an important role within the activities of the scientific community and influences the choices of politics and the common population. In this context, the use of non-fossil substances should be promoted for different reasons: to avoid the depletion and damage of the areas involved in the fossil fuel extraction, decrease the impact of emissions/by-products related to the industrial transformation of fossil-based products and possibly exploit residual biomasses as sources of carbon. This latter aspect also can be viewed as a way to revalorize lignocellulose waste, generally destined to dump as putrescible matter or to be incinerated. In this review, we are aiming to present a concise overview of the multiple functions of lignocellulose biomass in the broad field of catalysis for a sustainable development. The originality of the approach is considering the lignocellulose-derived matter in three different aspects: (i) as a precursor to convert into platform molecules, (ii) as an active material (i.e., humic-like substances as photosensitizers) and (iii) as a green support for catalytic applications. We find that this perspective can widen the awareness level of scientists involved in the catalysis field for the exploitation of residual biomass as a valuable and complementary resource.

Impact of Inorganic Ions and Organic Matter on the Removal of Trace Organic Contaminants by Combined Direct Contact Membrane Distillation-UV Photolysis

This study investigated the degradation of five trace organic contaminants (TrOCs) by integrated direct contact membrane distillation (DCMD) and UV photolysis. Specifically, the influence of inorganic ions including halide, nitrate, and carbonate on the performance of the DCMD–UV process was evaluated. TrOC degradation improved in the presence of different concentrations (1–100 mM) of fluoride ion and chloride ion (1 mM). With a few exceptions, a major negative impact of iodide ion was observed on the removal of the investigated TrOCs. Of particular interest, nitrate ion significantly improved TrOC degradation, while bicarbonate ion exerted variable influence—from promoting to inhibiting impact—on TrOC degradation. The performance of DCMD–UV photolysis was also studied for TrOC degradation in the presence of natural organic matter, humic acid. Results indicated that at a concentration of 1 mg/L, humic acid improved the degradation of the phenolic contaminants (bisphenol A and oxybenzone) while it inhibited the degradation of the non-phenolic contaminants (sulfamethoxazole, carbamazepine, and diclofenac). Overall, our study reports the varying impact of different inorganic and organic ions present in natural water on the degradation of TrOCs by integrated DCMD–UV photolysis: the nature and extent of the impact of the ions depend on the type of TrOCs and the concentration of the interfering ions.

Microbiological and Chemical Assessment of Wastewater Discharged by Infiltration Trenches in Fractured and Karstified Limestone (SCA.Re.S. Project 2019-2020)

This study investigated the environmental contamination of groundwater as a consequence of the discharge of treated wastewater into the soil. The investigation focused on a wastewater treatment plant located in an area fractured by karst in the Salento peninsula (Apulia, Italy). Water samples were collected at four sites (raw wastewater, treated wastewater, infiltration trench, and monitoring well), monthly from May to December 2019 (with the exception of August), and were tested for (1) panel of bacteria; (2) enteric viruses; and (3) chemical substances. A gradual reduction in the concentration of bacteria, viruses and contaminants of emerging concern was observed across the profile of soil fissured by karst. All monitored bacteria were absent from the monitoring well, except for Pseudomonas aeruginosa. Pepper mild mottle virus and adenovirus were detected at all sampling sites. Personal care products and X-ray contrast media showed the greatest decrease in concentration from infiltration trench to the monitoring well, while the highest residual concentrations in the monitoring well were found for anticonvulsants (78.5%), antimicrobials (41.3%), and antipsychotic drugs (38.6%). Our results show that parameters provided by current law may not always be sufficient to evaluate the sanitary risk relating to the discharge of treated wastewater to the soil.

