Élimination des colorants des eaux résiduaires de l'industrie textile par la bentonite et des sels d'aluminium

L'industrie textile utilise des colorants de synthèse toxiques qui polluent ses eaux résiduaires avec, parfois, des flux importants. Les procédés traditionnels les éliminent mal : ils sont peu iodégradables et la seule floculation, par exemple par des sels de fer, donne des résultats insuffisants. Or, en Algérie, la réutilisation agricole des eaux usées même industrielles est devenue une impérieuse nécessité. Le procédé proposé repose sur l'utilisation de sels d'aluminium ou, mieux encore, un polyhydroxyaluminium, associés à une bentonite de forage très fine présentant l'avantage d'être localement disponible et peu coûteuse. Quatre colorants ont été testés. Ils appartiennent à deux grandes familles : les colorants acides d'une part, Jaune Supranol 4GL et Vert Nylomine C8B et les colorants dispersifs d'autre part, Rouge Foron RDGL et Violet Foron S3RL. Les essais montrent que, si la bentonite seule ou les sels d'aluminium seuls présentent des efficacités insuffisantes, ces derniers du fait d'une mauvaise décantabilité des microflocs formés, l'association bentonite-aluminium permet d'éliminer les colorants en quasi totalité avec une excellente décantabilité. Les concentrations optimales à mettre en oeuvre sont relativement basses, de l'ordre de 13 mg/l de Al3+ et 250 mg/l de bentonite. Les coûts d'exploitation sont donc très raisonnables. Sur un effluent industriel réel, le procédé permet de passer d'une DCO de 770 mg/l à moins de 30 mg/l.The textile industry uses synthetic dyes, most of them being toxic. In Algeria, the agricultural reuse of treated wastewater, even of industrial origin, is becoming commonplace. It is therefore compulsory to drastically reduce pollutant fluxes. The presently operated conventional processes cannot meet the water quality requirements: bioelimination of dyes is negligible and flocculation with iron salts, as currently carried out in the SOITEX plant located in Tlemcen, Algeria, is not effective enough. The use of aluminum salts in the flocculation of such wastewaters is well known (FIESSINGER AND BERSILLON, 1977; LAHAV et al., 1978) but the resulting microflocs are not easily settleable. Bentonite, locally available at a low cost, can also eliminate micropollutants (LAHAV et al., 1978). Associated with polyhydroxyaluminum, it can reduce such compounds as benzene or toluene, favoring simultaneously the liquid-solids separation. This paper evaluates the treatability of dyes by bentonite associated with aluminum salts.All the runs were carried out in a 200 cm3 batch reactor, mechanically stirred and thermoregulated at 20·C. The main physico-chemical characteristics of the bentonite are given in Table 1. The flocculant was aluminum chloride, previously neutralized with sodium hydroxide (mass ratio OH-/Al=1.85). The solutions were used immediately or left to polymerize during 6 days leading to polyhydroxyaluminum PHAl (LAHAV et al., 1978). When the reactor was operated with bentonite and aluminum, the mass ratio Al/bentonite was maintained at 53.10-3 (KACHA, 1994). Four dyes belonging to two main families were tested: Supranol Yellow 4GL and Nylomine Green (acid dyes) and Foron Red RDGL and Foron Violet S3RL (dispersive dyes). Their concentrations were obtained by spectrophotometry.Bentonite alone does not induce a significant abatement excepted for low pH values around 4 (Figs. 1 and 2). Dye elimination appears to require a previous protonation step followed by cation exchange. The equilibrium can be modeled by a Freundlich equation (Fig. 3 and Table 2). The dyes can also be eliminated by aluminum salts alone (Fig. 4). The efficiency is then better with polyhydroxyaluminum, i.e. more than 90 % of the initial concentration is removed. Nevertheless, the dyes abatement probably results from an adsorption or chemical reaction on microflocs which are not easily settleable. By assuming that all the aluminum ions are precipitated as aluminum hydroxide, the equilibrium is modeled by the Langmuir equation which would indicate a monolayer adsorption (Fig. 5). When the reactor is operated with bentonite and aluminum salts, dye abatement is nearly complete and the liquid-solids separation is particularly efficient (Figs. 6 and 7). The best results are obtained with PHAl but the use of the monomer can be sufficient. The required concentrations are relatively low and the process is then economically feasible (Table 3). However, the experimental data can no longer be modeled by the Freundlich equation nor by the Langmuir equation. When the aluminum salts react alone with the dyes, the conductance displayed against the aluminum concentration shows two straight lines of different slopes (Fig. 8). The abscissa of the points where the slopes change are proportional to the initial dye concentration, suggesting a chemical reaction between the dye and the aluminum salts (Fig. 9). However, the final pH value lies at the limit value of aluminum hydroxide precipitation; an adsorption on aluminum hydroxide or an aluminum salt precipitation cannot then be assumed. In presence of bentonite, such changes of slope are not observed and, moreover, the final pH value does not correspond either to a precipitation value (Figs. 11 and 12). At this stage, a comprehensive mechanism cannot thus be proposed. However, the process using bentonite/PHAl is particularly efficient and easy to operate (Fig. 13 and Table 3). The results were confirmed with a true industrial effluent, the Chemical Oxygen Demand (COD) of which was reduced from 770 mg/l to less than 30 mg/l (Fig. 14). As a matter of comparison, the actual process, which includes an activated sludge treatment followed by an iron sulfate/lime flocculation, leads to an effluent containing only 140 mgCOD/l

