Ana V. Dordio

Evaluation of carbamazepine uptake and metabolization by Typha spp., a plant with potential use in phytotreatment

Phytoremediation technologies such as constructed wetlands have shown higher efficiencies in removal of pharmaceuticals from wastewaters than conventional wastewater treatment processes, and plants seem to have an important role in the removal of some of those compounds. In this context, a study was conducted to assess tolerance, uptake, and metabolism of the epilepsy drug, carbamazepine, by the macrophyte Typha spp. This evaluation was conducted in hydroponic solutions with 0.5-2.0mg/L of this pharmaceutical for a maximum period of 21 days. The removal of carbamazepine from nutrient solutions by the plants reached values of 82% of the initial contents. Furthermore, a metabolite (10,11-dihydro-10,11-epoxycarbamazepine) was detected in leaf tissues indicating carbamazepine translocation and metabolism inside plants. Activities of antioxidant enzymes catalase, superoxide dismutase, and guaiacol peroxidase generally increase (after some mild initial inhibition in the case of the latter enzyme) as result of the abiotic stress caused by the exposure to carbamazepine, but ultimately Typha seemed able to cope with its toxicity. The results obtained in this study suggest the ability of Typha spp., to actively participate in the removal of carbamazepine from water when used in phytotreatment systems.

Toxicity and removal efficiency of pharmaceutical metabolite clofibric acid by Typha spp. – Potential use for phytoremediation?

A study was conducted to assess Typha spp.s ability to withstand and remove, from water, a metabolite of blood lipid regulator drugs, clofibric acid (CA). At a concentration of 20 microg L(-1), Typha had removed >50% of CA within the first 48h, reaching a maximum of 80% by the end of the assay. Experimental conditions assured that photodegradation, adsorption to vessel walls and microbial degradation did not contribute to the removal. Exposure to higher CA concentrations did not affect Typhas photosynthetic pigments but the overall increase in enzyme activity (ascorbate and guaiacol peroxidases, catalase, superoxide dismutase) indicates that both roots and leaves were affected by the xenobiotic. Eventually, Typha seemed able to cope with the CAs induced oxidative damage suggesting its ability for phytoremediation of CA contaminated waters.

Organic xenobiotics removal in constructed wetlands, with emphasis on the importance of the support matrix

Constructed wetlands (CWs) are increasingly popular as an efficient and economical alternative to conventional wastewater treatment processes for removal, among other pollutants, of organic xenobiotics. In CWs, pollutants are removed through the concerted action of their components, whose contribution can be maximized by careful selection of those components. Specifically for non-biodegradable organic pollutants, the materials used as support matrix of CWs can play a major role through sorption phenomena. In this review the role played by such materials in CWs is examined with special focus on the amount of research that has been conducted to date on their sorption properties relatively to organic compounds. Where available, the reports on the utilization of some of those materials on pilot or full-scale CWs are also recognized. Greatest interest has been directed to cheaper and widely available materials. Among these, clays are generally regarded as efficient sorbents, but materials originated from agricultural wastes have also gained recent popularity. Most available studies are lab-scale batch sorption experiments, whereas assays performed in full-scale CWs are still scarce. However, the available lab-scale data points to an interesting potential of many of these materials for experimentation as support matrix of CWs targeted for organic xenobiotics removal.

Constructed wetlands with light expanded clay aggregates for agricultural wastewater treatment

