Article

# Solar photo-Fenton and UV/H2O2 processes against the antidepressant Venlafaxine in urban wastewaters and human urine. Intermediates formation and biodegradability assessment

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## Abstract

In this work, the use of Advanced Oxidation Processes (AOPs) against the degradation of an emerging contaminant has been subjected under systematic investigation. The optimization of treatment of the anti-depressant drug Venlafaxine (VFA) was performed, using UV light, the combined UV/H2O2 process, solar light, Fenton and finally the solar photo-Fenton process in laboratory scale. The degradation kinetics, the time necessary to remove 90% of the contaminant and the optimal reactants concentration were proposed. The treatment in pure water, (synthetic) wastewater and urine was assessed, in an effort to identify the opportunities and pitfalls the application of process would encounter in a field application. Treatment by the UV-based methods was found sufficiently efficient and the application of the solar photo-Fenton process showed feasibility in a potential field application with appropriate context. Real urban wastewater effluents after biological and physicochemical treatment were tested, as well as human urine, as a proposal for on-site collection and treatment was also treated. Biological treatment before applying the tested AOPs improved their efficiency, and the strategy of diluting urine prior to treatment greatly enhanced the efficacy of the process. Finally, the identification of the degradation pathway and the biodegradability tests of AOPs treated VFA solutions exhibit promising results concerning the strategy of treatment for similar pollutants of emerging concern.

## Supplementary resource (1)

... Although the ability of UV/H 2 O 2 to degrade VEN was established, a parametric analysis on the key parameters of UV dosage, UV intensity and H 2 O 2 dose was not presented, and is a requisite to determining practical applicability. This gap was partially filled by Giannakis et al., who performed parametric analysis of H 2 O 2 dosage and UV for the degradation of VEN in synthetic wastewater [22]. Further, the paper presented a brief experimental result on UV/H 2 O 2 to degrade VEN in real wastewater, though only data for initial concentration and a single point for full removal were considered in the result, limiting usefulness in process design. ...
... The study found that VEN degraded by pseudo first order kinetics at these concentrations as well as finding that kinetics in a pilot scale setting have very little variation from lab scale experiments. Additionally, Giannakis et al. determined that other AOPs (solar, Fenton, photo-Fenton) all followed pseudo-first order kinetics at environmentally relevant concentration of VEN in wastewater, although VEN degraded too fast by UV/H 2 O 2 to determine kinetics [22]. Experiments were conducted at a higher concentration in this paper to allow adequate time to take multiple samples during degradation to elucidate kinetics. ...
... Degradation pathway of VEN by HO • includes the following four primary reactions: (1) sequential hydroxylation of the aromatic ring, (2) alteration of the methoxygroup, (3) hydroxylation and truncation of the cyclohexanol ring and (4) attack on the nitrogen group [20][21][22][24][25][26]. HPLC-MS analysis was used in this present study to identify the intermediates of VEN formed during UV/ H 2 O 2 process. ...
Article
Many water and wastewater treatment plants (WWTPs) are fitted with a UV system that provides post treatment disinfection before the water is released to receiving water. This paper presents a study on expected removal for the pharmaceutical venlafaxine (VEN) in a typical UV unit at a municipal WWTP with analysis of removal rates of an advanced oxidation process using UV irradiation with injection of H2O2. The study is supported by bench scale degradation experiments on VEN. Results demonstrated that UV can completely degrade VEN, but the addition of H2O2 increased pseudo first order rate constant by up to 2.5 times. Extrapolations of the lab data indicated that removal rates of VEN at the UV disinfection unit of a typical municipal WWTP are approximately 0.4% at standard operating conditions. With the addition of 10 mg/L of H2O2, degradation of VEN can be increased by ten times over existing UV treatment. By studying the impact of adjusting parameters such as UV intensity, UV dosage, and H2O2 dosage, a framework is set to allow researchers and engineers to move forward with developing UV/H2O2 systems that meet their future design needs for pharmaceutical removal.
... En cuanto a los procesos de oxidación avanzada (AOP, por su sigla en inglés), presentan bajos niveles de mineralización y algunos subproductos de la oxidación química pueden llegar a ser más tóxicos que los contaminantes iniciales (Bethi et al., 2016;Giannakis et al., 2017;Gomes et al., 2017;Martini et al., 2018). ...
... Las configuraciones híbridas tienen mayor peso en este criterio por sus efectos sinérgicos, y algunos autores señalan que la degradación de los CE por una simple tecnología no es la mejor opción desde el punto de vista económico y ambiental (Herrera Sandoval y Morales Granados, 2020; Rodríguez-Narváez et al., 2017). En segundo lugar, los AOP surgen como buenas alternativas a bajas concentraciones de CE y altas velocidades de reacción, además posibilitan su mineralización (Babuponnusami y Muthukumar, 2014;Brienza et al., 2016;Giannakis et al., 2017;Rubio-Clemente et al., 2014). Los procesos biológicos, a pesar de tener altos índices de remoción, requieren de mayores controles y tiempos de retención; y presentan menores porcentajes de remoción para algunos antibióticos, antidepresivos y B-bloqueadores. ...
... La cantidad de peróxido de hidrógeno y catalizador dependerán del contaminante por tratar, y así mismo, cuanto mayor es la cantidad inicial de contaminantes, mayor el número de intermediarios generados (Babuponnusami y Muthukumar, 2014;Brienza et al., 2016;Rubio-Clemente et al., 2014). Además, se debe considerar la influencia del pH, la carga hidráulica y el tipo de contaminante durante el proceso (El-taliawy et al., 2017;Kharel et al., 2021), por lo que se deben establecer estrategias de mejoramiento para facilitar la viabilidad del modelo a gran escala, a sabiendas de que esta tecnología es la que menores tiempos de retención presenta, del orden de horas o, incluso, minutos (Brienza et al., 2016;Giannakis et al., 2017;Kantar et al., 2019;Ling et al., 2020;Martini et al., 2018;Riaz y Park, 2020;Serna-Galvis et al., 2019). ...
Article
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... Recent studies have indicated that advanced oxidative processes (AOPs) used to associate ultraviolet radiation, hydrogen peroxide and ozone, among others, can be highly efficient (99%) in removing certain pharmaceuticals in aqueous matrices (Anjali and Shanthakumar 2019) and also reduce toxicological risks (Alvim et al. 2020;Guo et al. 2020). However, unknown effects of metabolites can be generated by oxidation; their toxicity can be lower, higher or equivalent to that of the original compounds (Verlicchi et al. 2012;Gavrilescu et al. 2015;Azuma et al. 2016;Giannakis et al. 2017). Therefore, it is essential assessing the toxicity rates in order to estimate the potential risks of treating wastewater through AOPs (Guo et al. 2020). ...
... This outcome assumingly highlights metabolite formation resulting from the treatment process the effluent was exposed to. By-product formation during pharmaceuticals' degradation by advanced oxidative processes was reported by several authors (Gavrilescu et al. 2015;Azuma et al. 2016;Giannakis et al. 2017). Resulting metabolites may be less, equivalent or more toxic than the original compounds, depending on the treatment process and on the conditions of the environmental matrix where they are found (Xu et al. 2017). ...
Article
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Sewage effluent effects on the biochemical parameters of Astyanax bimaculatus organs were investigateted. Treated sewage was collected in a treatment plant; 43 compounds, among them, pharmaceuticals and hormones, were investigated. Caffeine, ciprofloxacin, clindamycin, ofloxacin, oxytetracycline, paracetamol, sulfadiazine, sulfamethoxazole, sulfathiazole and tylosin waste was detected in the collected material. Fish were divided into four groups: control, TSE (treated sewage effluent), TSE + P (TSE with increased concentration of five pharmaceuticals) and PTSE (TSE + P post-treated with O3/H2O2/UV). Biochemical parameters were evaluated in different organs after 14-day exposure. TBARS levels increased significantly in the brain of animals in the TSE and TSE + P groups in comparison to the control. There was significant reduction in TBARS levels recorded for the liver, muscle and gills of animals in the PTSE group in comparison to those of animals in the other groups. AChE activity reduced in the muscle of animals in the groups showing the highest pharmaceutical concentrations. CAT activity in the liver of animals in groups exposed to pharmaceutical effluent was inhibited. GST activity increased in brain of animals in the TSE + P and PTSE groups, whereas reduced levels of this activity were observed in liver of animals in the TSE group. Increased GST activity was observed in the brain of animals in TSE + P and PTSE groups. Based on integrated biomarker response values, the TSE + P group presented greater changes in the analyzed parameters. Results point out that pharmaceutical waste can cause oxidative stress, as well as affect biochemical and enzymatic parameters in Astyanax sp. Post-treatment can also reduce damages caused to fish, even in case of the likely formation of metabolites. Based on these results, these metabolites can be less toxic than the original compounds; however, they were not able to fully degrade the pharmaceutical waste found in the sewage, which can interfere in fish metabolism.
... The pretreatment with UV-based or solar-assisted AOPs enhanced the biodegradability of the treated effluent, compared to the initial one. The gold standard of biodegradability tests, the Zahn-Wellens test revealed up to 20% increase in biodegradability of the treated effluents, by UV/H2O2 or solar photo-Fenton [95], in simulated WW containing mg/L amounts of the selected pharmaceutical. Hence, the restriction of dilution of HWW or manufacturing flows could be effectively pre-treated. ...
... The pretreatment with UV-based or solar-assisted AOPs enhanced the biodegradability of the treated effluent, compared to the initial one. The gold standard of biodegradability tests, the Zahn-Wellens test revealed up to 20% increase in biodegradability of the treated effluents, by UV/H 2 O 2 or solar photo-Fenton [95], in simulated WW containing mg/L amounts of the selected pharmaceutical. Hence, the restriction of dilution of HWW or manufacturing flows could be effectively pre-treated. ...
