Traitement d'effluents de tannerie-mégisserie par microfiltration tangentielle

Dans ce travail un procédé de traitement des effluents issus de l'unité de préparation des peaux des animaux au tannage (travail en rivière) en tannerie-mégisserie a été étudié en utilisant la technique de microfiltration tangentielle sur membrane minérale en céramique. Les performances de ce procédé en terme de flux de filtration et de rendement épuratoire dépendent aussi bien des paramètres hydrodynamiques de filtration que de la qualité des effluents (collectés en été et en printemps) issus des différents bains de traitement et de rinçage des peaux dans l'atelier de rivière. Le flux de filtration varie entre 15 l/h.m2 pour l'effluent de printemps et 90 l/h.m2 pour l'effluent d'été. Les paramètres hydrodynamiques optimaux ont également été déterminés: la vitesse de circulation U=3 m/s, la pression transmembranaire Ptm=2 bar et la température T=43°C. L'étude de la microfiltration à concentration variable conduit à des facteurs de concentration volumique (FCV) de 6,5 pour l'effluent de l'été et de 2,4 pour l'effluent de printemps.The leather industry is responsible for the transformation of raw animal skin to a final form as shoes, bags, dresses, etc. This industry was known for centuries as a craft activity, and today with industrial development, environmental regulations and new emerging technologies, it has become necessary to include elaborate processes for its wastewater treatment. These industries consume a great amount of water. In Tunisia, more than 15000 tons of skin are treated per year, and about 600000 m3 per year of effluents are discharged. The waste water contains chemicals, fats, hair and protein, varying in composition depending on the season. Figure 1 represents the preparation of raw skin for the tanning operation and the amount of waste water produced. The amount of water used for the preparation of raw skin is about 70% of the total quantity of water used. This waste water has a significant polluting load (chemicals and organic matter), with 5000 - 7500 mg/l of COD and 100 to 150 mg/l of sulfur. Tunisian legislation and regulations concerning the standards for wastewater disposal are 1000 mg/l for COD, 3 mg/l for sulfur and a pH between 6.5-9. Different techniques for wastewater treatment such as: physico-chemical treatment, treatment by electrochemical oxidation and membrane technology were proposed. Wastewater treatment by microfiltration and ultrafiltration with mineral membranes is advantageous because no chemicals are used and it can be combined easily with other physico-chemical or biological pre-treatments. In this study, we have treated two types of effluents from the leather pre-treatment industry collected in the summer (effluent 1), and the spring (effluent 2) seasons. The physico-chemical characteristics of the two types effluents are given in Table 2. The filtration experiments were made on a test bench (Figure 2) equipped with a feed reservoir, a volumetric pump, a filtration module, flow meter, pressure transducers, a heat exchanger and control valves. Ceramic membranes of tubular geometry (7 channels), 0.08 m2 membrane surface area and of 0.1 µm (mean diameter) pores were used. During the microfiltration experiments, the following physico-chemical parameters were analysed in the permeate and retentate: turbidity, specific conductivity, pH, viscosity, chemical oxygen demand (COD), sulfur (volumetric method), fats (Standard JIS 0102.24.2), protein (using Kjeldahl nitrogen), and organic nitrogen. Hydrodynamic parameters such as temperature (25 < T < 50 °C), transmembrane pressure (1 < Ptm < 2.2 bar) and feed velocity (1 < U < 3 m/s) were fixed for experimentation. The COD concentration in the effluent was adjusted and kept constant at 5000 mg/l. The raw effluent was pre-filtered on a screen filter (150 µm pore size). For experiments with variable concentration, we regularly removed the filtrate and the concentration factor was represented by FCV=Vi / Vr, where Vi was the initial volume and Vr was the volume of the retentate. The performance of the microfiltration (J) was expressed in l/h×m2. The retention rate (TR) was defined by: TR=1 - (Cpermeate) / (Cfeed). The total hydraulic resistance (RT) was defined by Darcy's law: Jf=Ptm / µ RT. After each experiment, the membrane was regenerated following a standard protocol and it was verified by measuring water flux. Figure 3a represents the variation of the filtration flux with time for 4 different temperatures: 25 °C, 43 °C, 45 °C and 50 °C with effluent 1. The flux increased from 90 to 118 l/h×m2 when the temperature increased from 25 °C to 43 °C. After 90 min at 50 °C, the filtration flux was 123 l/h×m2. Table 3 shows that the viscosity of the effluent decreased with temperature, while the turbidity of the filtrate increased from 0.63 NTU at T=25 °C to 1.6 NTU for T=50 °C. The retention rate of COD was always superior to 50 %. On the basis of these results, we chose the optimum temperature of 43 °C for other experiments. Figure 4 summarises the variation of flux with transmembrane pressure at flow velocities of 1 m/s, 2 m/s and 3 m/s. The stabilized fluxes were practically the same for the flow velocities of 1 and 2 m/s (of the order of 80 l/h×m2), but were higher at 3 m/s (110 - 115 l/h×m2 at 2 bar). The physico-chemical characteristics of the raw effluent and the permeate obtained after 90 minutes of filtration are summarised in Table 4. Figure 7a shows the variation of filtration flux for 2 types of effluents. The filtration flux for the same conditions of experimentation and at stabilized conditions (at 90 min) was 118 l/h×m2 for effluent 1 and 20 l/h×m2 for effluent 2. The lower filtration flux for effluent 2 can be explained by high deposits of rejected matter on the membrane and in the pores. Table 5 gives a comparison of the characteristics of effluents 1 and 2 before and after microfiltration. At variable feed concentrations, FCV=6.5 for effluent 1 and FCV=2.4 for the effluent 2 and the stabilized flux was about 90 l/h×m2 for the effluent 1 and 15 l/h×m2 for the effluent 2. The time needed for treatment of effluent 1 was about 6 hours, while more that 16 hours was necessary for effluent 2. Table 6 provides physico-chemical characteristics for the two types of effluents. The contents of fat, protein, nitrogen and sulfur in the effluent were important factors for variation. These results indicate that microfiltration is very sensitive to the quantity of polluting matter present in the effluents, particularly sulfur and fat. Increased polluting matter in effluent 2 could be responsible for the membrane polarization and blocking of pores. The resistance model was used to verify this hypothesis. The irreversible resistance values for effluent 2 were greater, thus confirming the hypothesis that the increased adsorption on the membrane surface and passage of pores by the presence of sulfur and organic polluting matter. These experimental results confirm that the best performance can be obtained at the hydrodynamic conditions of: a temperature of 43 °C; a transmembrane pressure of 2 bar; and a flow velocity of 3 m/s. Seasonal variation changed the quality of effluents, which considerably affects the performances of the microfiltration. Effluent 2, which was obtained from the treatment of sheep skin during the spring season, led to more membrane pore blocking than effluent 1 for the same initial concentration in COD. The interactions of fats and sulfur with the membrane layer appear to play an important role in the formation of a cake layer

