Les effluents de tannerie caractérisation et impact sur le milieu marin

Dans ce travail, nous avons caractérisé et évalué l’impact sur le milieu marin des rejets industriels de tannerie. Les résultats montrent que la qualité des eaux usées varie considérablement d’une étape de production à l’autre. Les opérations de prétannage (travail de rivière) sont les plus polluantes avec des teneurs en DCO qui peuvent atteindre 30 000 mg/L. L’analyse des eaux usées au niveau du bassin de collecte, où s’achemine l’ensemble des effluents de l’usine, montre une charge polluante importante et variable avec le temps. La DCO fluctue entre 700 et 3 400 mg/L et les matières en suspension entre 500 et 8 000 mg/L avec des charges polluantes moyennes de 114 et 358 kg/jour respectivement. Ces eaux sont aussi chargées en chrome avec des teneurs qui se situent entre 40 et 115 mg/L, soit une charge de 6,5 kg/jour. La teneur en sulfures varie entre 65 et 160 mg/L. En outre, l’indice de biodégradabilité (DBO5/DCO : 0.1 – 0.2) indique que ce rejet n’est pas facilement biodégradable.L’examen des teneurs en chrome chez des espèces bioindicatrices, la moule Mytilus galloprovincialis et les algues Ulva lactuca et Corallina officinalis, montre l’ampleur des apports en polluants causée par ce type de rejets au niveau de la mer. Les teneurs en chrome au niveau de ces espèces à proximité de point du déversement de ces eaux usées, sont élevées comparées à d’autres points plus éloignés.In this study, the pollution load and the impact of tannery wastewaters on the marine environment were assessed. The composition of the effluents from different fabrication steps varied considerably. Pre-tanning operations seem to be more polluting than other tanning operations, with the Chemical Oxygen Demand (COD) reaching 30 000 mg•L‑1. The analysis of the global effluent showed an important and variable pollution load versus time. The COD ranged from 700 to 3,400 mg•L‑1, and the suspended matter from 500 to 8,000 mg•L‑1 for an average pollution load of 114 and 358 kg•d‑1 respectively. Chromium concentrations ranged from 40 to 115 mg•L‑1, giving a daily load of 6.5 kg•d‑1. Sulfide concentrations varied from 65 to 160 mg•L‑1. The biodegradability index (DBO5/DCO: 0.1‑0.2) indicates that the effluent is not readily biodegradable. In order to assess the impact of the tannery wastewaters on the marine environment, the mussel Mytilus galloprovincialis and the algae Ulva lactuca and Corallina officinalis were selected as bioindicators. The results indicated high chromium contents in the species living near the point of discharge into the sea

PLFAs of the microbial communities in composting mixtures of agro-industry sludge with different proportions of household waste

Phospholipid fatty acids (PLFAs) were analysed at different time periods during composting of two waste mixtures rich in fats, M1 (22%) and M2 (39%), with the aim of monitoring changes in microbial community structure. The two mixtures consisted of a sludge sample collected from a vegetable oil refinery effluent treatment plant combined with household wastes. The PLFA profiles of both mixtures revealed that, at the start of the process, fungi and Gram-negative bacteria (GÀ) were more abundant in M2 than in M1. During the thermophilic phase, branched PLFA (i15:0, a15:0, i16:0, and i17:0) markers of Gram-positive bacteria (Gþ), became more abundant in M1, while G- bacteria were predominant in M2. The PLFA profiles in M1 representing non-specific, Gþ and GÀ bacteria as well as fungi decreased during the cooling phase (maturation) while an increase was recorded in M2, which was richer in fats. The ShannoneWeaver diversity index (Ish) showed a greater increase during M1 composting (from 0.69 to 1.05), mainly for Gþ bacteria and GÀ bacteria, than in M2 composting (from 0.79 to 0.84). Principal components and cluster analyses revealed a succession of different communities during composting, which varied from fungi and GÀ bacteria to Gþ and thermophilic and thermotolerant GÀ bacteria. The end of composting was characterized by a reduction of all these microbial entities, especially for M1, except actinomycetes, which are associated with compost stability

