Oxidative removal of selected endocrine-disruptors and pharmaceuticals in drinking water treatment systems, and identification of degradation products of triclosan

Pharmaceuticals in raw and treated water from drinking water treatment plants nationwide: Insights into their sources and exposure risk assessment

Due to the large amounts of pharmaceuticals and personal care products (PPCPs) currently being consumed and released into the environment, this study provides a comprehensive analysis of pharmaceutical pollution in both raw and treated water from full-scale drinking water treatment plants nationwide. Our investigation revealed that 30 out of 37 PPCPs were present in raw water with mean concentrations ranging from 0.01-131 ng/L. The raw water sources, surface water (ND - 147 ng/L), subsurface water (ND - 123 ng/L) and reservoir sources (ND - 135 ng/L) exhibited higher mean concentration levels of pharmaceutical residues compared to groundwater sources (ND - 1.89 ng/L). Meanwhile, in treated water, 17 of the 37 analyzed PPCPs were present with carbamazepine, clarithromycin, fluconazole, telmisartan, valsartan, and cotinine being the most common (detection frequency > 40 %), and having mean concentrations of 1.22, 0.12, 3.48, 40.1, 6.36, and 3.73 ng/L, respectively. These findings highlight that, while water treatment processes are effective, there are some persistent compounds that prove challenging to fully eliminate. Using Monte Carlo simulations, risk assessment indicated that most of these compounds are likely to have negligible impact on human health, except for the antihypertensives. Telmisartan was identified as posing the highest ecological risk (RQ > 1), warranting further investigation, and monitoring. The study concludes by prioritizing specific 14 pharmaceuticals, including telmisartan, clarithromycin, lamotrigine, cotinine, lidocaine, tramadol, and others, for future monitoring to safeguard both ecological and human health.

Triclosan and related compounds in the environment: Recent updates on sources, fates, distribution, analytical extraction, analysis, and removal techniques

Triclosan (TCS) has been widely used in daily life because of its broad-spectrum antibacterial activities. The residue of TCS and related compounds in the environment is one of the critical environmental safety problems, and the pandemic of COVID-19 aggravates the accumulation of TCS and related compounds in the environment. Therefore, detecting TCS and related compound residues in the environment is of great significance to human health and environmental safety. The distribution of TCS and related compounds are slightly different worldwide, and the removal methods also have advantages and disadvantages. This paper summarized the research progress on the source, distribution, degradation, analytical extraction, detection, and removal techniques of TCS and related compounds in different environmental samples. The commonly used analytical extraction methods for TCS and related compounds include solid-phase extraction, liquid-liquid extraction, solid-phase microextraction, liquid-phase microextraction, and so on. The determination methods include liquid chromatography coupled with different detectors, gas chromatography and related methods, sensors, electrochemical method, capillary electrophoresis. The removal techniques in various environmental samples mainly include biodegradation, advanced oxidation, and adsorption methods. Besides, both the pros and cons of different techniques have been compared and summarized, and the development and prospect of each technique have been given.

Advanced oxidation of landfill leachate: Removal of micropollutants and identification of by-products

Landfill leachate contains several macropollutants and micropollutants that cannot be removed efficiently by conventional treatment processes. Therefore, an advanced oxidation process is a promising step in post or pre-treatment of leachate. In this study, the effects of Fenton and ozone oxidation on the removal of 16 emerging micropollutants including polycyclic aromatic hydrocarbons (PAHs), phthalates, alkylphenols and pesticides were investigated. The Fenton and ozone oxidation of the leachate were performed with four (reaction time: 20-90 min, Fe(II) dose: 0.51-2.55 g/L, H₂O₂ dose: 5.1-25.5 g/L and pH: 3-5) and two (ozonation time: 10-130 min and pH: 4-10) independent variables, respectively. Among these operating conditions, reaction time played more significant role (p-value < 0.05) in eliminating di-(2-Ethylhexyl) phthalate, 4-nonylphenol and 4-tert-octylphenol for both processes. The results showed that Fenton and ozone oxidation processes had a high degradation potential for micropollutants except for the PAHs including four and more rings. Removal efficiencies of micropollutants by ozone and Fenton oxidation were determined in the range of 5-100%. Although the removal efficiencies of chemical oxygen demand (COD) and some micropollutants such as phthalates were found much higher in the Fenton process than ozonation, the degradation products occurred during the Fenton oxidation were a higher molecular weight. Moreover, the oxidation intermediates for the both processes were found as mainly benzaldehyde, pentanoic acid and hydro cinnamic acid as well as derivatives of naphthalenone and naphthalenediol. Also, acid ester with higher molecular weight, naphthalene-based and phenolic compounds were detected in the Fenton oxidation.

Zebrafish as a Model for the Study of Lipid-Lowering Drug-Induced Myopathies

Drug-induced myopathies are classified as acquired myopathies caused by exogenous factors. These pathological conditions develop in patients without muscle disease and are triggered by a variety of medicaments, including lipid-lowering drugs (LLDs) such as statins, fibrates, and ezetimibe. Here we summarise the current knowledge gained via studies conducted using various models, such as cell lines and mammalian models, and compare them with the results obtained in zebrafish (Danio rerio) studies. Zebrafish have proven to be an excellent research tool for studying dyslipidaemias as a model of these pathological conditions. This system enables in-vivo characterization of drug and gene candidates to further the understanding of disease aetiology and develop new therapeutic strategies. Our review also considers important environmental issues arising from the indiscriminate use of LLDs worldwide. The widespread use and importance of drugs such as statins and fibrates justify the need for the meticulous study of their mechanism of action and the side effects they cause.

Indicator Compounds Representative of Contaminants of Emerging Concern (CECs) Found in the Water Cycle in the United States

The presence of contaminants of emerging concern (CECs) in the aquatic environment has recently become a global issue. The very large number of CECs reported in the literature makes it difficult to interpret potential risks as well as the removal efficiencies, especially for the more recalcitrant compounds. As such, there is a need for indicator compounds that are representative of CECs detected in systems worldwide. In an effort to develop such a list, five criteria were used to address the potential for applying indicator compounds; these criteria include usage, occurrence, resistance to treatment, persistence, and physicochemical properties that shed light on the potential degradability of a class of compounds. Additional constraints applied included the feasibility of procuring and analyzing compounds. In total, 22 CECs belonging to 13 groups were selected as indicator compounds. These compounds include acetaminophen and ibuprofen (analgesic); erythromycin, sulfamethoxazole, and trimethoprim (antibiotics); diazepam and fluoxetine (antidepressants); carbamazepine (antiepileptic); atenolol and propranolol (β-blockers); gemfibrozil (blood lipid regulator); tris(2-chloroethyl)phosphate (TCEP) (fire retardant); cotinine (nicotine metabolite); atrazine, metolachlor, and N,N-diethyl-meta-toluamide (DEET) (pesticides); 17β-estradiol and cholesterol (steroids); caffeine (psychomotor stimulant); perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) (surfactants); and iopromide (X-ray contrast agent). These thirteen groups of compounds represent CECs with the greatest resistance to treatment processes, most persistent in surface waters, and detected with significant frequency throughout the water cycle. Among the important implications of using indicator compounds are the ability to better understand the efficacy of treatment processes as well as the transport and fate of these compounds in the environment.