Photodegradation of polychlorinated diphenyl sulfides (PCDPSs) under simulated solar light irradiation: Kinetics, mechanism, and density functional theory calculations

The direct photolysis of 25 individual polychlorinated diphenyl sulfides (PCDPSs) substituted with 1-7 chlorine atoms was investigated using a 500-W Xe lamp. Photolysis of PCDPSs followed pseudo-first-order kinetics, with the higher chlorinated diphenyl sulfides generally degrading faster than the lower chlorinated congeners. A quantitative structure-activity relationship model to predict the photolysis rates of PCDPSs was developed using 16 fundamental quantum chemical descriptors. We found that the substitution pattern for chlorine atoms, the dipole moment, and E_LUMO - E_HOMO were major factors in the photolysis of PCPDSs. The reaction kinetics, products, and photodegradation pathways of 2,2',3',4,5-pentachlorodiphenyl sulfide (PeCDPS) suggest hydroxylation, direct photooxidation, the C-S bond cleavage reaction, and hydroxyl substitution were mainly involved in the photodegradation process, leading to the formation of 13 intermediates, detected by an electrospray time-of-flight mass spectrometer. The initial reaction sites of PCDPSs under photolysis were rationalized by density functional theory calculations. Anions (Cl^-, SO₄^2-, NO₃^-, and HCO₃^-) and Co²⁺ had no influence on the removal of PeCDPS, while Fe³⁺, Cu²⁺, and HA decreased the photolysis efficiency of PeCDPS. This report is the first to develop a logk quantitative structure-property relationships (QSPR) model of 25 PCDPSs and to describe mechanistic pathways for the photolysis of PeCDPS.

Occurrence, fate, and mass balance of selected pharmaceutical and personal care products (PPCPs) in an urbanized river

The identification and quantification of pharmaceutical and personal care products (PPCPs) in aquatic ecosystems is critical to further studies and elucidation of their fate as well as the potential threats to aquatic ecology and human health. This study used mass balances to analyse the sources, transformation, and transport of PPCPs in rivers based on the population and consumption habits of residents, the removal level of sewage treatment, the persistence and partitioning mechanisms of PPCPs, hydrological conditions, and other natural factors. Our results suggested that in an urbanized river of Guangzhou City, China, the daily consumption of PPCPs was the main reason for the variety of species and concentrations of PPCPs. Through the determination of PPCPs in the river water samples and a central composite design (CCD) methodology, the dominant elimination mechanisms of caffeine and carbamazepine from river water were photolysis and biodegradation, but that of triclosan was sorption rather than biodegradation. The mass data of 3 PPCPs were estimated and corroborated using the measured data to evaluate the accuracy of the mass balance. Finally, caffeine, carbamazepine and triclosan discharged from the Shijing River into the Pearl River accounted for 97.81%, 99.52%, and 28.00%, respectively, of the total mass of these three compounds in the surface water of Shijing River. The results suggest that photolysis are the main process of natural attenuation for selected PPCPs in surface waters of river systems, and the transfer processes of PPCPs is mainly attributed to riverine advection. In addition, the low concentration of dissolved oxygen inhibited the degradation of PPCPs in the surface water of Shijing River.

Photochemical reaction of tricresyl phosphate (TCP) in aqueous solution: Influencing factors and photolysis products

Organophosphate triesters (OPEs) have caused great concern as a class of emerging environmental contaminants due to their widespread use and their toxicity to organisms. However, the phototransformation behavior of OPE is still not fully understood, which is important for understanding their environmental fate. In the present study, the photodegradation of tricresyl phosphate (TCP), one of the most widely detected OPEs in aqueous environments, was investigated including the direct photolysis and in the presence of several natural water factors, NO₂^-, Fe³⁺ and humic acid. The degradation process followed the pseudo-first-order kinetics, with rate constant increasing slightly with increasing initial TCP concentration. The presence of NO₂^- and Fe³⁺ was observed to promote the photochemical loss of TCP, while humic acid played a negative role on TCP transformation. Electron spin resonance (EPR) analysis showed that carbon-centered radical was produced in the photolysis process of TCP, and hydroxyl radical contributed to the promotion of rate constant for Fe³⁺ and NO₂^-. Four photolysis products were tentatively identified by HPLC-LTQ-Orbitrap MS analysis, and the possible degradation pathways of TCP were proposed. These findings provide a meaningful reference for the fate and transformation of OPEs in natural water.

