Étude du traitement et du recyclage des eaux issues des serres horticoles

La gestion de l'eau dans les systèmes de culture hors-sol fait apparaître deux problèmes distincts. D'une part, les ressources en eau doivent être de bonne qualité et ne pas contenir de pesticides ou de germes pathogènes. D'autre part, les rejets fortement " chargés " en nutriments (NO3-, PO43-) polluants pour l'environnement, doivent être limités par le biais de leur recyclage ce qui implique nécessairement la désinfection des effluents.La technique mise en œuvre pour obtenir cette maîtrise de la qualité tant chimique que microbiologique des solutions circulantes en culture hors-sol est celle d'une oxydation à l'ozone seul et couplé au peroxyde d'hydrogène dans des réacteurs constitués de mélangeurs statiques. Les conditions de traitement sont une dose d'oxydant de 10 g O3/m3 d'effluent à traiter, un rapport H2O2/O3 de 0,15 g/g pour un temps de contact dans le réacteur de l'ordre de la seconde. Etudié sur site dans le cadre du traitement de effluents de serre réels, le procédé s'est révélé tout à fait adapté pour abattre les pesticides (# 90 % pour l'atrazine), maîtriser la prolifération des micro-organismes (Flore aérobie mésophile, flore fongique) et en particulier des germes pathogènes (Clavibacter michiganensis, Fusarium, Pythium sp ).Le procédé novateur O3/H2O2 sur mélangeurs statiques constitue donc pour les serristes une réponse nouvelle dont l'un des intérêts est de combiner les effets " détoxiquant " et désinfectant.The management of water resources in soil-less cultures presents two difficulties. On one hand, the quality of these resources has to be good, that is to say without pesticides or pathogens. On the other hand, the effluents contain high concentrations of nutrients (NO3-, PO43-), damageable for the environment, and should be recycled. Thus, recycling has to include necessarily a disinfection step to satisfy the quality requirement. The main disinfection treatments used in soil-less cultures are slow sand filtration, ultraviolet treatment, heat treatment, nanofiltration, ozone or hydrogen peroxide oxidation, iodine or chlorine treatment.In order to control the chemical as well as the microbiological quality of the recycled nutrient solution, we suggest oxidation (O3) and advanced oxidation (O3/H2O2) processes, carried out in static mixers as chemical reactors instead of bubble columns. We have been studying this process in situ for the treatment of a 1-hectare greenhouse. The pilot plant unit can be configured under three setups (Figure 2) according to the aim to favor either the molecular action of ozone or the formation of very reactive radical species such as the hydroxyl radical. In this second case, the mechanism of ozone decomposition is given by Figure 1.The first step of the study was to measure the influence of the nutrient solution to be recycled on the efficiency of atrazine removal (Figures 3 and 4). In comparison with tap water, the percentage of pesticide removal is lower by about 10 to 20 %. Solutions with nutrients do not drastically change the process efficiency. The experiments were carried out with various ozone dosages and various ozone / hydrogen peroxide mass ratios, using the three configurations (Figures 5 and 6). With these results, the best operating conditions for micropollutant removal are a treatment rate of about 10 g O3 /m3 of treated solution, a H2O2/O3 ratio equal to 0.15 g/g and a contact time in the reactor in the range of 1 to 2 seconds. The influence of the configuration type is not really marked. The results show that, under these conditions, this technique leads to good pesticide removal efficiencies (about 90 % for atrazine).In a second step, experiments were carried out on real solutions containing microorganisms from the greenhouse, sometimes spiked with special bacteria (Clavibacter) or fungi (Fusarium). Some results are reported in Figures 7, 8 and 9. With the same oxidant dosage conditions, the role of the configuration is clearly demonstrated. The best results are obtained with a molecular action of ozone in the first static mixed reactor followed by a free-radical action within the second reactor. Thus, it is possible to prevent germ proliferation (aerobic mesophilic flora and fungi flora) and particularly pathogenic species. The abatement of Clavibacter michiganensis reaches 3.5 to 4 logarithmic units, 1 to 1.5 units for Pythium and 2 to 4 units for Fusarium. The treatment does not effect a complete sterilization, e.g., the beneficial bacterium Pseudomonas fluorescens survives. The global impact of the treatment on the nutritive quality of the treated solution is negligible. Nevertheless, we can note that the process induces a decrease of the ion concentrations of Fe (II) (- 5 to 30 %) and Mn (II) (-10 to 15 %) as a result of the oxidation of the EDTA chelate. In fact, this problem is observed with all oxidation and UV treatments. The residual oxidant (O3, H2O2) concentrations are low and do not induce obvious toxic effects on the cultures.Thus, the technique is consistent with a recycling of the treated effluents. The advantages of the process include very short contact times, compactness of the equipment, no need for pretreatment, reasonable investment and operating costs, an increase of the oxygen concentration in the treated effluent, and possible curative effects on the culture's germ contamination due to the residual concentration of hydrogen peroxide. The disinfection efficiency of this suggested process is similar to those obtained with more common techniques like UV irradiation. Moreover, the studied process can also reduce, for example, an eventual chemical pollution of the water resource. In conclusion, the O3, H2O2 process in static mixers appears to be a new solution for greenhouse farmers