Total Knee Arthroplasty for Post-Traumatic Proximal Tibial Bone Defect: Three Cases Report

Bone stock deficiency in primary as well as in revision total knee arthroplasty (TKA) represents a difficult problem to surgeon with regard to maintaining proper alignment of the implant components and in establishing a stable bone-implant interface. Different surgical procedures are available in these situations, for instances the use of bone cement, prosthetic augments, custom implant, and wire mesh with morsellized bone grafting and structural bone allograft. Structural allograft offers a numerous advantages as easy remodeling and felling cavitary or segmental defects, excellent biocompatibility, bone stock restoration and potential for ligamentous reattachment. In this article we report a short term result of three cases affected by severe segmental medial post/traumatic tibial plateau defect in arthritic knee, for which massive structural allograft reconstruction and primary total knee replacement were carried. The heights of the bone defect were between 27-33 mm and with moderate medio-lateral knee instability. Pre-operative AKS score in three cases was 30, 34 and 51 points consecutively and improved at the last follow-up to 83, 78 and 85 consecutively. No acute or chronic complication was observed. Last radiological exam referred no signs of prosthetic loosening, no secondary resorption of bone graft and well integrated graft to host bone. These results achieved in our similar three cases have confirmed that the structural bone allograft is a successful biological material to restore hemi-condylar segmental tibial bone defect when total knee replacement is indicated

Measurement of ISR-FSR interference in the processes e+ e- --> mu+ mu- gamma and e+ e- --> pi+ pi- gamma

Charge asymmetry in processes e+ e- --> mu+ mu- gamma and e+ e- --> pi+ pi- gamma is measured using 232 fb-1 of data collected with the BABAR detector at center-of-mass energies near 10.58 GeV. An observable is introduced and shown to be very robust against detector asymmetries while keeping a large sensitivity to the physical charge asymmetry that results from the interference between initial and final state radiation. The asymmetry is determined as afunction of the invariant mass of the final-state tracks from production threshold to a few GeV/c2. It is compared to the expectation from QED for e+ e- --> mu+ mu- gamma and from theoretical models for e+ e- --> pi+ pi- gamma. A clear interference pattern is observed in e+ e- --> pi+ pi- gamma, particularly in the vicinity of the f_2(1270) resonance. The inferred rate of lowest order FSR production is consistent with the QED expectation for e+ e- --> mu+ mu- gamma, and is negligibly small for e+ e- --> pi+ pi- gamma.Comment: 32 pages,29 figures, to be submitted to Phys. Rev.

