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The impacts of chlorination on methylparaben (MP) removal, as well as of bromide and ammonia on the MP elimination kinetics, were studied. Bromide and ammonia react with chlorine and are promptly transformed into bromine and chloramines, respectively. Rate constants of chlorine, bromine, and monochloramine with MP were determined under different pH conditions. At pH 8.5, the apparent second-order rate constants of MP reactions with chlorine and bromine were found to be 3.37(±0.50) × 101 and 2.37 (±0.11) × 106 M-1.s-1 for kChlorine/MP and kBromine/MP, respectively, yet there was low reactivity with monochloramine ( $$ {\mathrm{k}}_{{\mathrm{NH}}_2\mathrm{Cl}/\mathrm{MP}} $$ = 0.045 M-1.s-1). Regarding chlorination and bromination, in order to gain further insight into the observed pH-dependence of the reaction, the elementary reactions were considered and the corresponding second-order rate constants were calculated. The experimental and modeled values were quite consistent under these conditions. Then, chlorination experiments with different bromide and/or ammonia concentrations were performed to assess the impact of inorganic water content on MP elimination and a kinetic model was designed to assess MP degradation. Under these conditions, MP degradation was found to be enhanced in the presence of bromide whereas it was inhibited in the presence of ammonia, and the overall impact was pH dependent.

With questions emerging on the presence and risks associated with metabolites and transformation products (TPs) of organic contaminants in the aquatic environment, progress has been made in terms of monitoring and regulation of pesticide metabolites. However, less interest is shown for pharmaceutical residues, although their pseudo-persistence and adverse effects on non-target organisms are proven. This study provides original knowledge about the contamination of ten sites located along three French rivers (water, sediments, biofilms, clams) by pharmaceutical metabolites and TPs, as well as a preliminary environmental risk assessment. Studied compounds included carbamazepine with five metabolites and TPs, and diclofenac with three metabolites and TPs. Results show that metabolites and TPs are present in all studied compartments, with mean concentrations up to 0.52 µg L-1 in water, 229 ng g-1 in sediments, 2153 ng g-1 in biofilms, and 1149 ng g-1 in clams. QSAR estimations (OECD toolbox) were involved to predict the studied compounds ecotoxicities. QSAR models showed that diclofenac and its metabolites and TPs could be more toxic than carbamazepine and its metabolites and TPs to three aquatic species representing green algae, invertebrates, and fish. However, real ecotoxicological effects are still to be determined. The environmental risk assessment showed that hydroxydiclofenac, 2-[(2-chlorophenyl)-amino]-benzaldehyde and dibenzazepine could present a greater risk than other studied compounds for aquatic organisms. In addition, the risk associated with a mixture of diclofenac and its related metabolites and TPs has been found to be greater than that of the compounds considered individually.

Using hybrid chitosan-montmorillonite materials as environmentally-friendly alternatives to metallic salts in water treatment, and especially for drinking water production, is a new challenge. However, the coagulation-flocculation process requires minimization of polymer release and reactivity optimization to guarantee low Dissolved Organic Carbon content of the treated waters. To meet these requirements, hybrid materials were designed in this study to combine structural stability and good sorption efficiency, even in hard waters. The influence of preparation parameters (polymer molecular weight, polymer to clay mass ratio, addition method and post-preparation treatment) was evaluated and the obtained composites were fully characterized by X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Jar-Test experiments were carried out to assess the performance of the hybrids toward MethylOrange, a model molecule for the hardly removable hydrophilic compounds. The best results were obtained by drying the hybrids prepared at a 0.5:1 polymer to clay mass ratio by the direct addition method. Structural analysis revealed that the polymer chains of the dried-hybrid were more strongly bound to the Montmorillonite particles while remaining accessible to the organic molecules. This structure prevented its destabilization in the presence of high ionic strength. Under these conditions, all chitosan based materials exhibited some reactivity loss. However, the dissolved chitosan release was reduced to 13% of the initial dosage for the optimized dried hybrid compared to 47% for the undried version. To conclude, the optimized hybrids still outperformed pristine chitosan, Montmorillonite and FeCl3 for the removal of MethylOrange, thus highlighting their potential for future use.

In this manuscript, we evidenced for the first time proteogenic like peptide sequences in meteorite thanks to an original stereoselective enzymatic hydrolysis. Within this framework, we have first characterised the amino acids content of two meteorites, Murchison and Allende, after the standard acid hydrolysis protocol currently used in astronomical studies. To reach this goal, we have developed a highly sensitive chiral LC-MS method and we have highlighted new l- and d-enantiomers, never detected before in both meteorites. These primary findings extend the list of amino acids already found in meteorites. We next investigated the presence of proteogenic like peptide sequences. For that, we have compared the amounts of amino acids l- and d-enantiomers released from either the standard acid hydrolysis or our stereoselective peptidase hydrolysis. Thanks to this strategy, we have highlighted the presence of peptide sequences involving proteogenic l-amino acids in the Murchison together with their absence in Allende, which is consistent with the respective organic content of both meteorites. Furthermore, we demonstrated that the peptide sequences were indigenous to the Murchison meteorite.

International audience; Method development is part of the objectives of astrophysical community for characterizing the organic matter in objects of the Solar System. In this context, we report on the development of an enzyme-catalyzed stereoselective hydrolysis, inspired from the proteomics discipline, which has enabled the indirect detection of peptide sequences in extraterrestrial samples. A proof of concept has been performed on a Murchison extract. We showed that our approach can successfully highlight L- and D-amino acids involved in peptide bonds. While we showed that some D-amino acids must have been involved in peptide bonds, we cannot at this stage conclude on the indigenous or exogenous nature of these biopolymers. However, our strategy constitutes the first step towards the direct UPLC-MS evidence of peptide sequences in extraterrestrial samples. It should thus participate to deepen knowledge on the molecules available in the Solar System, hence providing new clues on their chemical history, especially on Earth.

In this study, aqueous solutions of gallic acid (GA) were irradiated in an electron beam (EB) accelerator under different experimental conditions (various initial GA concentrations, presence or absence of oxidant and oxygen). For an initial GA concentration of 50 μM, complete GA degradation was achieved with an absorbed dose of 850 Gy in the presence of dissolved oxygen. Both GA removal and mineralization are favored when oxygen is present. The addition of persulfate anions (S2O82−) or hydrogen peroxide (H2O2) also increased the efficiency of GA degradation and mineralization. For an absorbed dose of 14 kGy, GA mineralization reached approximately 45%, 55%, and 72% for the EB, EB/H2O2, and EB/S2O82−systems, respectively. Three transformation products were tentatively identified in the presence of oxygen, these are the result of hydroxylation and ring opening reactions. No specific transformation product was found for the sulfate radical anion (SO4–●) reaction. Four additional compounds, including a dimer, were identified in oxygen-free solutions. These findings demonstrate that water radiolysis based on EB irradiation is an efficient process to activate H2O2 and S2O82− anions and is an advanced oxidation process (AOP).