Constructed wetlands (CWs) are receiving a renewed attention as a viable phytotechnology for treating agricultural wastewaters and for the removal of more specific pollutants, in particular recalcitrant ones. In this work, the performance of CW mesocosms using light expanded clay aggregates (LECA) as the beds substrate and planted with Phragmites australis was investigated for treatment of olive mill wastewater (OMW), swine wastewater (SW) contaminated with oxytetracycline and water contaminated with herbicide MCPA (2-methyl-4-chlorophenoxyacetic acid). Both wastewaters (OMW and SW) initially presented high organic matter content and total suspended solids which were removed by the system with efficiencies higher than 80%. Removal of polyphenols in OMW and nitrogen compounds in SW also showed similar or higher efficiencies in comparison with other treatment systems reported in the literature. The antibiotic oxytetracycline was completely removed from SW within the assay period in unplanted LECA beds, but planted beds allowed a significantly faster removal. In regard to water contaminated with MCPA, the results showed that LECA has a large sorption capacity for this herbicide (removal efficiencies of 56-97%). In general, considerably higher pollutant removal efficiencies were obtained when plants were used (up to 28% higher). The results obtained are indicative that CWs with LECA as substrate may be an adequate option for agricultural wastewater treatment.

Study on the use of Typha spp. for the phytotreatment of water contaminated with ibuprofen

Several studies on phytotoxic effects caused by organic xenobiotics and their removal from water by macrophytes have already been performed to evaluate the usefulness of these plants for phytoremediation technologies. In this context, a study was conducted to assess Typha spp.s ability to withstand and remove, from water, the non-steroidal anti-inflammatory drug ibuprofen. For an initial ibuprofen concentration of 20 µg L−1, Typha removed nearly 60% of it within the first 24 h, attaining over 99% removal by the end of the assay (21 days). Exposure to higher ibuprofen concentrations did affect Typhas growth but, by the end of the assays, plants’ growth as well as photosynthetic pigments approached normal values. An alteration in antioxidant enzymes activities (superoxide dismutase, catalase, guaiacol peroxidase) indicated that both roots and leaves were affected by the xenobiotic. Eventually, Typha seemed able to cope with ibuprofens induced oxidative damage suggesting its ability for phytotreatment of waters contaminated with ibuprofen.

Ultra-sensitive voltammetric sensor for trace analysis of carbamazepine

A multi-walled carbon nanotubes (MWCNTs) film-coated glassy carbon electrode (GCE) was used for the voltammetric determination of carbamazepine (CBZ). The results showed that this simple modified electrode exhibited excellent electrocatalytic activity towards the oxidation of CBZ. The voltammetric response of CBZ at this film-modified electrode increased significantly when compared with that at a bare glassy carbon electrode and the sensor response was reproducible. The proposed method was applied to the quantification of CBZ in wastewater samples, collected in a municipal wastewater treatment plant, and in pharmaceutical formulations. The developed methodology yields results in accord with those obtained by chromatographic techniques commonly used in the quantification of pharmaceutical compounds in real samples. Good recoveries have been obtained and the limits of detection and quantification (40 and 140 nM, respectively) are among the lowest that have been reported to date for this pharmaceutical compound using voltammetric techniques.

Pharmaceuticals sorption behaviour in granulated cork for the selection of a support matrix for a constructed wetlands system

Biosorbents have been recently gaining importance, with an increasing number of publications on their environmental applications, especially for removal of organic pollutants from aqueous media. The aim of this work was to evaluate the sorption capacity of a biosorbent, namely granulated cork, to remove mixtures of ibuprofen (IB), carbamazepine (CB) and clofibric acid (CA) from water and wastewater. High removal efficiencies were attained for IB and CB while a less satisfactory performance was observed for CA. Simultaneous removal of the three compounds mixed in the same aqueous solution showed no significant differences in comparison to the removal of the isolated compounds in separate solutions, which indicates that no competitive sorption effects occurred at the highest concentrations tested. On the other hand, in wastewater medium the mixture of pharmaceuticals underwent a decrease in the sorbed amounts of all the three substances, probably due to the presence of dissolved organic matter which increases their solubilities. These compounds were removed in the following order of efficiencies in all the tested conditions: IB > CB > CA. The sorption kinetics were characterised by an initial fast step within the first 6 h, during which most of the removed pharmaceuticals amounts were sorbed. After the first 6 h, CA attained equilibrium concentrations whereas the sorption kinetics for IB and CB were characterised by two pseudo-second order stages, the first one up to 48 h and a slower one beyond 48 h. Shorter equilibration times and larger removed amounts of pharmaceuticals per unit weight of sorbent were observed in this study for granulated cork in comparison with a previously studied clay material (LECA). The results of this study showed the sorptive qualities of granulated cork but are only a first step in the evaluation of this material for use as support matrix in constructed wetlands designed for removal of pharmaceuticals from wastewaters.