Measurement of B(B-->X_s {\gamma}), the B-->X_s {\gamma} photon energy spectrum, and the direct CP asymmetry in B-->X_{s+d} {\gamma} decays

The photon spectrum in B --> X_s {\gamma} decay, where X_s is any strange hadronic state, is studied using a data sample of (382.8\pm 4.2) \times 10^6 e^+ e^- --> \Upsilon(4S) --> BBbar events collected by the BABAR experiment at the PEP-II collider. The spectrum is used to measure the branching fraction B(B --> X_s \gamma) = (3.21 \pm 0.15 \pm 0.29 \pm 0.08)\times 10^{-4} and the first, second, and third moments = 2.267 \pm 0.019 \pm 0.032 \pm 0.003 GeV,, )^2> = 0.0484 \pm 0.0053 \pm 0.0077 \pm 0.0005 GeV^2, and )^3> = -0.0048 \pm 0.0011 \pm 0.0011 \pm 0.0004 GeV^3, for the range E_\gamma > 1.8 GeV, where E_{\gamma} is the photon energy in the B-meson rest frame. Results are also presented for narrower E_{\gamma} ranges. In addition, the direct CP asymmetry A_{CP}(B --> X_{s+d} \gamma) is measured to be 0.057 \pm 0.063. The spectrum itself is also unfolded to the B-meson rest frame; that is the frame in which theoretical predictions for its shape are made.Comment: 37 pages, 19 postscript figures, submitted to Phys. Rev. D. No analysis or results have changed from previous version. Some changes to improve clarity based on interactions with Phys. Rev. D referees, including one new Figure (Fig. 13), and some minor wording/punctuation/spelling mistakes fixe

Measurement of the Time-Dependent CP Asymmetry of Partially Reconstructed B0->D*+D*- Decays

We present a new measurement of the time-dependent CP asymmetry of B0->D*+D*- decays using (471+-5) million BBbar pairs collected with the BaBar detector at the PEP-II B Factory at the SLAC National Accelerator Laboratory. Using the technique of partial reconstruction, we measure the time-dependent CP asymmetry parameters S=-0.34+-0.12+-0.05$ and C=+0.15+-0.09+-0.04. Using the value for the CP-odd fraction R_perp=0.158+-0.028+-0.006, previously measured by BaBar with fully reconstructed B0->D*+D*- events, we extract the CP-even components S+=-0.49+-0.18+-0.07+-0.04 and C+=+0.15+-0.09+-0.04. In each case, the first uncertainty is statistical and the second is systematic; the third uncertainty on S+ is the contribution from the uncertainty on R_perp. The measured value of the CP-even component S+ is consistent with the value of sin(2Beta) measured in b->(ccbar)s transitions, and with the Standard Model expectation of small penguin contributions.Comment: 17 pages, 7 figures, submitted to Physical Review

Branching fraction and form-factor shape measurements of exclusive charmless semileptonic B decays, and determination of |V_{ub}|

We report the results of a study of the exclusive charmless semileptonic decays, B^0 --> pi^- l^+ nu, B^+ --> pi^0 l^+ nu, B^+ --> omega l^+ nu, B^+ --> eta l^+ nu and B^+ --> eta^' l^+ nu, (l = e or mu) undertaken with approximately 462x10^6 B\bar{B} pairs collected at the Upsilon(4S) resonance with the BABAR detector. The analysis uses events in which the signal B decays are reconstructed with a loose neutrino reconstruction technique. We obtain partial branching fractions in several bins of q^2, the square of the momentum transferred to the lepton-neutrino pair, for B^0 --> pi^- l^+ nu, B^+ --> pi^0 l^+ nu, B^+ --> omega l^+ nu and B^+ --> eta l^+ nu. From these distributions, we extract the form-factor shapes f_+(q^2) and the total branching fractions BF(B^0 --> pi^- l^+ nu) = (1.45 +/- 0.04_{stat} +/- 0.06_{syst})x10^-4 (combined pi^- and pi^0 decay channels assuming isospin symmetry), BF(B^+ --> omega l^+ nu) = (1.19 +/- 0.16_{stat} +/- 0.09_{syst})x10^-4 and BF(B^+ --> eta l^+ nu) = (0.38 +/- 0.05_{stat} +/- 0.05_{syst})x10^-4. We also measure BF(B^+ --> eta^' l^+ nu) = (0.24 +/- 0.08_{stat} +/- 0.03_{syst})x10^-4. We obtain values for the magnitude of the CKM matrix element V_{ub} by direct comparison with three different QCD calculations in restricted q^2 ranges of B --> pi l^+ nu decays. From a simultaneous fit to the experimental data over the full q^2 range and the FNAL/MILC lattice QCD predictions, we obtain |V_{ub}| = (3.25 +/- 0.31)x10^-3, where the error is the combined experimental and theoretical uncertainty.Comment: 35 pages, 14 figures, submitted to PR