Aromatic sulfonated compounds and naphthalene derivatives are major chemical compounds used in the industry. Electron beam irradiation of aqueous solutions of 2-naphthalenesulfonate (90 µM) was investigated under various experimental conditions. The results obtained demonstrate that the 2-NS concentration decreased dramatically on increasing the absorbed dose in the range 0–1000 Gy. The effectiveness of the radiolytic system was demonstrably enhanced by the addition of oxidants (S 2 O 8 2− or H 2 O 2 ). 2-NS removal was higher with S 2 O 8 2− than with H 2 O 2 . For the EB, EB/H 2 O 2 , and EB/S 2 O 8 2− systems, the absorbed doses for 90% elimination of 2-NS (D 90 ) were 700, 480, and 274 Gy, respectively. 2-NS is poorly mineralized by EB but more than 35% mineralization was reached for 15 kGy when oxidants (820 µM S 2 O 8 2− or 935 µM H 2 O 2 ) were added. In all systems, the mineralization yield was markedly higher when air (i.e. dissolved oxygen increase) was introduced between successive doses. For 50% 2-NS removal, seven sulfonated transformation products were identified using LC/MS analyses. For the highest absorbed doses the sulfonate group in 2-NS was converted to sulfate ions in the radiolytic systems.

This study focused on the presence of three biocidal products specific to healthcare facilities, i.e. chlorhexidine digluconate (CHD), bis(aminopropyl)laurylamine (BAPLA), and didecyldimethylammonium chloride (DDAC), in a hospital sewage system. Five sampling campaigns were conducted in 2016 and 2017 throughout the entire Poitiers University Hospital sewage system. DDAC concentrations ranging from 933 ± 119 to 3250 ± 482 μg/L were detected in 24-h composite samples, while lower concentrations (both within the same range) were detected for the two other compounds (i.e. 25 ± 5 to 97 ± 39 μg/L for CHD and 18 ± 3 to 142 ± 16 μg/L for BAPLA). Based on these findings, a mass balance was determined for these discharged compounds to compare the quantities detected in discharges to the amounts used for healthcare in the hospital. Hence, 60–90% of the quantities of DDAC used were found to be present at the hospital sewage outfall. Higher percentages of CHD (100–242%) were noted because of the high presumably quantities used for antiseptic applications, which were not considered in mass balance calculation. Finally, only 10–30% of BAPLA quantities used were detected at the site outfall. Analysis of the results for the different sampling points revealed the nature of the emission sources. For surface applications of DDAC and BAPLA, management of hospital linen is thus a major source of discharged biocidal products, probably following the washing of biocide-soaked textiles used for hospital facility maintenance. Moreover, discharge of biocidal products from a healthcare establishment depends especially on biocide handling practices in the emitting establishment. For BAPLA, compliance with hospital recommended dosages and practices whereby operators are required to prepare tailored quantities of detergents and disinfectants for each specific task could largely explain the limited release of this compound.

In wastewater treatment, advanced oxidation processes are largely accepted as efficient technologies. Unfortunately, in general, these approaches present a high operating cost due to an open-loop implementation, i.e. the inlet reagent is introduced in excess in order to respect discharge standards. Therefore a mixture between automatic control techniques and chemical engineering expertise should significantly improve and expand their industrial applications via closed-loop implementations. More precisely, the present paper deals with a catalytic ozonation reactor where the main objective is to reduce the oxygen consumption by minimizing the ozone overproduction. For this end, a H ∞ control strategy is used in order to obtain a significant abatement of the pollutant, and by the way illustrates the gain one can expect when applying such techniques to this kind of process.

Photocatalytic degradation of phenol has been investigated using a laboratory reactor and UV-A lamp (BLB) and different commercial catalysts: TiO 2 PC500 fixed on cellulose paper (Ahlstrom paper) and TiO 2 (Degussa P25) on stainless steel or conducting glass. Thin layers of TiO 2 on glass and stainless steel were prepared by electrophoretic deposition. Phenol and by-products were monitored by HPLC system equipped with a phenyl column and PDA detector. The effects of various operating parameters such as initial concentration of phenol (100–500 μmol L −1 ), initial pH (2.0–10.0) and addition of inorganic oxidants (H 2 O 2 , S 2 O 8 2 − ) were evaluated on Ahlstrom paper. The results revealed that the best conditions of phenol removal were 100 μmol L −1 of initial concentration, natural pH (5.0–6.0) and absence of inorganic oxidants when using Ahlstrom paper. Also, analysis of the by-products shows their dependence on initial pH. The comparison of phenol removal efficiency shows that thin layers of TiO 2 P25, deposited on glass, present the best photocatalytic activity. Several experiments performed with the same photocatalyst show that washing layers with pure water several times and drying at low temperature allow reactivation of the catalysts.

This paper deals with a grey-box model identification of a catalytic ozonation pilot process used in wastewater treatment. The grey-box model is presented. For the parametric estimation, a non convex optimization problem must be solved. Then, we propose to solve this problem, in practice, by using a Levenberg-Marquardt algorithm applied to a composite criterion based on a priori knowledge which imposes a physical meaning to the solution. The method is applied to experimental data.

This paper deals with the identification of a wastewater treatment pilot process by catalytic ozonation. In general, catalytic ozonation processes operate with a deliberate ozone overproduction to obtain a treated water which respects the discharge standards. But, in this case, the oxygen consumption is not optimal and the operating costs are important. The final objective of this study focuses on the optimization of the catalytic ozonation reactor. The first step, the system identification, is described in this paper. A one-input two-output model is identified to represent the pilot process behavior. The first output is modeled by a nonlinear continuous-time Wiener model, and the second one is given by a linear continuous-time transfer function.