Reducing Pollution of Stabilized Landfill Leachate by Mixing of Coagulants and Flocculants: A Comparative Study

The physico-chemical process of coagulation-flocculation is very efficient and economical for the treatment of leachate. The latter can have considerable impacts on the environment. The leachate from the landfill of the city of Mohammedia is characterized by a high COD content which varies between 2200 and 2700 mg/l, a total Kjeldahl nitrogen concentration varying from 1080 to 1405 mg/l while the ammonium content has a concentration varying between 587 and 1410 mg/l. Organic matter is not readily biodegradable (BOD5/COD: 0.2 to 0.13). Metal concentrations ranged from 0.1 to 4.2 mg/l for Cr, 40 to 5 mg/l for Cd, and 0.3 to 0.8 mg/l for lead. For monitoring the leachate treatment, several coagulants and flocculants were used (FeCl3, Al2(SO4)3, Alginate, cationic flocculants, anionic flocculants). In parallel with the monitoring of the physicochemical parameters we followed the production of the volume of the settled sludge over time. Treatment with all coagulants and flocculants used is pH dependent. Ferric Chloride has been shown to be effective at a pH of 6.5 while for Aluminum Sulfate the optimum pH is 5.3. The results showed that coagulation-flocculation by Ferric Chloride and Aluminum Sulfate is very effective in reducing turbidity. This reduction reaches 95 and 98% respectively for FeCl3 and Al2(SO4)3, while the reduction in COD for the two coagulants is around 60%. Organic flocculants alone do not lead to a significant reduction in turbidity and COD, while their combination with coagulants marks a good reduction in pollution. Hydrated iron hydroxides precipitate more easily than flocs formed by aluminum, resulting in more efficient removal of pollutants than that obtained at lower pH values. The order of introduction strongly influences the coagulation flocculation. The optimal doses of the various coagulants and flocculants chosen for the study vary from one reagent to another. FeCl3 remains the most suitable coagulant to further eliminate organic and metal pollution. The cost associated with the treatment using flocculants remains much higher when the flocculant is used in admixture with a coagulant

Etude de l'adsorption de tensioactifs cationiques sur charbon actif : influence de coadsorbats

CNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Étude de la co-adsorption de tensioactifs sur charbon actif dans l’eau

L’adsorption statique de quantité micromolaire de bromure de benzyldodécyldiméthylammonium (BBDDA) sur du charbon actif en poudre a été étudiée dans l’eau distillée seule, puis en présence de sels minéraux NaCl et CaCl2 et de composés organiques : le naphtol-2, le nonylphénoxyheptaéthoxyéthanol (NP8) et le dodécylétherpentaéthoxyéthanol (DE6). Les trois premiers composés ne modifient pas la capacité ultime d’adsorption du BBDDA (Γ∞ = 0,59 mmol.g–1), déterminée à partir des isothermes de Langmuir. Par contre, la co-adsorption en présence de NP8 ou de DE6 diminue fortement cette capacité ultime. L’utilisation d’un modèle montre que l’adsorption se ferait sur des sites spécifiques avec une inhibition due à la présence de l’autre composé. La détermination du potentiel zêta des suspensions de charbon a été faite sur le charbon seul (ζ = -22 mV), puis sur des suspensions de charbon contenant de 10–4 à 10–2M NaCl (ζ = -13 mV) ou 10–2M CaCl2 (ζ = -9 mV). La présence du tensioactif cationique dans tous les cas augmente la valeur du potentiel zêta vers des valeurs plus positives (-2 mV). La réduction de ce potentiel permet d’avoir une estimation de l’épaisseur de la « couche diffuse » de Debye-Hückel

Modeling using experimental design method of the physicochemical parameters of the water quality in Meknes city, Morocco

This study was focused on the characterization of physicochemical parameters of drinking water, which are mainly involved during water treatment or analysis processes. we were interested in the application of the experimental design methodology, according to the method of Yates on the parameters that characterize the quality of drinking water in Meknes, Morocco. Six factors have been identified to control this quality. The influence of these parameters on the responses accommodated at the exit was highlighted. The derivation of a theoretical model has been realized and a series of experiments was performed. The analysis of our results, based on a statistical approach, was presented and the parameters that have a significant influence on the outputs have been identified. From these results, we can conclude that the input factors such as hardness, pH, conductivity, residual chlorine and turbidity have a large influence on measured output response (pHs). Moreover, the theoretical and experimental results are very convergent which validate our studied model

