Synthesis, Characterization and Performance of Materials for a Sustainable Future

The current era has been defined as "The Plastic Era", considering that over the past 50 years the role and importance of polymeric materials in our economy has steadily grown, reaching a production of around a few hundred million tons per year which may even double in the next 20 years [...].

Synthesis, Characterization and Performance of Materials for a Sustainable Future

Today, sustainability represents the key factor for economic progress in compliance with social advancement and environmental protection, driving innovation in materials, processes and technologies [...].

A novel sensitive analytical method for the simultaneous analysis of vancomycin and teicoplanin in human urine via single high-performance liquid chromatography coupled with photodiode array and mass spectrometry in series

Analysis of vancomycin and teicoplanin in biological fluids is vital since they are used in the treatment of hospital infections. For the determination of both glycopeptides in urine, a sensitive and accurate analytical method using high‐performance liquid chromatography coupled with photodiode array and mass spectrometry was developed and validated. This research work is the first attempt to develop a chromatographic method for the determination of two glycopeptides with structural similarities. Moreover, the used non‐invasive sampling method is an advantage of this research effort, especially when the blood sampling is difficult. Urine was treated with acetonitrile and 5% trichloroacetic acid, followed by solid‐phase extraction. The chromatographic separation was established at a C18 column (4.6 × 150 mm, 5 μm), using a gradient method and an electrospray ionization source in a positive mode. The linearity of the method was R²≥ 0.9900. The precision was estimated with a maximum coefficient of variation below 15%, while the accuracy ranged from 64 to 121%. The limit of detection and quantification of both glycopeptides ranged from 0.076 up to 0.33 mg/L and 0.33 up to 2.1 mg/L, respectively, showing the same sensitivity as the triple quadrupole mass spectrometry, which is the most frequently used method.

Hybrid Biochar/Ceria Nanomaterials: Synthesis, Characterization and Activity Assessment for the Persulfate-Induced Degradation of Antibiotic Sulfamethoxazole

Biochar from spent malt rootlets was employed as the template to synthesize hybrid biochar-ceria materials through a wet impregnation method. The materials were tested for the activation of persulfate (SPS) and subsequent degradation of sulfamethoxazole (SMX), a representative antibiotic, in various matrices. Different calcination temperatures in the range 300-500 °C were employed and the resulting materials were characterized by means of N2 adsorption and potentiometric mass titration as well as TGA, XRD, SEM, FTIR, DRS, and Raman spectroscopy. Calcination temperature affects the biochar content and the physicochemical properties of the hybrid materials, which were tested for the degradation of 500 μg L-1 SMX with SPS (in the range 200-500 mg L-1) in various matrices including ultrapure water (UPW), bottled water, wastewater, and UPW spiked with bicarbonate, chloride, or humic acid. Materials calcined at 300-350 °C, with a surface area of ca. 120 m2 g-1, were the most active, yielding ca. 65% SMX degradation after 120 min of reaction in UPW; materials calcined at higher temperatures as well as bare biochar were less active. Degradation decreased with increasing matrix complexity due to the interactions amongst the surface, the contaminant, and the oxidant. Experiments in the presence of scavengers (i.e., methanol, t-butanol, and sodium azide) revealed that sulfate and hydroxyl radicals as well as singlet oxygen were the main oxidative species.

Spatio-temporal assessment of illicit drug use at large scale: evidence from 7 years of international wastewater monitoring

BACKGROUND AND AIMS

Wastewater-based epidemiology is an additional indicator of drug use that is gaining reliability to complement the current established panel of indicators. The aims of this study were to: (i) assess spatial and temporal trends of population-normalized mass loads of benzoylecgonine, amphetamine, methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) in raw wastewater over 7 years (2011-17); (ii) address overall drug use by estimating the average number of combined doses consumed per day in each city; and (iii) compare these with existing prevalence and seizure data.

DESIGN

Analysis of daily raw wastewater composite samples collected over 1 week per year from 2011 to 2017.

SETTING AND PARTICIPANTS

Catchment areas of 143 wastewater treatment plants in 120 cities in 37 countries.

MEASUREMENTS

Parent substances (amphetamine, methamphetamine and MDMA) and the metabolites of cocaine (benzoylecgonine) and of Δ⁹ -tetrahydrocannabinol (11-nor-9-carboxy-Δ⁹ -tetrahydrocannabinol) were measured in wastewater using liquid chromatography-tandem mass spectrometry. Daily mass loads (mg/day) were normalized to catchment population (mg/1000 people/day) and converted to the number of combined doses consumed per day. Spatial differences were assessed world-wide, and temporal trends were discerned at European level by comparing 2011-13 drug loads versus 2014-17 loads.

FINDINGS

Benzoylecgonine was the stimulant metabolite detected at higher loads in southern and western Europe, and amphetamine, MDMA and methamphetamine in East and North-Central Europe. In other continents, methamphetamine showed the highest levels in the United States and Australia and benzoylecgonine in South America. During the reporting period, benzoylecgonine loads increased in general across Europe, amphetamine and methamphetamine levels fluctuated and MDMA underwent an intermittent upsurge.