International audience; The electron beam irradiation of aqueous solutions of citric acid was studied. The results showed the effectiveness of the degradation of the carboxylic acid by the radiation process. The impact of pH was examined. It was demonstrated that the increase of pH induces a drop of the degradation due to the scavenging of radicals by the inorganic carbon. Moreover the interest of persulfate () addition that induces the formation of sulfate radicals () by the reaction of persulfate with the hydrated electrons was studied. The addition of persulfate leads to a great enhancement of the degradation of the carboxylic acid and also a large increase of the mineralization of the solution. Effectively, it was shown that the particular reactivity of the sulfate radical causes an enhancement of the mineralization yield

The degradation of acetic acid in aqueous solution by ionizing radiation was studied. The radiolysis of acetic acid solution induces the almost complete degradation and mineralization of this compound. The high yield of acetic acid mineralization is explained by the degradation of oxalic acid by solvated electron. The degradation of acetic acid depends on the pH of the solution. The best degradation is observed at pH 4.5 due to the higher rate constant of reaction of acetate with hydroxyl radicals and the competitive reactions of inorganic carbon which occur at higher pH. The influence of persulfate ion (S 2 O 8 2− ) addition that forms the sulfate radical (SO 4 − ) during irradiation in solution was examined. The persulfate addition induces an almost constant degradation of acetic acid whatever the initial pH of the solution. The decrease of pH during the persulfate radiolysis partly explains the high degradation observed. But the additional radicals formed by the persulfate introduction also improve the degradation.

These days, the use of persulfate in advanced oxidation processes (AOPs) has gained more attention as an emerging clean and efficient technology to degrade the organic pollutants. The objective of this study was to investigate the effect of the addition of persulfate on the oxidation of benzotriazole (BT) and humic acids (HAs) by irradiation. The degradation of BT (3.7 μM) was followed under the influence of persulfate addition (200–500 μM) in combination with a fixed radiation dose (15 Gy) in the absence and presence of HA (5 and 20 mg/L) in deionized water. The main results obtained in this study on the degradation of BT in the presence of HA showed a different effect of S 2 O 8 2− addition during irradiation, depending on whether HA are oxidized or not-oxidized. (1) An inhibitory effect of S 2 O 8 2− was observed in the presence of non-oxidized HA. (2) The removal of BT was generally more important during irradiation in the presence of S 2 O 8 2− when HA is pre-oxidized. This could be explained by the different structures of humic acids. These differences of structures of HA were identified by physico-chemical parameters such as the absorbance in the UV (254 nm), the fluorescence and the SUVA measurement.

The radiolysis of persulfate (S2O82−) aqueous solution was studied for the enhancement of electron beam process applied to water treatment. It was shown that the persulfate ion reacts with aqueous electron and produces additional radical species in aqueous solution. The oxidative radical species formed (sulfate radical SO4− ) is a very strong oxidant able to react with various recalcitrant pollutants. A model of the evolution of persulfate concentration in solution was performed. It was shown that the presence of persulfate induces a decrease of pH and also an increase of dissolved oxygen concentration in solution during irradiation. Moreover the interest of persulfate addition for the improvement of an organic compound degradation by radiolysis was shown.

Nowadays the removal of organic micropollutants is one of the major challenges of water and wastewater treatment plants. The objective of this study was to investigate the influence of persulfate addition on micropollutants degradation by ionizing radiation. In this system, the radicals SO4 −/OH can be present simultaneously due to persulfate reaction with solvated electrons. Ibuprofen (IB), progesterone (Pg) and benzotriazole (BT) have been selected for this study. The degradation of micropollutants was followed at various radiation doses and under the influence of persulfate (S2O82−) addition at a fixed dose (30 Gy), in deionized and tap water. In deionized water the addition of 500 μM persulfate improved the degradation of BT, IB and Pg by 17%, 36% and 24% respectively and the removal of micropollutants was increased when the concentration of persulfate ions increased. No influence of the presence of persulfate ions was observed in tap water. Contrary to tap water experiments, the persulfate (500 μM) increases the elimination of BT slightly in the presence of bicarbonate ions. In the case of IB and Pg the influence of persulfate addition is significant even in the presence of bicarbonate ions which indicate that the bicarbonate ions do not completely inhibit the influence of persulfate addition in tap water. Even if the bicarbonate ions have an inhibitory effect on the irradiation system, it was suggested that the inhibition could be explained by the presence of nitrate ions, which would prevent the formation of sulfate radicals.

Ozonation experiments were performed in batch reactors in order to determine the rate constants for the reaction of molecular ozone and OH radicals with benzotriazole (BT) at different pHs. The first group of ozonation experiments was carried out for the determination of the rate constant for the direct reactions between ozone and BT. Two different kinetic models were used for the determination of kinetic rate constants: (i) the log-reduction of BT with ozone in excess, (ii) the competition kinetic model. The second-order rate constants for BT with molecular ozone were determined to be 36.4+/-3.8M(-1) s(-1) and 18.4+/-0.8M(-1) s(-1) at pH 2 from the two methods respectively. With the competition method, the value at pH 5 was found to be 22.0+/-2.0M(-1) s(-1). In a following stage, the reaction of BT with OH radicals was investigated at pH values ranging from 2 to 10.2. Using a method involving two probe compounds during the ozonation, the second-order rate constants of the BT reaction with hydroxyl radicals were determined. The rate constants were found to vary from 6.2x10(9)M(-1) s(-1) at pH 10.2 to 1.7x10(10)M(-1) s(-1) at pH 2.

International audience; This work aims at envisaging the use of a solid catalyst in the catalytic ozonation process to avoid the separation step needed after the treatment for catalyst recovery when powdered material is involved. This work devoted to the removal of succinic acid (SA), a low molecular weight refractory organic acid whose heterogeneous catalytic ozonation was previously studied using powder form catalysts. Heterogeneous catalytic ozonation of succinic acid was carried out in a reactor fitted with a recirculation loop. This study investigated if the location of the solid catalyst, i.e. inside the reactor in the zone of ozone transfer or in a cartridge placed on the recirculation loop, had an influence on the amount of SA removed or on the elimination rate expression. No influence of the catalyst location was detected. The rates of SA removal by catalytic ozonation were found to depend on both the catalyst concentration and the initial SA concentration for weak SA initial concentrations, but only on the catalyst concentration for greater initial SA concentrations. The pattern of SA concentration from modelization closely matched the experimental results. This implementation of the catalytic ozonation process with solid catalyst is of interest for the application at industrial scale. The 1.8 ratio between the rates of SA and DOC removal showed that mineralization to CO2 did not occur simultaneously with SA removal.

International audience; The degradation of p-hydroxybenzoic acid (HBA) in aqueous solutions by ionizing radiation was studied. The phenolic pollutant was easily removed by the electron beam irradiation, as more than 80% of the initial 100 µM introduced was degraded for a dose of 600 Gy. It was shown that the addition of persulfate, producing the sulfate radical as additional reactive species, induced a change in the reaction pathway. LC–MS analyses were performed in order to identify the different by-products formed. In the absence of persulfate, the main by-product formed was 3,4-dihydroxybenzoic acid, while in presence of persulfate, 1,4-benzoquinone was detected and the hydroxylated by-products were not present. A reaction pathway of HBA degradation by hydroxyl and sulfate radicals was proposed from the identification of the chemical structure of the different by-products detected.The influences of pH and dissolved oxygen were also studied. A high decline of HBA degradation was observed at pH 11 compared to pH 4.5, this decrease was minimized in the presence of persulfate. The dissolved oxygen concentration was found to be a limiting parameter of HBA degradation, however an excess of dissolved oxygen in solution did not improve the degradation to a large extent.