Occurrence and distribution of pharmaceutical compounds in the Danshuei River Estuary and the Northern Taiwan Strait

Ten pharmaceutically active compounds (PhACs) were determined in northern Taiwan estuarine waters and Taiwan Strait (TS) seawater. The ecological risk of these PhACs was assessed using risk quotient (RQ), which is the ratio of the measured maximum concentration to the predicted no-effect concentration. Six PhACs were detected within the estuarine waters. Caffeine concentration (130-718 ng l^-1) was the highest among the analyzed PhACs. The distribution of PhACs in the Danshuei River Estuary generally exhibited addition behavior, except that caffeine showed conservative behavior. Carbamazepine, gemfibrozil, caffeine, and ketoprofen were detected in TS seawaters. Their concentrations follow the sequence: gemfibrozil > ketoprofen > caffeine > carbamazepine. The caffeine concentrations in TS seawaters were 2-3 orders of magnitude lower than those in Danshuei estuarine waters. With few exceptions for caffeine, erythromycin, and sulfadiazine posing low risk in some estuarine waters, most of the RQ values were <0.01, suggesting no adverse effects on aquatic organisms.

Experiments and numerical simulation on the degradation processes of carbamazepine and triclosan in surface water: A case study for the Shahe Stream, South China

We examined the occurrence and fate of pharmaceuticals and personal care products in surface water by combining laboratory experiments with numerical simulations. The degradation processes of two typical PPCPs (triclosan and carbamazepine) collected from the Shahe Stream were studied. Hydrolysis, biodegradation, and photolysis were the three major routes of triclosan (TCS) and carbamazepine (CBZ) degradation. A central composite design method was used to investigate the effects of related natural parameters (including pH, dissolved oxygen, salinity, temperature, light intensity, and humic acid) on the TCS and CBZ degradation processes in the laboratory. Our results showed that the main degradation pathway of CBZ and TCS was direct photolysis during the daytime and that the maximal biodegradation rates of CBZ and TCS occurred at 22 °C when the optimum temperature function was used. Based on our experimental results, the observed degradation of CBZ and TCS followed pseudo-first-order kinetics, and the degradation kinetic equations under the influence of multiple natural parameters were established with estimated average degradation rate constants of 1.2452E-7 s^-1 and 3.1260E-5 s^-1 for CBZ and TCS, respectively. The degradation rate constants were incorporated into a one-dimensional, simply integrated hydrodynamic and water quality model. The proposed numerical model was applied to depict the transportation and transformation of CBZ and TCS in surface water and was validated by observational data from the Shahe Stream. The results showed that our model reproduced the observed patterns of CBZ and TCS concentrations reasonably, with slight overestimations compared to the observed data; the relative errors between the simulated and the observed concentrations were 5.85%-6.82% for CBZ and -156.85%--7.18% for TCS. According to our simulation, the spatial distribution of TCS in surface water was determined by biochemical degradation processes that were most affected by temperature under natural conditions; in contrast, the distribution of CBZ was largely controlled by diffusion.

Innovative application of biobed bioremediation systems to remove emerging contaminants: Adsorption, degradation and bioaccesibility

Biobed bioremediation systems (BBSs) are widely used to prevent point-source pesticide contamination of water. However, these systems have never been investigated for possible elimination of emerging contaminants (ECs). In this study, two biobed systems, involving biomixtures elaborated with soil and raw olive mill cake (SCP) or its vermicompost (SVP), were assayed to determine their effectiveness in removing the ECs diclofenac, ibuprofen and triclosan from effluent wastewater. Adsorption, incubation and bioaccesibility experiments were carried out. The SCP and SVP biomixtures showed greater adsorption capacity than the soil (S), used as reference. In SVP and S, the degradation rates of the ECs applied were similar and over 94% of these compounds was removed after 84 days of incubation. However, SCP biomixture had a lower removal rate and the percentage of ECs removed ranged from 32 to 68%. In SVP, the bioaccesible fraction (E) reveals that approximately 82% of triclosan and diclofenac adsorption occurred in bioaccesible sites, thus explaining the more efficient decontamination observed in this biomixture. The relationship established between the bioaccesible and biodegradable fractions suggests that E values are a useful tool for predicting the endpoints of ECs biodegradation in bioremediation systems. UPLC/Q-TOF-MS analysis of samples showed different metabolite products.