Article
Full-text available
In this work, the issue of hospital and urban wastewater treatment is studied in two different contexts, in Switzerland and in developing countries (Ivory Coast and Colombia). For this purpose, the treatment of municipal wastewater effluents is studied, simulating the developed countries' context, while cheap and sustainable solutions are proposed for the developing countries, to form a barrier between effluents and receiving water bodies. In order to propose proper methods for each case, the characteristics of the matrices and the targets are described here in detail. In both contexts, the use of Advanced Oxidation Processes (AOPs) is implemented, focusing on UV-based and solar-supported ones, in the respective target areas. A list of emerging contaminants and bacteria are firstly studied to provide operational and engineering details on their removal by AOPs. Fundamental mechanistic insights are also provided on the degradation of the effluent wastewater organic matter. The use of viruses and yeasts as potential model pathogens is also accounted for, treated by the photo-Fenton process. In addition, two pharmaceutically active compound (PhAC) models of hospital and/or industrial origin are studied in wastewater and urine, treated by all accounted AOPs, as a proposed method to effectively control concentrated point-source pollution from hospital wastewaters. Their elimination was modeled and the degradation pathway was elucidated by the use of state-of-the-art analytical techniques. In conclusion, the use of light-supported AOPs was proven to be effective in degrading the respective target and further insights were provided by each application, which could facilitate their divulgation and potential application in the field.
... The cationic state of CIP is reported to have lower degradation rates for both photolysis and photocatalysis [63], and since the ionic state shifts from cationic to neutral around the tested pH range (Table S3), this can explain the kapp increase. The pKa values of TMP, SMX, VX, and DV are 7.1 [64], 5.6 [65], 9.0 [66], and 9.0 [67], respectively. Among these, the only compound with a shift of ionic states in the tested range was SMX. ...
... The cationic state of CIP is reported to have lower degradation rates for both photolysis and photocatalysis [63], and since the ionic state shifts from cationic to neutral around the tested pH range (Table S3), this can explain the k app increase. The pK a values of TMP, SMX, VX, and DV are 7.1 [64], 5.6 [65], 9.0 [66], and 9.0 [67], respectively. Among these, the only compound with a shift of ionic states in the tested range was SMX. ...
Article
Full-text available
Ultra-violet light-emitting diode (UV-LED)-based processes for water treatment have shown the potential to surpass the hurdles that prevent the adoption of photocatalysis at a large scale due to UV-LEDs’ unique features and design flexibility. In this work, the degradation of five EU Watch List 2020/1161 pharmaceutical compounds was comprehensively investigated. Initially, the UV-A and UV-C photolytic and photocatalytic degradation of individual compounds and their mixtures were explored. A design of experiments (DoE) approach was used to quantify the effects of numerous variables on the compounds’ degradation rate constant, total organic carbon abatement, and toxicity. The reaction mechanisms of UV-A photocatalysis were investigated by adding different radical scavengers to the mix. The influence of the initial pH was tested and a second DoE helped evaluate the impact of matrix constituents on degradation rates during UV-A photocatalysis. The results showed that each compound had widely different responses to each treatment/scenario, meaning that the optimized design will depend on matrix composition, target pollutant reactivity, and required effluent standards. Each situation should be analyzed individually with care. The levels of the electrical energy per order are still unfeasible for practical applications, but LEDs of lower wavelengths (UV-C) are now approaching UV-A performance levels.
... It should be mentioned that some previous works have evidenced the high potentiality of AOPs to eliminate pollutants in urine [11][12][13][14][15][16][17][18][19][20]. However, until now, the treatment of losartan in fresh urine, considering the intrinsic degradation abilities of UVC/H 2 O 2 and sonochemistry has not been reported. ...
... Water 2020, 12 Publisher's Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. ...
Article
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In this work, the degradation of the pharmaceutical losartan, in simulated fresh urine (which was considered because urine is the main excretion route for this compound) by sonochemistry and UVC/H2O2 individually, was studied. Initially, special attention was paid to the degrading action of the processes. Then, theoretical analyses on Fukui function indices, to determine electron-rich regions on the pharmaceutical susceptible to attacks by the hydroxyl radical, were performed. Afterward, the ability of the processes to mineralize losartan and remove the phyto-toxicity was tested. It was found that in the sonochemical treatment, hydroxyl radicals played the main degrading role. In turn, in UVC/H2O2, both the light and hydroxyl radical eliminated the target contaminant. The sonochemical system showed the lowest interference for the elimination of losartan in the fresh urine. It was established that atoms in the imidazole of the contaminant were the moieties most prone to primary transformations by radicals. This was coincident with the initial degradation products coming from the processes action. Although both processes exhibited low mineralizing ability toward losartan, the sonochemical treatment converted losartan into nonphytotoxic products. This research presents relevant results on the elimination of a representative pharmaceutical in fresh urine by two advanced oxidation processes.
... Moreover, the scavenging effect observed in the presence of excess PAA and Fe(II) can be another reason for radically oxidation of ACT by HO and ReO . This indicated that the contribution of HO is more important than ReO and that it resulted to higher levels of oxidation of the generated by-products (Giannakis et al., 2017a(Giannakis et al., , 2017b; besides, the HO is more environmentally friendly than that of ReO . ...
Article
... Municipal wastewater treatment plants (MWWTP) worldwide aim to remove suspended particles, organic matter, nutrients and pathogens from domestic sewage (Giannakis et al., 2017) prior to discharge or reuse. However, most MWWTPs in developing countries lack a tertiary treatment stage due to restricted investments in sanitation. ...
Article
Full-text available
The application of solar photo-Fenton as post-treatment of municipal secondary effluents (MSE) in developing tropical countries is the main topic of this review. Alternative technologies such as stabilization ponds and upflow anaerobic sludge blanket (UASB) are vastly applied in these countries. However, data related to the application of solar photo-Fenton to improve the quality of effluents from UASB systems are scarce. This review gathered main achievements and limitations associated to the application of solar photo-Fenton at neutral pH and at pilot scale to analyze possible challenges associated to its application as post-treatment of MSE generated by alternative treatments. To this end, the literature review considered studies published in the last decade focusing on CECs removal, toxicity reduction and disinfection via solar photo-Fenton. Physicochemical characteristics of effluents originated after UASB systems alone and followed by a biological post-treatment show significant difference when compared with effluents from conventional activated sludge (CAS) systems. Results obtained for solar photo-Fenton as post-treatment of MSE in developed countries indicate that remaining organic matter and alkalinity present in UASB effluents may pose challenges to the performance of solar advanced oxidation processes (AOPs). This drawback could result in a more toxic effluent. The use of chelating agents such as Fe3+-EDDS to perform solar photo-Fenton at neutral pH was compared to the application of intermittent additions of Fe2+ and both of these strategies were reported as effective to remove CECs from MSE. The latter strategy may be of greater interest in developing countries due to costs associated to complexing agents. In addition, more studies are needed to confirm the efficiency of solar photo-Fenton on the disinfection of effluent from UASB systems to verify reuse possibilities. Finally, future research urges to evaluate the efficiency of solar photo-Fenton at natural pH for the treatment of effluents from UASB systems.
... The UV-C/H 2 O 2 process presents some advantages over other advanced oxidation processes because H 2 O 2 is soluble in water, stable and commercially available; moreover, at the end of the process, there is no sludge formation [16]. Studies have been performed to evaluate alternatives for the degradation of antibiotics [17,18], antidepressants [19], chemotherapeutics [20], analgesics [13], anti-inflammatories [12], pesticides [21] and disinfectants [22], among others. The efficiency of the process is influenced by the following operating parameters: pH, H 2 O 2 and target compound concentrations, temperature, inorganic anions, and natural organic matter [13,23]. ...
... The UV-C/H 2 O 2 process presents some advantages over other advanced oxidation processes because H 2 O 2 is soluble in water, stable and commercially available; moreover, at the end of the process, there is no sludge formation [16]. Studies have been performed to evaluate alternatives for the degradation of antibiotics [17,18], antidepressants [19], chemotherapeutics [20], analgesics [13], anti-inflammatories [12], pesticides [21] and disinfectants [22], among others. The efficiency of the process is influenced by the following operating parameters: pH, H 2 O 2 and target compound concentrations, temperature, inorganic anions, and natural organic matter [13,23]. ...
... Among the most consumed pharmaceuticals classes are "Non-Steroidal Anti-Inflammatory Drugs" (NSAIDs), with concentrations from ng L −1 to μg L −1 detected in effluents of wastewater treatment plants, surface water, groundwater and even in drinking water [6,7]. NSAIDs are considered as potentially dangerous emerging environmental pollutants [8][9][10][11] because of their acute and chronic toxicological effects on humans and animals [12,13]. Thereby, effective technologies are required to prevent the release of such contaminants into natural aquatic environment [7,[14][15][16]. ...
Article
The degradation kinetics, the operational influencing factors, the determination of short-chain organic by-products , the mineralization degree, the evolution of residual toxicity, as well as the treatment of complex matrices were systematically investigated on removal of piroxicam by Electro-Fenton process (EF), due to its persistence and low removal in water matrices. The second order reaction rate constant between piroxicam and hydroxyl radical (• OH) was determined as (2.19 ± 0.01) × 10 9 M −1 s −1. It was found that the process was able to almost completely mineralize 0.08 mM piroxicam solution (92% TOC removal) at 6 h treatment. Based on identification of short-chain carboxylic acids, released inorganic ions and the removal of total organic carbon, a schematic proposal of piroxicam degradation by EF treatment was done. The evolution of the acute toxicity of treated piroxicam solution was monitored by Microtox method, showing a significant toxicity reduction at 180 min treatment. Remarkably, piroxicam in simulated urine and hospital wastewater was completely degraded after 120 min of EF treatment. Therefore, the results indicate that the tested EF process constitutes an efficient option for the elimination of piroxicam in aqueous media.
... where TOC 0 and TOC t denote the TOC concentrations before and after oxidation, respectively. Residual (Giannakis et al. 2017). The concentrations of residual Fe 2+ and Fe 3+ ions at the end of electrolysis were determined using the phenanthroline colorimetric method recommended by the American Public Health Association (APHA 1998). ...