Rapid destruction of triclosan by Iron(III)-Tetraamidomacrocyclic ligand/hydrogen peroxide system

Iron(III)-tetraamidomacrocyclic ligand (Fe(III)-TAML) activators can activate hydrogen peroxide to oxidize many kinds of organic pollutants. In this study, we investigated the degradation of triclosan, a widely used broad-spectrum bactericide, under the treatment of Fe(III)-TAML/H₂O₂ system at different pH conditions. We also studied the influence of natural organic matter (NOM) on the degradation process. Our results showed that complete removal of triclosan could be obtained within several minutes under the optimal conditions. The degradation of triclosan by Fe(III)-TAML/H₂O₂ system exhibited strong pH-dependence and the degradation rate increased with the increase in pH level from 7.0 to 10.0. When adding fulvic acid (FA) or humic acid (HA) in the reaction system, the degradation of triclosan could be suppressed slightly, and HA exhibited stronger inhibition than FA. Based on the analysis of reaction intermediates, phenoxyl radical reaction and ring open reaction were involved in the decomposition of triclosan. Significant inhibition of overall toxicity to Photobacterium phosphoreum further confirmed the high efficiency of Fe(III)-TAML/H₂O₂ system for the removal of antibiotic activities resulting from the parent triclosan molecule and its degradation products.

Environment-Friendly Removal Methods for Endocrine Disrupting Chemicals

In the past few decades, many emerging pollutants have been detected and monitored in different water sources because of their universal consumption and improper disposal. Among these, endocrine-disrupting chemicals (EDCs), a group of organic chemicals, have received global attention due to their estrogen effect, toxicity, persistence and bioaccumulation. For the removal of EDCs, conventional wastewater treatment methods include flocculation, precipitation, adsorption, etc. However, there are some limitations on these common methods. Herein, in order to enhance the public’s understanding of environmental EDCs, the definition of EDCs and the characteristics of several typical EDCs (physical and chemical properties, sources, usage, concentrations in the environment) are reviewed and summarized in this paper. In particular, the methods of EDC removal are reviewed, including the traditional methods of EDC removal, photocatalysis, biodegradation of EDCs and the latest research results of EDC removal. It is proposed that photocatalysis and biodegradation could be used as an environmentally friendly and efficient EDC removal technology. Photocatalytic technology could be one of the water treatment methods with the most potential, with great development prospects due to its high catalytic efficiency and low energy consumption. Biodegradation is expected to replace traditional water treatment methods and is also considered to be a highly promising method for efficient removal of EDCs. Besides, we summarize several photocatalysts with high catalytic activity and some fungi, bacteria and algae with strong biodegradability.

Efficient removal of triclosan via peroxymonosulfate activated by a ppb level dosage of Co(II) in water: Reaction kinetics, mechanisms and detoxification

Triclosan (TCS), an extensively used broad-spectrum antimicrobial agent, has raised significant environmental concerns regarding its widespread occurrence in waters. In this study, the removal of TCS in aqueous solution via peroxymonosulfate (PMS) activated by an extremely low-level Co²⁺ (0.02 μM) was systematically investigated. During preliminary test, TCS (10 μM) was totally degraded in 30 min by using 0.1 μM Co²⁺ and 40 μM PMS at pH 7.0 with a degradation rate constant of 0.1219 min^-1. A first-order apparent degradation rate of TCS was found with respect to the PMS concentrations. At extremely low dosage of Co²⁺ (0.02 μM), the presence of NO₃^-, HCO₃^-, PLFA, and SRHA within test concentrations significantly inhibited TCS removal, while a dual effect of Cl^- on the degradation rate of TCS was observed. The quenching experiments verified that SO₄^- was the dominant reactive oxygen species (ROS) rather than OH. Six major intermediates were identified using TOF-LC-MS, based on which we proposed three associated reaction pathways including hydroxylation, ether bond breakage, and dechlorination. Toxicity predictions by ECOSAR software exhibited aquatic toxicity reduction of TCS after Co²⁺/PMS treatment. We outlook these findings to advance the feasibility of organic contaminants removal via Co²⁺/PMS system with Co²⁺ at extremely low levels.

Critical Perspective on Advanced Treatment Processes for Water and Wastewater: AOPs, ARPs, and AORPs

Emerging contaminants’ presence in water, wastewater, and aquatic environments has been widely reported. Their environmental and health-related effects, and the increasing tendency towards wastewater reuse require technology that could remove to a greater degree, or even mineralize, all these contaminants. Currently, the most commonly used process technologies for their removal are advanced oxidation processes (AOPs); however, recent advances have highlighted other advanced treatment processes (ATPs) as possible alternatives, such as advanced reduction processes (ARPs) and advanced oxidation-reduction processes (AORPs). Although they are not yet widely diffused, they may remove contaminants that are not readily treatable by AOPs, or offer better performance than the former. This paper presents an overview of some of the most common or promising ATPs for the removal of contaminants from water and wastewater, and their application, with discussion of their limitations and merits. Issues about technologies’ costs and future perspectives in the water sector are discussed.

LcSABP2, a salicylic acid binding protein 2 gene from Lycium chinense, confers resistance to triclosan stress in Nicotiana tabacum

The triclosan (TCS) is one of the most commonly detected organic pollutants in the sewage sludge. TCS could induce phytotoxicity in plants. Salicylic acid (SA) is a phenolic compound capable of enhancing plant growth and development. It is well documented that abiotic stress tolerance could be enhanced by exogenous application of SA. However, the regulatory mechanisms for functions of endogenous SA in plants' responses to xenobiotics stress remains unclear. Our results indicated that TCS suppressed plant growth by restricting photosynthesis, decreasing chlorophyll contents and inducing over production of reactive oxygen species (ROS). Interestingly, SA or glutathione (GSH) application could significantly improve plant tolerance to TCS. Moreover, endogenous SA and the expression of a SA binding protein 2 (SABP2) gene were found to be elevated in tobacco under TCS treatment. The overexpression of LcSABP, a SABP2-like gene cloned from the leaves of Lycium chinense, markedly enhanced the SA content in the transgenic plants under TCS stress. The LcSABP-overexpressing plants presented higher photosynthesis rate, chlorophyll content, glutathione reductase (GR) and glutathione-S-transferase (GST) enzymes activities, GSH content and lower O2-•, H2O2 and malondialdehyde (MDA) content in comparison with WT tobacco with TCS treatment. One of the GSH synthesis-related gene, NtGSHS, also showed higher expression level in the transgenic tobacco in comparison with control plants with TCS stress treatment. These results indicated that SABP2 played a positive regulatory role in plant response to TCS stress via increasing the endogenous SA levels. The increased SA content might then increase the GSH content, probably through an increase in GR activity and GSHS gene expression, thus inducing the antioxidant and xenobiotics detoxification systems, which promoted TCS stress tolerance in tobacco plants.