Analytical and mathematical assessment of emerging pollutants fate in a river system

The fate of several emerging pollutants in a Greek river system was assessed through analytical measurements and mathematical modelling. Target compounds selected in this study consist of five endocrine disrupting chemicals and four non-steroidal anti-inflammatory drugs. Two sampling campaigns were implemented to assess target compounds concentrations along the river system during dry period. Furthermore a mathematical model was developed in order to simulate the spatial distribution of target compounds concentration. The mathematical model describes several abiotic and biotic processes (sorption, photodegradation, biodegradation, biotransformation) in order to account for the removal of target compounds. Following sensitivity analysis, the model was calibrated and validated against measured values. Environmental risk assessment was performed based on both analytical measurements and simulation results. Uncertainty analysis was also conducted by applying Monte Carlo technique. According to the results the simulation data matched very satisfactorily with the analytical measurements, thus confirming the main experimental observations showing that the primary removal mechanism for the photo-sensitive chemicals is photodegradation, the latter being mostly influenced by weather conditions and river general quality characteristics (e.g. chlorophyll, turbidity). Model results demonstrate a gradual increase of uncertainty from the upstream to the downstream of the river system for all target compounds.

Photocatalytic oxidation of diuron using nickel organic xerogel under simulated solar irradiation

In this study, a nickel organic xerogel (X-Ni) was used as semiconductor photocatalyst for the degradation of the herbicide diuron (DRN) in aqueous solution. The main objective of this work was to analyze and compare the effectiveness of solar irradiation to remove DRN from water both by direct photolysis and photocatalytic degradation. We examined the influence of the initial concentration of the herbicide, the solution pH, the presence of different ions in the medium, the chemical composition of the water, and the presence of a photocatalyst, after 240 min of irradiation. Direct photolysis achieved a low percentage of DRN degradation but was favored: i) by a reduction in the initial concentration of the herbicide (from 35.6% to 79.0% for 0.150 × 10^-3 mol/L and 0.021 × 10^-3 mol/L of DRN, respectively) and ii) at solution pHs at which diuron is positively charged (78.6% for pH 2 and 50.4% for pH 7), as suggested by DFT calculations carried out for DRN and its protonated form (DRN-H⁺). The corresponding mono-demethylated DRN derivative, 1-(3,4-dichlorophenyl)-3-methylurea (DCPU), was identified as a DRN degradation byproduct. In addition, the presence of certain anions in the medium significantly affected the overall degradation process by direct photolysis, due to the additional generation of HO radicals. We highlight that the presence of X-Ni considerably improved the photodegradation process under solar irradiation. The photocatalytic degradation rate constant was directly proportional to the xerogel concentration, because an increase in catalyst dose produced an increase in surface active sites for the photodegradation of DRN, enhancing the overall efficiency of the process. Thus, when 4167 mg/g of X-Ni was added, the DRN removal rate was 3-fold higher and both percentage of degradation and mineralization increased 88.5% with respect to the results obtained by direct photolysis.

Endocrine-disrupting compounds in the Xiangjiang River of China: Spatio-temporal distribution, source apportionment, and risk assessment

Endocrine-disrupting compounds (EDCs) were seasonally investigated in the surface water of the Xiangjiang River (south China) in order to understand their spatio-temporal distribution, source apportionment, and ecological risks. The occurrence of 21 EDCs were determined with liquid chromatography-tandem mass spectrometry in the water samples collected along the river over four seasons, and the results were statistically analyzed. The concentrations of progestagens, androgens, estrogens ranged from not detected (ND) to 98.3 ng L^-1; while the concentrations of alkylphenols ranged from 0.8 to 3.1 × 10³ ng L^-1; and that of caffeine ranged from 0.1 to 49.8 ng L^-1. The detection frequencies of bisphenol A, 4-tert-octylphenol, 4-n-nonylphenol, estrone, and 17β-estradiol were 95-100% during the four sampling campaigns. The seasonal and spatial variation trend of EDCs in the Xiangjiang River was noticeable. The concentration of EDCs in Yueyang section (downstream) was the highest in winter, while the concentration in Yongzhou (upstream) section was the lowest in spring. The concentration of EDCs in the Xiangjiang River was significantly correlated with the levels of the total organic carbon, water temperature, and dissolved oxygen. Source analysis indicated that untreated sewage was the major source of EDCs. Furthermore, the potential risks of EDCs in the surface water to aquatic organisms were assessed with the risk quotient method (European Commission, 2003), and the results indicated the highest ecological risk of 17β-estradiol in the Xiangjiang River.