International audience; The aim of this study was to assess the impact of chlorination on the degradation of one of the most commonly used UV filters (benzophenone-3 (BP-3)) and the effects of bromide and ammonia on the kinetics of BP-3 elimination. Bromide and ammonia are rapidly converted to bromine and chloramines during chlorination. At first, the rate constants of chlorine, bromine and monochloramine with BP-3 were determined at various pH levels. BP-3 was found to react rapidly with chlorine and bromine, with values of apparent second order rate constants equal to 1.25(±0.14) × 10(3) M(-1)·s(-1) and 4.04(±0.54) × 10(6) M(-1)·s(-1) at pH 8.5 for kChlorine/BP-3 and kBromine/BP-3, respectively, whereas low monochloramine reactivity was observed (kNH2Cl/BP-3 = 0.112 M(-1)·s(-1)). To assess the impact of the inorganic content of water on BP-3 degradation, chlorination experiments with different added concentrations of bromide and/or ammonia were conducted. Under these conditions, BP-3 degradation was found to be enhanced in the presence of bromide due to the formation of bromine, whereas it was inhibited in the presence of ammonia. However, the results obtained were pH dependent. Finally, a kinetic model considering 18 reactions was developed using Copasi to estimate BP-3 degradation during chlorination in the presence of bromide and ammonia.

International audience; Due to water scarcity, development of innovative processes for wastewater reuse has become a priority. Hence, hybrid processes coupling membrane separation with advanced oxidation processes could play a decisive role in the production of safe water. However, membrane fouling is still one of the main limitations to process widespread application. Thus, the present study investigates the impact of e-beam irradiation on the fouling ability of a secondary effluent (SE) filtered on MF and subsequently on RD membranes. For this, two electron beam radiation doses (1 and 5 kGy) were investigated. Results demonstrate that whatever the radiation dose investigated, no change in terms of TOC in SE was observed (prior to filtration). However, a strong decrease in 1JV254 and fluorescence signal was observed for organic matter (OM) exhibiting a MW ranging from 135 to 10 kDa. Pre -oxidation was found to efficiently optimize ME filtration permeate flux whereas no improvement could be observed regarding RD separation. Moreover it was demonstrated that ME efficiently removed the high MW compounds and was barely efficient in low MW compounds removal. Energetic balance based on experimental results demonstrates that 1 kGy was a sufficient dose to operate the hybrid e-beam irradiation and ME process.

The pH influence on the catalytic ozonation of small carboxylic acids (succinic (SA), chloroacetic (CAA) and pyruvic (PA) acids) was studied and compared to ozonation alone. In the acidic systems, the conversion of these carboxylic acids and total organic carbon (TOC) during the catalytic ozonation is mainly due to the catalytic effect. Experiments on SA indicate that in the pH range 3.6–5.0, in contrast to the ozone behavior, the efficiency of the catalytic ozonation system is decreased with increasing pH due to the change of charges on the catalyst surface. In the basic pH range (7.2–10.0), the effect of the ozonation alone becomes important and the reaction in the presence of the catalyst is a combined effect of ozonation alone and catalytic oxidation. Although the apparent SA conversion by the catalytic ozonation in the basic systems is higher than in the acidic systems, the Total Organic Carbon conversion is not so much higher than in the latter. During the ozonation with the same catalyst, more than 80 of the CAA converted are mineralized. The oxidation of CAA leads to almost equimolar release of chloride ions. This ion has no detrimental influence on the catalytic effects under our experimental conditions. However, in the very dilute systems with pH value lower than the pKa of CAA, when the CAA concentration is decreased to about 0.6 mM, the catalytic oxidation is almost stopped. The low concentration of the dissociated CAA induces only weak adsorption and consequently small reaction rates. The total elimination of CAA with low concentration can be reached only if the pH is increased above the pKa. In addition to the distinct pH effect in the ozonation and catalytic ozonation system observed in this work, a further demonstration that separate mechanisms are involved in the two processes is provided by the analysis of oxidation by-products of pyruvic acid.

The catalytic mineralization of chloroacetic acid (CAA) and chlorosuccinic acid (CSA) by ozone with Ru/CeO2–TiO2 solid catalyst in aqueous systems was studied. The catalyst significantly improves the oxidation and degradation at acidic pH. More than 80 to 90% of the converted CAA and CSA are mineralized during the reaction. The chloride is nearly completely released along with the decomposition of CAA and CSA. The catalytic oxidation of CAA and CSA and conversion of total organic carbon can be simply simulated with a pseudo-first-order behavior with little dependence on the concentration of the dissolved ozone in the aqueous systems, which is maintained in sufficient quantity during the reaction. The catalytic ozonation displays a higher ozone use efficiency than ozonation alone. CSA is apparently easier to degrade than CAA. The chloride ion in the solution has little detrimental influence on the catalytic effects under our experimental conditions. The oxidation of 2 mM CAA is apparently stopped after about 50 min when the CAA concentration decreases to about 0.6 mM and the pH value of the system is lower than the pKa of CAA. The explanation is that in very dilute systems with pH values lower than the pKa, the low-concentration of CAA ions slows the adsorption and reaction rates. The near-total elimination of CAA at low concentrations can be achieved only if the pH value is increased above the pKa. The results demonstrate that catalytic ozonation is an effective and promising method for the oxidation and elimination of chlorocarboxylic acids.

Paracetamol oxidation by ozonation and H2O2/UV processes was investigated. The second-order rate constant for the reaction of paracetamol with ozone was determined at pH 7.2 ( k O 3 / PRC = 2.57 × 10 6 M - 1 s - 1 ) . The rate constant of the elementary reaction of ozone with the ionized form of PRC was then calculated and the pH dependence of the ozonation reaction of PRC was estimated. The second-order rate constant of the reaction of paracetamol with HO radicals was also determined at pH 5 through the H2O2/UV oxidation system ( k HO / PRC = 4.94 × 10 9 M - 1 s - 1 ) . In the light of the high rate constants obtained, two conclusions on the kinetics of paracetamol ozonation in real water were drawn: (i) hydroxyl radicals do not have any impact on the removal of paracetamol during ozonation of real waters; (ii) a half-life of 0.03 s can be estimated for paracetamol, for a residual ozone concentration of 0.4 mg L−1. Hydroquinone and two other ozonation transformation products were identified by LC/UV, LC/MS and MS/MS analyses. In parallel, for the first time, toxicity was measured in ozonated paracetamol solutions with the luminescent bacteria Vibrio fisheri test. The results showed an increase in toxicity as paracetamol degraded. This toxicity could not be assigned to hydroquinone formation only. One or several other transformation products more toxic than paracetamol might be formed.

