Mineralization of synthetic and industrial pharmaceutical effluent containing trimethoprim by combining electro-Fenton and activated sludge treatment

International audienceA combined process coupling of an electro-Fenton and a biological degradation was investigated in order to mineralize synthetic and industrial pharmaceutical effluent containing trimethoprim, a bacteriostatic antibiotic. Electro-Fenton degradation of trimethoprim was optimized by means of a Doehlert experimental design, showing that 0.69 mM Fe2+, 466 mA and 30 min electrolysis time were optimal, leading to total trimethoprim removal, while mineralization remained limited, 12% for 30 min electrolysis times. The aromatic and aliphatic by-products were identified and a plausible degradation pathway was proposed. Biodegradability was improved, since the BOD5/COD ratio increased from 0.11 initially to 0.32 and 0.52 after 30 and 60 min electrolysis times respectively, confirmed by activated sludge culture, 47 and 59% mineralization of the byproducts from electrolysis.The relevance of the proposed combined process was then confirmed on an industrial pharmaceutical effluent. Its electrolysis under the above conditions showed an almost total removal of trimethoprim after 180 min of electrolysis, while TOC removal remained low, 14 and 16% for 180 and 300 min reaction times, respectively. Overall removal yields of the industrial effluent during the combined process were therefore 80 and 89% for 180 and 300 min of effluent pretreatment followed by 15 days activated sludge culture, respectively

Degradation of enoxacin antibiotic by the electro-Fenton process: Optimization, biodegradability improvement and degradation mechanism

International audienceThis study aims to investigate the effectiveness of the electro-Fenton process on the removal of a second generation of fluoroquinolone, enoxacin. The electrochemical reactor involved a carbon-felt cathode and a platinum anode. The influence of some experimental parameters, namely the initial enoxacin concentration, the applied current intensity and the Fe(II) amount, was examined. The degradation of the target molecule was accompanied by an increase of the biodegradability, assessed from the BOD5 on COD ratio, which increased from 0 before treatment until 0.5 after 180 min of electrolysis at 50 mg L−1 initial enoxacin concentration, 0.2 mmol L−1 Fe(II) concentration and 300 mA applied current intensity. TOC and COD time-courses were also evaluated during electrolysis and reached maximum residual yields of 54% and 43% after 120 min of treatment, respectively. Moreover, a simultaneous generation of inorganic ions (fluorides, ammonium and nitrates) were observed and 3 short chain carboxylic acids (formic, acetic and oxalic acids) were identified and monitored during 180 min of electrolysis. By-products were identified according to UPLC-MS/MS results and a degradation pathway was propose

Flow electrolysis on high surface electrode for biodegradability enhancement of sulfamethazine solutions

International audienceThe main objective of this study was to examine the feasibility of coupling an electrochemical process with a biological treatment for the degradation of sulfamethazine, a biorecalcitrant antibiotic. The electrochemical behavior of sulfamethazine was examined by cyclic voltammetry, showing an electroactivity in oxidation. The pre-treatment was carried out using an electrochemical flow cell involving a graphite felt electrode of high specific area. After a single pass through the cell, the analysis of the electrolyzed solution showed a promising trend in view of the proposed combined process, namely a high degradation of the target compound (more than 90%) while the mineralization level remained low (it did not exceed 20%). The optimization of the operating conditions, viz. flow rate and applied potential, allowed to improve the biodegradability of sulfamethazine solutions. Indeed, under optimal conditions, the biodegradability based on the BOD5 on COD ratio measurement was improved from 0.08 to 0.58, namely above the threshold limit value (0.4)

Improvement of the activated sludge treatment by its combination with electro Fenton for the mineralization of sulfamethazine

International audienceA combined process coupling an electro-Fenton pretreatment and a biological degradation in order to mineralize sulfamethazine (SMT) was investigated. The electro-Fenton pretreatment of SMT was first examined and the intermediates products were identified for an initial SMT amount of 0.36 mM, after 1 h electrolysis at pH 3, 18 °C, 200 mA. 94.2% SMT was degraded but the level of mineralization remained low (6.5%), ensuring significant residual organic content for a subsequent biological treatment. Two possible degradation reaction pathways involving all the identified and quantified intermediates are proposed. In a second part, biological treatments with fresh activated sludge were performed to complete the mineralization of the electrolyzed solution of SMT, showing an increase of the mineralization yield with time duration of the pretreatment. For an initial SMT concentration of 0.2 mM, a ferrous ions concentration of 0.5 mM, at pH 3, 18 °C and 500 mA, the mineralization yield during the biological treatment increased as follows: 61.4, 78.8 and 93.9% for 0.5, 1 and 4 h pretreatment, confirming the relevance of the proposed combined process

Experimental Design Methodology Applied to the Oxidation of Quinolines in Aqueous Medium by Electro-Fenton Process