Oxidation kinetics of anilines by aqueous permanganate and effects of manganese products: Comparison to phenols

In this study, the potential applicability of potassium permanganate (Mn(VII)) for anilines elimination was systematically investigated firstly, with a focus on the effect of manganese intermediates on the kinetics of anilines versus phenols. It was found that Mn(VII) could fairly oxidize anilines, where the second-order rate constants (k_Mn(VII)) values for anilines always decreased as pH increased from 5 to 9. This interesting pH-dependency was successfully described by the kinetic models proposed in literature to account for the unusual pH-rate profiles for phenols, where the formation of intermediates between Mn(VII) and phenols or anilines was likely involved. The effect of manganese products such as MnO₂ and Mn(III) on the oxidation of anilines by Mn(VII) was demonstrated. Under slightly acidic conditions, the reactions of Mn(VII) with anilines displayed autocatalysis, suggesting a similar catalytic role of MnO₂ formed in situ as compared to phenols. Several ligands (e.g., pyrophosphate) inhibited the formation of MnO₂ colloids and lowered the oxidation rates of anilines by Mn(VII) at acidic pH, while these ligands greatly accelerated the kinetics of phenols under similar conditions. The contrasting effects of ligands might be mainly attributed to the different reactivity of ligand-stabilized Mn(III) formed in situ toward anilines vs phenols. The complex effect of humic acid was highly dependent on solution pH, possible due to the dual role of humic acid that it could act as a reductant (competitively consuming Mn(VII) and phenoxy or aniline radical) as well as a ligand (stabilizing manganese intermediates such as Mn(III) species) to affect Mn(VII) reactions.

Contaminants of Emerging Concern Removal by High-Energy Oxidation-Reduction Processes: State of the Art

The presence of ‘emerging contaminants’, i.e., chemicals yet without a regulatory status and poorly understood impact on human health and environment, in wastewater and aquatic environments is widely reported. No established technology, to date, can simultaneously and completely remove all these contaminants, even though some Advanced Oxidation Processes (AOPs,) have demonstrated capacity for some degradation of these compounds. High-energy, radiolytic processing of water matrices using various sources: electron beam (EB), ɣ-rays or non-thermal plasma (NTP) have shown excellent results in many applications, although these remain at the moment isolated examples and scarcely known. High-energy irradiation constitutes an additive-free process that uses short-lived, highly reactive radicals (both oxidating and reducing) generated by water radiolysis, which can instantaneously decompose organic pollutants. Several studies have demonstrated its effectiveness, as a stand-alone process or combined with others, in the rapid decomposition (up to complete mineralization) of organic compounds in pure and complex solutions, and in the removal or inactivation of microorganisms and parasites, without production of leftover residual compounds in solution. High-energy oxidation processes (a.k.a. Advanced Oxidation & Reduction Processes—AORPs) could have a primary role in future strategies addressing emerging contaminants.

Occurrence, removal and seasonal variation of pharmaceuticals in Brasilian drinking water treatment plants

The presence of pharmaceuticals in aquatic environments has become a major issue of concern for scientific community, since there is a lack of information about risks and impacts to the environment and public health. In the context of Brazil, many cities do not have Wastewater Treatment Plants (WWTPs) and domestic sewage is dumped directly into the water bodies, aggravating the problem. Thus, the present study aimed to evaluate the presence of 28 prescribed pharmaceuticals from different therapeutic classes in six full-scale Drinking Water Treatment Plants (DWTPs) in Minas Gerais state. Samples were collected in twelve field campaigns from August 2016 to August 2017 and water quality were monitored. Analytical methodology was based on solid phase extraction (C18 cartridge) followed by High Performance Liquid Chromatography (Prominence DGU/20A3 - Shimadzu) coupled to Mass Spectrometry (micrOTOF-QII - Bruker). Considering the 28 pharmaceuticals analyzed, 18 were detected in the surface water source at concentrations ranging from Method Quantification Limit (MQL) to 11,960 ng/L. In drinking water, the concentration of the 11 pharmaceuticals detected ranged from <MQL to 6323 ng/L. Betamethasone, Fluconazole, Atorvastatin and Prednisone were the most detected pharmaceuticals. The drinking water monitoring showed a decrease in the concentration of all detected pharmaceuticals, indicating some removal of these compounds by the water treatment processes. The removal efficiency assessed shows a great variation among different compounds, DWTPs and over the year, ranging from an average of 32% ± 6% (Prednisone -DWTP3) to 100% ± 0% for some pharmaceuticals. The highest total concentrations and the maximum concentration values for the most frequently detected pharmaceuticals were related to the winter due, presumably, to lower dilution and temperature. Trace levels of pharmaceuticals were detected in surface and drinking water in Brazil and conventional DWTPs were not able to remove the pharmaceuticals completely.

Triclosan: An Update on Biochemical and Molecular Mechanisms

Triclosan (TCS) is a synthetic, chlorinated phenolic antimicrobial agent commonly used in commercial and healthcare products. Items made with TCS include soaps, deodorants, shampoos, cosmetics, textiles, plastics, surgical sutures, and prosthetics. A wealth of information obtained from in vitro and in vivo studies has demonstrated the therapeutic effects of TCS, particularly against inflammatory skin conditions. Nevertheless, extensive investigations on the molecular aspects of TCS action have identified numerous adversaries associated with the disinfectant including oxidative injury and influence of physiological lifespan and longevity. This review presents a summary of the biochemical alterations pertaining to TCS exposure, with special emphasis on the diverse molecular pathways responsive to TCS that have been elucidated during the present decade.

Sonochemical degradation of triclosan in water in a multifrequency reactor

Degradation of triclosan (TCS) by multifrequency ultrasound (US) was studied at high and low frequencies. Frequency effect on initial degradation rates was analyzed, and an optimum frequency was found. Power density always has a positive effect on degradation rates over the whole equipment work range. A reaction mechanism similar to that proposed by Serpone resulted in a pseudo-linear model that fitted statistically better than the nonlinear model proposed by Okitsu. Pulsed US showed a positive effect on degradation rates; however, simultaneous analysis of the effect of power, frequency, pulse time, and silent time did not show a clear trend for degradation as a function of pulse US variables. According to these results and those for degradation in the presence of radical scavengers, it was concluded that US TCS degradation was taking place in the bubble/liquid interface. A toxicity test was conducted by Microtox®, showing a decrease in toxicity as TCS concentration decreased and increase in toxicity after total depletion of TCS. Eight possible degradation by-products were identified by GC-MS analysis, and a degradation pathway was proposed.