+Study of metallic contamination of Oued Sebou sediments, Morocco

International audienc

Biological treatment of fuel wastewater generated from a thermal power plant by continuous and discontinuous aeration

International audienc

Les effluents de tannerie caractérisation et impact sur le milieu marin

Dans ce travail, nous avons caractérisé et évalué l’impact sur le milieu marin des rejets industriels de tannerie. Les résultats montrent que la qualité des eaux usées varie considérablement d’une étape de production à l’autre. Les opérations de prétannage (travail de rivière) sont les plus polluantes avec des teneurs en DCO qui peuvent atteindre 30 000 mg/L. L’analyse des eaux usées au niveau du bassin de collecte, où s’achemine l’ensemble des effluents de l’usine, montre une charge polluante importante et variable avec le temps. La DCO fluctue entre 700 et 3 400 mg/L et les matières en suspension entre 500 et 8 000 mg/L avec des charges polluantes moyennes de 114 et 358 kg/jour respectivement. Ces eaux sont aussi chargées en chrome avec des teneurs qui se situent entre 40 et 115 mg/L, soit une charge de 6,5 kg/jour. La teneur en sulfures varie entre 65 et 160 mg/L. En outre, l’indice de biodégradabilité (DBO5/DCO : 0.1 – 0.2) indique que ce rejet n’est pas facilement biodégradable.L’examen des teneurs en chrome chez des espèces bioindicatrices, la moule Mytilus galloprovincialis et les algues Ulva lactuca et Corallina officinalis, montre l’ampleur des apports en polluants causée par ce type de rejets au niveau de la mer. Les teneurs en chrome au niveau de ces espèces à proximité de point du déversement de ces eaux usées, sont élevées comparées à d’autres points plus éloignés.In this study, the pollution load and the impact of tannery wastewaters on the marine environment were assessed. The composition of the effluents from different fabrication steps varied considerably. Pre-tanning operations seem to be more polluting than other tanning operations, with the Chemical Oxygen Demand (COD) reaching 30 000 mg•L‑1. The analysis of the global effluent showed an important and variable pollution load versus time. The COD ranged from 700 to 3,400 mg•L‑1, and the suspended matter from 500 to 8,000 mg•L‑1 for an average pollution load of 114 and 358 kg•d‑1 respectively. Chromium concentrations ranged from 40 to 115 mg•L‑1, giving a daily load of 6.5 kg•d‑1. Sulfide concentrations varied from 65 to 160 mg•L‑1. The biodegradability index (DBO5/DCO: 0.1‑0.2) indicates that the effluent is not readily biodegradable. In order to assess the impact of the tannery wastewaters on the marine environment, the mussel Mytilus galloprovincialis and the algae Ulva lactuca and Corallina officinalis were selected as bioindicators. The results indicated high chromium contents in the species living near the point of discharge into the sea

VALORISATION D’UN REJET INDUSTRIEL RICHE EN CHLORURE FERRIQUE : APPLICATION AUX TRAITEMENTS DES EAUX RESIDUAIRES

Intense coloring due to the presence of the non biodegradable dyes, often toxic, in industrial wastewater, enormously poses problems of degradation of the receiving medium (i.e. surface waters). This study relates to the control of pollution of the industrial wastewater with physicochemical treatment by using an industrial waste rich in ferric chloride like original coagulant. This was tested for the control of pollution of the liquid effluents from the textile industry strongly polluted with organic matter. Several parameters were selected to control the purification of our effluents: turbidity, chemical oxygen demand (COD), and volume of sludge. The optimal concentration of the coagulant used in this treatment varies from one waste to another, according to the polluting load to treat. The output of this physicochemical treatment shows an important reduction of the polluting load of textile wastewaters: 91 – 87% of the organic matter and 84 – 85% of suspended solids, with less sludge production