Article
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This study aims to evaluate the degradation and mineralization of Malachite Green (MG) in an electro-Fenton process (EFP). We studied the influence of several important parameters including solution pH (2–11), current density (0–20 mA/cm²), H2O2 concentration (0–200 mg/L) and MG concentrations (200, 600, 1000, 1500, 2000, 3000 mg/L) at different reaction time (2.5–30 min). The intermediates produced during the degradation were determined by GC–MS. The optimum pH, current density and H2O2 concentration were found to be approximately 3, 10 mA/cm² and 50 mg/L, respectively. It was concluded that acidic pH was required to increase the efficiency of the EFP. At optimum conditions and a reaction time of 15 min, MG was completely removed without any significant variation in the corresponding maximum wavelengths or new absorption bands. Due to formation of intermediates, almost all the organic compounds were completely mineralized (95.3%) to CO2 and water at reaction time of 30 min. Results indicated the effect of hydroxyl radical (·OH) on MG degradation is greater than that of superoxide radical scavenger ($${\text{O}}_{2}^{ \cdot - }$$). The results showed that the degradation process of MG followed pseudo-first-order kinetic model and the treatment time required in EFP was 4.6 times lower than ECP. Furthermore, the results showed that EFP was an extremely efficient process for degradation and mineralization of a high concentration of MG (1000 mg/L) at a short reaction time (30 min).
... AOPs such as Fenton's process, have been considered as a promising choice for degradation of these compounds and achieve both human and eco-friendly results [9][10][11]. The parting of CECs in a Fenton oxidation process is through electron interactions taking place between the reactants, H 2 O 2 , employed as the oxidant, and Fe 2+ , as the catalyst, that, ultimately, will lead to • OH radical's generation, as described by Eq. (1). ...
Article
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The ubiquitous presence of CBZ, SMX and LRZ in water is a subject of increasing concern. This study represents a new approach in terms of these contaminants’ removal through Fenton process in three different ways, employing a solid catalyst, RM, which, alone, is a source of Fe3＋ just as much is a source of environmental problems. Alongside RM, 100 mg/L of H2O2 were utilized as the initial solution’s pH remained unaltered. It was observed that, at these operating conditions, an appreciable degradation rate of contaminants was achieved. Solar photo-Fenton under visible light radiation led the way by attaining more than 50% removal for all three contaminants, reaching its peak when degrading around 62% of LRZ initially present. Therefore, RM, a residue from the alumina industry, seems to be a promising choice in terms of CECs degradation through Fenton process. Nevertheless, some parameters still need optimization, in order to achieve a better understanding and certainty of this oxidation process’ skilfulness for detoxifying CECs from the world’s water resources. Keywords: Decontamination, Fenton process, Pharmaceuticals, Red mud, Sunlight radiation, Waste management
... In both cases of batch and continuous mode operation, samples were also kept for an additional test regarding micropollutant elimination estimation. A custom UPLC/MS-MS method was used to evaluate the micropollutant concentration present in the wastewater effluent, as used in our previous studies [41][42][43]. 25 different micropollutant (Bezafibrate, Citalopram, Venlafaxine, Carbamazepine, Gabapentin, Amisulpride, Diclofenac, Naproxen, Primidone, Atenolol, Metoprolol, Candesartan, Irbesartan, Clarithromycin, Metronidazole, Ofloxacin, Sulfamethoxazole, Trimethoprim, Iomeprol, Benzotriazole, Methylbenzotriazole, Atrazine, Diuron, Mecoprop and Terbutryn) were selected in order to evaluate the removal percentage during the photo-Fenton experiments. Their removal was calculated on the basis of molar mass elimination with weighted average as described [44] in previous study, and calculated by the following formula (Eq 1): ...
Article
In this work, iron oxides have been proposed as low-cost heterogeneous photo-Fenton catalysts for the simultaneous disinfection and reduction of microcontaminant load from urban wastewater in raceway pond reactors at near-neutral pH. The objective was not finding the best operating conditions but understanding the mechanisms of FeOx driven disinfection and the implications presented by the matrix constituents, namely organic matter and (bi)carbonates, as well as the possibility to apply this system after different secondary treatments in continuous flow mode. Notable bacterial inactivations were obtained in both batch and continuous flow modes by any iron oxide used, with total inactivation (5 log reduction) in the case of Hematite. The heterogeneous photo-Fenton process was proven to be the driving bacterial inactivation force in urban wastewaters. Additionally, monitoring the elimination of 25 emerging contaminants in the secondary effluents was performed. The operation mode (batch-continuous) was assessed, attaining a minimum of 35% micropollutant removal.
... Among the most consumed pharmaceuticals classes are "Non-Steroidal Anti-Inflammatory Drugs" (NSAIDs), with concentrations from ng L −1 to μg L −1 detected in effluents of wastewater treatment plants, surface water, groundwater and even in drinking water [6,7]. NSAIDs are considered as potentially dangerous emerging environmental pollutants [8][9][10][11] because of their acute and chronic toxicological effects on humans and animals [12,13]. Thereby, effective technologies are required to prevent the release of such contaminants into natural aquatic environment [7,[14][15][16]. ...
... The UV-C/H 2 O 2 process presents some advantages over other advanced oxidation processes because H 2 O 2 is soluble in water, stable and commercially available; moreover, at the end of the process, there is no sludge formation [16]. Studies have been performed to evaluate alternatives for the degradation of antibiotics [17,18], antidepressants [19], chemotherapeutics [20], analgesics [13], anti-inflammatories [12], pesticides [21] and disinfectants [22], among others. The efficiency of the process is influenced by the following operating parameters: pH, H 2 O 2 and target compound concentrations, temperature, inorganic anions, and natural organic matter [13,23]. ...
... A specific amount of H 2 O 2 (mg/L) was added to reactor before the treatment, and no further hydrogen peroxide was added during the degradation. At the end of process, the residual concentration of hydrogen peroxide was determined through a spectrophotometer at 410 nm using titanium(IV) oxysulfate in accordance with the DIN 38402H15 method (Giannakis et al. 2017). To determine the apparent reaction rate constant (k app ) values for the degradation of ceftriaxone, a pseudo-first-order kinetics model was used. ...
Article
Full-text available
This study investigated the performance of UVC/H2O2 and UVC processes for the degradation and mineralization of ceftriaxone as an antibiotic. The highest ceftriaxone degradation was obtained at a solution pH of 5 and H2O2 concentration of 10 mg/L. The apparent rate constant of ceftriaxone degradation was found to be 0.0302, 0.0165, and 0.0065 min⁻¹ in the UVC/H2O2 process for the initial ceftriaxone concentrations of 5, 10, and 20 mg/L, respectively. Degradation and mineralization efficiencies of ceftriaxone was obtained to be 100% and 58%, respectively, in UVC/H2O2 process at reaction time of 120 min, whereas only 61% and 2.5% of ceftriaxone could be degraded and mineralized by UVC. The synergistic effect of UVC/H2O2 was found to be 35%. The presence of anionic species improved the photolysis efficiency which degraded ceftriaxone from 61 to 83%, while, in the UVC/H2O2 process, ability degradation declined from 100 to 70%. The efficiency of UVC/H2O2 and UVC process was not greatly affected in real tap water. Besides, the reduction patterns in the UVC/H2O2 and UVC processes were better described by pseudo-first- and second-order kinetics model with a reaction rate constant of 0.0165 and 0.0012 min⁻¹, respectively. The rate constant of ceftriaxone degradation in the UVC/H2O2 process and at the presence of radical scavenger was found to be around 3.3 times lower than the one in its absence.
... As for the transformation products (TPs) formed during the oxidation of the CECs, additional irradiation time may be required for complete degradation. Indeed TPs products of some single CECs (spiked at concentration in the range of a few mg/L) after photo-Fenton treatment have been recently reported [24,25]. However, it is not technically possible to quantify TPs generated from dozens of parent compounds found in real secondary effluents at concentration level of ng/L along with tens of mg/L of natural organic matter and other organic compounds, preventing from any reliable study about TPs. ...
Article
This paper presents for the first time the treatment of contaminants of emerging concern (CECs) in a systematic study in different municipal wastewater treatment plants (MWWTPs) of the Mediterranean area, more than 1000 km away. Solar photo-Fenton process at neutral pH with Fe ³⁺ -EDDS has been demonstrated to be very efficient under controlled conditions and must be validated in realistic and variable conditions such as real MWWTP effluents of different composition. To this end, CEC removal was studied in effluents from 5 treatment plants in the Mediterranean area of Spain, the inorganic and organic composition varying in the range 161–641 mg L ⁻¹ (sulfate), 133–538 mg L ⁻¹ (chloride) and 10–20 mg L ⁻¹ (dissolved organic carbon). More than 45 CECs were quantified in MWW and results showed that the effect on CEC elimination of the concentration of anions and organic matter was interfered by the nature of the organic matter. However, origin and composition of MWW was not critic for attaining >80% degradation of CECs after 15 min of reaction. Moreover, conventional anions (sulfate, chloride) had a positive effect on CEC degradation rate. This paper demonstrates the consistency and predictability of the solar photo-Fenton process at circumneutral pH for treating CECs in simple and cheap photoreactors.
... The remaining concentrations of H 2 O 2 after the completion of reactions were determined using a titanium oxalate spectrophotometric method at λ max = 500 nm [36,37]. The dissolution of both Cu(T) [total copper] and Cu(I) [cuprous ion] was analyzed using a UV/VIS spectroscopy (model Genesys 10S, ThermoFisher, US) according to the method of Chen et al. [38]. ...
Article
... Regardless of the reaction time (C:H 2 O 2 1:0 at 20, 60 or 120 min), the post-AOP effluents showed lower biodegradability (56.9, 61.0 and 65.5% for 20, 60 and 120 min respectively) and a higher inert COD (35.6, 30.5 and 25.4% for 20, 60 and 120 min respectively) compared to the raw effluent (66.9 and 25.2% for biodegradability and inert COD, respectively) and the tests containing H 2 O 2 (20.8 and 12.2% inert COD for C:H 2 O 2 1:1 and 1:2 respectively). As previously mentioned in Section 3.1, and demonstrated by Giannakis et al. [30], photolysis reaction without H 2 O 2 has a slower degradation rate. Consequently, the organic compounds have been partially broken down and generated recalcitrant by-products that are not degraded at the end of the reaction. ...