Application of advanced oxidation processes and toxicity assessment of transformation products

Advanced Oxidation Processes (AOPs) are the techniques employed for oxidation of various organic contaminants in polluted water with the objective of making it suitable for human consumption like household and drinking purpose. AOPs use potent chemical oxidants to bring down the contaminant level in the water. In addition to this function, these processes are also capable to kills microbes (as disinfectant) and remove odor as well as improve taste of the drinking water. The non-photochemical AOPs methods include generation of hydroxyl radical in absence of light either by ozonation or through Fenton reaction. The photochemical AOPs methods use UV light along with H₂O₂, O₃ and/or Fe⁺² to generate reactive hydroxyl radical. Non-photochemical method is the commonly used whereas, photochemical method is used when conventional O₃ and H₂O₂ cannot completely oxidize organic pollutants. However, the choice of AOPs methods is depended upon the type of contaminant to be removed. AOPs cause loss of biological activity of the pollutant present in drinking water without generation of any toxicity. Conventional ozonation and AOPs can inactivate estrogenic compounds, antiviral compounds, antibiotics, and herbicides. However, the study of different AOPs methods for the treatment of drinking water has shown that oxidation of parent compound can also lead to the generation of a degradation/transformation product having biological activity/chemical toxicity similar to or different from the parent compound. Furthermore, an increased toxicity can also occur in AOPs treated drinking water. This review discusses various methods of AOPs, their merits, its application in drinking water treatment, the related issue of the evolution of toxicity in AOPs treated drinking water, biocatalyst, and analytical methods for identification of pollutants /transformed products and provides future directions to address such an issue.

Comparison of different advanced degradation processes for the removal of the pharmaceutical compounds diclofenac and carbamazepine from liquid solutions

Carbamazepine and diclofenac are two examples of drugs with widespread geographical and environmental media proliferation that are poorly removed by traditional wastewater treatment processes. Advanced oxidation processes (AOPs) have been proposed as alternative methods to remove these compounds in solution. AOPs are based on a wide class of powerful technologies, including UV radiation, ozone, hydrogen peroxide, Fenton process, catalytic wet peroxide oxidation, heterogeneous photocatalysis, electrochemical oxidation and their combinations, sonolysis, and microwaves applicable to both water and wastewater. Moreover, processes rely on the production of oxidizing radicals (•OH and others) in a solution to decompose present pollutants. Water radiolysis-based processes, which are an alternative to the former, involve the use of concentrated energy (beams of accelerated electrons or γ-rays) to split water molecules, generating strong oxidants and reductants (radicals) at the same time. In this paper, the degradation of carbamazepine and diclofenac by means of all these processes is discussed and compared. Energy and byproduct generation issues are also addressed.

Applying analytical decision methods for determination of the best treatment alternative to remove emerging micropollutants from drinking water and wastewater: triclosan example

Increasing human activities have not only substantially altered the natural material cycle but also created new synthetic chemicals flows. Some of these chemicals, which are described as micropollutants (MPs), may result in adverse effects on human health, aquatic organisms, and ecosystems. MPs can be transported to the environment and water resources in a variety ways including domestic and industrial wastewater. Unfortunately, most MPs are only partially removed in existing conventional treatment plants. Therefore, conventional treatment plants should be modernized by advanced treatment technologies to protect the environment and human health. However, there are various mysteries about best treatment techniques, evaluation criteria, and decision-making methods. In this study, it was aimed to determine the best treatment alternatives for triclosan (TCS) which is one of the priority MPs. A total of 18 evaluation criteria were identified and prioritized by employing analytical hierarchy process (AHP) and entropy methods. Treatment alternatives were identified and their performance was assessed through a comprehensive literature investigation. In decision-making processes of determining these alternatives, "technique for order preference by similarity to ideal solution (TOPSIS)," "preference ranking organization method for enrichment evaluation (PROMETHEE)," and "Višekriterijumsko kompromisno rangiranje (VIKOR)" analytical decision-making methods were employed, and priority rankings were determined according to each decision method. The final priority ranking was found as adsorption > membrane filtration > hybrid processes > advanced oxidation processes > constructed wetlands > conventional treatment processes > biological treatment > other treatment processes. Although the obtained results are specific to TCS, the employed analytical decision methods can be also used to decide the best treatment alternatives for other MPs.

Degradation of triclosan by chlorine dioxide: Reaction mechanism,2,4-dichlorophenol accumulation and toxicity evaluation

The mechanism and toxicity of TCS degradation by ClO₂ was investigated. Intermediate products during the oxidation process were identified by GC/MS and LC/MS. A microtox bioassay and a SOS/umu assay were employed to evaluate the acute toxicity and genotoxicity of the resulting solutions during the chlorination process. The results showed that the reaction between TCS and ClO₂ was of second-order overall. The pseudo first-order rate constants (k_obs) exhibited significant dependence on solution pH and chlorine dioxide concentration, with the apparent second-order rate constant, k_app, being 7.07 × 10⁴ M^-1s^-1 in the pH range of 6.80-7.02. TCS decomposition was accompanied by the accumulation of 2,4-dichlorophenol (2,4-DCP), and the maximum molar yield ratios of 2,4-DCP/TCS were in the range of 31.71%-35.43%. The major intermediates identified were 2,7/2,8-dichlorodibenzop-dioxin (2,7/2.8-Cl₂DD), 2,4-DCP, 2,4,6-trichlorophenol (2,4,6-TCP), tetraclosan and pentaclosan. The proposed mechanism for TCS oxidation involved the cleavage of the ether link in TCS, chlorination of the phenolic ring and ring closure of a single TCS molecule. The transformation and degradation of TCS led to reduction of the acute toxicity and genotoxicity. However, irregular fluctuations in the toxicity changes indicated that the oxidation of TCS was not a simultaneous detoxification process.

Nanocomposite Au NP/TiO2 thin film in the efficient remediation of aqueous solutions contaminated with emerging micro-pollutants

The present communication specifically aims to synthesize novel nanocomposite material Au NPs/TiO₂ in a simple template process using the polyethylene glycol as filler media. The thin film of the nanocomposite material was characterized by the advanced analytical tools. The surface morphology was obtained by the scanning electron microscopic (SEM) and transmission electron microscopic (TEM) images of solids. Similarly, the surface topography and roughness of solid were obtained by the atomic force microscopic (AFM) image of thin film. X-ray diffraction (XRD) data enabled to confirm that the TiO₂ was predominantly present with its anatase phase. The specific surface area and pore size of the solid were obtained using the N₂ adsorption/desorption data. Nanocomposite Au NP/TiO₂ thin film was employed in the photocatalytic removal of sulfamethoxazole and triclosan from aqueous solutions using less harmful UV-A light (λ_max = 330 nm). Various physicochemical parametric studies enabled to deduce the mechanism involved in the degradation process. The degradation kinetics as a function of pH (pH 4.0-10.0) and micro-pollutant concentrations (0.5-15.0 mg/L) was extensively studied. The mineralization of these pollutants was obtained using the non-purgeable organic carbon (NPOC) data. The stability of thin film was assessed by the repeated operations, and presence of several co-existing ions simulates the studies to real matrix treatment. Further, the presence of scavengers enabled to pin point the radical-induced degradation of sulfamethoxazole and triclosan from aqueous solutions.