CONCLUSIONS

The analysis of wastewater to quantify drug loads provides near real-time drug use estimates that globally correspond to prevalence and seizure data.

Uptake and bioaccumulation of three widely prescribed pharmaceutically active compounds in tomato fruits and mediated effects on fruit quality attributes

Pharmaceutically active compounds (PhACs) released in agroecosystems have been found to be taken up by and accumulated in the edible parts of crop plants. By employing simulated hydroponic cultivation under controlled conditions, the present study aimed at evaluating 1) the uptake and bioaccumulation of three common PhACs (diclofenac, DCF; sulfamethoxazole, SMX; trimethoprim, TMP), either applied individually (10 μg L^-1) or as mixture (10 μg L^-1 each), in tomato fruits harvested from the first three fruit sets, and 2) the PhACs-mediated effects on fruit quality attributes. DCF was not detected in tomato fruits, whereas both SMX and TMP were detected in varying concentrations in fruits, depending on the time of harvest, the mode of application and the allocation of plants in the greenhouse. The studied PhACs applied at environmentally relevant concentrations did not significantly affect plant productivity. Nevertheless, important fruit quality attributes, such as soluble solids and carbohydrate (fructose, glucose, sucrose, total sugars) content were significantly impacted by all studied PhACs applied individually, suggesting that for DCF, potentially its transformation products (TPs) (not examined in this study) may exert significant effects on fruits quality attributes. In addition, no additive or synergistic effects of the mixture of PhACs on studied fruits quality attributes were revealed. Gene expression analysis showed that the PhACs-mediated effects on the carbohydrate content of fruits can be attributed, at least to some extent, to the significant modulation of the abundance of transcripts related to the biosynthesis and catabolism of sucrose, such as SlSuSys, SlLin5 and SlLin7. To our knowledge, this is the first report highlighting the potential effects of PhACs released in agroecosystems on the quality of widely consumed agricultural products. In any case, further studies are warranted for the overall assessment of the potential impacts of PhACs on the quality of agricultural products under conventional agricultural conditions.

Pharmaceuticals and illicit drugs in wastewater samples in north-eastern Tunisia

Pharmaceutically active substances (PhACs) and drugs of abuse (DAs) are two classes of contaminants of emerging concern that have attracted great concern and interest by the scientific community during the last two decades. Numerous studies have revealed their presence in treated urban wastewaters. This is mainly due to the fact that some compounds are not efficiently removed during wastewater treatment processes, and are thus able to reach the aquatic environment through wastewater discharge and reuse practices. The application of an optimized multi-residue method for the simultaneous confirmation and quantification of licit and illicit drugs has been investigated in influent and effluent wastewater samples from seven wastewater treatment plants (WWTPs) located in north-eastern Tunisia. Analysis was performed through ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Out of 12 pharmaceutical compounds analyzed, 11 of them were detected mainly in effluent wastewaters. In both matrices, antibiotics and β-blockers were the most detected groups. This suggests that these compounds show noticeable resistance against biological treatment in WWTPs. The estimated concentrations of antibiotics in effluents ranged from ca. 35 ng/L to 1.2 μg/L. However, all five studied illicit drugs were detected, mainly in influent wastewaters. Forensic investigation performed on people suspected to be drug abusers covering all Tunisian cities was conducted by monitoring an epidemiological study of human urine samples surveying rate of consumption for illicit drugs. Hence, these preliminary results confirmed the presence of illicit drugs in the influent wastewater samples. For example, quantification ranges for cocaine were found to be 25-450 ng/L in influent wastewater samples. Significant differences for cocaine consumption across the two sampling methods were observed. Consequently, we conclude that the analyses in wastewater are more reflective of the real levels of illicit drug consumption. Moreover, the cost for chromatographic analysis is lower than the screening test methods for human biological specimen, particularly staffing, which are likely to be much lower.

Assessing the presence of enrofloxacin and ciprofloxacin in piggery wastewater and their adsorption behaviour onto solid materials, with a newly developed chromatographic method

Veterinary antibiotics could enter the environment after the application of manure or farm wastewater on soil as fertilizer. In this study, a UPLC-MS/MS analytical method was developed and validated for the simultaneous determination of enrofloxacin (ENR) and ciprofloxacin (CIP) at environmental relevant concentrations in piggery wastewater, piggery wastewater solids, agricultural soil and ground water with good performance characteristics. The method recovery for ENR and CIP was 94.2 and 89.9% in the filtered piggery wastewater, 81.3 and 82% in the wastewater solid material, 78.1 and 76.8% in the soil and 95.6 and 97.3% in the ground water. The Limit of Detection (LOD) and Limit of Quantification (LOQ) for ENR were 21 and 64 ng L^-1 and for CIP was 18 and 54 ng L^-1, respectively. The method was implemented to monitor ENR and CIP in the wastewater of a piggery facility in Cyprus which applied anaerobic treatment before the final disposal of the reclaimed water. The highest antibiotic concentrations were measured in the wastewater samples collected from the nursery, where ENR is continuously used, with average concentration 31.4 μg L^-1 for ENR and 16.0 μg L^-1 for CIP. After the anaerobic digester, the two antibiotics were found only on the solid matter of the treated wastewater with an average concentration of 1.7 μg kg^-1 for ENR and 1.0 μg kg^-1 for CIP. The antibiotics adsorption at pH = 7 on clay soil, quartz sand and on solid matter isolated from the piggery wastewater was found to be higher than 95% for all solid materials. The concentration of the antibiotics in soil samples taken from a field where reclaimed piggery wastewater was applied for 10 years and in samples of groundwater from a nearby well was found for all samples below the LOD.

