Lidia Favier

Response surface optimization of experimental conditions for carbamazepine biodegradation by Streptomyces MIUG 4.89.

Carbamazepine an iminostilbene derivative compound with a tricyclic structure is one of the most widely prescribed drugs for the treatment of epilepsy. It is hardly or not degraded during the conventional technology used in wastewater treatment plants (WWTPs) (up to 7%) and many studies have found it ubiquitous in various environmental matrices in concentrations typically ranging from μg L(-1) to ng L(-1). Streptomyces MIUG 4.89 was previously studied for its ability in carbamazepine biodegradation (up to 14%) during cultivation in submerged system under aerobic conditions at an initial CBZ concentration of 0.2 mg L(-1). The influence of some factors (independent variables) upon biodegradation potential was examined by Plackett-Burman analysis. Central composite design of experiments (CCD) and response surface methodology (RSM) were used to get more information about the significant effects and their interactions of the five parameters selected upon their biodegradation potential in order to increase the elimination yield of this drug from a liquid medium. The investigated ranges of the independent variables were: 1.0-3.0 g L(-1) yeast extract, 3.0-10.0 g L(-1) glucose, 4.0-10.0% (v/v) inoculation level, pH 5.0-7.0 and 50-250 mL of medium at a constant initial concentration of carbamazepine (CBZ) of 0.2 mg L(-1). The response surface analysis results showed that the capacity of the selected strain Streptomyces MIUG 4.89 to degrade carbamazepine was high in submerged cultivation system by cultivation in a liquid medium containing 6.5 g L(-1) glucose and 2 g L(-1) yeast extract, inoculated at 7% (v/v) and cultivated at pH 6.0, during 7 days of incubation at 25 °C and 150 rpm. Under these culture conditions the achieved experimental CBZ biotransformation yield was 30%.

Potential of newly isolated wild Streptomyces strains as agents for the biodegradation of a recalcitrant pharmaceutical, carbamazepine

Carbamazepine (CBZ) is a recalcitrant xenobiotic pharmaceutical pollutant highly stable in soil and wastewater during treatment. The biodegradation of CBZ using streptomycetes has been few studied up to now. Sixteen newly filamentous bacteria belong to genus Streptomyces spp. isolated from different Romanian soil samples and three strains from a collection of microorganisms (MIUG) were morphologically characterized, tested based on their resistance against CBZ toxicity and then selected as agents for bioremediation. Five Streptomyces spp. strains coded MIUG 4.88, MIUG 4.89, SNA, LP1 and LP2 showed CBZ tolerance at all of the tested concentrations, i.e. 0.05, 0.2, 1, 5 and 8 mg L−1. Two of these (MIUG 4.89 and SNA strains) were selected based on their resistance to target compound and were then assessed for CBZ biodegradation. The strain Streptomyces MIUG 4.89 showed an interesting efficiency for CBZ removal, with a yield of 35% when it was cultivated in submerged conditions on a minimal medium supplemented with 5 g L−1 glucose. This ability was linked to extracellular laccase production. These results are promising for the use of these filamentous bacteria as bioremediation agents.

Kinetic study of spiramycin removal from aqueous solution using heterogeneous photocatalysis

Spiramycin macrolide antibiotic (SPM) can be photocatalytically degraded on TiO2 (anatase variety). The experiments are done in a batch reactor and the effect of some key parameters is investigated under low energy of artificial UV light. The reaction rate is affected by varying TiO2 dose, pH and SPM concentration. Under optimized conditions, a photodegradation efficiency of 98% is achieved and the SPM photodegradation follows pseudo-first order kinetics. The Langmuir–Hinshelwood (L–H) model is successfully used to fit the experimental data, indicating the dependence of the reaction rate on the chemical reaction step. The L–H model led to the determination of both reaction kinetic and adsorption/desorption equilibrium constants. In order to give an overall estimate of the by-products, chemical oxygen demand, total organic carbon, and calculated average oxidation state monitor the photodegradation process.

A highly sensitive liquid chromatography-tandem mass spectrometry method for the analysis of a toxic water disinfection by-product, N-nitrosomethylethylamine

Recently, among the emerging contaminants, N-nitrosomethylethylamine has become of special concern because it is a potent human mutagenic and carcinogenic contaminant detected in chlorinated or chloraminated drinking waters and wastewaters. In this work a sensitive and robust method, which was based on solid-phase extraction followed by ultra-high-pressure liquid chromatography coupled with tandem mass spectrometry, was developed for the determination of N-nitrosomethylethylamine in water at ultra-trace levels. Chromatographic separation was performed on a C18 column. Quantification of N-nitrosomethylethylamine was achieved by using a triple quadrupole mass spectrometer that was equipped with an electrospray interface and was operated in positive ionization mode. Under optimized conditions, the calibration curve was linear from 0.1 to 100 μg L−1 (r2 ≥ 0.999). The precision of the intra- and inter-day values was found to be less than 2.5%, and the accuracy of the method was within ±3%. Moreover, an extraction efficiency greater than 86% was obtained at different concentration levels with relative standard deviation, RSD < 4.2%. Therefore, the experimental results showed that the proposed analytical method can be used successfully to determine N-nitrosomethylethylamine at ultra-trace levels (ng L−1) in aqueous samples.