Alternatives aux pesticides pour la protection des cultures maraichères en Afrique sub-Saharienne

Sous les tropiques, les fruits et les légumes sont attaqués en toute saison par une grande diversité de ravageurs qui peuvent avoir un impact considérable sur la production. Les pullulations de ravageurs sont variables selon les régions, les facteurs climatiques et les espèces cultivées, qu'elles soient locales ou exotiques. Les plantes locales sont généralement plus résistantes aux maladies et ravageurs locaux. Cependant des espèces étrangères invasives venues, sans leur cortège d'ennemis naturels telles que la mouche des fruits, l'acarien rouge ou la teigne de la tomate ne font qu'accroître les problèmes phytosanitaires des maraichers. Les résultats des enquêtes sur les pratiques phytosanitaires des maraichers en Afrique sub-Saharienne sont les mêmes partout : une utilisation systématique et croissante de pesticides chimiques inadaptés aux ravageurs ciblés voire non homologués sur les cultures traitées, le non-respect des doses et des dates d'épandages avant récolte, des conditions d'utilisation et de stockage à risque pour la santé de l'agriculteur, des consommateurs et de l'environnement. L'arrivée de nouveaux ravageurs et la sélection de ravageurs résistants aux mêmes pesticides chimiques utilisés depuis plus de 30 ans n'arrangent pas la situation. Dans les périmètres horticoles, un système de cultures diversifié sera toujours moins attractif qu'une monoculture. Des variétés adaptées aux conditions locales et des plantes bien alimentées et non stressées seront toujours plus résistantes aux bio-agresseurs. La rotation des espèces cultivées et leurs associations sont des techniques primordiales pour réduire les risques de maladies. Enfin des plantes compagnes aromatiques ou à usage médicinal peuvent avoir leur intérêt pour assainir les sols, repousser les ravageurs ou attirer les insectes utiles (prédateurs, parasitoïdes ou pollinisateurs). De même, faut-il attirer et préserver leurs ennemis naturels que sont les oiseux, les prédateurs et les parasitoïdes. La combinaison de la lutte physique avec différentes techniques de lutte biologique peut être une alternative à la lutte chimique pour protéger les fruits et légumes à forte valeur ajoutée qui sont souvent les plus traitées (tomate, aubergine, piment, chou, haricot,…). Les recherches conduites au Benin et au Kenya sur l'usage des filets anti-insectes ont montré qu'on pouvait réduire de 70% l'usage des pesticides chimiques sur chou voire de 100% sur tomate et haricot au Kenya. Les extraits de plantes et des micro-organismes entomopathogènes produits localement peuvent être utilisés en préventif en plus des pièges à insectes classiques visuels ou impliquant des phéromones. Si les techniques alternatives aux pesticides chimiques ne manquent pas, de nouveaux systèmes de production sont donc à co-concevoir avec les producteurs