Observation of time-reversal violation in the B0 meson system

The individually named authors work collectively as The BABAR Collaboration. Copyright @ 2012 American Physical Society.Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavor states (B0 or B¯¯¯0), and J/ψK0L or cc¯K0S final states (referred to as B+ or B−), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, B¯¯¯0→B− and B−→B¯¯¯0, as a function of the time difference between the two B decays. Using 468×106 BB¯¯¯ pairs produced in Υ(4S) decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding ΔS+T=−1.37±0.14(stat)±0.06(syst) and ΔS−T=1.17±0.18(stat)±0.11(syst). These nonzero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.DOE and NSF (USA), NSERC (Canada), CEA and CNRS-IN2P3 (France), BMBF and DFG(Germany), INFN (Italy), FOM (The Netherlands), NFR (Norway), MES (Russia), MINECO (Spain), STFC (United Kingdom). Individuals have received support from the Marie Curie EIF (European Union), the A. P. Sloan Foundation (USA) and the Binational Science Foundation (USA-Israel)

Precise Measurement of the e+ e- --> pi+ pi- (gamma) Cross Section with the Initial-State Radiation Method at BABAR

A precise measurement of the cross section of the process $e^+e^-\to\pi^+\pi^-(\gamma)$ from threshold to an energy of 3GeV is obtained with the initial-state radiation (ISR) method using 232fb$^{-1}$ of data collected with the BaBar detector at $e^+e^-$ center-of-mass energies near 10.6GeV. The ISR luminosity is determined from a study of the leptonic process $e^+e^-\to\mu^+\mu^-(\gamma)\gamma_{\rm ISR}$, which is found to agree with the next-to-leading-order QED prediction to within 1.1%. The cross section for the process $e^+e^-\to\pi^+\pi^-(\gamma)$ is obtained with a systematic uncertainty of 0.5% in the dominant $\rho$ resonance region. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the measured $\pi\pi$ cross section from threshold to 1.8GeV is $(514.1 \pm 2.2({\rm stat}) \pm 3.1({\rm syst}))\times 10^{-10}$.Comment: 58 pages, 56 figures, to be submitted to Phys. Rev.

Measurement of CP Asymmetries and Branching Fractions in Charmless Two-Body B-Meson Decays to Pions and Kaons

We present improved measurements of CP-violation parameters in the decays $B^0 \to \pi^+ \pi^-$, $B^0 \to K^+ \pi^-$, and $B^0 \to \pi^0 \pi^0$, and of the branching fractions for $B^0 \to \pi^0 \pi^0$ and $B^0 \to K^0 \pi^0$. The results are obtained with the full data set collected at the $\Upsilon(4S)$ resonance by the BABAR experiment at the PEP-II asymmetric-energy $B$ factory at the SLAC National Accelerator Laboratory, corresponding to $467 \pm 5$ million $B\bar B$ pairs. We find the CP-violation parameter values and branching fractions $S_{\pi^+\pi^-} = -0.68 \pm 0.10 \pm 0.03, C_{\pi^+\pi^-} = -0.25 \pm 0.08 \pm 0.02, A_{K^-\pi^+} = -0.107 \pm 0.016 ^{+0.006}_{-0.004}, C_{\pi^0\pi^0} = -0.43 \pm 0.26 \pm 0.05, Br(B^0 \to \pi^0 \pi^0) = (1.83 \pm 0.21 \pm 0.13) \times 10^{-6}, Br(B^0 \to K^0 \pi^0) = (10.1 \pm 0.6 \pm 0.4) \times 10^{-6},$ where in each case, the first uncertainties are statistical and the second are systematic. We observe CP violation with a significance of 6.7 standard deviations for $B^0 \to\pi^+\pi^-$ and 6.1 standard deviations for $B^0 \to K^+ \pi^-$, including systematic uncertainties. Constraints on the Unitarity Triangle angle $\alpha$ are determined from the isospin relations among the $B \to \pi\pi$ rates and asymmetries. Considering only the solution preferred by the Standard Model, we find $\alpha$ to be in the range $[71^\circ,109^\circ]$ at the 68% confidence level.Comment: 18 pages, 11 postscript figures, submitted to Phys. Rev.