Atenolol removal in microcosm constructed wetlands

Microcosm constructed wetland systems established with a matrix of light expanded clay aggregates (LECA) and Typha spp. or Phragmites australis were used to evaluate their ability to remove atenolol from wastewater. Combined with an efficient SPE concentration step, the use of HPLC-DAD yielded an analytical method for atenolol quantification with very low LOQ (9 ng mL−1) and high reproducibility (RSD < 4%). Overall removal efficiencies of 92.5% and 94.5% were achieved after a retention time of only 4 days with the microcosm systems planted with Phragmites australis and Typha spp., respectively. The removal kinetics was characterised by an initial fast step (removal of about 75% after just 24 h) which is mainly attributable to adsorption on the LECA matrix. Atenolol removal in LECA beds continues to increase in a steady pace up to the end of the assay (8 days) being nevertheless about 5–10% lower than those observed in the planted beds after the first 4 days. For the retention time of 4 days most of the atenolol is removed by the LECA matrix but an additional 12–14% of the overall removal efficiency can be attributed to the Typha and Phragmites plants, which is in agreement with other published reports. Despite the fact that further tests using larger-scale flowing systems are required to evaluate fully the atenolol behaviour in constructed wetlands, this study points to the possible application of these low-cost wastewater treatment systems to treat atenolol contaminated wastewater.

Mechanisms of removal of three widespread pharmaceuticals by two clay materials

Pharmaceutical residues presence in the environment is among nowadays top emergent environmental issues. For removal of such pollutants, adsorption is a generally efficient process that can be complementary to conventional treatment. Research of cheap, widely available adsorbents may make this process economically attractive. The aim of the present work was to evaluate the capacity of two clay materials (exfoliated vermiculite, LECA) to adsorb gemfibrozil, mefenamic acid and naproxen in lab-scale batch assays. Results show that both adsorbents are able to remove the pharmaceuticals from aqueous medium. Although vermiculite exhibited higher adsorption capacities per unit mass of adsorbent, LECA yielded higher absolute removals of the pharmaceuticals due to the larger mass of adsorbent. Quantum chemistry calculations predicted that the forms of binding of the three molecules to the vermiculite surface are essentially identical, but the adsorption isotherm of naproxen differs substantially from the other twos. The linear forms of the latter impose limits at lower concentrations to the removal efficiencies of these pharmaceuticals by vermiculite, thereby electing LECA as more efficient. Notwithstanding, vermiculites high specific adsorption capacity and also its much faster adsorption kinetics suggest that there may be some benefits in combining both materials as a composite adsorbent solution.

Adsorption of two phenoxyacid compounds on a clay surface: a theoretical study

Using density functional theory methods, we studied the adsorption of (4-chloro-2-methylphenoxy)acetic acid (MCPA) and 2-(4-chlorophenoxy)-2-methylpropanoic acid, therapeutically used under the name of clofibric acid (CA), two commonly detected water pollutants, both in neutral and ionized form on a model surface of muscovite. We report the geometries of the adsorbed species and discuss their interaction with the surface. It was found that the ionized adsorbates interact more strongly with the surface than do their neutral forms particularly for MCPA when compared with CA, which points to the same direction of previous experimental findings. Changes on the electron density due to adsorption has been studied by means of Bader charges analysis and it was found that electronic density is transferred from the anions to the surface and less significantly from the surface to the neutral molecules on adsorption.