Article
An UV/H2O2 process was considered prior to the biological treatment of a petroleum refinery effluent for its biodegradability enhancement and toxicity reduction. The effect of different C:H2O2 molar ratios and reaction time were investigated over the reduction of chemical oxygen demand (COD) and absorbance at 254 nm. When photolysis was considered, an incomplete and slower degradation rate was noticed, which generated additional recalcitrant by-products and reduced the effluent biodegradability. However, when H2O2 was added, toxicity was reduced and biodegradability was enhanced. The production of soluble extracellular polymeric substances (EPS) decreased in comparison to the raw effluent in all tests in which pretreatment was carried out because of the reduced effluent toxicity. Carbohydrates and proteins were less than 45% of soluble microbial products and less than 30% of EPS, which suggests the presence of other substances as humic acids, nucleic acids and lipids. The substances later identified by FTIR reinforced the presence of recalcitrant compounds (mostly phenols, alcohols and proteinaceous materials). From all experimental conditions investigated, C:H2O2 1:2 (20 min) was considered the most appropriate in terms of energy requirement (51 Wh/L), COD (87.9%) and toxicity removals. Considering that the oil refinery processes 24,000 m3 of petroleum per day, the total capital and operation expenditures corresponded to ∼US$690,000 and 0.51 US$/m3, respectively.
... Although more convenient, Xe/Hg lamps emitting radiation in the 210e240 nm range are expensive. To reduce costs, H 2 O 2 photolysis is almost invariably performed using mercury vapor lamps (Bensalah et al., 2017;Giannakis et al., 2017;Lin et al., 2016;Romero et al., 2015;Russo et al., 2017;Souza et al., 2014;Zhang et al., 2017a). ...
Article
Nimesulide (Nim) degradation in ultrapure water (UW) and municipal sewage (MS) via UV-ABC/H2O2 was investigated. The variables included in the experimental design were time, initial Nim, and initial H2O2 concentrations. Resulting decreases in Nim concentration (monitored by high performance liquid chromatography (HPLC) using a photodiode array detector operating at a maximum UV absorbance of 300 nm), mineralization (from total organic carbon (TOC) measurements), and ecotoxicity (assays employing the bioindicators Daphnia similis, Artemia salina, and Allium cepa) were also studied. Degradation rates of 90% or higher were found for 15-20 min reaction times, employing combinations of [H2O2] = 50-150 mg L-1 and [Nim] = 8.5-15 mg L-1 prepared with MS. Mineralization rates of 70% and higher were attained within 60 min of reaction for [Nim] = 15 mg L-1 prepared in MS with [H2O2] = 100 mg L-1. Nim by-products were detected and possible degradation pathways proposed. Ecotoxicity evaluation using A. salina, D. similis, and A. cepa revealed that the treated samples had significantly lower toxicity. Exposure to treated samples resulted in survival rates of 79% for A. salina and over 90% for D. similis. No root growth inhibition was observed in A. cepa exposed to treated samples, whereas exposure to untreated samples inhibited root growth by 60%. Statistical analysis revealed elimination of cytotoxicity and reduction of genotoxicity against A. cepa. The results showed that the UV-ABC/H2O2 process can be employed as a pre- or post-treatment method to remove Nim from contaminated wastewater.
... The composition of the synthetic urine is shown in Table S1 of the Supplementary Material (hereinafter SM), and it is the same as reported by Giannakis et al. (2017). Reagents were dissolved in Milli-Q water and two stock solutions (five times more concentrated than shown in the table) were prepared. ...
Article
The release in the environment of antibiotics develop microbial resistance. In this work we investigated the feasibility of the electrochemical degradation in synthetic urine of cefazolin (CFZ), an antibiotic used for the treatment of antibiotic-resistant infections, which could be carried out in hospital wards on source-separated urine. CFZ is primarily excreted in urine without modifications. The removal of CFZ from human wastes would contribute to slow down the diffusion of CFZ-resistant bacterial strains more efficiently, compared to the treatment of much larger volumes of wastewater. CFZ can be electrochemically degraded using relatively low current density (≥0.5 mA cm⁻²) and without important generation of toxic by-products such as chlorate (<100 μg L⁻¹). Oxidation of the S atoms of CFZ constitutes its main electrodegradation pathway, while the electrochemical generation of H2O2 accounts for most of the bacterial toxicity observed in electrodegraded mixtures. The treatment costs are not an issue because of the relatively low electricity consumption required for CFZ degradation (EEO at 0.5 mA cm⁻² current density was always < 1 kWh m⁻³), while the most challenging endeavours could be the manufacturing of a sufficiently compact apparatus and possibly its management in hospital wards.
... SHP process allowed their removal up to 48%, whereas SPF completely removed 3 out of 4 of them after 60 min (Fig. 4d). These results are in agreement with a recent study where the removal of Venlafaxine (VNF) by solar light and solar photo-Fenton was compared [66]. The immune depressant MPA was one of the few compound sensitive to SPD process, 94% removal was achieved at 5.5 KJ/L. ...
Article
Thirty contaminants of emerging concern (CECs) were identified and quantified in hospital wastewater (HWW) by LC-MS and their removal by solar photo Fenton (SPF) with ethylenediamine-N,N’-disuccinic acid (EDDS) at spontaneous pH (7.5) was compared to other solar driven advanced oxidation processes (AOPs) (namely, sunlight/persoxydisulphate (SPD) and sunlight/H2O2 (SHP)). Almost all the detected CECs (28) are pharmaceuticals and belong to 13 different classes, with concentrations varied between 0.08 µg/L (psychiatric drug) to 38.92 µg/L (antidiabetic). First, the formation of iron-EDDS complexes was characterized by electrochemical methods to compare Fe²⁺ and Fe³⁺ behavior. The effect on a carbamazepine (CBZ) aqueous solution of solar driven Fe²⁺/EDDS and Fe³⁺/EDDS Fenton processes was comparatively evaluated to select the most effective one for advanced oxidation tests on real HWW and sunlight/Fe²⁺-EDDS/H2O2 was the most effective one with 48% removal after 12.5 kJ/L⁻¹ (78% total removal, 30% being under dark Fenton condition). SPF process was also more effective than SPD and SHP (60 min sunlight exposure, 5 kJ/L⁻¹). Subsequently, the effect of the solar AOPs (SPF, Fe²⁺ 0.1 mM, EDDS 0.2 Mm, H2O2 2.7 Mm; SPD, PD 1.48 mM; SHP, H2O2 2.7 Mm; 60 min sunlight exposure) was investigated in the treatment of the HWW and SPF resulted the most effective one, all CECs being removed from 70% to 100%.
... To evaluate the applicability of the EAOPs to degrade NAX in matrices more complex than tap water, the pollutant treatment was carried out in simulated urine and wastewater (Table 1). These matrices were considered as the main excretion way of this pharmaceutical in humans is the urine [60,61], and hospital wastewater is a recognized source of anti-inflammatories discharge into municipal treatment plants [62,63]. Moreover, the application at primary sources of pollution by NAX (as urine and hospital wastewaters) could contribute to mitigate the negative environmental impact of this pharmaceutical [64]. ...
Article
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The removal of the non-steroidal anti-inflammatory drug (NSAID) Naproxen (NAX) in water by hydroxyl radicals (•OH) was performed by electrochemical advanced oxidation processes either with Pt or BDD anodes and a 3D carbon felt cathode. The degradation of NAX by (•OH vs. electrolysis time) was well fitted to a pseudo-first-order reaction rate kinetic. The detected reaction intermediates (aromatic compounds and carboxylic acids) were experimentally monitored during the process via LC, while density functional theory (DFT) was applied to uncover undetected intermediates, some for the first time in literature. The formation of toxic intermediates with higher toxicity than NAX were identified, such as IMS4b (6-Methoxy-1-[1-(6-methoxynaphthalen-2-yl) ethyl] naphthalen-2-ol), catechol, and glycolic acid. Based on these data, a detailed oxidation pathway of NAX by •OH was proposed. The evolution of solution toxicity indicated that formed toxic intermediates were subsequently removed during the TOC removal process. Finally, almost complete mineralization of NAX was achieved in simulated urine or wastewater, by the electro-Fenton treatment with an optimized dose of iron as catalyst, showing the EAOPs’ potential to efficiently remove NAX even from challenging matrices. In extension, the strategies developed can be applied to the treatment of other NSAIDs.
... For all AOPs experiments, the pH of the samples was adjusted to 2.8 with H 2 SO 4 (Pignatello et al., 2006). The initial concentration of Fe 2+ was 5 mg L − 1 , while H 2 O 2 was 50 mg L − 1 (Giannakis et al., 2017). The monitoring of iron and H 2 O 2 was every 10 min of reaction time. ...
Article
Literature is scarce on the performance of Fenton-based processes as post-treatment of municipal wastewater treated by upflow anaerobic sludge blanket (UASB) reactor. This study aims to perform Fenton and photo-Fenton from UASB influent and effluent matrices to remove micropollutants (MPs) models: atrazine (ATZ), rifampicin (RIF), and 17α-ethynylestradiol (EE2). A UASB reactor at bench-scale (14 L) was operated with these MPs, and the AOPs experiments at bench-scale were performed on a conventional photochemical reactor (1 L). A high-pressure vapor mercury lamp was used for photo-Fenton process (UVA-Vis) as a radiation source. Microcrustacean Daphnia magna (acute toxicity) and seeds of Lactuca sativa (phytotoxicity) were indicator organisms for toxicity monitoring. The UASB reactor showed stability removing 90% of the mean chemical oxygen demand, and removal efficiencies for ATZ, RIF, and EE2 were 16.5%, 45.9%, and 15.7%, respectively. A matrix effect was noted regarding the application of both Fenton and photo-Fenton in UASB influent and effluent to remove MPs and toxicity responses. The pesticide ATZ was the most recalcitrant compound, yet the processes carried out from UASB effluent achieved removal >99.99%. The post-treatment of the UASB reactor by photo-Fenton removed acute toxicity in D. magna for all treatment times. However, only the photo-Fenton conducted for 90 min did not result in a phytotoxic effect in L. sativa.
