Traitements d'effluents issus de l'industrie de la pêche par un procédé de coagulation/floculation

La présente étude porte sur le traitement physico-chimique d'un effluent industriel chargé d'encre de seiche issu de l'industrie de conditionnement des produits de la pêche. Différentes combinaisons de coagulant -floculant ont été étudiées. Le sulfate d'aluminium (SA), divers polyélectrolytes et certains adjuvants pulvérulents ont été utilisés. L'efficacité du traitement par coagulation-floculation a été analysée en suivant l'évolution de la turbidité et de la DCO résiduelle du surnageant.Les résultats de cette étude ont révélé qu'à pH 6-7, l'addition de SA à une concentration supérieure à 1000 mg.l-1 entraîne la coagulation des particules d'encre de seiche. L'addition d'un polyélectrolyte en association avec le SA permet de réduire la concentration requise en SA à environ 300 mg.l-1, tout en améliorant l'efficacité du processus de coagulation-floculation. Le recours à un adjuvant pulvérulent en combinaison avec le SA et un polyélectrolyte accroît notablement les performances du traitement et permet d'obtenir un effluent ayant une turbidité résiduelle de 7 NTU.The aim of this work was to compare the efficiency of a coagulation-flocculation process using different systems individually or in combination. The waste water used was an industrial cuttlefish effluent principally composed of colloidal particles from the cuttlefish. The initial turbidity and chemical oxygen demand were approximately 700 NTU and 22,000 mg×L-1 respectively. Two parameters were used to assess the process efficiency: the residual turbidity and the chemical oxygen demand (COD) of the supernatant.Three systems were investigated: aluminium sulphate (SA), polyelectrolytes and a ternary combination of SA-polyelectrolyte and colloidal microparticle adjuvant. Results demonstrated that at pH 6-7, SA caused some coagulation of the suspension, but the dosage required (about 1000 mg×L-1) far exceeded those conventionally used in water treatment. As a consequence, an appreciable amount of SA, which was above the authorised limits, remained in the supernatant. Indeed, adsorption isotherm measurements revealed that at pH 6.5-7 the residual proportion of SA attained was about 20%. The addition of polyelectrolytes in combination with SA allowed reduction of the SA dosage to 150 mg×L-1. Amongst the polymers tested, the cationic polymer was the most efficient. The ability to bring about flocculation was positively related to the molecular weight, which is in agreement with a bridging flocculation mechanism. Starch, a natural, low-cost polymer was also an efficient flocculent even though it is a non-charged polymer. The ability of starch to bring about a flocculation action was explained by its relatively low solubility, which leads to some aggregation of macromolecular chains that act as anchoring sites for the coagulated ink particles. With this system, a double treatment in the presence of 150 mg×L-1 SA and 25 mg×L-1 polydiallyldimethylammonium chloride (PDMAC) or starch lead to a supernatant with a turbidity and COD of 150 NTU and 5500 mg×L-1 respectively.The third part of our study was concerned with the effect of the addition of an insoluble microparticle adjuvant in combination with SA and polyelectrolytes. Different components were investigated, but among them only colloidal silica and MgO bring about a significant enhancement of the flocculation process. This effect was explained by a bridging mechanism in which the adjuvant microparticles act as sites that favour the anchoring of the coagulated ink particles. Using a triple treatment in the presence of 150 mg×L-1 SA, 25 mg×L-1 PDMAC and 0.75 g×L-1 MgO removed about 95 % of the ink particles. The supernatant obtained was characterised by a low turbidity value (about 7 NTU) and a COD value about 2000 mg×L-1

Observation of the Inverse Cotton-Mouton Effect

We report the observation of the Inverse Cotton-Mouton Effect (ICME) i.e. a magnetization induced in a medium by non resonant linearly polarized light propagating in the presence of a transverse magnetic field. We present a detailed study of the ICME in a TGG crystal showing the dependence of the measured effect on the light intensity, the optical polarization, and on the external magnetic field. We derive a relation between the Cotton-Mouton and Inverse Cotton-Mouton effects that is roughly in agreement with existing experimental data. Our results open the way to applications of the ICME in optical devices

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

Knowledge and awareness about Iron deficiency and megaloblastic anaemia among blood donors: a study at rural based tertiary care hospital

Background: Voluntary blood donation is promoted in order to make the blood banking safe and successful. Research in the area of blood donation has found that, iron stores are influenced by regular blood donation if dietary intake of iron is inadequate. Awareness and knowledge among blood donors regarding iron and B12 deficiency and its prevention is very much required. Objective: To assess the knowledge and awareness about iron deficiency and megaloblastic anaemia among blood donors.  Methods: A cross sectional study was conducted among the 500 voluntary blood donors during the span of 1 year at one of the blood bank of tertiary care hospital  using prestructured questionnaire on the various aspect of iron and B12 deficiency/folate deficiency anemia. The data was analysed with the help of Microsoft excel and SPSS.Results: Out of 500 blood donors, 15.6% donors were regular blood donor. It was observed 60% blood donors were having knowledge of anemia in general. Iron deficiency and vitamin B12 deficiency were known to 42% and 31.6% donors, respectively. Only 20% donors could able to answer the acceptable level of hemoglobin require for donating the blood. About 42% donors were aware about importance of iron, folate and vitamin B12 in maintaining normal hemoglobin level. Majority (82.7%) of regular blood donors were willing to get information regarding iron, folate and vitamin B12 deficiency.Conclusion: Significant lack of awareness regarding iron and vitamin B12 deficiency was observed in regular voluntary blood donors. The present study recommends the provision of health education on iron and vitamin B12 deficiency as well as Iron, folate and vitamin B12 rich foods to regular blood donor to prevent anaemia among them.