On the capacity of ozonation to remove antimicrobial compounds, resistant bacteria and toxicity from urban wastewater effluents

The degradation of erythromycin (ERY) and ethylparaben (EtP) in urban wastewater effluents at low concentration level during ozonation was investigated under different experimental conditions. Both substrates were rapidly eliminated within 2min at low ozone dose of 0.3mgL^-1 and the experimental data were well fitted in the pseudo-first-order kinetic model. The ratio of HO- and O₃-exposure (R_ct) at the inherent pH was found to be 1.9×10^-8. The degradation of ERY and EtP was pronounced at pH 8 compared to acidic pH conditions, while the degradation rate of both substrates was found to be matrix-depended. It was also shown that both O₃- and HO-mediated pathways are involved in the degradation of EtP, whereas the saturated-rich structure of ERY renders it O₃-recalcitrant. Under the optimum O₃ dose, the BrO₃^- concentration was found to be lower than 10μgL^-1. Five and fifteen transformation products were elucidated during ERY and EtP oxidation, respectively. The root and shoot inhibition can be attributed to the oxidation products formed upon dissolved effluent organic matter transformation. Escherichia coli harbouring resistance to ERY survived ozonation better than EtP-resistant E. coli. However, neither ERY- nor EtP-resistant E. coli were detected after 15min of ozonation.

Long-term wastewater irrigation of vegetables in real agricultural systems: Concentration of pharmaceuticals in soil, uptake and bioaccumulation in tomato fruits and human health risk assessment

Wastewater (WW) reuse for vegetable crops irrigation is regularly applied worldwide. Such a practice has been found to allow the uptake of pharmaceutical active compounds (PhACs) by plants and their subsequent entrance to the food web, representing an important alternative pathway for the exposure of humans to PhACs, with potential health implications. Herein we report the impacts of the long-term (three consecutive years) WW irrigation of a tomato crop with two differently treated effluents under real agricultural conditions, on (1) the soil concentration of selected PhACs (i.e. diclofenac, DCF; sulfamethoxazole, SMX; trimethoprim, TMP), (2) the bioaccumulation of these PhACs in tomato fruits, and (3) the human risks associated with the consumption of WW-irrigated fruits. Results revealed that the concentration of the studied PhACs in both the soil and tomato fruits varied depending on the qualitative characteristics of the treated effluent applied and the duration of WW irrigation. The PhAC with the highest soil concentration throughout the studied period was SMX (0.98 μg kg^-1), followed by TMP (0.62 μg kg^-1) and DCF (0.35 μg kg^-1). DCF was not found in tomato fruits harvested from WW-irrigated plants during the first year of the study. However, DCF displayed the highest fruit concentration (11.63 μg kg^-1) throughout the study (as a result of prolonged WW irrigation), followed by SMX (5.26 μg kg^-1) and TMP (3.40 μg kg^-1). The calculated fruit bioconcentration factors (BCF_F) were extremely high for DCF in the 2nd (108) and 3rd year (132) of the experimental period, with the respective values for SMX (0.5-5.4) and TMP (0.2-6.4) being significantly lower. The estimated threshold of toxicity concern (TTC) and hazard quotients (HQ) values revealed that the consumption of fruits harvested from tomato plants irrigated for long period with the WW applied for irrigation under field conditions in this study represent a de minimis risk to human health. However, more studies need to be performed in order to obtain more solid information on the safety of WW reuse for irrigation.

Measuring biomarkers in wastewater as a new source of epidemiological information: Current state and future perspectives

The information obtained from the chemical analysis of specific human excretion products (biomarkers) in urban wastewater can be used to estimate the exposure or consumption of the population under investigation to a defined substance. A proper biomarker can provide relevant information about lifestyle habits, health and wellbeing, but its selection is not an easy task as it should fulfil several specific requirements in order to be successfully employed. This paper aims to summarize the current knowledge related to the most relevant biomarkers used so far. In addition, some potential wastewater biomarkers that could be used for future applications were evaluated. For this purpose, representative chemical classes have been chosen and grouped in four main categories: (i) those that provide estimates of lifestyle factors and substance use, (ii) those used to estimate the exposure to toxicants present in the environment and food, (iii) those that have the potential to provide information about public health and illness and (iv) those used to estimate the population size. To facilitate the evaluation of the eligibility of a compound as a biomarker, information, when available, on stability in urine and wastewater and pharmacokinetic data (i.e. metabolism and urinary excretion profile) has been reviewed. Finally, several needs and recommendations for future research are proposed.