Photodegradation of fluazaindolizine in water under simulated sunlight irradiation: Identification of transformation products and elucidation of transformation mechanism

The photodegradation of fluazaindolizine in water was investigated under simulated sunlight irradiation. The effects of solution pH, humic acids (HA), nitrates (NO₃^-) and Fe(III) ions on photolysis of fluazaindolizine were studied. The results indicated that pH did not significantly affect its photodegradation. At low concentration (up to 5 mg/L), HA slightly facilitated the photodegradation of fluazaindolizine, while at high concentration (10-20 mg/L), HA inhibited its photodegradation. The presence of NO₃^- (0-10 mg/L) and Fe(III) (0-5 mg/L) noticeably accelerated the photodegradation of fluazaindolizine. Moreover, eleven direct transformation products (TPs) were isolated and identified by liquid chromatography quadrupole time-of-flight mass spectrometry. Density functional theory (DFT) calculation was utilized to characterize molecular property of fluazaindolizine and predict the potentiality of the possible photodegradation reaction. Ultimately, a possible transformation mechanism was proposed based on the identified TPs, degradation profiles and DFT calculation. The predominant photoproduct came from ring opening of imidazole-ring and dechlorination. Other TPs resulted from a series of photochemical reactions involving hydroxyl substitution, ring-opening, cleavage, oxidation and decarboxylation. These results were important in elucidating environmental fate of fluazaindolizine in aquatic system and further environmental risk assessment.

The design of a sunlight-focusing and solar tracking system: A potential application for the degradation of pharmaceuticals in water

Photolysis is considered one of the most important mechanisms for the degradation of pharmaceuticals. Photodecomposition processes to remove pharmaceuticals in water treatment presently use artificial UV light incorporated in advanced oxidation processes. However, UV lighting devices consume a substantial amount of energy and have high operational costs. To develop low energy treatment systems and make good use of abundant sunlight, a natural energy resource as a green technology is needed. As such, a system that combines sunlight focusing, solar tracking and continuous reaction was designed and constructed in the present study, and its application potential as a pharmaceutical water treatment option was tested. Two representative photolabile pharmaceuticals, ciprofloxacin and sulfamethoxazole, were chosen as the target pollutants. The results indicate that the sunlight-focusing system consisting of a UV-enhancing-coated parabolic receiver can concentrate solar energy effectively and hence result in a more than 40% improvement in the direct photolysis efficiency of easily photoconvertible ciprofloxacin. The sunlight-focusing coupled with a solar tracker (SFST) system can improve the sunlight-focusing efficiency by more than 2-fold, thus leading to the maximization of the efficient use of solar energy. Sulfamethoxazole, which is difficult to photoconvert, was successfully degraded by more than 60% compared to direct photolysis through the designed SFST system in the presence of persulfate. The treatment system exhibited good and consistent performance during clear and cloudy days of summer. It is proven that the UV-enhanced coated SFST system with the addition of persulfate indeed has development potential for application in the degradation of pharmaceuticals in water.