... No mesmo foi utilizado um reator composto por lâmpadas de xenônio de 500 W imersas e fotólise UV artificial no mesmo reator por lâmpadas de descarga de mercúrio com emissão na região UV-C do espectro. Os autores reportaram uma cinética de pseudo-primeira ordem em ambos os experimentos, com k 1 de 0,0002 min -1 e 0,014 min -1 , respectivamente (GIANNAKIS et al., 2016). Considerando a semelhança da matriz testada com o esgoto tratado empregado em nossa pesquisa e as variações no aparato instrumental verifica-se similaridade em termos de ordem de grandeza para os valores de constante cinética em ambos os estudos. ...
Chapter
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... with H2O2 to generate sufficient HO • for intensification of PHE degradation. Similar results, i. e. that photo-Fenton process was no more efficient than UVB/H2O2 process, were also reported in previous researches (Giannakis et al., 2017;Karci et al., 2014). In UVB/H2O2/Fe(III)-CA process, PHE oxidation was strongly intensified and reached a final removal of 46.4% (Figure 4-4a). ...
Thesis
... According to the World Health Organization (WHO), the global prevalence of depression was about 4.5% of the population (332 million people) in 2015 [39]. After consumption, the antidepressants and their metabolites, which are formed by biotransformation in the body, usually follow the renal elimination route and consequently reach the wastewater treatment stations [40,41]. However, these compounds are not eliminated by the treatment processes and can reach surface waters in concentrations on the nanometric scale [42]. ...
Article
Abstarct Antidepressants are drugs widely used in nervous disorders, such as anxiety, depression, and panic, and are eliminated through the urinary system. In bodies of water, they present high persistence and toxicity, even at low concentrations, conforming to the classification of emerging micropollutants. This work addresses the construction of phase diagrams for different biphasic systems, based on ionic liquids (ILs) and organic solvents, and their subsequent application in the partitioning of antidepressants such as fluoxetine hydrochloride, paroxetine hydrochloride and sertraline hydrochloride. The phase diagrams were measured gravimetrically at 298.15 ± 1.00 K and atmospheric pressure using the turbidity method. The ILs of the imidazolium family, with shorter chain length [C2mim]±, were the only ones able to form biphasic systems using 1,3-dioxolane. The driving force for phase separation is the comparison of hydrophobic/hydrophilic characteristics between the constituents. In this sense, the pair of constituents [C2min][OAc] and 1,3-dioxolane provided the phase diagram with the largest biphasic area. The partitioning of antidepressants was studied in systems formed by IL (25 wt%) + 1,3-dioxolane (50 wt%) + water (25 wt%) containing 1.05 µg.L⁻¹ of fluoxetine hydrochloride, 1.42 µg.L⁻¹ of paroxetine hydrochloride or 0.23 µg.L⁻¹ sertraline hydrochloride at 298.15 ± 1.00 K and atmospheric pressure. The partitioning followed the characteristics of antidepressant σ-profiles generated through COSMO-RS. The recoveries were high, and the proposed systems were shown to promote the selective isolation of pairs of these antidepressants.
... According to this description, the performance of the SEF process in 2 O  degrading PCT was evaluated in the presence of these quenching agents (TBA = EtOH = 100 mM and BQ = 20 mM) and the results are presented in Fig. 5a. As shown, TBA and EtOH effectively hindered PCT degradation in which after 60 min reaction time, PCT degradation reached 28%, and 25%, respectively, indicating that • OH radicals are the main agents for the degradation of PCT [57]. While BQ had a meager role in the degradation of PCT (80%). ...
Article
Pharmaceuticals are one of the most reported categories of anthropogenic micropollutants, which often require a specific remediation type to be eliminated from the environment. This study aimed to address the potential of degrading the pharmaceutical pollutant paracetamol (PCT) in the aqueous environment under ultrasound (US) assisted electro-Fenton by Fe2O3 (hematite) nanoparticles (HNPs) as a catalyst. The synthesized sample was characterized by various techniques including XRD, FESEM, EDS, X-ray dot-mapping, and FTIR. The performance of the electro-Fenton (EF) and US processes was evaluated separately and in combination under optimum conditions. The results showed that the sonoelectro-Fenton (SEF) process under optimum conditions, including pH of 5, HNPs dosage 0.15 g/L, applied current 230 mA, initial PCT concentration 20 mg/L, resulted in a PCT degradation of 98.9% within 60 min of electrolysis time. PCT degradation was well-fitted to the pseudo-first-order kinetic model. Meanwhile, scavenging experiments indicated the vital role of OH in the decomposition of PCT compared to the negligible role of O2∙-. The nitrate ions had a strong inhibitory effect, whereas chloride anions affected PCT elimination slightly. The reusability test of HNPs revealed that almost a 14% drop occurred at the end of the fourth cycle. The HNPs showed high catalytic activity for degradation of PCT compared to other conventional homogeneous transition metals. Besides, SEF-HNPs can successfully detoxify the PCT solution based on the bioassay test. The by-products of PCT degradation by SEF-HNPs were determined and degradation pathway was also proposed. Conclusively, the SEF-HNPs process could be an appropriate system for the removal of various contaminants from aqueous solutions.
... Low-pressure UV, alone or in combination with hydrogen peroxide (H 2 O 2 ), peroxydisulfate (PDS) and H 2 O 2 /Fenton, has been tested on different drugs in synthetic urine, with the combinations with PDS and H 2 O 2 /Fenton reaching the best results (Giannakis et al. 2017a, Giannakis et al. 2017b, Giannakis et al. 2017c, Zhang et al. 2016a ...
Article
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Over the last 15 years, urine treatment technologies have developed from lab studies of a few pioneers to an interesting innovation, attracting attention from a growing number of process engineers. In this broad review, we present literature from more than a decade on biological, physical-chemical and electrochemical urine treatment processes. Like in the first review on urine treatment from 2006, we categorize the technologies according to the following objectives: stabilization, volume reduction, targeted N-recovery, targeted P-recovery, nutrient removal, sanitization, and handling of organic micropollutants. We add energy recovery as a new objective, because extensive work has been done on electrochemical energy harvesting, especially with bio-electrochemical systems. Our review reveals that biological processes are a good choice for urine stabilization. They have the advantage of little demand for chemicals and energy. Due to instabilities, however, they are not suited for bathroom applications and they cannot provide the desired volume reduction on their own. A number of physical-chemical treatment technologies are applicable at bathroom scale and can provide the necessary volume reduction, but only with a steady supply of chemicals and often with high demand for energy and maintenance. Electrochemical processes is a recent, but rapidly growing field, which could give rise to exciting technologies at bathroom scale, although energy production might only be interesting for niche applications. The review includes a qualitative assessment of all unit processes. A quantitative comparison of treatment performance was not the goal of the study and could anyway only be done for complete treatment trains. An important next step in urine technology research and development will be the combination of unit processes to set up and test robust treatment trains. We hope that the present review will help guide these efforts to accelerate the development towards a mature technology with pilot scale and eventually full-scale implementations.
Chapter
For several years now, many substances that are known for saving the lives of billions of people, have paradoxically appeared as a new group of very dangerous contaminants. These compounds (for example, pharmaceuticals, pesticides, their metabolites, etc.) often have chronic and acute dangerous effects on humankind and other living beings. The presence of these pollutants is being documented and novel systems are being developed for their treatment every day. In this chapter, we review the literature from approximately the past 10 years, illustrating the decontamination of these chemicals by advanced oxidation processes (AOPs). A range of methods including novel catalytic systems for hydroxyl radical production as well as computation methods for prediction of CEC removal rate constants and their transformations are discussed. Furthermore, many (bio)transformation (by)products possess different (lower/higher) toxicological fingerprints, which can now also be assessed by advanced modelling. Moreover, many of these AOPs are limited commercially by their high capital and operating costs. All of these issues are addressed in this book chapter.
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Herbicides are chemicals used globally to kill unwanted plants so as to obtain high agricultural yields and good agricultural products. Herbicides are sometimes transported from the farmlands into water bodies mainly through runoffs. These chemicals are recalcitrant, and their accumulation is hazardous to abiotic and biotic components of the ecosystem. At present, the best alternative technology for elimination of herbicides in water is the usage of advanced oxidation processes (AOPs). The AOPs, which are performed homogeneously or heterogeneously, are capable of breaking down complex pollutants in water into carbon dioxide and mineral compounds. In these processes, ·OH is produced and used for degradation process. It is recommended that the total organic carbon (TOC) produced during degradation reaction be monitored because the ‧OH produced or generated can react to form intermediates before complete mineralisation is achieved. Different kinds of AOPs for degradation of herbicides have their specific advantages as well as limitations. This report shows that AOPs are excellent techniques for degradation of herbicides in aqueous solutions, and the mechanisms showed that herbicides were mineralised. The amount and type of photocatalysts, pH of the medium, surface characteristics of the photocatalysts, doping of the photocatalysts, temperature of the medium, concentration of herbicides, presence of competing ions, intensity and irradiation period, and type of oxidants have great influence on the degradation of herbicides in water. Overall, this report showed that most AOPs could not completely degrade herbicides in water and complete degradation can be achieved by developing novel and robust AOPs that will completely mineralise herbicides in water—this will pave way for water and environmental safety.