Assessing the potential of pharmaceuticals and their transformation products to cause mutagenic effects: Implications for gene expression profiling

The selection and prioritization of pharmaceuticals and their transformation products for evaluating effects on the environment and human health is a challenging task. One common approach is based on compounds (e.g., mixture composition, concentrations), and another on biology (e.g., relevant endpoint, biological organizational level). Both of these approaches often resemble a Lernaean Hydra-they can create more questions than answers. The present study embraces this complexity, providing an integrated approach toward assessing the potential effects of transformation products of pharmaceuticals by means of mutagenicity, estrogenicity, and differences in the gene expression profiles. Mutagenicity using the tk kinase assay was applied to assess a list of 11 priority pharmaceuticals, namely, atenolol, azithromycin, carbamazepine, diclofenac, ibuprofen, erythromycin, metoprolol, ofloxacin, propranolol, sulfamethoxazole, and trimethoprim. The most mutagenic compounds were found to be β-blockers. In parallel, the photolabile pharmaceuticals were assessed for their mixture effects on mutagenicity (tk assay), estrogenicity (T47D- KBluc assay), and gene expression (microarrays). Interestingly, the mixtures were mutagenic at the µg/L level, indicating a synergistic effect. None of the photolysed mixtures were statistically significantly estrogenic. Gene expression profiling revealed effects related mainly to certain pathways, those of the p53 gene, mitogen-activated protein kinase, alanine, aspartate, and glutamate metabolism, and translation-related (spliceosome). Fourteen phototransformation products are proposed based on the m/z values found through ultra-performance liquid chromatography-tandem mass spectrometry analysis. The transformation routes of the photolysed mixtures indicate a strong similarity with those obtained for each pharmaceutical separately. This finding reinforces the view that transformation products are to be expected in naturally occurring mixtures. Environ Toxicol Chem 2016;35:2753-2764. © 2016 SETAC.

Stress-related phenomena and detoxification mechanisms induced by common pharmaceuticals in alfalfa (Medicago sativa L.) plants

Pharmaceutically active compounds (PhACs) have been recently shown to exert phytotoxic effects. The present study explores the uptake, systemic translocation, and abiotic stress responses and detoxification mechanisms induced by the exposure of alfalfa plants grown in sand under greenhouse conditions to four common, individually applied PhACs (10μgL(-1)) (diclofenac, sulfamethoxazole, trimethoprim, 17a-ethinylestradiol) and their mixture. Stress physiology markers (lipid peroxidation, proline, H2O2 and NO content, antioxidant activity assays) and gene expression levels of key plant detoxification components (including glutathione S-transferases, GST7, GST17; superoxide dismutases, CuZnSOD, FeSOD; proton pump, H(+)-ATP, and cytochrome c oxidase, CytcOx), were evaluated. PhACs were detected in significantly higher concentrations in roots compared with leaves. Stress related effects, manifested via membrane lipid peroxidation and oxidative burst, were local (roots) rather than systemic (leaves), and exacerbated when the tested PhACs were applied in mixture. Systemic accumulation of H2O2 in leaves suggests its involvement in signal transduction and detoxification responses. Increased antioxidant enzymatic activities, as well as upregulated transcript levels of GST7, GST17, H(+)-ATPase and CytcOx, propose their role in the detoxification of the selected PhACs in plants. The current findings provide novel biochemical and molecular evidence highlighting the studied PhACs as an emerging abiotic stress factor, and point the need for further research on wastewater flows under natural agricultural environments.

Erythromycin oxidation and ERY-resistant Escherichia coli inactivation in urban wastewater by sulfate radical-based oxidation process under UV-C irradiation

This study evaluates the feasibility of UV-C-driven advanced oxidation process induced by sulfate radicals SO4(.)- in degrading erythromycin (ERY) in secondary treated wastewater. The results revealed that 10 mg L(-1) of sodium persulfate (SPS) can result in rapid and complete antibiotic degradation within 90 min of irradiation, while ERY decay exhibited a pseudo-first-order kinetics pattern under the different experimental conditions applied. ERY degradation rate was strongly affected by the chemical composition of the aqueous matrix and it decreased in the order of: ultrapure water (kapp = 0.55 min(-1)) > bottled water (kapp = 0.26 min(-1)) > humic acid solution (kapp = 0.05 min(-1)) > wastewater effluents (kapp = 0.03 min(-1)). Inherent pH conditions (i.e. pH 8) yielded an increased ERY degradation rate, compared to that observed at pH 3 and 5. The contribution of hydroxyl and sulfate radicals (HO. and SO4(.)-) on ERY degradation was found to be ca. 37% and 63%, respectively. Seven transformation products (TPs) were tentatively elucidated during ERY oxidation, with the 14-membered lactone ring of the ERY molecule being intact in all cases. The observed phytotoxicity against the tested plant species can potentially be attributed to the dissolved effluent organic matter (dEfOM) present in wastewater effluents and its associated-oxidation products and not to the TPs generated from the oxidation of ERY. This study evidences the potential use of the UV-C/SPS process in producing a final treated effluent with lower phytotoxicity (<10%) compared to the untreated wastewater. Finally, under the optimum experimental conditions, the UV-C/SPS process resulted in total inactivation of ERY-resistant Escherichia coli within 90 min.

Ultraviolet-activated persulfate oxidation of methyl orange: a comparison between artificial neural networks and factorial design for process modelling

In this work, the degradation of the azo dye methyl orange in model aqueous solutions by UVC light-induced persulfate oxidation was studied.