A fugacity model assessment of ibuprofen, diclofenac, carbamazepine, and their transformation product concentrations in an aquatic environment

An updated version of FATEMOD, a multimedia fugacity model for environmental fate of organic chemicals, was set up to assess environmental behaviour of three pharmaceuticals in northern Lake Päijänne, Finland. Concentrations of ibuprofen, diclofenac, and carbamazepine were estimated at various depths at two sites: near a wastewater treatment plant and 3.5 km downstream the plant. When compared with environmental sampling data from corresponding depths and sites, the predicted concentrations, ranging from nanograms to hundreds of nanograms per litre, were found to be in good agreement. Weather data were utilised with the model to rationalise the effects of various environmental parameters on the sampling results, and, e.g. the roles of various properties of lake dynamics and photodegradation were identified. The new model also enables simultaneous assessment of transformation products. Environmentally formed transformation product concentrations were estimated to be at highest an order of magnitude lower than those of the parent compounds, and unlikely to reach a detectable level. However, a possibility that conjugates of ibuprofen are present at higher levels than the parent compound was identified. Simulation results suggest that environmental degradation half-lives of the inspected contaminants under stratified lake conditions are in the range of some weeks to months.

Hydrolysis and Photolysis Kinetics, and Identification of Degradation Products of the Novel Bactericide 2-(4-Fluorobenzyl)-5-(Methylsulfonyl)-1,3,4-Oxadiazole in Water

Hydrolysis and photolysis kinetics of Fubianezuofeng (FBEZF) in water were investigated in detail. The hydrolysis half-lives of FBEZF depending on pH, initial concentration, and temperature were (14.44 d at pH = 5; 1.60 d at pH = 7), (36.48 h at 1.0 mg L⁻¹; 38.51 h at 5.0 mg L⁻¹; and 31.51 h at 10.0 mg L⁻¹), and (77.02 h at 15 °C; 38.51 h at 25 °C; 19.80 h at 35 °C; and 3.00 h at 45 °C), respectively. The photolysis half-life of FBEZF in different initial concentrations were 8.77 h at 1.0 mg L⁻¹, 8.35 h at 5.0 mg L⁻¹, and 8.66 h at 10.0 mg L⁻¹, respectively. Results indicated that the degradation of FBEZF followed first-order kinetics, as the initial concentration of FBEZF only had a slight effect on the UV irradiation effects, and the increase in pH and temperature can substantially accelerate the degradation. The hydrolysis Ea of FBEZF was 49.90 kJ mol⁻¹, which indicates that FBEZF belongs to medium hydrolysis. In addition, the degradation products were identified using ultra-high-performance liquid chromatography coupled with an Orbitrap high-resolution mass spectrometer. One degradation product was extracted and further analyzed by ¹H-NMR, ¹³C-NMR, ¹⁹F-NMR, and MS. The degradation product was identified as 2-(4-fluorobenazyl)-5-methoxy-1,3,4-oxadiazole, therefore a degradation mechanism of FBEZF in water was proposed. The research on FBEZF can be helpful for its safety assessment and increase the understanding of FBEZF in water environments.

Assessment of the environmental fate of endocrine disrupting chemicals in rivers

Laboratory tests were conducted with five endocrine disruptors (bishenol A, triclosan. nonylphenol, nonylphenol monoethoxylate and nonylphenol diethoxylate) under different redox conditions (aerobic, anoxic, anaerobic and sulfate-reducing conditions) to assess abiotic and biotic degradation in a river water/sediment system. The river water sample was collected from Spercheios River while the sediment was collected from the banks of a tributary of the river at the point where the discharge point of a wastewater treatment plant is located. To describe quantitatively elimination kinetics of the target compounds, pseudo first-order kinetics were adopted. According to the results from the microcosms studies, it can be stated that the substances are eliminated from the aqueous phase with relatively high rates under aerobic conditions due to both sorption and biotransformation processes. However, when reduced oxygen conditions were established in the microcosms incubations, biotransformation decreased, indicating the almost complete cease of the EDCs microbial degradation, while substances' sorption onto sediments showed no significant differences. All compounds were found to be biodegradable under aerobic conditions, and the low to high order of the calculated dissipation rate constants was 0.064±0.004d^-1 (TCS)→0.067±0.006d^-1 (NP)→0.076±0.009d^-1 (NP2EO)→0.081±0.007d^-1 (NP1EO)→0.103±0.011d^-1 (BPA). Finally, regarding the biotransformation experiments, the elimination of the compounds limited in the absence of oxygen as compared to aerobic.