Ozonation of aqueous solutions of succinic acid ([SA]0=1 mM) was studied in the presence of ruthenium (2%) deposited on cerium dioxide catalysts. The influence of ruthenium, of the catalyst preparation mode (impregnation or exchange), of the support pretreatment, of the surface area and of the final treatment of the catalyst (by calcination or reduction) has been examined. Under our experimental conditions, the acid was not removed by ozone alone and its adsorption on the catalytic material was limited (

The oxidation of hydroxylamine in aqueous solution ([NH2OH]o = 1 mM, pH = 7) by OH radicals was studied using H2O2/UV and γ-irradiation as radicals generation processes. Nitrites and nitrates were identified as the major by-products in the aqueous phase. Their concentration depends on the experimental conditions, i.e. the presence or the absence of oxygen, and the concentration of hydrogen peroxide(H2O2). For the smallest initial concentrations of H2O2 studied (below 10 mM), hydroxylamine was oxidized into gases of low solubility. It is assumed that these gases are mainly constituted of N2 and N2O. Subsequently to the H-abstraction from the molecule of hydroxylamine by OH radicals, NHOH radical recombinations are favored in the absence of oxygen and H2O2 and would lead to N2. In the presence of oxygen, NOH can be produced and can dimerise into N2O or react with NH2OH to form N2. Reactions involving O2 and H2O2, or O 2 − can account for nitrites then nitrates.

The removal of atrazine from water containing humic substances by means of γ-irradiation was studied. γ-irradiation experiments were carried out under 4 different conditions: with continuous bubbling of N 2 , O 2 , N 2 O alone and N 2 O with O 2 (N 2 O/O 2 =80/20) during irradiation. Some results were compared with those obtained using the combination O 3 /γ-irradiation. It was shown that atrazine is removed by both OH and e − aq . But opposite to data from OH radicals action, neither desethylatrazine nor deisopropylatrazine are major byproducts from e − aq . The natural organic matter (humic substances) content of the aqueous solution was characterized by 254 nm wavelength absorbance, total organic carbon, hydrophobicity and ultrafiltration on 1000 D cutoff membranes. Results indicate that for a radiation dose of 800 Gy, which has been applied for atrazine removal, among the three species examined (i.e. OH , O − 2 and e − aq ), mostly OH and O − 2 lead to organic matter properties changes.

This study has been undertaken to determine the conditions of formation of organoiodinated compounds responsible for medicinal tastes and odors frequently observed after chlorination of waters containing iodides. It has been shown that iodoform was formed in the presence of chloramines, in a region where the formation of the most classical chlorinated and brominated THMs is usually unfavored. Reactions would take place between monochloramine, organic matter, and iodides to yield iodoform. These interactions are favored when iodide ions are replaced by iodine. Oxidation by iodine alone in the presence of ammonia and without monochloramine does not explain the yield of the iodinated THMs observed. However, nitrogenated molecules such as amines and amino acids would take part during chlorination in the production of organoiodinated compounds to a small extent.

The aim of this work is to study the mechanism of the reaction of hydroxyl radicals with simple aliphatic acids (acetic, glycolic, glyoxylic and oxalic acids; see Table 1) in aqueous solution. The decomposition of organic acids by hydroxyl radicals has been studied using the photolysis of hydrogen peroxide and the ozone/hydrogen peroxide system.

International audience; This work was carried out to investigate the fate of the antibiotic levofloxacin upon oxidation with ozone and hydroxyl radicals. A kinetic study was conducted at 20 degrees C for each oxidant. Ozonation experiments were performed using a competitive kinetic method with carbamazepin as competitor. Significant levofloxacin removal was observed during ozonation and a rate constant value of 6.0 x 10(4) M-1 s(-1) was obtained at pH 7.2. An H2O2/UV system was used for the formation of hydroxyl radicals HO.. The rate constant of HO was determined in the presence of a high H2O2 concentration. The kinetic expressions yielded a k(Ho/LVF) value of 4.5 x 10(9) M-1 s(-1) at pH 6.0 and 5.2 x 10(9) M-1 s(-1) at pH 7.2. These results were used to develop a model to predict the efficacy of the ozonation process and pharmaceutical removal was estimated under different ozonation conditions (i.e. oxidant concentrations and contact times). The results showed that levofloxacin was completely degraded by molecular ozone during ozonation of water and that hydroxyl radicals had no effect in real waters conditions. Moreover, LC/MS/MS and toxicity assays using Lumistox test were performed to identify ozonation transformation products. Under these conditions, four transformation products were observed and their chemical structures were proposed. The results showed an increase in toxicity during ozonation, even after degradation of all of the observed transformation products. The formation of other transformation products not identified under our experimental conditions could be responsible for the observed toxicity. These products might be ozone-resistant and more toxic to Vibrio fisheri than levofloxacin

This paper deals with the control of a wastewater treatment pilot by catalytic ozonation. In general, catalytic ozonation processes operate with a deliberate ozone overproduction to obtain a treated water which respects the discharge standards. But, in this case, the oxygen consumption is not optimal and the operating costs are important. The objective of this study focuses on the optimization of the catalytic ozonation pilot. An optimal control is proposed to obtain a significant abatement of the pollutant. In this application, the pollutant abatement is represented by the absorbance.

This paper deals with the control of a wastewater treatment pilot by catalytic ozonation. In general, catalytic ozonation processes operate with a deliberate ozone overproduction to obtain a treated water which respects discharge standards. But, in this case, the oxygen consumption is not optimal and the operating costs are important. The objective of this study focuses on the optimization of the catalytic ozonation reactor. A continuous-time transfer function model is identified to represent the pilot behavior, and an optimal control is proposed to obtain a significant abatement of the pollutant. In this application, the pollutant abatement is represented by the absorbance.