Assessment of long-term wastewater irrigation impacts on the soil geochemical properties and the bioaccumulation of heavy metals to the agricultural products

An extensive field survey was employed for assessing the impacts of long-term wastewater irrigation of forage crops and orange orchards in three suburban agricultural areas in Cyprus (areas I, II, and III), as compared to rainfed agriculture, on the soil geochemical properties and the bioaccumulation of heavy metals (Zn, Ni, Mn, Cu, Co) to the agricultural products. Both ryegrass fields and orange orchards in areas I and II were continuously wastewater irrigated for 10 years, whereas clover fields in area III for 0.5, 4, and 8 years. The results revealed that wastewater reuse for irrigation caused a slight increase in soil salinity and Cl(-) content in areas I and II, and a remarkable increase, having strong correlation with the period in which wastewater irrigation was practiced, in area III. Soil salinization in area III was due to the high electrical conductivity (EC) of the wastewater applied for irrigation, attributed to the influx of seawater to the sewage collection network in area III. In addition, the wastewater irrigation practice resulted in a slight decrease of the soil pH values in area III, while a subtle impact was identified regarding the CaCO3, Fe, and heavy metal content in the three areas surveyed. The heavy metal content quantified in the forage plants' above-ground parts was below the critical levels of phytotoxicity and the maximum acceptable concentration in dairy feed, whereas heavy metals quantified in orange fruit pulp were below the maximum permissible levels (MPLs). Heavy metal phytoavailability was confined due to soil properties (high pH and clay content), as evidenced by the calculated low transfer factor (TF).

Transformation products and reaction pathways of carbamazepine during photocatalytic and sonophotocatalytic treatment

This study examines the degradation of the antiepileptic carbamazepine (CBZ) by sonolysis, TiO2-based heterogeneous photocatalysis under UV-A and simulated solar irradiation, and by the combined use of UV-A and ultrasound irradiation (i.e. sonophotocatalysis) in demineralized water, ground water and effluent wastewater. The processes were compared with respect to substrate conversion rate and the extent of DOC reduction as a measure of mineralization. CBZ was degraded following a pseudo-first order kinetics. Sonophotocatalysis provided the highest rate of CBZ transformation over the time-course of the experiment while the degree of DOC removal in pure water was similar for all the studied treatments (around 40%), and always lower than CBZ conversion. This indicated that a considerable organic load remained in the treated solutions that could also be attributed to the presence of persistent oxidation products. UPLC-(+ESI)-QToF-MS was employed to determine major CBZ-related transformation products. Several recalcitrant hydroxy- and keto-derivatives of CBZ were tentatively identified. A Daphnia magna bioassay was used to evaluate the potential toxicity of the samples collected at different time points showing that the mixtures were highly toxic to D. magna.

Light-induced catalytic transformation of ofloxacin by solar Fenton in various water matrices at a pilot plant: mineralization and characterization of major intermediate products

This work investigated the application of a solar driven advanced oxidation process (solar Fenton), for the degradation of the antibiotic ofloxacin (OFX) in various environmental matrices at a pilot-scale. All experiments were carried out in a compound parabolic collector pilot plant in the presence of doses of H2O2 (2.5 mg L(-1)) and at an initial Fe(2+) concentration of 2 mg L(-1). The water matrices used for the solar Fenton experiments were: demineralized water (DW), simulated natural freshwater (SW), simulated effluent from municipal wastewater treatment plant (SWW) and pre-treated real effluent from municipal wastewater treatment plant (RE) to which OFX had been spiked at 10 mg L(-1). Dissolved organic carbon removal was found to be dependent on the chemical composition of the water matrix. OFX mineralization was higher in DW (78.1%) than in SW (58.3%) at 12 mg L(-1) of H2O2 consumption, implying the complexation of iron or the scavenging of hydroxyl radicals by the inorganic ions present in SW. On the other hand, the presence of dissolved organic matter (DOM) in SWW and RE, led to lower mineralization per dose of H2O2 compared to DW and SW. The major transformation products (TPs) formed during the solar Fenton treatment of OFX, were elucidated using liquid chromatography-time of flight-mass spectrometry (LC-ToF-MS). The transformation of OFX proceeded through a defluorination reaction, accompanied by some degree of piperazine and quinolone substituent transformation while a hydroxylation mechanism occurred by attack of the hydroxyl radicals generated during the process leading to the formation of TPs in all the water matrices, seven of which were tentatively identified. The results obtained from the toxicity bioassays indicated that the toxicity originates from the DOM present in RE and its oxidation products formed during the photocatalytic treatment and not from the TPs resulted from the oxidation of OFX.