Article
Antidepressant drugs such as Venlafaxine (VFX) and O-desmethylvenlafaxine (ODMVFX) are emerging contaminants that are commonly detected in aquatic environments, since conventional wastewater treatment plants are unable to completely remove them. They can be precursors of hazardous by-products, such as the carcinogenic N-nitrosodimethylamine (NDMA), generated upon water chlorination, as they contain the dimethylamino moiety, necessary for the formation of NDMA. In this study, the capability of three white rot fungi (Trametes versicolor, Ganoderma lucidum and Pleurotus ostreatus) to remove both antidepressants from water and to decrease NDMA formation potential was investigated. Furthermore, transformation by-products (TPs) generated along the treatment process were elucidated and also correlated with their NDMA formation potential. Very promising results were obtained for T. versicolor and G. lucidum, both being able to remove up to 100% of ODMVFX. In the case of VFX, which is very recalcitrant to conventional wastewater treatment, a 70% of removal was achieved by T. versicolor, along with a reduction in NDMA formation potential, thus decreasing the associated problems for human health and the environment. However, the NDMA formation potential remained practically constant during treatment with G. lucidum despite of the equally high VFX removal (70%). This difference was attributed to the generation of different TPs during both fungal treatments. For example, G. lucidum generated more ODMVFX, which actually has a higher NDMA formation potential than the parent compound itself.
Article
The ubiquity of antidepressants in the environment has posed a potential threat to eco-systematic safety. In this study, six kinds of antidepressants including fluoxetine (FLU), paroxetine (PAR), sertraline (SER), fluvoxamine (FLX), citalopram (CTP), and venlafaxine (VEN) were selected to explore their degrading kinetics, transformation pathways, and the acute toxicity of the reaction solution during UV oxidation. The results showed that the order of the photodegradation rate was FLU > PAR > SER > CTP > FLX > VEN. The calculation results of density functional theory (DFT) and molecular orbital theory showed that it was positively correlated with the frontier electron density of drugs and negatively correlated with the HOMO-LUMO gap, respectively. Intermediates were identified with UHPLC-Q-TOF/MS/MS to propose the possible degradation pathways of the drugs and the most likely directions of the reactions were determined by the single point energy calculation. The results of toxicity tests indicated that the acute toxicity of the reaction solution of PAR did not change significantly. The photolysates toxicity of FLU, SER, and FLX decreased at the end of the reaction, while that of CTP and VEN was increased by 1.5 and 1.3 times compared with the parent compound, respectively. Toxicity predictions by the quantitative structure activity relationship (QSAR) model showed that except FLU-162, FLX-174, and VEN-230, other degradation products have developmental toxicity. The results revealed the transformation pathways of these drugs under the UV disinfection process in wastewater treatment plants, especially the formation of toxic by-products during the disinfection process.
Article
The effective removal of refractory antidepressant in wastewater is challenging. In this study, a novel strategy of cysteine-assisted Fe²⁺/persulfate system (Fe²⁺/Cys/PS) was applied for the venlafaxine (Ven, as a typical antidepressant) degradation. The obtained results revealed that the Ven removal was evidently accelerated and enhanced in Fe²⁺/Cys/PS process, and achieved complete degradation in 5 min with optimal dosage. Further analysis indicated that the Ven degradation efficiency was associated with the chemical concentrations (i.e. Fe²⁺, Cys and PS) and operational conditions (i.e. pH and temperature). Moreover, the reactions were not impacted by the co-occurring organic matters (i.e. fulvic acid) and inorganic ions (i.e. Cl⁻) potentially existing in real wastewater matrices. Mechanistic explorations demonstrated that the presence of Cys promoted the Fe³⁺/Fe²⁺ redox cycle, and thus enhanced the reactive oxygen species yields (ROS). The OH was considered as the primary ROS in Fe²⁺/Cys/PS process for Ven degradation via the radical scavenger verification. Also, the main intermediates of Ven degradation were identified, and the possible transformation pathway was proposed, in which the hydroxylation attacked by the OH was the main reaction. Moreover, the active reaction sites in Ven were calculated with the density function theory (DFT), which was consistent with the observed metabolic routes.
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The degradation of p-nitrophenol (pNP) was investigated in the chemical-less UVC/VUV process (Advanced Oxidation/Reduction Process, AORP), the packed bed bioreactor (PBR), and the hybrid of AORP/PBR system. The control UVC/VUV process degraded and mineralized pNP with rate constants of 0.098 and 0.032 min⁻¹, respectively, at neutral initial pH. Operating the UVC/VUV process in a fluidized bed reactor improved the rate of pNP degradation by 21 % at a packing ratio of 0.5 %. The fluidized bed AORP was operated under continuous-flow mode, where 79 % degradation and 28 % mineralization of pNP were obtained along a significant improvement in the biodegradability (41 %) at a hydraulic retention time of 20 min. The oxidation with HO and reduction with eaq− simultaneously contributed to the degradation of pNP in the UVC/VUV process. In comparison, degradation and mineralization of pNP in a single PBR process (without pretreatment) was found to be 84.7 % and 47.2 %, respectively, during 30 h biotreatment. Coupling the fluidized bed UVC/VUV with the PBR attained complete biodegradation of the residual pNP within 1 h and over 89 % of TOC reduction during 3 h post treatment in the PBR. Accordingly, the hybrid, fluidized bed UVC/VUV reactor coupled with the PBR is an efficient and promising technology for treating toxic environmental contaminants.
Article
Resources in urine-containing wastewater are useful if recovered as nutrients. In this study, a three-chamber resource recovery microbial fuel cell (RRMFC) is proposed to treat synthetic urine-containing wastewater with various organic pollutants and recover N, P, and S nutrients. In the treatment, urea hydrolysis was increased by microbial and electrical processes. Ions migration driven by the self-generated electric field was used to recover nutrients from the wastewater. Over one cycle (∼3 days), 99% of urea, 97% of COD, 99% of histidine, 91% of creatinine, 99% of sodium acetate, 98% of SO42−, and 99% of PO43− were removed from the wastewater, and at the same time, 42% of total nitrogen, 37% of PO43−, 59% of SO42−, and 33% of total salts were recovered in the middle chamber. This technology is very attractive for sustainable resource recovery from urine-containing wastewater.
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Vacuum UV (VUV) technologies have recently attracted high interest due to their high efficacy in generating reactive oxygen species (ROS). To date, no systematic study of the modes of action of the integrated VUV/Fe(II)/H2O2 process against contaminants elimination exists; the present study reports the oxidation of MTBE in a new light-assisted Fenton-process, by employing either narrowband UVC (254 nm) or VUV (185 and 254 nm) irradiation, in a comparative evaluation. The processes under investigation were the UVC- or VUV/Fe(II)/H2O2 sensitized ones and their constituents, i.e. Fe(II)/H2O2, VUV, VUV/Fe(II), VUV/H2O2, VUV/Fe(II)/H2O2, as well as the UVC, UVC/H2O2 and UVC/Fe(II)/H2O2. We scrutinize the operational parameters of the VUV-assisted process, its enhancements and synergies, comparison with the UVC-based ones, as well as their inflicted pathways towards MTBE degradation. Complete degradation and 87.8% mineralization of 50 mg/L MTBE was achieved in the VUV/Fe(II)/H2O2 process (0.9 mM Fe(II) and 3 mM H2O2), at near-neutral pH (reaction times: ∼30 and 60 min, respectively). Irradiation with VUV light was found to act synergistically and in high kinetic rates enhancement compared to the UVC source, sensitizing the Fenton process for effective oxidation of MTBE in the aqueous solution. A scavenger study and degradation by-products investigation has been performed, leading to a mechanistic pathway proposition, elucidating MTBE degradation. The VUV/Fe(II)/H2O2 process demonstrated potential applicability in the field since it could efficiently treat (100% degradation and 86.4% mineralization) groundwater spiked with MTBE, operated either under batch or continuous-flow mode. The findings clearly indicates the VUV-assisted Fenton as an emerging and viable technology for field application to treat the MTBE-contaminated effluents or waters.
Article
Sedentary lifestyle, malnutrition and intense work hours resulting in high stress are challenging the human mind and psychology. Many people are genetically predisposed, but many, unfortunately, are unable to withstand this life and need professional support. Although technology is produced to make life easier, in practice it causes many people to live outside the border. Antidepressants, which are used as a result of professional support, benefit in the short term, but they cause serious damage to environmental and aquatic life on the invisible side of the iceberg due to personal waste, irregular use and overdose. If there is no follow-up and environmental removal, all non-target creatures other than humans will be damaged in a very short time, and hence this damage will return to the human being, like a boomerang. Although many methods have been developed for the treatment of these types of pollutants today, it is clear that new agents and methods should be developed that will enable mobile study in natural environment where the pollution emerges. Accordingly, the aim of this review is to make a critical analysis of studies on the determination, removal, and elimination of antidepressants in recent years and to inspire future studies.
Article
One of the new electrochemical sensors has been devised and fabricated for the highly sensitive determination of venlafaxine on the basis of ZnO nanoflowers (ZnO-NF) as modified materials. Therefore, hydrothermal methods have been used to synthesize zinc oxide nanoflowers. The formation of ZnO nanoflower has been confirmed via Fourier transform infrared (FTIR), XRD, and FESEM. Owing to the ZnO nanoflowers with the greater surface areas to oxidation of venlafaxine, venlafaxine has been sensitively determined with the linear ranges between 0.04 and 475.0 µM and LOD equal to 0.01 µM (S/N = 3). This new technique has been substantially utilized to determine venlafaxine in real samples.