The aim of this work was to study the oxidation of aliphatic acids by radicals resulting from the protolysis of hydrogen peroxide. Experiments carried out in dilute aqueous solutions (pH = 2.9−3.5) of mono and dicarboxylic acids with 1 to 4 carbon atoms showed (i) the oxidation of the carboxylic group is slow, (ii) the hydroxyl group of hydroxylated acids activates the adjacent CH bond and leads, after hydrogen atoms abstraction, O2 addition and HO2 removal, to the carbonyl group, (iii) a CC bond cleavage occurs after hydrogen atom abstraction and oxygen addition for unsubstituted dicarboxylic acids. Except for oxalic acid, the mechanism of oxidation into CO2 of the acids studied involves oxygen consumption and O2−/HO2 release.

The aim of this work was to study the mechanism of oxidation of dicarboxylic acids by hydroxyl radicals resulting from the photolysis of hydrogen peroxide. Experiments have been carried out with aqueous solutions (Co ≈ 1 mmol.L−1) of malonic acid, hydroxymalonic, ketomalonic, succinic, malic and tartaric acids. Results showed that in the presence of dissolved oxygen, OH• reacts with hydroxyacids by H-abstraction at the carbon atom carrying the hydroxyl group. The radical formed fixes one oxygen molecule and then releases one HO2 • radical. On the other hand, the reaction of OH• radicals with the unsubstituted analogues leads to a C-C bond cleavage. In each case, the mechanism proposed involves oxygen consumption.

International audience; The aim of this study was to gain further insight into the fate of levofloxacin during the chlorination process. First, a kinetic study was thus performed at pH 7.2, 20 °C and in the presence of an excess of total chlorine. A slower apparent removal of levofloxacin (k ∼ 26 M−1 s−1) was noted when sodium thiosulfate was used to stop the chlorination reaction compared to the degradation observed without using a reducing agent (k ∼ 4400 M−1 s−1). The formation of a chlorammonium intermediate which could be converted back into the parent compound through a reaction with thiosulfate was thus expected. This intermediate would result from an initial chlorine attack on the tertiary amine function of levofloxacin. Secondly, four chlorination transformation products were detected by LC/UV/MS analysis. The chemical structures of two of them are proposed. It was suggested that these compounds could come from a secondary reaction of the chlorammonium intermediate on levofloxacin. A reactional pathway is then proposed. Finally, a bioassay using Vibrio fisheri was carried out to study the toxicity pattern during levofloxacin chlorination. An increase in toxicity was observed during chlorination suggesting that the first transformations products formed were more toxic than the parent compound.

This paper deals with the control of a wastewater treatment pilot by catalytic ozonation. In general, catalytic ozonation processes operate with a deliberate ozone overproduction to obtain a treated water which respects the discharge standards. But, in this case, the oxygen consumption is not optimal and the operating costs are important. The objective of this study focuses on the optimization of the catalytic ozonation pilot. A continuous-time transfer function model is identified to represent the pilot behavior, and an internal model control is proposed to obtain a significant abatement of the pollutant. In this application, the pollutant abatement is represented by the absorbance.

The effect of phenolic compounds (phenol and p-nitrophenol) on the removal of chlorite in aqueous solution (50 mg/L; pH=7.2; 20 o C) by filtration though granular activated carbon beds (3.0g of CECA 40 activated carbon) was examined. No reaction between chlorite and phenol or p-nitrophenol was observed in the absence of activated carbon. The presence of phenol or p-nitrophenol in solution or preadsorbed on carbon decreased the capacity of activated carbon to remove chlorite. High-performance liquid chromatography, total organic halogen, and gas chromatography/mass spectrometry analyses showed that many organic byproducts such as chlorophenols, p-benzoquinone, dimerization, and carboxylation products were formed on the surface of activated carbon

The removal of phenol (Co = 100 μM) during electron beam irradiation was studied in pure water and in the presence of HCO 3 − and Br − ions. It was found that the introduction of S 2 O 8 2− ions (1 mM), by generating SO 4 − radicals increases the radiation yield of phenol removal. 90% removal of phenol was obtained with radiation doses 600 and 1200 Gy with and without S 2 O 8 2− ions respectively. This system induced smaller oxygen consumption with smaller concentration of catechol and hydroquinone found in the solution. HCO 3 − and Br − have an inhibiting effect in the presence as in the absence of S 2 O 8 2− . In most cases, the introduction of S 2 O 8 2− ions in water radiolysis system can advantageously increase the yield of organic compounds removal by oxidation.

The photolysis of S(2)O(8)(2-) was studied for the removal of acetic acid in aqueous solution and compared with the H(2)O(2)/UV system. The SO(4)(-) radicals generated from the UV irradiation of S(2)O(8)(2-) ions yield a greater mineralization of acetic acid than the ()OH radicals. Acetic acid is oxidized by SO(4)(-) radicals without significant formation of intermediate by-products. Increasing system pH results in the formation of ()OH radicals from SO(4)(-) radicals. Maximum acetic acid degradation occurred at pH 5. The results suggest that above this pH, competitive reactions with the carbon mineralized inhibit the reaction of the solute with SO(4)(-) and also ()OH radicals. Scavenging effects of two naturally occurring ions were tested; in contrast to HCO(3)(-) ions, the presence of Cl(-) ions enhances the efficiency of the S(2)O(8)(2-)/UV process towards the acetate removal. It is attributed to the formation of the Cl() radical and its great reactivity towards acetate.