Removal of Astrazone Blue from aqueous solutions onto brown peat. Equilibrium and kinetics studies

The aim of this study is to characterize and assess the sorption potential of brown peat, in relation to colored pollutants from the textile industry wastewater. The objectives of this paper were: the physicochemical, morphological, and mineralogical characterization of brown peat, testing the adsorption capacity of natural and chemically treated peat samples for Astrazone Blue, evaluation of adsorption process from equilibrium isotherm and kinetic point of view. The characteristics of the peat samples were investigated using elemental analysis, scanning electron microscopy and X-ray diffractometry. Experimental data indicated that the brown peat tested confirm a high level of adsorption (removal efficiency >93.00%, adsorption capacity reaching up to 24.27 mg/g) of Astrazone Blue from aqueous solution. The Langmuir and Freundlich adsorption isotherm models were used to find the best equation able to describe the adsorption process. Experimental adsorption data were successfully described by the Langmuir equilibrium isotherm model. This fact is supported by the agreement between the q values obtained using the Langmuir equation (26.32 mg/g), and the ones obtained experimentally (24.27 mg/g). The kinetic studies showed that the pseudo-second-order model described Astrazone Blue sorption kinetics, as confirmed by the high values of R2, which are over 0.99 for the whole investigated concentration range (200 to 800 mg/L). The use of brown peat adsorbent is more advantageous compared with other materials since it does not require a preliminary treatment, is low-cost and is an eco-friendly adsorbent. Hence, this peat appears to be a viable material for the decontamination of effluents containing dyes.

Macrolide antibiotics removal using a circulating TiO2-coated paper photoreactor: parametric study and hydrodynamic flow characterization.

The present work investigates the photocatalytic degradation efficiency of biorecalcitrant macrolide antibiotics in a circulating tubular photoreactor. As target pollutants, spiramycin (SPM) and tylosin (TYL) were considered in this study. The photoreactor leads to the use of an immobilized titanium dioxide on non-woven paper under artificial UV-lamp irradiation. Maximum removal efficiency was achieved at the optimum conditions of natural pH, low pollutant concentration and a 0.35 L min(-1) flow rate. A Langmuir-Hinshelwood model was used to fit experimental results and the model constants were determined. Moreover, the total organic carbon analysis reveals that SPM and TYL mineralization is not complete. In addition, the study of the residence time distribution allowed us to investigate the flow regime of the reactor. Electrical energy consumption for photocatalytic degradation of macrolides using circulating TiO2-coated paper photoreactor was lower compared with some reported photoreactors used for the elimination of pharmaceutic compounds. A repetitive reuse of the immobilized catalyst was also studied in order to check its photoactivity performance.

Improved Determination of Dichloroacetic and Trichloroacetic Acids in Water by Solid Phase Extraction Followed by Ultra-high Performance Liquid Chromatography–Tandem Mass Spectrometry

ABSTRACT A simple, rapid, and sensitive ultra-high performance liquid chromatography–electrospray ionization tandem mass spectrometry method was developed for the determination of dichloroacetic acid and trichloroacetic acid in water. Analytes were extracted and concentrated by solid phase extraction. Under the optimized conditions, the extraction recoveries ranged from 98.13 to 100.57% for both analytes. The separation was performed on a reversed phase C18 column by using gradient elution. Detection was performed in multiple reaction monitoring mode using negative electrospray ionization. The developed method yielded limits of detection from 0.04 to 0.08 ng/mL. The intra-day and inter-day precisions for the analytes were less than 4% and the accuracy was between 99.12 and 102.38%. To the best of our knowledge, this work describes for the first use of solid phase extraction with ultra-high performance liquid chromatography tandem mass spectrometry for dichloroacetic acid and trichloroacetic acid in water.

Successful Biodegradation of a Refractory Pharmaceutical Compound by an Indigenous Phenol-Tolerant Pseudomonas aeruginosa Strain

This study provides an alternative solution for the bioremediation of a recalcitrant pharmaceutical micropollutant. Clofibric acid (CLA) was chosen as target molecule, because of its environmental persistence and resistance to wastewater treatment technologies. The aim of this study was to investigate the potential of a phenol-resistant Pseudomonas aeruginosa strain isolated from the activated sludge to degrade CLA. In order to evaluate the effect of acclimation process with glucose as carbon co-substrate, two protocols were performed, in which the transfer of the inoculum is carried out either in the exponential growth phase or in the decline phase. The results showed a removal efficiency of CLA of 35% when cells in the decline phase were used for inoculation. In contrast, a very low removal yield (10%) was achieved when cells harvested in the exponential phase were used as inoculum. This work is the first one reporting on the capability of this bacterium to remove this drug. The obtained data showed that the isolated strain is able to degrade target molecule and might be a promising agent for the elimination of this refractory compound.

Optimization of Different Key Culture Conditions for Enhanced Biodegradation of a Refractory Emerging Pollutant by a Bacterial Isolate Through a Statistical Approach

Over the last decade, the problem of pollution of aquatic environment by pharmaceutically active (PhACs) compounds including drugs and their active metabolites has raised an increasing concern because of their persistence in surface water and their negative impact on living organisms.

Removal of some endocrine disruptors via adsorption on activated carbon

The present paper was dedicated to the study of endocrine disruptors removal from ultra-pure and real water solutions by adsorption on two types of activated carbon. This category of compounds includes natural substances such as hormones (reproductive, thyroid) or corticosteroids but also numerous chemicals as polycyclic aromatic hydrocarbons, dioxins, pharmaceuticals or pesticides. Their removal constitute an important preoccupation worldwide due to the fact that they are recognized as affecting the human health in a negative way. Among them, bisphenol A (BPA) and ethinylestradiol (EE2), are widely used for plastic and respectively for oral contraceptive pills production. The adsorption efficiencies of tested activated carbons on the BPA and EE2 removal were investigated using batch adsorption experiments. The recorded results revealed that the used adsorbents possess a high adsorption capacity (1521 µmol/g on NC90 and 1395 µmol/g on F400 for BPA and 1667µmol/g on NC90 and 1196 µmol/g on F400 for EE2) which recommends them for pollutant removal from real water.