Predicted environmental concentration and fate of the top 10 most dispensed Australian prescription pharmaceuticals

A basic environmental risk assessment was carried out for the top 10 dispensed pharmaceuticals in Melbourne, Australia, in contrast to the more commonly assessed measure of the most used drugs by physical mass. This allowed for the evaluation of compounds that had not previously been the subject of risk assessment. Estimations of the possible fate and behaviour of the target pharmaceuticals in sewage treatment plants were also made. The predicted removal rates of most drugs within standard sewage treatment were expected to be low, with the exception of the statins, which had high removal rates. Each pharmaceutical was predicted to be present in Melbourne wastewater at the nanogram per litre range or lower. All compounds were predicted to be of low toxicity risk, although it was not possible to model mixture effects. Atorvastatin and Irbesartan were also found to possess the potential to possibly bioaccumulate in the aquatic food chain but not to the extent that would require regulation or labelling.

Biodegradation of triclosan in diatom Navicula sp.: Kinetics, transformation products, toxicity evaluation and the effects of pH and potassium permanganate

Triclosan (TCS) is one of the most widely used pharmaceutically active compounds and frequently detected in treated wastewater and the impacted aquatic environment. However, the fate and toxicity of TCS in aquatic organisms is poorly known, including in particular the potential for the formation of incomplete biological transformation products. In this study, TCS posed high toxic effects (e.g., growth inhibition and damage of photosynthesis) to typical freshwater diatom Navicula sp., with the 24h and 72h EC₅₀ values of 173.3 and 145.6μgL^-1, respectively. The bioaccumulation of TCS in diatom cells increased with the increasing exposure to TCS and showed to be time-dependent. The higher intracellular TCS lead to higher toxicity on Navicula sp. The intracellular TCS concentration and the growth inhibition of TCS in Navicula sp. at pH 7.5 was obviously higher than that at pH 8.3, which was likely due to the higher abundance of unionized TCS in the culture. KMnO₄ reduced both bioaccumulation and toxicity of TCS in Navicula sp., especially at pH 8.3. A total of seven products were detected by liquid chromatography-tandem mass spectrometry (LC-MS/MS). These findings will provide a reference for the risk assessment of TCS in aquatic environment.

Permanganate with a double-edge role in photodegradation of sulfamethoxazole: Kinetic, reaction mechanism and toxicity

In this study, the double-edge role of permanganate in sulfamethoxazole (SMX) photodegradation with a recyclable catalyst was revealed for the first time. The role of the catalyst under different UV wavelength, the role of permanganate in the treatment process, the effects of permanganate dosage and solution pH on the removal efficiency were investigated. Moreover, the transformation products, TOC reduction and the toxicity of the treated final product to Chlorella vulgaris and Artemia salina were determined. Sole permanganate showed no effect in SMX degradation, while its introduction to the photocatalytic process doubled the reaction rate at the optimal dosage. It is interesting to find that the reaction rate showed a fluctuation trend in terms of permanganate dosage due to the summation of positive effect of permanganate oxidation and the negative effect of the formed MnO₂ at the surface of the catalyst, as well as the light attenuation due to overdosed permanganate. The determined intermediates, the higher inorganic ions release and TOC reduction provided a clue on a higher mineralization compared to SMX degradation in the same process without permanganate. Permanganate above 1 μM may pose a threat to the algae growth, therefore a good monitoring and control of residual permanganate dosage should be incorporated into the process design. A good toxicity reduction to A. salina was observed in the treated effluent; a longer detention is suggested for the complete removal of toxicity.

Triclosan removal from surface water by ozonation - Kinetics and by-products formation

Removal of triclosan from surface water by ozonation was investigated. The results showed that complete elimination of triclosan from a surface water bearing 1-5 mg/L triclosan via continuous ozonation at 5 mg/L, require an ozonation time of 20-30 min depending on pH. Triclosan oxidation followed pseudo-first order kinetics with an apparent reaction rate constant varying from 0.214 min^-1 to 0.964 min^-1 depending on pH, initial triclosan concentration and water composition. Although the effect of pH was complex due to possible existence of different moieties, higher TCS removal efficiencies were obvious at weak-base conditions. Experiments performed to identify degradation by-products showed the formation of four by-products, namely, 2,4-dichlorophenol, 4-chlorocatechol and two unidentified compounds. Additionally, 2,4-dichloroanisole was detected when a methyl moieties exist in water. By-products were found to be eliminated upon further ozonation. The required exposure time varied from 20 to 30 min depending on pH of water. The ozone demand exerted for the complete oxidation of triclosan and its by-products was calculated as 13.04 mg ozone per mg of triclosan. A triclosan degradation pathway, which was found to be highly pH dependent, was proposed.

Toxicity study of reclaimed water on human embryonic kidney cells

The importance of evaluating the toxic effects associated with the use of reclaimed water has been increasing. The purpose of this research was to investigate the cytotoxicity and molecular toxicity of reclaimed water on the human embryonic kidney 293 (HEK293) cells. The culture medium was synthesized using the reclaimed water samples. Wastewater treatment plant influent (WTI) and effluent (WTE), containing micropollutants at the nanogram per liter level, decreased cell proliferation (93.4-98.9% and 91.5-96.6% of the control, respectively) and increased cell damage (103.6-117.5% and 100.7-109% of the control, respectively) at all exposure times, except for a decrease in cell damage observed after an 8-h exposure to WTE. Membrane bioreactor permeate (MBRP) increased cell proliferation (102.1-106.7% of the control) and decreased cell damage at 8 and 12 h (92.4 and 98.4% of the control, respectively), but slightly increased cell damage at 24 h and later time points (101.1-104.9% of the control). All three water samples induced cell apoptosis (120.9-123.4% of the control). They also affected the expression of cell-cycle regulatory proteins (p16^INK4a, p27^Kip1, cyclin-dependent kinases 2 and 4, cyclin D1, and cyclin E) and apoptosis-related regulatory proteins (p-JNK, Bcl-2, caspase-9, and caspase-3). In conclusion, all three water samples showed cytotoxicity and molecular toxicity in the HEK293 cells, and the results of the cell-cycle and apoptosis regulatory protein expression after WTI and WTE treatments were consistent with the results of the cytotoxicity.

Can radiation chemistry supply a highly efficient AO(R)P process for organics removal from drinking and waste water? A review

The increasing role of chemistry in industrial production and its direct and indirect impacts in everyday life create the need for continuous search and efficiency improvement of new methods for decomposition/removal of different classes of waterborne anthropogenic pollutants. This review paper addresses a highly promising class of water treatment solutions, aimed at tackling the pressing problem of emerging contaminants in natural and drinking waters and wastewater discharges. Radiation processing, a technology originating from radiation chemistry studies, has shown encouraging results in the treatment of (mainly) organic water pollution. Radiation ("high energy") processing is an additive-free technology using short-lived reactive species formed by the radiolysis of water, both oxidative and reducing, to carry out decomposition of organic pollutants. The paper illustrates the basic principles of radiolytic treatment of organic pollutants in water and wastewaters and specifically of one of its most practical implementations (electron beam processing). Application examples, highlighting the technology's strong points and operational conditions are described, and a discussion on the possible future of this technology follows.