采用碳毡阴极和铂阳极的电芬顿工艺研究了喹啉模型分子8-羟基喹啉硫酸盐（8-HQS）在水溶液介质中的降解行为. 由于电化学诱导芬顿药剂（H2O2，Fe2+）产生大量的羟基活性基（OH），成为与有机物发生反应直到有机物完全矿化的强有力氧化剂，因此，电芬顿工艺具有很强的氧化能力. 采用正交实验设计确定了水溶液介质中8-HQS降解的操作参数. 结果表明，电流密度和8-HQS的初始浓度是影响降解速度的主要因素. 8-HQS浓度随着电解时间而减少，说明8-HQS的氧化遵循准一级反应动力学. 通过竞争动力学方法确定的由OH引起8-HQS氧化的绝对反应速度常数为1.62×109 mol-1·L·s-1. 通过Doehlert 矩阵研究了8-HQS矿化的最佳实验参数，由此确定最佳条件下电芬顿工艺能导致8-HQS在水溶液中的准完全矿化（总有机成分去除率95%）. 对8-HQS水溶液的处理，使得8-HQS矿化前的最终产物为短链羧酸. 同时研究了电芬顿处理中短链羧酸的演变行为. 溶液毒性演变的跟踪研究发现，中间产物的毒性比8-HQS强，但溶液的毒性在中间产物矿化后可以完全消除.The degradation behavior of 8-hydroxyquinoleine sulfate (8-HQS), a model molecule of quinolines, was studied in an aqueous medium by electro-Fenton process using a carbon felt cathode and a platinum anode. The great oxidation ability of this process is due to a large production of hydroxyl radical (OH) by electrochemically induced Fenton’s reagent (H2O2, Fe2+). Hydroxyl radicals are very powerful oxidizing agents which react on organics up to complete mineralization. A factorial experimental design was used for determining the operating parameters on the degradation of 8-HQS in an aqueous medium. The results showed that the current intensity and the initial concentration of 8-HQS were the main factors that influenced the degradation rate. The decay in concentration of 8-HQS with the electrolysis time shows that the oxidation of 8-HQS follows pseudo-first order kinetics. The absolute rate constant for the oxidation of 8-HQS by OH was determined by using competition kinetics method and found to be 1.62×109 mol-1·L·s-1. The optimal experimental parameters for the mineralization of 8-HQS have also been investigated by the use of Doehlert matrix. It has been demonstrated that under the optimal conditions determined by this method, electro-Fenton process can lead to a quasi-complete mineralization (95% of TOC removal) of 8-HQS aqueous solution. The treatment of 8-HQS aqueous solutions leads to the formation of short-chain carboxylic acids as end-products before mineralization. Their evolution during electro-Fenton treatment was studied. The follow-up of the solution toxicity evolution shows the formation of intermediates more toxic than 8-HQS. However, the solution toxicity was totally removed after mineralization of these intermediates.作者联系地址：1. Université Paris-Est, Laboratoire Géomatériaux et Environnement (LGE), UPEMLV, 77454 Marne-la-Vallée, France; 2. Laboratoire de Chimie Analytique et Electrochimie, Département de Chimie, Faculté des Sciences de Tunis, Campus Universitaire 2092, El Manar Tunis, Tunisia;3. Département de Génie Chimique et Biologique Institut National des Sciences Appliquées et de Technologie 1080 Tunis, TunisiaAuthor's Address: 1. Université Paris-Est, Laboratoire Géomatériaux et Environnement LGE, UPEMLV, 77454 Marne-la-Vallée, France; 2. Laboratoire de Chimie Analytique et Electrochimie, Département de Chimie, Faculté des Sciences de Tunis, Campus Universitaire 2092, El Manar Tunis, Tunisia;3. Département de Génie Chimique et Biologique Institut National des Sciences Appliquées et de Technologie 1080 Tunis, Tunisia通讯作者E-mail：[email protected]

Traitement des polluants organiques persistants par décharges à barrières diélectriques (DBD) et par décharges glissantes (Glidarc)