Kinetics of fragmentation-annihilation processes

We investigate the kinetics of systems in which particles of one species undergo binary fragmentation and pair annihilation. In the latter, nonlinear process, fragments react at collision to produce an inert species, causing loss of mass. We analyse these systems in the reaction-limited regime by solving a continuous model within the mean-field approximation. The rate of fragmentation, for a particle of mass $x$ to break into fragments of masses $y$ and $x-y$, has the form $x^{\lambda-1}$ ($\lambda>0$), and the annihilation rate is constant and independent of the masses of the reactants. We find that the asymptotic regime is characterized by the annihilation of small-mass clusters. The results are compared with those for a model with linear mass-loss (i.e.\ with a sink). We also study more complex models, in which the processes of fragmentation and annihilation are controlled by mutually-reacting catalysts. Both pair- and linear-annihilation are considered. Depending on the specific model and initial densities of the catalysts, the time-decay of the cluster-density can now be very unconventional and even non-universal. The interplay between the intervening processes and the existence of a scaling regime are determined by the asymptotic behaviour of the average-mass and of the mass-density, which may either decay indefinitely or tend to a constant value. We discuss further developments of this class of models and their potential applications.Comment: 16 pages(LaTeX), submitted to Phys. Rev.

Λ\Lambda CDM jerk parameter in symmetric teleparallel cosmology

In this paper, we have examined the recently proposed modified symmetric teleparallel gravity, in which gravitational Lagrangian is given by an arbitrary function of non-metricity scalar $Q$. We have considered the $\Lambda$CDM jerk parameter to express the Hubble rate. Moreover, we have used 57 points of Hubble $H\left( z\right)$ and 1048 points of Pantheon datasets to constraint our model parameters by means of the Markov Chain Monte Carlo analysis. The mean values and the best fit obtained give consistent Hubble rate and deceleration parameter compared to the observation values. In order to study the current accelerated expansion scenario of the Universe with the presence of the cosmological fluid as a perfect fluid, we have considered two forms of teleparallel gravity. We have studied the obtained field equations with the proposed forms of $f(Q)$ models, specifically, linear $f\left( Q\right) =\alpha Q+\beta$ and non-linear $f\left( Q\right) =Q+mQ^{n}$ models. Next, we have discussed the physical behavior of cosmological parameters such as energy density, pressure, EoS parameter, and deceleration parameter for both model. To ensure the validity of our proposed cosmological models, we have checked all energy conditions. The properties of these parameters confirm that our models describe the current acceleration of the expansion of the Universe. This result is also corroborated by the energy conditions criteria. the Finally, the EoS parameter for both models indicates that the cosmological fluid behaves like a quintessence dark energy model.Comment: 12 pages, 10 figure

Chronic dehydration affects hydroelectrolytic equilibrium and adrenal gland morphology in wistar rat: comparison with Gerbillus tarabuli

Shortage of water supply is the most stressful condition that can meet man and animals. Since the adrenal gland plays a pivotal role in the stress response, the objective of this work is to study, in the male Wistar rat, the repercussions of chronic dehydration on adrenal gland structure compared to that of a desert rodent: Gerbillus tarabuli. Adults and male Wistar rats and gerbils were divided into: i) control rats (n=8) given free access to tap water); ii) dehydrated rats (n=8) given 2% NaCl solution ad libitum for 7 days and (iii) G.tarabuli (n=6) given barely seeds ad libitum without access to water. Chronic dehydration caused strong adreno-chromaffin cells degranulation in rats. For the gerbils, adrenal zona fasciculate and medulla features suggest respectively an increased production and release of glucocorticoides but a basal stress hormones release. These results suppose that shortage of water in arid environment does not represent a stress factor for this species.Keywords: adrenal gland; chronic dehydration; plasmatic parameters; histology; Wistar rat; Gerbillus tarabul