Investigating the fate of iodinated X-ray contrast media iohexol and diatrizoate during microbial degradation in an MBBR system treating urban wastewater

The capability of a moving bed biofilm reactor (MBBR) to remove the iodinated contrast media (ICM) iohexol (IOX) and diatrizoate (DTZ) from municipal wastewater was studied. A selected number of clones of microorganisms present in the biofilm were identified. Biotransformation products were tentatively identified and the toxicity of the treated effluent was assessed. Microbial samples were DNA-sequenced and subjected to phylogenetic analysis in order to confirm the identity of the microorganisms present and determine the microbial diversity. The analysis demonstrated that the wastewater was populated by a bacterial consortium related to different members of Proteobacteria, Firmicutes, and Nitrisporae. The optimum removal values of the ICM achieved were 79 % for IOX and 73 % for DTZ, whereas 13 biotransformation products for IOX and 14 for DTZ were identified. Their determination was performed using ultra-performance liquid chromatography-tandem mass spectrometry. The toxicity of the treated effluent tested to Daphnia magna showed no statistical difference compared to that without the addition of the two ICM. The MBBR was proven to be a technology able to remove a significant percentage of the two ICM from urban wastewater without the formation of toxic biodegradation products. A large number of biotransformation products was found to be formed. Even though the amount of clones sequenced in this study does not reveal the entire bacterial diversity present, it provides an indication of the predominating phylotypes inhabiting the study site.

Chronic ecotoxic effects to Pseudomonas putida and Vibrio fischeri, and cytostatic and genotoxic effects to the hepatoma cell line (HepG2) of ofloxacin photo(cata)lytically treated solutions

Ofloxacin (OFL), a broad-spectrum and widespread-used photolabile fluoroquinolone, is frequently found in treated wastewaters, aquatic and terrestrial ecosystems leading to increasing concern during the past decades regarding its effects to the environment and human health. The elimination of OFL and other xenobiotics by the application of advanced oxidation processes using photolytic (PL) and photocatalytic (PC) treatments seems promising. However, an integrated assessment scheme is needed, in which, not only the removal of the parent compound, but also the effects of the photo-transformation products (PTPs) are investigated. For this purpose, in the present study, a chronic ecotoxic assessment using representative bacteria of marine and terrestrial ecosystems and a cytostatic and genotoxic evaluation using hepatoma cell line were performed. PL and PC treatments of OFL were applied using UV radiation. The photo-transformation of OFL during the treatments was monitored by DOC measurements and UPLC-MS/MS analysis. The chronic ecotoxicity of OFL and treated samples was evaluated using Pseudomonas putida and Vibrio fischeri; whereas the cytostasis and genotoxicity were estimated by the cytokinesis-block micronucleus assay (CBMN). The main results suggest that photo-transformation of OFL took place during these treatments since the concentration of OFL decreased when the irradiation time increased, as quantified by UPLC-MS/MS analysis, and this was not coupled with an analogous DOC removal. Furthermore, nine compounds were identified as probable PTPs formed through piperazinyl dealkylation and decarboxylation. The ecotoxicity of treated solutions to the bacteria studied decreased while the cytostasis to the hepatoma cell line remained at low levels during both treatments. However, the genotoxicity to the hepatoma cell line demonstrated a different pattern in which treated samples induced a greater number of MNi for the 4-16 min of irradiation (p<0.05) during both treatments. After 64 min of irradiation, the effects decreased to non genotoxic levels (p<0.05). These findings suggest that UV radiation for various treatment processes (catalytic or not), such as disinfection, may create genotoxic by-products. Therefore, in relevant technical applications, the residence time during treatment should receive special attention.

Biodegradation potential of ofloxacin and its resulting transformation products during photolytic and photocatalytic treatment

The release of pharmaceuticals in the environment, as parent compounds, metabolites and transformation products, and the consequent risks posed to living organisms due to the unintended exposure of the latter to these chemicals are nowadays of increasing scientific concern. The development of advanced oxidation processes able to degrade these substances is in the core of the current research objectives, the main target being the removal of these compounds from wastewaters. Often the focus is on the removal of the parent compound only. However, these processes can form transformation products. Knowledge on the risk related to such transformation products is scarce. Among others, knowledge on their toxic effects and their biodegradability is of importance not only when they are present in the environment but also for the assessment of the advanced oxidation processes' efficiency applied for their degradation. Photolytic (UV irradiation) and photocatalytic treatment (UV irradiation in the presence of TiO(2)) of the fluoroquinolone ofloxacin were applied, and the biodegradability of the formed products was investigated using the Closed Bottle test (OECD 301 D). Various transformation products, formed both during the photo(cata)lytic treatment and the Closed Bottle test, were identified using chromatographic analysis with an ultra high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) system. The transformation products formed during the phototreatments were found to be non-readily biodegradable as the biodegradation percentages were close to zero. The persistence of the various photo(cata)lytic transformation products during the Closed Bottle test may be attributed to the fluorine present in all the transformation products formed. The transformation products identified suggest that two transformation routes were present: decarboxylation and opening of the piperazinyl ring. Interestingly, it was observed that in the presence of a readily biodegradable carbon source (sodium acetate), the biodegradation percentage increased drastically for some of the photolytically treated samples. This was not the case for the photocatalytically treated samples, in which also mineralization of the parent compound was achieved faster. Further research is needed, however, in order to increase the understanding of the conditions that may lead to less potent and persistent substances during the application of such engineered or natural processes.