Ces travaux de recherche entrent dans le cadre de l étude de la dépollution et la dégradation des polluants organiques par procédé plasma qui permet la production in situ des espèces fortement oxydantes capables de dégrader les composés organiques. Notre intérêt a été porté à l étude de la dégradation de quelques polluants organiques par la technique de l arc électrique glissant (Glidarc) et par décharges à barrières diélectriques (DBD). Une première partie a été dédiée à la dégradation des mercaptans par Glidarc avec une optimisation de différents paramètres expérimentaux pour finir avec une application sur un rejet industriel riche en mercaptans issu d une usine lubrifiante Tunisienne. Une deuxième partie a été consacrée à l étude de la dégradation du rouge de méthyle par Glidarc en premier lieu ensuite par DBD. Après une optimisation des différents paramètres expérimentaux, une comparaison entre les deux techniques a été réalisée. La troisième partie a présenté les résultats obtenus lors du traitement du sulfure de triphénylphosphine présent dans une phase organique surnageant une phase aqueuse par Glidarc. Enfin, une dernière partie a été consacrée à la modélisation de la dégradation du rouge de méthyle par un réacteur Glidarc horizontal envisagé. L ensemble des résultats enregistrés lors de cette étude montre l efficacité du procédé plasma type Glidarc ou DBD pour le traitement et la dégradation des polluants organiques. Ce qui la place comme une technique alternative par rapport aux autres techniques de dépollution conventionnelles et usuelles puisqu elle a l avantage d être écologique, économique et efficace.This work reports on using plasma process that produces in situ highly oxidizing species able to degrade organic compounds to study the treatment of organic pollutants. By this way, we studied the degradation of some organic pollutant by gliding arc plasma (Glidarc) and by dielectrics barriers discharges (DBD). The first part was dedicated to the degradation of mercaptans by Glidarc with an optimization of different experimental parameters to finish with and application of this process to the decontamination of an industrial effluent rich in mercaptans. A second part was devoted to the study of the degradation of methyl red by Glidarc firstly then by DBD. After optimization of various experimental parameters, a comparison between the two techniques was performed. The third part presented the results obtained from the treatment of triphenylphosphine sulfide present in an organic phase on top of a water phase by Glidarc. A final section was devoted to the modeling of the degradation of methyl red by a new considered horizontal Glidarc reactor. Results show the efficiency of plasma process, DBD and Glidarc, for the treatment and degradation of organic pollutants. So plasma can be considered as an alternative technique compared to other conventional and usual remediation techniques as it has the advantage of being environmentally friendly, economical and efficient.PARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

M(II) transfer across a liquid-liquid microinterface facilitated by a complex formation with 8-Hydroxyquinoline: Application to quantification of Pb(II), Cd(II) and Zn(II) alone or in mixture in effluents

International audienceFor the first time, the assisted transfer of Pb(II) across a water/1,2-Dichloroethane (DCE) microinterface was investigated in the presence of 8-Hydroxyquinoline (named also oxine or 8-HQ) in the organic phase. A monocharged complex was formed in the aqueous phase and then transferred in the organic phase. A good relationship was obtained between currents and Pb(II) concentrations in the 10−4 to 5 10−3 M range and 10−5 to 6 10−5 M range using cyclic voltammetry and square wave voltammetry respectively. In presence of other heavy metals such as Cd(II) and Zn(II), only one electrochemical process is observed regardless of the mixture. Moreover, stationary currents increase in direct linear relation with the sum of M(II) concentrations added in water, allowing an overall detection of heavy metals. This result indicates that this method can be very interesting for monitoring all toxic metals in effluents. The limit of detection was found equal to 0.2 ppm for lead. This value allows us to reach levels significant for industrial effluents, in comparison to the limits fixed by the French ministry of ecology for lead, cadmium and zinc to 0.5 ppm, 0.2 ppm and 2.0 ppm respectively. This study highlights the real interest of devices based on a liquid-liquid microinterface

Performances of carbon-based screen-printed electrodes modified by diazonium salts with various carboxylic functions for trace metal sensors

The electrochemically induced functionalization of carbon-based screen-printed-electrodes (SPEs) by phenyl groups, having one or two carboxylic functions, was achieved by reduction of in situ generated diazonium salts in aqueous media. The corresponding diazonium cations of 4-aminobenzoic acid, 4-aminophthalic acid, 3-(4-aminophenyl) propionic acid, 3-(4-aminophenyl)-2-propenoic acid and 5-aminoisophthalic acid were generated in situ with sodium nitrite in aqueous H2SO4. The electrochemical detection of Pb(II) with the grafted SPEs was investigated using Pb(II) 5 × 10−8 M solutions. The performances of the grafted SPEs were found to be dependent on the number of carboxylic groups, on their position on the phenyl ring, on the olefinic or the aliphatic character of the chain bearing the carboxylic group. The performances of mono-4-carboxyphenyl and 3,5-dicarboxyphenyl grafted SPEs for Cd(II) and Cu(II) trace detection were tested and compared. Keywords: Trace element detection, Carbon-screen-printed electrode, Environmental analysis, Carboxylic diazonium sal

Plasma chemical oxidation of phthalic anhydride: application to the treatment of Tunisian landfill leachate

7 p.International audienceThe performance of several catalysts (Fe (III), Fe (II) and TiO2) for the removal of phthalic anhydride by gliding arc plasma was studied, among which Fe (II) was the best catalyst (75 % of removal after 180 min). Indeed, the addition of Fe (II) into the reaction allows a better elimination of the organic matter through the production of additional .OH radicals. The oxidation of Persistent Organic Pollutants present in landfill leachate was studied by varying the loading of TiO2, and after 8h of treatment 51 % of removal was reached for 15 g L-1 of TiO2