Visible Light Degradation of Naproxen by Enhanced Photocatalytic Activity of NiO and NiS, Scavenger Study and Focus on Catalyst Support and Magnetization

This research was aimed to prepare a magnetically photocatalyst enabling to degrade pharmaceutical wastewater and detoxification of pollutant such as naproxen, by visible light irradiation. The nano-sized NiS and NiO photocatalysts exhibit higher reactivity than their microsized counterparts, but separation of the used photocatalyst from the degradation solution is hard and imperfect. To remove this difficulty, magnetic polypyrrole core-shell (Fe₃ O₄ @PPY) was synthesized and employed as catalyst support. The magnetization property of the synthesized photocatalysts measured by VSM technique indicated that the photocatalysts were sufficiently magnetized to be readily separated from degradation solution by use of external magnetic field. The DRS study showed that the band gap of the photocatalysts shifted to lower energy after immobilization on the support materials leading to higher degradation efficiency. The optimal efficiency was obtained with the catalysts loaded with 50% of NiO and 50% of NiS. The augmenting effect of H₂ O₂ and the inhibition influence of some organic and inorganic compounds on the degradation process were studied. Regeneration of the used photocatalyst was performed by heat treatment, and the catalyst treated at 400°C retained most of its initial capacity. The degradation capacity was kinetically fast, and the equilibrium was attained within 30 min.

Role of humic substances in the photodegradation of naproxen under simulated sunlight

Humic substances (HS) including humic acid (HA) and fulvic acid (FA) are ubiquitous in the natural waters. Although numerous studies documented their role in photodegradation of organic pollutants, the competitive effects of photosensitization and light-screening of HS on the photodegradation of pollutants are not yet clear. In this work, the role of HS in the photodegradation of the pharmaceutical naproxen (NP) was studied under simulated sunlight. The direct photodegradation quantum yield of NP in deionized water was 2.1 × 10^-2, and the apparent quantum yields for photosensitized degradation of NP in the presence of FA and HA were 2.3 × 10^-4 and 2.6 × 10^-5, respectively. Both direct and photosensitized photodegradation decreased with increasing pH, consistent with the trend of singlet oxygen (¹O₂) reaction rate constants of NP. HA inhibited the photodegradation of naproxen thoroughly. In contrast, FA accelerated the photodegradation of NP at lower substrate concentration and light intensity, and vice versa. Direct photodegradation of NP declined sharply with spectral radiation attenuation of UV region, when HS-mediated photosensitization predominantly accounted for the photodegradation. The direct photodegradation was ascribed to decomposition of excited triplet state of naproxen (³NP^∗) and self-sensitization effect involving ¹O₂. The FA-mediated photodegradation was mainly attributed to ¹O₂ oxidation in aerated solution. These findings are important for assessing the competitive effects of humic substances on the photodegradation of pollutants under various conditions in natural waters.

Direct and indirect photolysis of seven micropollutants in secondary effluent from a wastewater lagoon

The photodegradation of seven micropollutants commonly found in municipal wastewater, namely caffeine, carbamazepine, diuron, simazine, sulfamethoxazole, triclosan and 2,4-D, was investigated in pure water and secondary effluent to understand the direct and indirect photolysis of these compounds under natural sunlight irradiation. Sulfamethoxazole and triclosan were readily photodegraded with half-lives of 5.8 and 1.8 h, respectively, whilst the others were relatively resistant towards sunlight irradiation. Enhanced degradation was observed in secondary effluent compared with in the pure water matrix for all compounds, except for triclosan. It was confirmed that hydroxyl radicals played an important role in the photodegradation of the micropollutants while singlet oxygen may also play a role. The contribution of hydroxyl radical to the overall degradation of the five compounds that were resistant to direct sunlight accounted for 32%-70%. The impact of humic acid and nitrate, two known photosensitisers and wastewater components, on the photodegradation of the seven micropollutants in pure water was investigated under simulated solar radiation. The presence of nitrate promoted the photochemical loss of all seven micropollutants, however, humic acid caused promotion or inhibition, depending on the characteristics of the micropollutant. Humic acid enhanced the photolytic degradation of caffeine, sulfamethoxazole and diuron, while it hindered the photodegradation of the other four compounds by absorbing the available irradiation energy and/or reforming the parent compound. Furthermore, it was shown that there was only a small increase (up to 15%) in photodegradation of the compounds at 25 °C compared with that at 10 °C in the simulated system.