Superiority of solar Fenton oxidation over TiO2 photocatalysis for the degradation of trimethoprim in secondary treated effluents

The overall aim of this work was to examine the degradation of trimethoprim (TMP), which is an antibacterial agent, during the application of two advanced oxidation process (AOP) systems in secondary treated domestic effluents. The homogeneous solar Fenton process (hv/Fe(2+)/H2O2) and heterogeneous photocatalysis with titanium dioxide (TiO2) suspensions were tested. It was found that the degradation of TMP depends on several parameters such as the amount of iron salt and H2O2, concentration of TiO2, pH of solution, solar irradiation, temperature and initial substrate concentration. The optimum dosages of Fe(2+) and H2O2 for homogeneous ([Fe(2+)] = 5 mg L(-1), [H2O2] = 3.062 mmol L(-1)) and TiO2 ([TiO2] = 3 g L(-1)) for heterogeneous photocatalysis were established. The study indicated that the degradation of TMP during the solar Fenton process is described by a pseudo-first-order reaction and the substrate degradation during the heterogeneous photocatalysis by the Langmuir-Hinshelwood kinetics. The toxicity of the treated samples was evaluated using a Daphnia magna bioassay and was finally decreased by both processes. The results indicated that solar Fenton is more effective than the solar TiO2 process, yielding complete degradation of the examined substrate within 30 min of illumination and dissolved organic carbon (DOC) reduction of about 44% whereas the respective values for the TiO2 process were ∼70% degradation of TMP within 120 min of treatment and 13% DOC removal.

Solar photo-Fenton process on the abatement of antibiotics at a pilot scale: Degradation kinetics, ecotoxicity and phytotoxicity assessment and removal of antibiotic resistant enterococci

This work investigated the application of a solar driven advanced oxidation process (solar photo-Fenton), for the degradation of antibiotics at low concentration level (μg L(-1)) in secondary treated domestic effluents at a pilot-scale. The examined antibiotics were ofloxacin (OFX) and trimethoprim (TMP). A compound parabolic collector (CPC) pilot plant was used for the photocatalytic experiments. The process was mainly evaluated by a fast and reliable analytical method based on a UPLC-MS/MS system. Solar photo-Fenton process using low iron and hydrogen peroxide doses ([Fe(2+)](0) = 5 mg L(-1); [H(2)O(2)](0) = 75 mg L(-1)) was proved to be an efficient method for the elimination of these compounds with relatively high degradation rates. The photocatalytic degradation of OFX and TMP with the solar photo-Fenton process followed apparent first-order kinetics. A modification of the first-order kinetic expression was proposed and has been successfully used to explain the degradation kinetics of the compounds during the solar photo-Fenton treatment. The results demonstrated the capacity of the applied advanced process to reduce the initial wastewater toxicity against the examined plant species (Sorghum saccharatum, Lepidium sativum, Sinapis alba) and the water flea Daphnia magna. The phytotoxicity of the treated samples, expressed as root growth inhibition, was higher compared to that observed on the inhibition of seed germination. Enterococci, including those resistant to OFX and TMP, were completely eliminated at the end of the treatment. The total cost of the full scale unit for the treatment of 150 m(3) day(-1) of secondary wastewater effluent was found to be 0.85 € m(-3).

Solar photocatalytic treatment of trimethoprim in four environmental matrices at a pilot scale: transformation products and ecotoxicity evaluation

The pilot-scale solar degradation of trimethoprim (TMP) in different water matrices (demineralized water: DW, simulated natural freshwater: SW; simulated wastewater: SWW; and real effluent: RE) was investigated in this study. DOC removal was lower in the case of SW compared to DW, which can be attributed to the presence of inorganic anions which may act as scavengers of the HO·. Furthermore, the presence of organic carbon and higher salt content in SWW and RE led to lower mineralization per dose of hydrogen peroxide compared to DW and SW. Toxicity assays in SWW and RE were also performed indicating that toxicity is attributed to the compounds present in RE and their by-products formed during solar Fenton treatment and not to the intermediates formed by the oxidation of TMP. A large number of compounds generated by the photocatalytic transformation of TMP were identified by UPLC-QToF/MS. The degradation pathway revealed differences among the four matrices; however hydroxylation, demethylation and cleavage reactions were observed in all matrices. To the best of our knowledge this is the first time that TMP degradation products have been identified by adopting a solar Fenton process at a pilot-scale set-up, using four different aqueous matrices.

Development and validation of a UPLC-MS/MS method for studying the degradation kinetics of ofloxacin and trimethoprim during the application of solar Fenton process in secondary treated sewage

In this work, a sensitive and highly selective method was developed and validated to study the degradation of two antibiotic compounds (ofloxacin (OFX) and trimethoprim (TMP)), spiked in secondary treated domestic effluents, by the solar Fenton process. Three different chromatographic columns were tested on a ultra performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) instrument working in the electrospray ionization (ESI) mode with twelve combinations of eluting solvents. Samples were enriched prior to the analysis by solid phase extraction using the hydrophilic-lipophilic balanced (HLB) reversed phase polymeric sorbent. The method was optimized and showed very good performance characteristics and was successfully applied to study the degradation kinetics of the selected antibiotics during the solar Fenton process applied. The degradation was found to follow a pseudo first-order kinetics for both compounds at initial concentration of 100 μg L(-1) with k = 0.0345 min(-1) for OFX and k = 0.0768 min(-1) for TMP, whereas the complete removal was achieved after 120 min of treatment for both compounds.