Article
Article
The presence of serotonin-norepinephrine reuptake inhibitors (SNRIs) such as venlafaxine (VEN) in surface waters has caused some concerns due to their harmful impacts on the human health and environment security. In the study, ultraviolet (UV) coupled with chlorine was developed for degrading VEN. Among the experiments, the UV/chlorine process demonstrated the highest performance in eliminating VEN. UV irradiation alone played a negligible role in VEN degradation. 39.56% of VEN was degraded by dark chlorination in 30 min, while 76.02% of VEN was decayed by UV/chlorine treatment within 30 min. Adding chlorine dosage and raising solution pH both facilitated the VEN removal. HCO3⁻, Cl⁻ and HA inhibited VEN degradation during UV/chlorine treatment in accordance with predicted data. Furthermore, Kintecus software was applied to simulate the process of VEN degradation. Under UV/chlorine co-exposure, hydroxyl radical (HO·), chlorine and reactive chlorine species (RCS) were all proved to provide significant contribution to VEN oxidation. Note that both experimental and predicted contributions of HO· decreased as solution pH increased from 5.0 to 8.0. Four transformation pathways of VEN during UV/chlorine process were elucidated on basis of the DFT calculation and LC/MS analysis. Moreover, ECOSAR model program showed that UV/chlorine process reduced ecological toxicity of VEN obviously. Considering the influence of various factors, the most economical experimental conditions consist of chlorine (2.0-4.0 mg L⁻¹) and pH (7.0-8.0).
Article
Venlafaxine, a representative antidepressant, has been detected frequently in aquatic environments. The treatment of venlafaxine by free chlorine (NaOCl) and chlorine dioxide (ClO2) was investigated in this study. The effects of operational variables and the water matrix on venlafaxine degradation were evaluated. The transformation pathways of venlafaxine were also studied. The results indicated that venlafaxine was removed efficiently during disinfection processes, especially when reacted with ClO2. A higher dosage of disinfectant and mildly alkaline conditions (pH 9) enhanced the degradation of venlafaxine. The reactions were impacted when the tests were conducted in real water matrices, especially in secondary effluent. The presence of chloride and low concentrations of fulvic acid enhanced venlafaxine decomposition. The presence of Br⁻ also accelerated the reaction between venlafaxine and NaOCl. However, NO2⁻ inhibited venlafaxine removal in both disinfection processes. Six intermediates were identified during venlafaxine degradation by ultrahigh-performance liquid chromatography with quadrupole-time-of-flight mass spectrometry, and the main reactions included dehydration and demethylation.
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One of the most important sources of reactive oxygen species (ROS) in biological systems is the Fenton reaction. In this, the Fe2+ or Fe3+ reacts with H2O2 to produce ROS as the hydroxyl radical (∙OH), superoxide radical (O2-) and singlet oxygen (1O2). The main ROS, responsible for the high oxidizing power of the Fenton reaction, is not clear. Some authors claim that the principal reactive species is ∙OH, while others propose a ferryl specie (Fe4+ or [FeO]2+)(1,2). Recently, have been proposed that the kind of reaction species produced depends mainly of pH and the iron composition of the coordination sphere. This is highlighted for Fe3+, because in mono and (some) bis-complexes Fe3+ is reduced to Fe2+ and there are some positions occupied by water or hydroxide ligands, readily to be exchanged by H2O2. On the other hand, in tris-complexes there are not any positions occupied by water or hydroxide, avoiding the formation of peroxo-complexes, necessary for Fenton or Fenton like reaction. The 1,2-dihydroxybenzenes (DHBs) have been described as modulators of Fenton reaction. The DHBs driven Fenton reaction have been used for environmental applications as an advanced oxidation process. Furthermore, these systems participate in different biological process, as the wood biodegradation by fungi and oxidative stress in neurodegenerative diseases. In this review, the effect of 1,2-dihydroxybenzenes on the activated species production by the Fenton and Fenton like reaction will be discussed and its participation in different systems.
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Photochemical degradation of fluoroquinolone ciprofloxacin (CIP) in water by UV and UV/H2O2 were investigated. The degradation rate of CIP was affected by pH, H2O2 dosage, as well as the presence of other inorganic components. The optimized pH value and H2O2 concentration were 7.0 and 5 mM. Carbonate and nitrate both impeded CIP degradation. According to liquid chromatography–tandem mass spectrometry analysis, four and 16 products were identified in UV and UV/H2O2 system, respectively. Proposed degradation pathways suggest that reactions including the piperazinyl substituent, quinolone moiety, and cyclopropyl group lead to the photochemical degradation of CIP. Toxicity of products assessed by Vibrio qinghaiensis demonstrated that UV/H2O2 process was more capable on controlling the toxicity of intermediates in CIP degradation than UV process.
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Water Reuse: An International Survey of current practice, issues and needs examines water reuse practices around the world from different perspectives. The objective is to show how differently wastewater reuse is conceived and practised around the world as well as to present the varied needs and possibilities for reusing wastewater. In the first section water reuse practices around the world are described for regions having common water availability, reuse needs and social aspects. The second section refers to the "stakeholders" point of view. Each reuse purpose demands different water quality, not only to protect health and the environment but also to fulfil the requirements of the specific reuse. Reuses considered are agricultural, urban agriculture as a special case of the former, municipal and industrial. Alongside these uses, the indirect reuse for human consumption through aquifer recharge is also discussed. The third section deals with emerging and controversial topics. Ethical and economical dilemmas in the field are presented as a subject not frequently addressed in this field. The role of governments in respect of public policy in reuse is discussed as well as the different international criteria and standards for reusing wastewater. The importance of public acceptance and the way to properly handle it is also considered. The fourth section of the book presents contrasting case studies; typical situations in the developed world (Japan and Germany) are compared to those in developing countries (Pakistan and Brazil) for agricultural and industrial reuse. Indirect planned reuse for human consumption (Germany) is compared with an unplanned one (Mexico). The Windhoek, Namibia case study is presented to emphasize why if the direct reuse of wastewater for human consumption has been performed with success for more than 35 years it is still the only example of this type around the world. To illustrate the difficulties of having a common framework for regulating water reuse in several countries, the Mediterranean situation is described. Other case studies presented refer to the reuse situation in Israel, Spain, Cameroon, Nepal and Vietnam, these latter countries being located in water rich areas. This book will be an invaluable information source for all those concerned with water reuse including water utility managers, wastewater policy makers and water resources planners as well as researchers and students in environmental engineering, water resources planning and sanitary engineering. This title belongs to Scientific and Technical Report Series ISBN: 9781780401881 (eBook) ISBN: 9781843390893 (Print)
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Abstract— A solution of 0.6 M iodide and 0.1 M iodate in 0.01 M borate buffer (pH 9.25) can be used as a chemical actinometer to measure the incident fluence from a low-pressure mercury lamp that puts out more than 85% of its energy at 254 nm. The actinometric solution is optically opaque to light below 290 nm and is optically transparent to wavelengths greater than 330 nm. Hence, the solution absorbs all of the germicidal wavelengths but little if any of the ambient light normally present in the laboratory. Iodate acts as an electron scavenger and prevents the back reaction of the free electron with the iodine atom following UV excitation of KI. Irradiation results in the linear formation of triiodide, which is quantitated by measuring its absorbance at 352 nm. The quantum yield for this system is approximately 0.75 0.03 at 20.7AoC or approximately three times greater than that obtained previously using nitrous oxide as an electron scavenger. A model is proposed to account for this difference. A precise expression to account for the concentration and temperature dependence of the quantum yield is given by pH = 0.75(1 + 0.23[C - 0.577])(1 + 0.02[T - 20.7]) where C is the concentration of iodide and T is the temperature. The concentration of iodide can be obtained from the absorbance at 300 nm prior to irradiation using 1.061 MJ cm−1 as the molar extinction coefficient. This actinometric system meets the quality criteria established by the International Union of Pure and Applied Chemistry with the caveat that it is designed to measure only germicidal radiation (i.e. wavelengths less than 290 nm).
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Some of the pharmaceuticals that are not extensively investigated in the aquatic environment are the anesthetic lidocaine (LDC), the analgesic tramadol (TRA), and the antidepressant venlafaxine (VEN). LDC metabolizes to 2,6-xylidine (2,6-DMA) and monoethylglycinexylidine (MEGX), TRA to O-desmethyltramadol (ODT), and VEN to O-desmethylvenlafaxine (ODV). Within this study, the distribution and behavior of these compounds in German wastewater treatment plants (WWTPs) were investigated. Samples of influents and effluents from WWTPs in Hesse, Germany were collected between January and September 2010. Analytes were extracted from wastewater samples by solid-phase extraction and from solid samples by sonication. Extracts were measured using gas chromatography/mass spectrometry. LDC, TRA, VEN, ODT, and ODV were detected in all analyzed influent and effluent samples. 2,6-DMA could not be identified. MEGX was not detected. TRA and ODV were present in untreated wastewater at the highest concentrations (max, 1,129 (TRA) and 3,302 ng L⁻¹ (ODV)), while the concentrations of LDC and VEN were all significantly lower (mean, 135 (LDC) and 116 ng L⁻¹ (VEN)). All of the analytes were only partially removed in the WWTPs. The mean ratios between the concentrations of the metabolites and their respective parent compounds in influents were 4.7 (ODV/VEN) and 0.7 (ODT/TRA). These values remain approximately constant comparing influents and effluents. LDC, TRA, VEN, ODT, and ODV are only partially removed from sewage water by WWTPs and thus are continuously discharged in respective recipient rivers. A further transformation of TRA and VEN into the known metabolites during treatment in the WWTPs is not observed.
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Human enteric viruses are causative agents in both developed and developing countries of many non-bacterial gastrointestinal tract infections, respiratory tract infections, conjunctivitis, hepatitis and other more serious infections with high morbidity and mortality in immunocompromised individuals such as meningitis, encephalitis and paralysis. Human enteric viruses infect and replicate in the gastrointestinal tract of their hosts and are released in large quantities in the stools of infected individuals. The discharge of inadequately treated sewage effluents is the most common source of enteric viral pathogens in aquatic environments. Due to the lack of correlation between the inactivation rates of bacterial indicators and viral pathogens, human adenoviruses have been proposed as a suitable index for the effective indication of viral contaminants in aquatic environments. This paper reviews the major genera of pathogenic human enteric viruses, their pathogenicity and epidemiology, as well as the role of wastewater effluents in their transmission.