Triclosan exposure, transformation, and human health effects

Triclosan (TCS) is an antimicrobial used so ubiquitously that 75% of the US population is likely exposed to this compound via consumer goods and personal care products. In September 2016, TCS was banned from soap products following the risk assessment by the US Food and Drug Administration (FDA). However, TCS still remains, at high concentrations, in other personal care products such as toothpaste, mouthwash, hand sanitizer, and surgical soaps. TCS is readily absorbed into human skin and oral mucosa and found in various human tissues and fluids. The aim of this review was to describe TCS exposure routes and levels as well as metabolism and transformation processes. The burgeoning literature on human health effects associated with TCS exposure, such as reproductive problems, was also summarized.

Does KMnO4 preoxidation reduce the genotoxicity of disinfection by-products?

Potassium permanganate (KMnO4) preoxidation is capable of affecting the formation of disinfection by-products (DBPs). However, few studies have focused on the toxicity of DBPs after KMnO4 preoxidation, which is an important index to evaluate alternative treatment processes. Herein genotoxicity (SOS/umu test) was used to clarify the impact of KMnO4 preoxidation on the chlorination byproducts produced from two representative precursors, tyrosine (Tyr) and 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (BP-4), and their mixture. Results revealed that although KMnO4 could not oxidize BP-4, after chlorination KMnO4 could oxidize the chlorination byproducts of BP-4 and thus decrease the genotoxicity production. For Tyr, KMnO4 preoxidation could increase or decrease the genotoxicity of DBPs, depending on the KMnO4 dose. The optimal initial molar ratio of KMnO4 to Tyr was confirmed to be 1:1. It has been proved that both the oxidation of Tyr by KMnO4 and manganese dioxide (MnO2, the reduction product of KMnO4) and the oxidation of chlorination byproducts by MnO2 can decrease the genotoxicity production of chlorinated Tyr. Remarkably, during chlorination, the competition of manganese(II) oxidation with organic oxidation can result in less chlorine reacting with organics, to induce an increase in genotoxicity. This is the main cause for the increase in genotoxicity of chlorinated Tyr after KMnO4 preoxidation. Additionally, the genotoxicity of the chlorinated mixture was shifted from being higher than the sum of individual genotoxicities of the chlorinated precursors to being lower than their sum with increasing KMnO4 dosage, due to the combined effects between the preoxidation-chlorination products from the two compounds.

Oxidative degradation of triclosan by potassium permanganate: Kinetics, degradation products, reaction mechanism, and toxicity evaluation

In this study, we systematically investigated the potential applicability of potassium permanganate for removal of triclosan (TCS) in water treatment. A series of kinetic experiments were carried out to study the influence of various factors, including the pH, oxidant doses, temperature, and presence of typical anions (Cl(-), SO4(2-), NO3(-)), humic acid (HA), and fulvic acid (FA) on triclosan removal. The optimal reaction conditions were: pH = 8.0, [TCS]0:[KMnO4]0 = 1:2.5, and T = 25 °C, where 20 mg/L of TCS could be completely degraded in 120 s. However, the rate of TCS (20 μg/L) oxidation by KMnO4 ([TCS]0:[KMnO4]0 = 1:2.5) was 1.64 × 10(-3) mg L(-1)·h(-1), lower than that at an initial concentration of 20 mg/L (2.24 × 10(3) mg L(-1)·h(-1)). A total of eleven products were detected by liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-Q-TOF-MS) analysis, including phenol and its derivatives, benzoquinone, an organic acid, and aldehyde. Two main reaction pathways involving CO bond cleavage (-C(8)O(7)-) and benzene ring opening (in the less chlorinated benzene ring) were proposed, and were further confirmed based on frontier electron density calculations and point charges. Furthermore, the changes in the toxicity of the reaction solution during TCS oxidation by KMnO4 were evaluated by using both the luminescent bacteria Photobacterium phosphoreum and the water flea Daphnia magna. The toxicity of 20 mg/L triclosan to D. magna and P. phosphoreum after 60 min was reduced by 95.2% and 43.0%, respectively. Phenol and 1,4-benzoquinone, the two representative degradation products formed during permanganate oxidation, would yield low concentrations of DBPs (STHMFP, 20.99-278.97 μg/mg; SHAAFP, 7.86 × 10(-4)-45.77 μg/mg) after chlorination and chloramination. Overall, KMnO4 can be used as an effective oxidizing agent for TCS removal in water and wastewater treatment.

Triclosan in water, implications for human and environmental health

Triclosan (TCS) is a broad spectrum antibacterial agent present as an active ingredient in some personal care products such as soaps, toothpastes and sterilizers. It is an endocrine disrupting compound and its increasing presence in water resources as well as in biosolid-amended soils used in farming, its potential for bioaccumulation in fatty tissues and toxicity in aquatic organisms are a cause for concern to human and environmental health. TCS has also been detected in blood, breast milk, urine and nails of humans. The significance of this is not precisely understood. Data on its bioaccumulation in humans are also lacking. Cell based studies however showed that TCS is a pro-oxidant and may be cytotoxic via a number of mechanisms. Uncoupling of oxidative phosphorylation appears to be prevailing as a toxicity mechanism though the compound's role in apoptosis has been cited. TCS is not known to be carcinogenic per se in vitro but has been reported to promote tumourigenesis in the presence of a carcinogen, in mice. Recent laboratory reports appear to support the view that TCS oestrogenicity as well as its anti-oestrogenicity play significant role in cancer progression. Results from epidemiological studies on the effect of TCS on human health have implicated the compound as responsible for certain allergies and reproductive defects. Its presence in chlorinated water also raises toxicity concern for humans as carcinogenic metabolites such as chlorophenols may be generated in the presence of the residual chlorine. In this paper, we carried out a detailed overview of TCS pollution and the implications for human and environmental health.

Emerging contaminants in the environment: Risk-based analysis for better management

Emerging contaminants (ECs) are chemicals of a synthetic origin or deriving from a natural source that has recently been discovered and for which environmental or public health risks are yet to be established. This is due to limited available information on their interaction and toxicological impacts on receptors. Several types of ECs exist such as antibiotics, pesticides, pharmaceuticals, personal care products, effluents, certain naturally occurring contaminants and more recently nanomaterials. ECs may derive from a known source, for example released directly to the aquatic environment from direct discharges such as those from wastewater treatment plants. Although in most instances the direct source cannot be identified, ECs have been detected in virtually every country's natural environment and as a consequence they represent a global problem. There is very limited information on the fate and transport of ECs in the environment and their toxicological impact. This lack of information can be attributed to limited financial resources and the lack of analytical techniques for detecting their effects on ecosystems and human health on their own or as mixture. We do not know how ECs interact with each other or various contaminants. This paper presents an overview of existing knowledge on ECs, their fate and transport and a risk-based analysis for ECs management and complementary strategies.