Solar Fenton and solar TiO2 catalytic treatment of ofloxacin in secondary treated effluents: evaluation of operational and kinetic parameters

Two different technical approaches based on advanced oxidation processes (AOPs), solar Fenton homogeneous photocatalysis (hv/Fe(2+)/H(2)O(2)) and heterogeneous photocatalysis with titanium dioxide (TiO(2)) suspensions were studied for the chemical degradation of the fluoroquinolone ofloxacin in secondary treated effluents. A bench-scale solar simulator in combination with an appropriate photochemical batch reactor was used to evaluate and select the optimal oxidation conditions of ofloxacin spiked in secondary treated domestic effluents. The concentration profile of the examined substrate during degradation was determined by UV/Vis spectrophotometry. Mineralization was monitored by measuring the dissolved organic carbon (DOC). The concentrations of Fe(2+) and H(2)O(2) were the key factors for the solar Fenton process, while the most important parameter of the heterogeneous photocatalysis was proved to be the catalyst loading. Kinetic analyses indicated that the photodegradation of ofloxacin can be described by a pseudo-first-order reaction. The rate constant (k) for the solar Fenton process was determined at different Fe(2+) and H(2)O(2) concentrations whereas the Langmuir-Hinshelwood (LH) kinetic expression was used to assess the kinetics of the heterogeneous photocatalytic process. The conversion of ofloxacin depends on several parameters based on the various experimental conditions, which were investigated. A Daphnia magna bioassay was used to evaluate the potential toxicity of the parent compound and its photo-oxidation by-products in different stages of oxidation. In the present study solar Fenton has been demonstrated to be more effective than the solar TiO(2) process, yielding complete degradation of the examined substrate and DOC reduction of about 50% in 30 min of the photocatalytic treatment.

Drugs degrading photocatalytically: Kinetics and mechanisms of ofloxacin and atenolol removal on titania suspensions

The conversion of the antibiotic ofloxacin and the beta-blocker atenolol by means of TiO(2) photocatalysis was investigated. Irradiation was provided by a UVA lamp at 3.37x10(-6)einstein/s photon flux, while emphasis was given on the effect of catalyst type and loading (50-1500mg/L), initial substrate concentration (5-20mg/L), initial pH (3-10) and the effect of H(2)O(2) (0.07-1.4mM) as an additional oxidant on substrate conversion and mineralization in various matrices (i.e. pure water, groundwater and treated municipal effluent). Conversion was assessed measuring sample absorbance at 288 and 224nm for ofloxacin and atenolol, respectively, while mineralization measuring the dissolved organic carbon. Degussa P25 TiO(2) was found to be more active than other TiO(2) samples for either substrate degradation, with ofloxacin being more reactive than atenolol. Conversion generally increased with increasing catalyst loading, decreasing initial substrate concentration and adding H(2)O(2), while the effect of solution pH was substrate-specific. Reaction rates, following a Langmuir-Hinshelwood kinetic expression, were maximized at a catalyst to substrate concentration ratio (w/w) of 50 and 15 for ofloxacin and atenolol, respectively, while higher ratios led to reduced efficiency. Likewise, high concentrations of H(2)O(2) had an adverse effect on reaction, presumably due to excessive oxidant scavenging radicals and other reactive species. The ecotoxicity of ofloxacin and atenolol to freshwater species Daphnia magna was found to increase with increasing substrate concentration (1-10mg/L) and exposure time (24-48h), with atenolol being more toxic than ofloxacin. Photocatalytic treatment eliminated nearly completely toxicity and this was more pronounced for atenolol.

Sonochemical degradation of ofloxacin in aqueous solutions

The use of low frequency (20 kHz), high energy ultrasound for the degradation of the antibiotic ofloxacin in water was investigated. Experiments were performed with a horn-type ultrasound generator at varying applied power densities (130-640 W/L), drug concentrations (5-20 mg/L), hydrogen peroxide concentrations (0-100 mM) and sparging gases (air, oxygen, nitrogen and argon). In general, conversion (which was assessed following sample absorbance at 288 nm) increased with increasing ultrasound energy and peroxide concentration and decreasing initial drug concentration. Moreover, reactions under an argon atmosphere were faster than with diatomic gases, possibly due to argon's physical properties (e.g. solubility, thermal conductivity and specific heat ratio) favoring sonochemical activity. Overall, low to moderate levels of ofloxacin degradation were achieved (i.e. it never exceeded 50%), thus indicating that radical reactions in the liquid bulk rather than thermal reactions in the vicinity of the cavitation bubble are responsible for ofloxacin degradation.

Study of the Crystallization of Nanoporous Mixed Metal Oxide Phases

A systematic study of the synthesis and characterization of pristine ceria and of mixed cerium/metal oxides has been undertaken. Various synthetic routes were explored, with the crystallization process being examined via thermal analysis, XRD and electron microscopy. It was shown that even when multiple phases were generated upon heat treatment, mixed phases were also generated. However, the presence of organic molecules during the syntheses, as matrices, solvents or precipitating bases, had a profound effect upon the surface texture of the samples prepared.