Seasonal fluctuations of phlebotomines sand fly populations (Diptera: Psychodidae) in the Moulay Yacoub province, centre Morocco: Effect of ecological factors

An entomological survey of phlebotomine sand flies was conducted in the Moulay Yacoub province, central Morocco. An anthropic niche (Ouled Aid) and a wild niche (Zliligh) were selected. Sand flies were collected twice a month between April 2011 and March 2012, using sticky traps and CDC light traps. 3675 specimens were collected (78.3% males/21.7% females) which composed of eight species divided into two genera: Phlebotomus (90.34%), wide Phlebotomus papatasi (49.78%), Phlebotomus sergenti (27.17%), Phlebotomus longicuspis (13.69%), Phlebotomus pernicuosis (9.36%) and Sergentomyia (9.66%) composed of Sergentomyia fallax (52.36%), Sergentomyia minuta (34.26%) Sergentomyia antennata (11.16%) and Sergentomyia dreyfussi (2.22%). P. papatasi is dominant in the anthropic niche and P. longicuspis is dominant in the wild niche. The population dynamics showed a bimodal pattern with a first peak in June for both studied stations and a second one in September for Ouled Aid and in August for Zliligh. A significant positive correlation between the density and the temperature(r = 0.64, r = 0.66) and a significant negative correlation with humidity (r = -0.64, r = -0.62) are shown. Density (119 specimens/m2/night) of sand flies showed that Moulay Yacoub’s province presents a risk for the inhabitants in the vicinity of Fez. This situation requires continuous monitoring to prevent and reduce the leishmania risk.Key words: Sand flies, leishmaniasis, seasonality; risk period, Moulay Yacoub, Morocco

Qualité physicochimique et bactériologique de trois stations thermales dans les régions de Fès, Maroc

Les sources thermales au Maroc constituent une richesse inestimable et sont fréquemment exploitées par la population pour différents usages. Cette dernière peut être exposée à des risques de contamination par des germes pathogènes dans les stations thermales mal entretenues. C'est dans ce cadre qu'une étude portant sur la qualité physicochimique et bactériologique de trois sources situées près de la ville de Fès : Sidi Harazem, Moulay Yaâcoub et Ain Allah a été réalisée. Les prélèvements d'eau effectués mensuellement entre Octobre 2012 et Mars 2013 dans les trois stations et à différents points, ont été analysés selon des protocoles standardisés conformément aux normes. Les résultats ont montré que les paramètres physico-chimiques des eaux des trois stations prélevées au niveau des fontaines et du réservoir répondent aux normes marocaines en vigueur. Les analyses bactériologiques ont montré l’absence des germes pathogènes dans les eaux de fontaine des trois stations étudiées. Les eaux de piscine de la station Ain Allah ont présenté, une forte contamination par la flore mésophile et les indicateurs de pollution fécale (coliformes totaux, coliformes fécaux, Escherichia coli et les streptocoques fécaux) par rapport aux eaux de piscine de la station Moulay Yaâcoub qui présentent des densités très faibles. Cette charge bactérienne est liée essentiellement à la fréquentation de cette station par nombre important de baigneurs durant cette saison ainsi qu’à la température qui favorise la croissance des micro-organismes. L’utilisation de ces eaux pour la baignade pourrait être à l’origine de maladies transmises par les eaux de baignade. Ces piscines doivent donc être soumises à un contrôle régulier de la charge et de la nature de la flore microbienne de leurs eaux.Mots-clés: sidi harazem, moulay Yaâcoub, ain allah, physico-chimie, bactériologie, fès, Maroc. Physicochemical and bacteriological quality of three spas in Fez region (Morocco)Hot springs in Morocco are an invaluable wealth and are frequently used by the population for different purposes. The latter may be exposed to the risk of contamination by pathogens in poorly maintained spas. It is in this context, a study of the physico-chemical and bacteriological quality of three springs near Fez city: Sidi Harazem, Moulay Yaâcoub and Ain Allah was performed. Water samples collected monthly between October 2012 and March 2013 in the three stations and at different points were analyzed according to standardized and normalized protocols. The results showed that the physico-chemical parameters of the three station’s waters collected from fountain and reservoir meet Moroccan standards (NM 03.07.001/2006). Bacteriological analysis showed the absence of pathogens in the fountain’s water of the three studied stations. The swimming pool’s water of Ain Allah station presented a strong contamination by mesophilic flora and by faecal pollution indicators (total coliforms, fecal coliforms, Escherichia coli and faecal streptococci) comparing to the water of Moulay Yacoub station swimming pool which exhibit very low bacterial densities. This bacterial density is mainly related to the large number of bathers in this station during this season and also to the temperature that promotes the microorganism’sgrowth. The use of these waters for swimming could be the cause of diseases and illness transmitted by bathing waters. These swimming pools must be subject to regular monitoring of the density and the nature oftheir water’s microbial flora.Keywords: sidi harazem, moulay yaâcoub, ain allah, physico-chemical, bacteriology, fez, Morocco