Removal of Endocrine Disruptors from Urban Wastewater by Advanced Oxidation Processes (AOPs): A Review

Over the last years the growing presence of endocrine disrupting compounds in the environment has been regarded as a serious sanitary issue. The more and more frequent detection of these compounds in the effluents of wastewater treatment plants poses the risk associated to their persistence into the aquatic systems as well as to their adverse effects on both public health and environment.

As conventional systems do not allow their efficient removal, great attention has been raised towards their possible treatment by Advanced Oxidation Processes (AOPs). They rely on the action of hydroxyl radicals, which are highly reactive species, able to oxidize recalcitrant and non-biodegradable pollutants.

AOPs can either provide contaminant partial degradation or their complete removal. As their effectiveness has been proved for a wide spectrum of both organic and inorganic pollutants, they are considered a suitable option for the treatment of contaminated aqueous media, especially when combined with conventional biological processes.

This paper aims at reviewing main AOPs for the removal of endocrine disruptors, in order to highlight the most important features of different technologies, thus providing their comparative assessment. To this end, a brief overview of the most frequently detected endocrine disruptor compounds was also discussed, in order to clarify their fate into the environment as well as the contamination pathways of greatest concern for human health.

Removal of Mefenamic acid from aqueous solutions by oxidative process: Optimization through experimental design and HPLC/UV analysis

Mefenamic acid (MEF) is a non-steroidal anti-inflammatory drug indicated for relief of mild to moderate pain, and for the treatment of primary dysmenorrhea. The presence of MEF in raw and sewage waters has been detected worldwide at concentrations exceeding the predicted no-effect concentration. In this study, using experimental designs, different oxidative processes (H2O2, H2O2/UV, fenton and Photo-fenton) were simultaneously evaluated for MEF degradation efficiency. The influence and interaction effects of the most important variables in the oxidative process (concentration and addition mode of hydrogen peroxide, concentration and type of catalyst, pH, reaction period and presence/absence of light) were investigated. The parameters were determined based on the maximum efficiency to save time and minimize the consumption of reagents. According to the results, the photo-Fenton process is the best procedure to remove the drug from water. A reaction mixture containing 1.005 mmol L(-1) of ferrioxalate and 17.5 mmol L(-1) of hydrogen peroxide, added at the initial reaction period, pH of 6.1 and 60 min of degradation indicated the most efficient degradation, promoting 95% of MEF removal. The development and validation of a rapid and efficient qualitative and quantitative HPLC/UV methodology for detecting this pollutant in aqueous solution is also reported. The method can be applied in water quality control that is generated and/or treated in municipal or industrial wastewater treatment plants.

Chronic effects of clofibric acid in zebrafish (Danio rerio): a multigenerational study

Clofibric acid (CA) is an active metabolite of the blood lipid lowering agent clofibrate, a pharmaceutical designed to work as agonist of peroxisome proliferator-activated receptor alpha (PPARa). It is the most commonly reported fibrate in aquatic environments with low degradation rate and potential environmental persistence. Previous fish exposures showed that CA may impact spermatogenesis, growth and the expression of fat binding protein genes. However, there are limited data on the effects of chronic multigenerational CA exposures. Here, we assessed chronic multigenerational effects of CA exposure using zebrafish (Danio rerio) as a teleost model. Zebrafish were exposed through the diet to CA (1 and 10mg/g) during their whole lifetime. Growth, reproduction-related parameters and embryonic development were assessed in the exposed fish (F1 generation) and their offspring (F2 generation), together with muscle triglyceride content and gonad histology. In order to study the potential underlying mechanisms, the transcription levels of genes coding for enzymes involved in lipid metabolism pathways were determined. The results show that chronic life-cycle exposure to CA induced a significant reduction in growth of F1 generation and lowered triglyceride muscle content (10mg/g group). Also, an impact in male gonad development was observed together with a decrease in the fecundity (10mg/g group) and higher frequency of embryo abnormalities in the offspring of fish exposed to the lowest CA dose. The profile of the target genes was sex- and tissue-dependent. In F1 an up-regulation of male hepatic pparaa, pparb and acox transcript levels was observed, suggesting an activation of the fatty acid metabolism (provided that transcript level change indicates also a protein level change). Interestingly, the F2 generation, raised with control diet, displayed a response pattern different from that observed in F1, showing an increase in weight in the descendants of CA exposed fish, in comparison with control animals, which points to a multigenerational effect.

Understanding the role of manganese dioxide in the oxidation of phenolic compounds by aqueous permanganate

Recent studies have shown that manganese dioxide (MnO2) can significantly accelerate the oxidation kinetics of phenolic compounds such as triclosan and chlorophenols by potassium permanganate (Mn(VII)) in slightly acidic solutions. However, the role of MnO2 (i.e., as an oxidant vs catalyst) is still unclear. In this work, it was demonstrated that Mn(VII) oxidized triclosan (i.e., trichloro-2-phenoxyphenol) and its analogue 2-phenoxyphenol, mainly generating ether bond cleavage products (i.e., 2,4-dichlorophenol and phenol, respectively), while MnO2 reacted with them producing appreciable dimers as well as hydroxylated and quinone-like products. Using these two phenoxyphenols as mechanistic probes, it was interestingly found that MnO2 formed in situ or prepared ex situ greatly accelerated the kinetics but negligibly affected the pathways of their oxidation by Mn(VII) at acidic pH 5. The yields (R) of indicative products 2,4-dichlorophenol and phenol from their respective probes (i.e., molar ratios of product formed to probe lost) under various experimental conditions were quantified. Comparable R values were obtained during the treatment by Mn(VII) in the absence vs presence of MnO2. Meanwhile, it was confirmed that MnO2 could accelerate the kinetics of Mn(VII) oxidation of refractory nitrophenols (i.e., 2-nitrophenol and 4-nitrophenol), which otherwise showed negligible reactivity toward Mn(VII) and MnO2 individually, and the effect of MnO2 was strongly dependent upon its concentration as well as solution pH. These results clearly rule out the role of MnO2 as a mild co-oxidant and suggest a potential catalytic effect on Mn(VII) oxidation of phenolic compounds regardless of their susceptibility to oxidation by MnO2.

Kinetic modeling of the photocatalytic degradation of clofibric acid in a slurry reactor

A kinetic study of the photocatalytic degradation of the pharmaceutical clofibric acid is presented. Experiments were carried out under UV radiation employing titanium dioxide in water suspension. The main reaction intermediates were identified and quantified. Intrinsic expressions to represent the kinetics of clofibric acid and the main intermediates were derived. The modeling of the radiation field in the reactor was carried out by Monte Carlo simulation. Experimental runs were performed by varying the catalyst concentration and the incident radiation. Kinetic parameters were estimated from the experiments by applying a non-linear regression procedure. Good agreement was obtained between model predictions and experimental data, with an error of 5.9 % in the estimations of the primary pollutant concentration.