Roughness of moving elastic lines - crack and wetting fronts

We investigate propagating fronts in disordered media that belong to the universality class of wetting contact lines and planar tensile crack fronts. We derive from first principles their nonlinear equations of motion, using the generalized Griffith criterion for crack fronts and three standard mobility laws for contact lines. Then we study their roughness using the self-consistent expansion. When neglecting the irreversibility of fracture and wetting processes, we find a possible dynamic rough phase with a roughness exponent of $\zeta=1/2$ and a dynamic exponent of z=2. When including the irreversibility, we conclude that the front propagation can become history dependent, and thus we consider the value $\zeta=1/2$ as a lower bound for the roughness exponent. Interestingly, for propagating contact line in wetting, where irreversibility is weaker than in fracture, the experimental results are close to 0.5, while for fracture the reported values of 0.55--0.65 are higher.Comment: 15 pages, 6 figure

Applications of microsatellite markers for the characterization of olive genetic resources of tunisia

Among the countries of the Mediterranean Basin, Tunisia is located at the crossroad for the immigration of several civilizations over the last two millennia, becoming a strategic place for gene flow, and a secondary center of diversity for olive species. Olive is one of the principal crop species in Tunisia and now it strongly characterizes the rural landscape of the country. In recent years, collecting missions on farm and in situ were carried out by various institutes, with special emphasis given to ex situ collections serving as a reference for the identification of olive germplasm. Simple Sequence Repeats (SSRs) represent the easiest and cheapest markers for olive genetic fingerprinting and have been the tool of choice for studying the genetic diversity of this crop in Tunisia, to resolve cases of homonymy and synonymy among the commercialized varieties, to identify rare cultivars, to improve knowledge about the genetic variability of this crop, to identify a hot spot of olive biodiversity in the Tunisian oasis of Degache, and to enrich the national reference collection of olive varieties. The present review describes the state of the art of the genetic characterization of the Tunisian olive germplasm and illustrate the progress obtained through the SSR markers, in individuating interesting genotypes that could be used for facing incoming problems determined by climate changes

Bilateral synchronous spermatocytic seminoma: a rare case report from rural India and literature review

Spermatocytic Seminoma is an unusual germ cell tumour known to arise from testis only. It is associated with good prognosis. Testicular tumours as such are uncommon in Asia as compared to western countries. In the literature only five cases of bilateral synchronous Spermatocytic Seminoma have been reported. Fifty years male patient presented to us with bilateral scrotal swelling and evaluation revealed neoplastic aetiology of bilateral testicular enlargement. Left side radical orchidectomy was performed initially which histopathologically revealed spermatocytic seminoma. Subsequently right side radical orchidectomy was performed after intra-op frozen section confirmation of neoplastic nature. Histopathology revealed same pathology as on left side. Immunohistochemistry of specimen from both testes was again conclusive of spermatocytic seminoma. We hereby report this rare case of Bilateral Synchronous Spermatocytic Seminoma. This is the first case report from entire Asian continent except for Japan.Pan African Medical Journal 2012; 13:3

1D Aging

We derive exact expressions for a number of aging functions that are scaling limits of non-equilibrium correlations, R(tw,tw+t) as tw --> infinity with t/tw --> theta, in the 1D homogenous q-state Potts model for all q with T=0 dynamics following a quench from infinite temperature. One such quantity is (the two-point, two-time correlation function) when n/sqrt(tw) --> z. Exact, closed-form expressions are also obtained when one or more interludes of infinite temperature dynamics occur. Our derivations express the scaling limit via coalescing Brownian paths and a ``Brownian space-time spanning tree,'' which also yields other aging functions, such as the persistence probability of no spin flip at 0 between tw and tw+t.Comment: 4 pages (RevTeX); 2 figures; submitted to Physical Review Letter

Analytical Estimate of the Critical Velocity for Vortex Pair Creation in Trapped Bose Condensates

We use a modified Thomas-Fermi approximation to estimate analytically the critical velocity for the formation of vortices in harmonically trapped BEC. We compare this analytical estimate to numerical calculations and to recent experiments on trapped alkali condensates.Comment: 12 page

Dynamic Scaling of an Adsorption-Diffusion Process on Fractals

A dynamic scaling of a diffusion process involving the Langmuir type adsorption is studied. We find dynamic scaling functions in one and two dimensions and compare them with direct numerical simulations, and we further study the dynamic scaling law on fractal surfaces. The adsorption-diffusion process obeys the fracton dynamics on the fractal surfaces.Comment: 9 pages, 7 figure