International audience

The dispersion of micropollutants, especially from wastewater treatment plants (WWTP), has been a recurring topic for several years regarding the need of aquatic environments protection i.e. towards chemical quality and ecotoxicity considerations. The development of high-resolution mass spectrometry (UHPLC-HRMS) and the access to databases allowed the development of non-targeted analysis for environmental matrices such as WWTP water and surface water. The objectives of this PhD work were to develop a non-targeted analysis method and to apply it to water samples from wastewater treatment plants in order to characterize them. The possibly of tracing these waters close to river discharges has been studied. Relevant features and tracers of WWTP discharge were thus sought by the use of differential analyses.Two methods based on Mzmine 2 software (combined with the use of R 3.5.1 and Excel) and Compound Discoverer were developed. As a result of these developments, the use of Compound Discoverer software was favored for the rest of this work. The use of three injection replicas during the analyses by UHPLC-HRMS resulted in a reduction in the number of false positives. The matrix effect was also evaluated as well as the use of solid phase extraction which was generally positive. The application of non-targeted analysis on samples from WWTP influents and treated waters showed a decrease in the number of features detected in the treated water, especially in the case of features corresponding to apolar molecules and/or with a high molecular mass. However new features were also observed in these waters. From the differential analysis, 375 stable or increasing relevant features in treated waters were selected and a chemical structure was proposed for some of them. The study of the impact of the discharge of treated water highlighted the addition of new features in the river. Despite a decrease in the area values of the features immediately downstream, a return to the initial state of the upstream was not observed. 305 relevant features were selected on the basis of a downstream/upstream comparison whose a small number which were common with the relevant features list made from the analysis of WWTP samples. These results underline both the interest of the method and the difficulty of determining tracers that are really related to WWTP discharges. Analyses of suspects were also carried out in addition to the non-targeted analysis.; La diffusion des micropolluants et plus particulièrement de la diffusion par les rejets de stations d’épuration (STEP) est une problématique récurrente depuis de plusieurs années dans la nécessité de protéger les milieux aquatiques du point de vu de la qualité chimique et écotoxique. Le développement de la spectrométrie de masse haute résolution et de l’accès aux bases de données a permis l’essor de l’analyse non ciblée appliquée aux matrices environnementales dont les eaux de STEP et les eaux de surfaces. Les objectifs de ce travail de thèse ont été de développer une méthode d’analyse non ciblée, de l’appliquer sur des eaux de stations d’épuration afin de les caractériser et d’étudier l’impact du traitement des eaux usées et du rejet des eaux traitées dans la rivière Clain. Des signaux pertinents et traceurs du rejet de STEP ont également été recherchés par l’utilisation d’analyses différentielles.Deux méthodes se basant sur les logiciels Mzmine 2 (avec R 3.5.1 et Excel en complément) et Compound Discoverer ont été développées. À la suite de ces développements, le logiciel Compound Discoverer a été conservé pour le reste des travaux de thèse. L’usage de trois réplicas a montré une réduction du nombre de faux positifs. L’effet matrice a également été évaluée de même que l’utilisation de l’extraction sur phase solide qui s’est avérée globalement positive. L’application de l’analyse non ciblée sur des entrées et sortie de STEP a montré une diminution du nombre de signaux détectés en sortie, principalement des signaux plutôt apolaires et/ou de taille importante mais a montré aussi l’apparition de nouveaux signaux. À partir de l’analyse différentielle, 375 signaux pertinents stables ou augmentant en sortie ont été sélectionnés et l’annotation d’une partie d’entre eux a été effectuée. L’étude de l’impact du rejet des eaux traitées a mis en lumière l’apport de nouveaux signaux dans le Clain. Malgré une baisse des valeurs des aires en aval immédiat, il n’a pas été observé de retour à l’état initial en amont. Une sélection de 305 signaux pertinents a été effectuée donc un faible nombre sont communs avec la liste réalisée à partir des échantillons de STEP, témoignant à la fois de l’intérêt de la méthode mais également de la difficulté de déterminer des traceurs apparentés réellement aux rejets de STEP. Des analyses de suspects ont également été réalisées en complément de l’analyse non ciblée.

Coagulation-flocculation is a crucial step during drinking water production. Metallic salts are used for the removal of suspended particles, colloids and Dissolved Organic Matter (DOM). However, these reactants produce large quantities of non-recoverable sludge. Bio-sourced polymers, such as chitosan (CS), are well-known for their flocculent properties. Yet, they are not presently considered as a viable alternative because of their low reactivity towards DOM, the accumulation of unreactive dissolved polymer that tends to increase the organic content of treated waters and the risk to create dysfunctions in downstream processes (membrane fouling, formation of disinfection by-products).This work aims at investigating the feasibility of combining the flocculent properties of CS with the sorption capacities of clay particles (Montmorillonite-MMT) to form ballasted flocs and to prevent chitosan from being released in solution. The preparation of CS-MMT hybrids was optimized and a structure-reactivity relationship was established. The drying step in the hybrids preparation played a key-role by preventing hybrids destabilization that occurred when competitive cations were present in the water matrix. The optimized hybrids were selected and tested on river waters (Vienne, Clain) to determine their reactivity and selectivity. The results were compared with FeCl3, CS and MMT performances. Dried hybrids were thus more efficient for the removal of low molecular weight and weakly hydrophobic compounds. Metallic salts exhibited higher performances for the removal of hydrophobic and aromatic compounds with higher molecular weights. Because dried hybrids release a low concentration of chitosan in treated waters, their performance can potentially be improved by increasing the treatment doses.; Le procédé de coagulation-floculation est une étape cruciale dans les filières de production d’eau potable. Les sels métalliques sont utilisés comme réactifs pour éliminer les particules en suspension, les colloïdes et la Matière Organique Dissoute (MOD) contenus dans les eaux de surface. Cependant, ils génèrent d’importantes quantités de boues difficilement valorisables. Bien que leurs propriétés floculantes soient reconnues depuis longtemps, les polymères bio-sourcés, comme le chitosan (CS), ne peuvent pas être considérés comme des alternatives viables en replacement de ces sels métalliques. Du fait de leur faible réactivité vis-à-vis des MOD et de l'apport en carbone organique dissous dans les eaux traitées provenant des polymères non réactifs, ils peuvent entrainer des dysfonctionnements dans les procédés situés en aval (colmatage des filtres, formation de sous-produits de désinfection). Dans ce manuscrit, l’association du chitosan avec des particules d’argile (Montmorillonite-MMT) a été étudiée afin de combiner les propriétés floculantes du biopolymère avec les capacités de sorption de l’argile pour former des flocs lestés et ainsi minimiser le relargage de CS dans les eaux traitées. Lors de l’optimisation de la préparation des hybrides CS-MMT dans l’objectif d’éliminer un composé modèle une relation structure-réactivité des hybrides a été démontrée. Le procédé de séchage, lors de la préparation des matériaux, s’est avéré être un paramètre-clé dans la stabilisation des hybrides sensibles à la minéralisation des eaux modèles et naturelles. L’application des hybrides optimisés pour le traitement de deux eaux de rivières (Vienne, Clain) a mis en évidence des différences de réactivité et de sélectivité entre les divers hybrides, FeCl3, CS et MMT. Les hybrides séchés ont ainsi présenté une meilleure élimination des composés de faibles poids moléculaires et peu hydrophobes tandis que les sels métalliques sont plus performants vis-à-vis des composés aromatiques, hydrophobes et de poids moléculaires élevés. Ces hybrides relarguant peu de chitosan résiduel dans les eaux traitées, leur performance peut être améliorée par une augmentation des doses de traitement.