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In this work, disinfection by 5 Advanced Oxidation Processes was preceded by 3 different secondary treatment systems present in the wastewater treatment plant of Vidy, Lausanne (Switzerland). 5 AOPs after two biological treatment methods (conventional activated sludge and moving bed bioreactor) and a physiochemical process (coagulation-flocculation) were tested in laboratory scale. The dependence among AOPs efficiency and secondary (pre)treatment was estimated by following the bacterial concentration i) before secondary treatment, ii) after the different secondary treatment methods and iii) after the various AOPs. Disinfection and post-treatment bacterial regrowth were the evaluation indicators. The order of efficiency was Moving Bed Bioreactor > Activated Sludge > Coagulation-Flocculation > Primary Treatment. As far as the different AOPs are concerned, the disinfection kinetics were: UVC/H2O2 > UVC and solar photo-Fenton > Fenton or solar light. The contextualization and parallel study of microorganisms with the micropollutants of the effluents revealed that higher exposure times were necessary for complete degradation compared to microorganisms for the UV-based processes and inversed for the Fenton-related ones. Nevertheless, in the Fenton-related systems, the nominal 80% removal of micropollutants deriving from the Swiss legislation, often took place before the elimination of bacterial regrowth risk.
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In this study, wastewater from the output of three different secondary treatment facilities (Activated Sludge, Moving Bed Bioreactor and Coagulation-Flocculation) present in the municipal wastewater treatment plant of Vidy, Lausanne (Switzerland), was further treated with various oxidation processes (UV, UV/H2O2, solar irradiation, Fenton, solar photo-Fenton), at laboratory scale. For this assessment, 6 organic micropollutants in agreement with the new environmental legislation requirements in Switzerland were selected (Carbamazepine, Clarithromycin, Diclofenac, Metoprolol, Benzotriazole, Mecoprop) and monitored throughout the treatment. Also, the overall removal of the organic load was assessed. After each secondary treatment, the efficiency of the AOPs increased in the following order: Coagulation-Flocculation < Activated Sludge < Moving Bed Bioreactor, in almost all cases. From the different combinations tested, municipal wastewater subjected to biological treatment followed by UV/H2O2 resulted in the highest elimination levels. Wastewater previously treated by physicochemical treatment demonstrated considerably inhibited micropollutant degradation rates. The degradation kinetics were determined, yielding: k (UV) < k (UV/H2O2) and k (Fenton) < k (solar irradiation) < k (photo-Fenton). Finally, the evolution of global pollution parameters (COD & TOC elimination) was followed and the degradation pathways for the effluent organic matter are discussed.
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Escherichia coli is the predominant nonpathogenic facultative flora of the human intestine. Some E. coli strains, however, have developed the ability to cause disease of the gastrointestinal, urinary, or central nervous system in even the most robust human hosts. Diarrheagenic strains of E. coli can be divided into at least six different categories with corresponding distinct pathogenic schemes. Taken together, these organisms probably represent the most common cause of pediatric diarrhea worldwide. Several distinct clinical syndromes accompany infection with diarrheagenic E. coli categories, including traveler’s diarrhea (enterotoxigenic E. coli), hemorrhagic colitis and hemolytic-uremic syndrome (enterohemorrhagic E. coli), persistent diarrhea (enteroaggregative E. coli), and watery diarrhea of infants (enteropathogenic E. coli). This review discusses the current level of understanding of the pathogenesis of the diarrheagenic E. coli strains and describes how their pathogenic schemes underlie the clinical manifestations, diagnostic approach, and epidemiologic investigation of these important pathogens.
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In this work, an Iodinated Contrast Medium (ICM), Iohexol, was subjected to treatment by 3 Advanced Oxidation Processes (AOPs) (UV, UV/H2O2, UV/H2O2/Fe2+). Water, wastewater and urine were spiked with Iohexol, in order to investigate the treatment efficiency of AOPs. A tri-level approach has been deployed to assess the UV-based AOPs efficacy. The treatment was heavily influenced by the UV transmittance and the organics content of the matrix, as dilution and acidification improved the degradation but iron/H2O2 increase only moderately. Furthermore, optimization of the treatment conditions, as well as modeling of the degradation was performed, by step-wise constructed quadratic or product models, and determination of the optimal operational regions was achieved through desirability functions. Finally, global chemical parameters (COD, TOC and UV-Vis absorbance) were followed in parallel with specific analyses to elucidate the degradation process of Iohexol by UV-based AOPs. Through HPLC/MS analysis the degradation pathway and the effects the operational parameters were monitored, thus attributing the pathways the respective modifications. The addition of iron in the UV/H2O2 process inflicted additional pathways beneficial for both Iohexol and organics removal from the matrix.
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In this work, disinfection by 5 Advanced Oxidation Processes was preceded by 3 different secondary treatment systems present in the wastewater treatment plant of Vidy, Lausanne (Switzerland). 5 AOPs after two biological treatment methods (conventional activated sludge and moving bed bioreactor) and a physiochemical process (coagulation-flocculation) were tested in laboratory scale. The dependence among AOPs efficiency and secondary (pre)treatment was estimated by following the bacterial concentration i) before secondary treatment, ii) after the different secondary treatment methods and iii) after the various AOPs. Disinfection and post-treatment bacterial regrowth were the evaluation indicators. The order of efficiency was Moving Bed Bioreactor > Activated Sludge > Coagulation-Flocculation > Primary Treatment. As far as the different AOPs are concerned, the disinfection kinetics were: UVC/H2O2 > UVC and solar photo-Fenton > Fenton or solar light. The contextualization and parallel study of microorganisms with the micropollutants of the effluents revealed that higher exposure times were necessary for complete degradation compared to microorganisms for the UV-based processes and inversed for the Fenton-related ones. Nevertheless, in the Fenton-related systems, the nominal 80% removal of micropollutants deriving from the Swiss legislation, often took place before the elimination of bacterial regrowth risk.
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The photochemical degradation of the antidepressant drug venlafaxine (VNF) by UV/TiO2 process was investigated in the present study. Prescreening experiments were conducted to study the effects of main parameters affecting the photocatalytic process. In addition, the effects and interactions of most influenced parameters were evaluated and optimized by using a central composite design model and a response surface methodology. Results indicated that VNF was quickly removed in all the irradiation experiments and its degradation was mainly affected by the studied variables (catalyst dose, initial VNF concentration and pH), as well as their interaction effects. Parallel to kinetic studies, the transformation products (TPs) generated during the treatment was investigated using LC coupled to low and high resolution mass spectrometry. Based on identification of the main TPs, tentative transformation pathways were proposed, including hydroxylation, demethylation and dehydration as major transformation routes. Τhe potential risk of VNF and its TPs to aqueous organisms was also investigated using Microtox bioassay before and during the processes. The obtained results showed an increment in the acute toxicity in the first stages and a continuously decreasing after then to very low values reached within 240 min of the photocatalytic treatment, demonstrating that UV/TiO2 can lead to the elimination of parent compound and the detoxification of the solution.
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The aim of the present work is to investigate the removal and transformation of the antidepressants venlafaxine (VFX) and its main metabolite O-desmethylvenlafaxine (DVFX) upon advanced oxidation with UV/H2O2 under lab conditions. High-resolution mass spectrometry (HRMS) analyses were carried out by means of ultra-high pressure liquid chromatography (UHPLC)-linear ion trap high resolution Orbitrap instrument (LTQ-Orbitrap-MS) in order to elucidate the different transformation products (TPs) generated. The depletion of both VFX and DVFX was very significant, with the 99.9% of both compounds eliminated after 5 and 30 min of reaction, respectively. Eleven TPs for VFX and six for DVFX were detected and their molecular structures elucidated by means of MS2 and MS3 scans, and the corresponding degradation pathways were proposed. The combined ecotoxicity at different treatment times was evaluated by means of bioluminescence inhibition assays with the marine bacteria Vibrio fischeri. Results showed an increase in the ecotoxicity during the UV/H2O2 experiment, especially at those reaction times where the total abundance of TPs was higher.
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Escherichia coli is the predominant nonpathogenic facultative flora of the human intestine. Some E. coli strains, however, have developed the ability to cause disease of the gastrointestinal, urinary, or central nervous system in even the most robust human hosts. Diarrheagenic strains of E. coli can be divided into at least six different categories with corresponding distinct pathogenic schemes. Taken together, these organisms probably represent the most common cause of pediatric diarrhea worldwide. Several distinct clinical syndromes accompany infection with diarrheagenic E. coli categories, including traveler's diarrhea (enterotoxigenic E. coli), hemorrhagic colitis and hemolytic-uremic syndrome (enterohemorrhagic E. coli), persistent diarrhea (enteroaggregative E. coli), and watery diarrhea of infants (entero-pathogenic E. coli). This review discusses the current level of understanding of the pathogenesis of the diarrheagenic E. coli strains and describes how their pathogenic schemes underlie the clinical manifestations, diagnostic approach, and epidemiologic investigation of these important pathogens.
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Venlafaxine, gemfibrozil, ibuprofen, irbesartan and ofloxacin are highly-consumed pharmaceuticals that show considerable removal efficiencies (between 40 and 98%) in wastewater treatment plants (WWTPs). Consequently, they are expected to generate transformation products (TPs) during wastewater treatment and in surface water (SW) receiving WWTP effluent. In this work, degradation experiments for these five pharmaceuticals have been carried out with SW and WWTP activated sludge under laboratory-controlled aerobic conditions to identify their transformation products by liquid chromatography coupled to time-of-flight mass spectrometry (LC-QTOF MS). Initially, 22 pharmaceutical TPs were tentatively identified. A retrospective analysis was performed in effluent wastewater (EWW) and SW samples. All parent compounds as well as several TPs were found in some of the selected EWW and SW samples. Additionally, valsartan and 3 TPs were also detected by searching for common fragments in these waters. It is important to highlight that some TPs, such as O-desmethyl-venlafaxine and an oxidized gemfibrozil TP, were more frequently found than their corresponding parent compounds. On the basis of these results, it would be recommendable to include these TPs (at least those found in EWW and SW samples analyzed) in monitoring programs in order to gain a more realistic understanding of the impact of pharmaceuticals on water quality.
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