Effet de la matrice de l'eau sur l'élimination des micropolluants organiques par ozonation. Partie 1. Consommation spécifique de l'ozone dans un réacteur

A partir des réactions possibles entre l'ozone, les radicaux et les principaux composants d'une eau à potabiliser, des formules théoriques de formations de radicaux et de décomposition de l'ozone sont établies. La matière organique est schématisée par les composés qui réagissent avec l'ozone (Si), les initiateurs, les promoteurs et les inhibiteurs de la réaction radicalaire (SIi, Sp,i, Ss,i). La décomposition de l'ozone est ensuite mesurée pour 56 eaux naturelles caractérisées par les analyses suivantes (pH, Absorbance à 254 nm, COT, Alcalinité). En se basant sur les connaissances acquises et les valeurs expérimentales du taux spécifique de consommation de l'ozone w, l'équation théorique est simplifiée et on obtient:-(d[O3]/dt)=([O3](∑kDlSl,i)(∑klDP,i[SP,i])) / ([HCO3-](k9+k10 10pH-10,25))En prenant le COT comme représentatif des [Sp,i] (attaque radicalaire non sélective) et l'absorbance à 254 nm comme representative de SI,i (attaque directe sur les cycles aromatiques), une analyse multifactorielle permet d'obtenir l'expression:log10w = -3,93 + 0,24pH + 0,75 log10 Absorbance à 254 mm + 1,08 log10 COT - 0,19 log10 alcalinitéL'équation ainsi obtenue peut être utilisée dans tous les modèles prédictifs faisant appel aux bilans massiques sur l'oxydant.From the numerous reactions between ozone and other components of raw water in a drinking water plant, we obtain theoretical equations for hydroxy radical concentrations (1) and for the disappearance of ozone (2). Dissolved organic matter is divided in to four components: substances which react with ozone by a direct mechanism (Si), initiators, promotors, and scavengers ofradical reactions (SI,i, SP,i, SS,i). We also take into account the reactions between hydrogen peii*iâô. orThe, and free radicals to simulate advanced oxidation processes.[OH∘]= ([O3]{2k1∙10pH-14+2k2 10pH-11,6 [H2O2] + ∑kdl,i [Sl,i]}) / (klD[P]+[HCO3-] (k9+k10∙10pH-10,25)+∑klDS,i [Ss,i])   (1)-(d[O3])/(dt) = {kD[P]+∑kD,i[Si]+∑kDl,i[Sl,i]+3k110pH-14+k210pH-11,6H2O2]}[O3]+[OH∘]{k8[O3]+[H2O2](k210pH-11,6+K7)+∑klDP,i[SP,i]   (2)For 56 natural water samples, we measured the disappearence of ozone directly in a completely stirred batch reactor. Water samples were characterized by pH, TOC, 254 nm UV absorbance and alkalinity. Kinetics were first order with respect to ozone(d[O3])/(dt) = -w[O3]with w : specific ozone disappearence rate.Each term of equation 2 is discussed and, based on the experimental values of w, a simplified equation 3 obtained :-(d[O3])/(dt) = ([O3](∑kDISl,i)(∑klDP,i[SP,i))/([HCO3](k9+k10 10pH-10,25))The TOC parameter can represent [SP,i] because radical reactions are non selective, where as the 254 nm UV absorbance can represent [Si] because organic matter (Fulvic and Humic acid) can react directly with ozone via its constituent aromatic rings.Using the data set of 56 w values measured in natual water samples, mathematical correlations can be calculated :log10w = -3,93 + 0,24pH + 0,75 log10 Absorbance à 254 mm + 1,08 log10 COT - 0,19 log10 alcalinityA strong correlation between experimental measurements and predicted w values is obtained

Effects of Cr/Ni ratio on physical properties of Cr–Mn–Fe–Co–Ni high-entropy alloys