Numerical simulation of seasonality in the distribution and fate of pyrene in multimedia aquatic environments with Markov chains

This case study investigated the distribution and fate of organic pollutants in aquatic environments based on laboratory experiments and modeling. Pyrene (Pyr) is a hydrocarbon pollutant with adverse effects on aquatic ecosystems and human health, and was thus selected for this case study. The movement of Pyr was primarily influenced by its sorption from water onto sediment, and its desorption from sediment into water. Its elimination was mainly via biodegradation by microorganisms in sediment and by volatilization from water into air. The transport and elimination rates for Pyr were considerably influenced by temperature and moisture. Results of modeling with Markov chains revealed that the elimination of Pyr from water/sediment systems was the most rapid under wet conditions. Under average conditions, a Pyr concentration of 100 μg/L of in water in such a system declined to a negligible level over 250 h. Under wet conditions, this decrease occurred over 120 h. Finally, under dry conditions, it took 550 h to achieve the same degree of elimination.

Temporal and spatial features of selected wastewater-marking pharmaceuticals and potential mechanisms of their removal from urban rivers

The investigations on seasonal and spatial distribution of 12 selected wastewater-marking pharmaceuticals (WWMPs) belonging to different therapeutic classes were conducted in three major urban rivers of Yangpu District, Shanghai, East China. The potential mechanisms for the removal of WWMPs in the rivers were also experimentally investigated. The detection frequencies of most WWMPs were in the range of 56-100%, with the exception of clofibric acid, which was not detected during the storm events. The median concentrations ranged from not detected to 5821 ng/L (caffeine) and the maximum concentration was 8662 ng/L, found in caffeine. Part of WWMPs such as paracetamol and caffeine showed significant seasonal variation (P < 0.05), while most of pharmaceuticals displayed limited concentration fluctuation under different seasons for relative low levels. The spatial pattern of most WWMPs has not showed obvious difference in the three rivers (P > 0.05). WWMPs could come from different sources, such as wastewater treatment plants, hospitals, untreated domestic wastewater, or some unknown sources. Lab-scale tests showed that the biodegradation and adsorption were the main removal pathways for WWMPs with lesser contribution from photodegradation and hydrolysis.

Photodegradation of diclofenac in aqueous solution by simulated sunlight irradiation: kinetics, thermodynamics and pathways

Diclofenac (DCF) is one of the most frequently detected pharmaceuticals in various water samples. This paper studied the effects of aquatic environmental factors (pH, temperature and dissolved organic matter) on photodegradation of DCF under simulated sunlight. The results demonstrate that degradation pathways proceed via pseudo first-order kinetics in all cases and the photodegradation of DCF by simulated sunlight. Thermodynamic study indicated that the photodegradation course is spontaneous, exothermic and irreversible. The rate constant gradually increased when the pH increased from 3 to 5, then decreased when the pH increased from 5 to 8, and finally increased when the pH further increased from 8 to 12. Humic acid inhibited the photodegradation of DCF. Three kinds of main degradation products were observed by high performance liquid chromatography/mass spectrometry and the degradation pathways were suggested. A toxicity test using Photobacterium phosphoreum T₃ Sp indicated the generation of some more toxic products than DCF.

Photodegradation of diclofenac in seawater by simulated sunlight irradiation: The comprehensive effect of nitrate, Fe(III) and chloride

Diclofenac is one of the most frequently detected pharmaceuticals in various aquatic environments. The photodegradation of diclofenac in the absence/presence of nitrate, Fe(III) and chloride, especially their interactions, were systematically studied. Under the study conditions, photodegradation rate was decreased with increasing nitrate, Fe(III) and chloride concentrations. Nitrate has an synergistic action for Fe(III). Nitrate and chloride have antagonistic effect. An antagonistic action is present between nitrate, Fe(III) and chloride. Moreover, a simple linear model which very well describes the results is given.