Observational Constraints and Cosmological Implications of Scalar-Tensor f(R,T)f(R, T) Gravity

Recently, the scalar-tensor representation of $f (R,T)$ gravity was used to explore gravitationally induced particle production/annihilation. Using the framework of irreversible thermodynamics of open systems in the presence of matter creation/annihilation, the physical and cosmological consequences of this setup were investigated in detail. In this paper, we test observationally the scalar-tensor representation of $f(R,T)$ gravity in the context of the aforementioned framework, using the Hubble and Pantheon+ measurements. The best fit parameters are obtained by solving numerically the modified Friedmann equations of two distinct cosmological models in scalar tensor $f(R, T)$ gravity, corresponding to two different choices of the potential, and by performing a Markov Chain Monte Carlo analysis. The best parameters are used to compute the cosmographic parameters, i.e., the deceleration, the jerk and the snap parameters. Using the output resulting from the Markov Chain Monte Carlo analysis, the cosmological evolution of the creation pressure and of the matter creation rates are presented for both models. To figure out the statistical significance of the studied scalar-tensor $f(R,T)$ gravity, the Bayesian and the corrected Akaike information criteria are used. The latter indicates that the first considered model in scalar tensor $f(R,T)$ gravity is statistically better than $\Lambda$CDM, i.e., it is more favored by observations. Besides, a continuous particle creation process is present in Model 1. On the other hand, for large redshifts, in Model 2 the particle creation rate may become negative, thus indicating the presence of particle annihilation processes. However, both models lead to an accelerating expansion of the Universe at late times, with a deceleration parameter equivalent to that of the $\Lambda$CDM model.Comment: 17 pages, 14 figures; accepted for publication in MNRA

Méningo-vascularite bactérienne révélant un adénome hypophysaire

Un macroadénome à prolactine se présente généralement par un syndrome hormonal associé à un syndrome tumoral. Une méningite bactérienne compliquant un macroprolactinome en dehors de toute thérapie médicale ou chirurgicale est rarement rapporté dans la littérature. Mme R.C âgée de 48 ans s'est présentée aux urgences pour trouble de conscience fébrile. La ponction lombaire a révélé une méningite  bactérienne. L'imagerie cérébrale a mis en évidence un aspect de vascularite cérébrale et un processus de la loge sellaire avec lyse du plancher faisant évoquer une brèche ostéoméningée. Le bilan biologique a montré une hyperprolactinémie à 200 mg/dl. La patiente est mise sous antibiothérapie à dose méningée et une corticothérapie associée à un traitement par la Cabergoline. Le traitement chirurgical de la brèche ostéoméningée s'est fait par voie endonasale. L'évolution est marquée par une nette amélioration clinique et biologique et l'absence de récidive de la méningite après un recul de 14 mois. Un macroprolactinome peut  provoquer une brèche ostéoméningée en dehors de tout traitement médical ou chirurgical et avoir comme première manifestation une méningite infectieuse