Oxidation of bromophenols and formation of brominated polymeric products of concern during water treatment with potassium permanganate

The extensive use of bromophenols (BrPs) in industrial products leads to their occurrence in freshwater environments. This study explored the oxidation kinetics of several BrPs (i.e., 2-BrP, 3-BrP, 4-BrP, 2,4-diBrP, and 2,6-diBrP) and potential formation of brominated polymeric products of concern during water treatment with potassium permanganate [Mn(VII)]. These BrPs exhibited appreciable reactivity toward Mn(VII) with the maxima of second-order rate constants (kMn(VII)) at pH near their pKa values, producing bell-shaped pH-rate profiles. The unusual pH-dependency of kMn(VII) was reasonably explained by a tentative reaction model, where the formation of an intermediate between Mn(VII) and dissociated BrP was likely involved. A novel and powerful precursor ion scan (PIS) approach was used for selective detection of brominated oxidation products by liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry. Results showed that brominated dimeric products such as hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and hydroxylated polybrominated biphenyls (OH-PBBs) were readily produced. For instance, 2'-OH-BDE-68, one of the most naturally abundant OH-PBDEs, could be formed at a relatively high yield possibly via the coupling between bromophenoxyl radicals generated from the one-electron oxidation of 2,4-diBrP by Mn(VII). Given the altered or enhanced toxicological effects of these brominated polymeric products compared to the BrP precursors, it is important to better understand their reactivity and fate before Mn(VII) is applied by water utilities for the oxidative treatment of BrP-containing waters.

Transformation of anti-estrogenic-activity related dissolved organic matter in secondary effluents during ozonation

Anti-estrogenic activity of dissolved organic matter (DOM) in reclaimed water is gaining increasing attention. In this study, anti-estrogenic activity removal efficiency by ozonation in the tertiary treatment process of domestic wastewater was investigated. The anti-estrogenic activity in the secondary effluents used in this study ranged between 0.95 and 2.00 mg-TAM L(-1) and decreased significantly after ozonation. The removal efficiency of anti-estrogenic activity at a dose of 10 mg-O3 L(-1) was 65-87%. The removal of the anti-estrogenic activity was highly correlated with the removal of UV254, suggesting that UV254 can be used as a surrogate for anti-estrogenic activity during ozonation. The results of size exclusion chromatography of the wastewater samples during ozonation showed that the UV254 absorbance of the DOM fraction with large apparent molecular weight (MW) around 7.6 k Da dropped significantly, and the DOM fraction was suspected to be humic substances which have been previously identified as anti-estrogenic constituents in secondary effluents. The excitation emission matrix fluorescence spectra of the wastewater samples proved that humic substances existed in the DOM and indeed reacted with the ozone. With the help of two-dimensional correlation of Fourier transform infrared, it was confirmed that the aromatic structures in the DOM were largely destroyed by ozonation. Therefore, it was suggested that the destruction of the aromatic structures in the DOM was related to the removal of the anti-estrogenic activity.

Ozonation of ibuprofen: a degradation and toxicity study

This paper presents the results obtained in the degradation of ibuprofen by ozonation. This study aims to evaluate the degradation of ibuprofen by ozonation once the operating variables have been optimized, investigating the degradation and degradation efficiency of the compound and assessing the toxic effect of ibuprofen and of the intermediate compounds generated during oxidative treatment. Work was carried out to optimize the four operating variables: pH, conductivity, hydraulic retention time and the use of a maze of pipes to enhance contact between the ozone and the drug. All the trials were conducted in a purpose-built pilot-scale reactor. Analyses of the compound were carried out after solid-liquid phase extraction on high resolution liquid chromatography (HPLC). Working under optimal operating conditions (pH=9, HRT=20 min and 12 ± 2 gN/m(3)), a degradation value of 99% was obtained, although degradation efficiency or mineralization of the compound was not achieved. The toxicity of ibuprofen and its intermediate compounds formed during the oxidative process was likewise studied. This toxicity was found to increase with increasing initial concentrations of the compound, with the intermediate compounds thus formed being more toxic than the starting compound.

Oxidation of flame retardant tetrabromobisphenol a by aqueous permanganate: reaction kinetics, brominated products, and pathways

In this work, the most widely used brominated flame retardant tetrabromobisphenol A (TBrBPA) was shown to exhibit appreciable reactivity toward potassium permanganate [Mn(VII)] in water over a wide pH range of 5-10 with the maxima of second-order rate constants (kMn(VII) = 15-700 M(-1) s(-1)) at pH near its pKa values (7.5/8.5). A novel precursor ion scan (PIS) approach using negative electrospray ionization-triple quadrupole mass spectrometry (ESI-QqQMS) was adopted and further optimized for fast selective detection of brominated oxidation products of TBrBPA by Mn(VII). By setting PIS of m/z 79 and 81, two major products (i.e., 4-(2-hydroxyisopropyl)-2,6-dibromophenol and 4-isopropylene-2,6-dibromophenol) and five minor ones (including 2,6-dibromophenol, 2,6-dibromo-1,4-benzoquinone, and three dimers) were detected and suggested with chemical structures from their product ion spectra and bromine isotope patterns. Reaction pathways mainly involving the initial one-electron oxidation of TBrBPA and subsequent release and further reactions of 2,6-dibromo-4-isopropylphenol carbocation intermediate were proposed. The effectiveness of Mn(VII) for treatment of TBrBPA in real waters was confirmed. It is important to better understand the reactivity and toxicity of primary brominated products before Mn(VII) can be applied for treatment of TBrBPA-contaminated wastewater and source water.

Influence of seasonal climate differences on the pharmaceutical, hormone and personal care product removal efficiency of a drinking water treatment plant

The potential presence of pharmaceuticals, hormones and personal care products in drinking water supplies has raised concerned over the efficiency with which these substances are removed by water treatment processes. In this work, we analyzed samples of raw, unprocessed water collected in different periods and found them to contain higher levels of these contaminants in the colder periods (viz. 12-314 ng L(-1) in autumn and winter as compared to 8-127 ng L(-1) in spring and summer) as a result of their biodegradation being favoured by high temperatures and solar irradiance. We also assessed the efficiency with which these contaminants are removed from drinking water by a water treatment plant operating in south-eastern Spain. Preoxidation with potassium permanganate and chloramination with sodium hypochlorite in the presence of highly concentrated ammonia were found to be the treatment steps most markedly contributing to the removal of pharmaceuticals, hormones and personal care products from drinking water (especially in the warmer periods, where these contaminants were completely removed from the water). By contrast, water treated in the colder periods (autumn and winter) still contained small amounts of ibuprofen and carbamazepine (0.09-0.5 ng L(-1)) which, however, accounted for less than 0.2% of their original concentrations in the water prior to treatment.