With progress being made in terms of monitoring and regulation of many organic contaminants in the aquatic environment, the presence and risks associated with their degradation products are now raising many questions. Particularly, little interest has been paid to pharmaceutical residues, although their presence and harmful effects on non-target organisms have been proven. This work provides answers on the contamination of rivers by pharmaceutical degradation products (carbamazepine and diclofenac), as well as a first assessment of the associated environmental risks.The study of epilithic biofilms has shown that the contamination is not entirely governed by the physicochemical properties of the compounds or the hydrological regimes of the rivers. In addition, the geography as well as the respective physicochemical properties can explain some of the differences observed between the studied rivers (the Vienne and the Clain). Furthermore, discharges from wastewater treatment plants (WWTPs) play an important role in the enrichment of the environment in certain compounds. The comparison with integrative passive samplers (POCIS) revealed the complementarity as well as the importance of the two types of sampling (biofilms, POCIS) for a more global monitoring of the quality of the environment.This work has also shown that pharmaceutical degradation products are present in all the studied compartments of the aquatic environment (i.e. waters, sediments, biofilms, Corbicula fluminea), with variable concentrations and distributions which depend on the nature of the compartment, the watercourse where the sampling was carried out as well as the location of the sampling site in relation to discharge areas (city or WWTP).An ecotoxicological approach by QSAR showed that diclofenac and its degradation products are more toxic than carbamazepine and its degradation products for three typical species, representing green algae, invertebrates, and fish. An environmental risk assessment (hazard quotient) showed that hydroxydiclofenac, 2-[(2-chlorophenyl)-amino]-benzaldehyde and dibenzazepine pose a higher risk than the other studied compounds for different aquatic organisms. In addition, the risk associated with a mixture of diclofenac and its related degradation products is found to be greater than that of compounds considered individually.; Alors que des progrès ont été réalisés en termes de surveillance et de régulation de nombreux contaminants organiques dans le milieu aquatique, la présence et les risques associés à leurs produits de dégradation suscitent désormais beaucoup d’interrogations. Notamment, peu d'intérêt a été porté aux résidus de médicaments, bien que leur présence et leurs effets néfastes sur les organismes non-ciblés soient avérés. Ce travail apporte des éléments de réponse quant à la contamination de rivières par des produits de dégradation de médicaments (carbamazépine et diclofénac), ainsi qu’une première évaluation des risques environnementaux associés.L’étude de biofilms épilithiques a montré que la contamination n’est pas entièrement régie par les propriétés physico-chimiques des composés ou les régimes hydrologiques des cours d’eau. Par ailleurs, la géographie ainsi que les physico-chimies respectives peuvent expliquer certaines des différences observées entre les rivières étudiées (la Vienne et le Clain). De plus, les rejets de stations de traitement des eaux usées (STEU) jouent un rôle important dans l’enrichissement du milieu en certains composés. La comparaison avec les échantillonneurs passifs intégratifs (POCIS) a révélé la complémentarité ainsi que l’importance des deux types d’échantillonnage (biofilms, POCIS) pour une surveillance plus globale de la qualité du milieu.Ce travail a aussi démontré que des produits de dégradation de médicaments sont présents dans tous les compartiments du milieu aquatique étudiés (i.e. eaux, sédiments, biofilms, Corbicula fluminea), avec des concentrations et des distributions variables qui dépendent de la nature du compartiment, du cours d’eau où l’échantillonnage a été effectué ainsi que de la localisation du site d’échantillonnage par rapport à des zones de rejets (ville ou STEU).Une approche écotoxicologique par QSAR a mis en évidence que le diclofénac et ses produits de dégradation sont plus toxiques que la carbamazépine et ses produits de dégradation pour trois espèces types, représentant les algues vertes, les invertébrés et les poissons. Une évaluation des risques environnementaux (quotient de risque) a montré que l'hydroxydiclofénac, la 2-[(2-chlorophényl)-amine]-benzaldéhyde et la dibenzazépine présentent un risque plus élevé que les autres composés étudiés pour les différents organismes aquatiques. De plus, le risque associé à un mélange de diclofénac et de ses produits de dégradation associés s’avère supérieur à celui des composés considérés individuellement.

The objectives of this study was to study the presence, the fate and the treatment of some biocides in the wastewaters from a hospital. 3 biocidal substances specific to healthcare activities (i.e. didecylmethylammonium chloride (DDAC), chlorhexidine digluconate (CHD) and bis(aminopropryl)laurylamine (BAPLA)) were selected and 5 sampling campaigns were conducted throughout the entire Poitiers University Hospital sewage system. Under these conditions, a continuous biocide discharges over 24 h was shown, with higher quantities discharged during the day. This was pointing out the greater healthcare and facility cleaning activities taking place during this period. Concentrations of a few mg/L for DDAC and a few dozens of µg/L for CHD and BAPLA were detected. In terms of mass flows, the comparison of the quantities found in the discharges with the quantities used by the university hospital made it possible to specify the nature of the sources of emission as well as the uses and / or the practices most favorable to these discharges.In parallel, a laboratory study of the stability and fate of biocides in wastewater was conducted. A first estimate of the amounts adsorbed on suspended solids was obtained. Similarly, the degradation products likely to be generated during the release of biocides in the presence of a chlorine residual have been identified and the evolution of the ecotoxicity towards Vibrio fisheri has been evaluated.Finally, the proposal of an ozone based treatment at source was carried out to limit biocide discharges and a pilot study was conducted on the hospital wastewaters.; L’objectif de ce travail a été d’étudier la présence, le devenir et le traitement de biocides dans les rejets d’un établissement hospitalier. Pour cela, 3 substances biocides, représentatives d’une activité de soins (i.e. didécylmethylammonium (DDAC), digluconate de chlorhexidine (CHD) et bis(aminopropryl)laurylamine (BAPLA)) ont été ciblées et 5 campagnes de prélèvements réalisées sur l’ensemble du réseau de collecte des eaux usées du CHU de Poitiers ont été menées. Dans ces conditions, une émission continue de biocides sur 24 h, avec des quantités rejetées en journée plus importantes du fait de la plus forte activité de soins et de nettoyage durant cette période a été montrée. Des concentrations de l’ordre de quelques mg/L pour le DDAC et de quelques dizaines de µg/L pour le CHD et le BAPLA ont été observées. En termes de flux massiques, la comparaison des quantités retrouvées dans les rejets aux quantités utilisées par le CHU a permis de préciser la nature des sources d’émission ainsi que les usages et/ou les pratiques les plus propices à ces rejets.Parallèlement, une étude laboratoire de la stabilité et du devenir des biocides dans les eaux résiduaires a été menée. Une première estimation des quantités adsorbées sur les matières en suspension a été obtenue. De même, les produits de dégradation susceptibles d’être générés lors du rejet de biocides en présence d’un résiduel de chlore ont été identifiés et l’évolution de l’écotoxicité vis-à-vis de Vibrio fisheri a été évaluée.Enfin, la possibilité d’un traitement à la source utilisant l’ozone pour limiter les rejets de biocides a été envisagée et une étude pilote sur le terrain a été menée.