Physical properties of ten single-phase FCC CrxMn20Fe20Co20Ni40-x high-entropy alloys (HEAs) were investigated for 0 ≤ x ≤ 26 at%. The lattice parameters of these alloys were nearly independent of composition while solidus temperatures increased linearly by ∼30 K as x increased from 0 to 26 at.%. For x ≥ 10 at.%, the alloys are not ferromagnetic between 100 and 673 K and the temperature dependencies of their coefficients of thermal expansion and elastic moduli are independent of composition. Magnetic transitions and associated magnetostriction were detected below ∼200 K and ∼440 K in Cr5Mn20Fe20Co20Ni35 and Mn20Fe20Co20Ni40, respectively. These composition and temperature dependencies could be qualitatively reproduced by ab initio simulations that took into account a ferrimagnetic ↔ paramagnetic transition. Transmission electron microscopy revealed that plastic deformation occurs initially by the glide of perfect dislocations dissociated into Shockley partials on {111} planes. From their separations, the stacking fault energy (SFE) was determined, which decreases linearly from 69 to 23 mJ·m−2 as x increases from 14 to 26 at.%. Ab initio simulations were performed to calculate stable and unstable SFEs and estimate the partial separation distances using the Peierls-Nabarro model. While the compositional trends were reasonably well reproduced, the calculated intrinsic SFEs were systematically lower than the experimental ones. Our ab initio simulations show that, individually, atomic relaxations, finite temperatures, and magnetism strongly increase the intrinsic SFE. If these factors can be simultaneously included in future computations, calculated SFEs will likely better match experimentally determined SFEs

p53 status correlates with histopathological response in patients with soft tissue sarcomas treated using isolated limb perfusion with TNF-α and melphalan

Background: Recombinant tumor necrosis factor-α (TNF-α) combined to melphalan is clinically administered through isolated limb perfusion (ILP) for regionally advanced soft tissue sarcomas of the limbs. In preclinical studies, wild-type p53 gene is involved in the regulation of cytotoxic action of TNF-α and loss of p53 function contributes to the resistance of tumour cells to TNF-α. The relationship between p53 status and response to TNF-α and melphalan in patients undergoing ILP is unknown. Patients and methods: We studied 110 cases of unresectable limbs sarcomas treated by ILP. Immunohistochemistry was carried out using DO7mAb, which reacts with an antigenic determinant from the N-terminal region of both the wild-type and mutant forms of the p53 protein, and PAb1620mAb, which reacts with the 1620 epitope characteristic of the wild-type native conformation of the p53 protein. The immunohistochemistry data were then correlated with various clinical parameters. Results: P53DO7 was found expressed at high levels in 28 patients, whereas PAb1620 was negative in 20. The tumours with poor histological response to ILP with TNF-α and melphalan showed significantly higher levels of p53-mutated protein. Conclusions: Our results might be a clue to a role of p53 protein status in TNF-α and melphalan response in clinical us

Technical design and performance of the NEMO3 detector

The development of the NEMO3 detector, which is now running in the Frejus Underground Laboratory (L.S.M. Laboratoire Souterrain de Modane), was begun more than ten years ago. The NEMO3 detector uses a tracking-calorimeter technique in order to investigate double beta decay processes for several isotopes. The technical description of the detector is followed by the presentation of its performance.Comment: Preprint submitted to Nucl. Instrum. Methods A Corresponding author: Corinne Augier ([email protected]

Limb salvage with isolated perfusion for soft tissue sarcoma: could less TNF-α be better?

Background: The optimal dose of TNF-α delivered by isolated limb perfusion (ILP) in patients with locally advanced soft tissue sarcoma is still unknown. Patients and methods: Randomised phase II trial comparing hyperthermic ILP (38-40°) with melphalan and one of the four assigned doses of TNF-α: 0.5 mg, 1 mg, 2 mg, and 3/4 mg upper/lower limb. The main end point was objective tumour response on MRI. Secondary end points were histological response, rate of amputation and toxicity. Resection of the remnant tumour was performed 2-3 months after ILP. The sample size was calculated assuming a linear increase of 10% in the objective response rates between each dose level group. Results: One hundred patients (25 per arm) were included. Thirteen per cent of patients had a systemic leakage with a cardiac toxicity in six patients correlated with high doses of TNF-α. Objective tumour responses were: 68%, 56%, 72% and 64% in the 0.5 mg, 1 mg, 2 mg and 3 or 4 mg arms, respectively (NS). Sixteen per cent of patients were not operated, 71% had a conservative surgery and 13% were amputated with no difference between the groups. With a median follow-up of 24 months, the 2 year overall and disease-free survival rates (95% CI) were 82% (73% to 89%) and 49% (39% to 59%), respectively. Conclusion: At the range of TNF-α doses tested, there was no dose effect detected for the objective tumour response, but systemic toxicity was significantly correlated with higher TNF-α doses. Efficacy and safety of low-dose TNF-α could greatly facilitate ILP procedures in the near futur

GPS network monitor the Western Alps deformation over a five year period: 1993-1998

GPS surveys in the Western Alps, performed in the time span 1993-2003, estimated the current crustal deformation of this area.Published63-763.2. Tettonica attivaJCR Journalreserve