Static Sorption of Phenol and 4-Nitrophenol onto Composite Geomaterials based on Montmorillonite, Activated Carbon and Cement

International audienceThis paper studies the sorption of phenol and 4-nitrophenol (4NP) onto solid sorbents derived from mixtures of montmorillonite, activated carbon (AC) and cement, denoted herein MACC. These materials are mesoporous and some of their physicochemical properties have been measured and discussed. The weight fraction X1 (%) of montmorillonite in the mixtures strongly influences the sorbate removal rate. The sorption isotherms were experimentally established by batch testing on geomaterials with various X1 values at 20 °C and at different pH values (from 3 to 8). The Langmuir model correctly fits the sorption isotherm data (R2 > 0.95). The results show increased sorption behavior for both phenol and 4NP on the composite geomaterials compared to the pure components, yielding the order: MACC > AC > montmorillonite

Efficiency of Modified Granular Activated Carbon Coupled with Membrane Bioreactor for Trace Organic Contaminants Removal

The aim of the study is to improve removal of trace organic contaminants dissolved in activated sludge by the process of filtration with membrane bioreactor combined with modified activated carbon, for a maximum removal of organic compounds characterized by low molecular weight. Special treatment was conducted in laboratory on activated carbon. Tow reaction parameters: The pH of aqueous middle and the type of granular activated carbon were very important to improve the removal and to motivate the electrostatic Interactions of organic compounds with modified activated carbon in addition to physical adsorption, ligand exchange or complexation on the surface activated carbon. The results indicate that modified activated carbon has a strong impact in removal 21 of organic contaminants and in percentage of 100% of the process

Effects of treated wastewater irrigation on soil salinity and sodicity in Sfax (Tunisia): A case study

In arid regions such as near Sfax (Tunisia), treated wastewater effluents (TWE) are often applied as agricultural irrigation. Irrigation TWE usually contain large amounts of carbon, nitrogen and sodium. The objective of this study was to evaluate the impact of TWE irrigation on soil salinity and sodicity. In the city of Sfax, two sites were selected with two soil types (fluvisol and calcisol) having been irrigated for 4 and 15 years respectively. Soils were sampled at three different depths (0-30, 30-60 and 60-90 cm) in the TWE irrigated area and in a non-irrigated control area. Irrigated and non-irrigated study soils were analyzed for pH, nitrate and ammonia, electrical conductivity (ECs), exchangeable sodium percentage (ESP), sodium absorption ratio (SAR) and soil organic matter.The fluvisol, irrigated for only four years, is more affected by salinity than the calcisol irrigated for 15 years. In the upper fluvisol layer irrigated by the treated wastewater, ECs reach 8 mS•cm-1 and ESP a value of 15% while in all layers of the calcisol, ECs and ESP are lower and rarely exceed 4 mS•cm-1 and 6% respectively. This result is due to a combination of factors in the fluvisol treatment area including texture, cation exchange capacity, irrigation procedure and crop management.Dans les régions arides telles que le cas de Sfax (Tunisie), les eaux usées traitées (EUT) sont souvent utilisées en irrigation agricole. Généralement, les EUT sont riches en composés organiques, en azote et en sodium. L’objectif de cette étude est d’évaluer l’impact de l’irrigation par les EUT sur la salinité et la sodicité des sols. Dans la région de Sfax, deux sites ont été sélectionnés, représentant deux types de sols différents (fluvisol et calcisol) irrigués par les EUT, respectivement depuis 4 et 15 ans. Des échantillons des sols ont été prélevés systématiquement à trois profondeurs différentes (0-30, 30-60 et 60-90 cm) au niveau des parcelles irriguées et sur des placettes contrôle non irriguées (témoin). Sur chaque échantillon composite de sol, les pH (eau, KCl), teneurs en nitrate et ammonium, capacité d’échange cationique (CEC), conductivités électriques (CEs), taux de sodium échangeable (ESP), ratios d’absorption de sodium et teneurs en matières organiques ont été mesurés.Le fluvisol, irrigué depuis seulement quatre ans, est plus affecté par la salinité que le calcisol, irrigué depuis 15 ans. Dans les niveaux de surface du fluvisol, la CEs et l’ESP ont atteint les seuils critiques de 8 mS•cm-1 et 15 % respectivement, alors qu’au niveau du calcisol, la CEs et l’ESP sont plus faibles et dépassent rarement 4 mS•cm-1 et 5 % respectivement. Pour le fluvisol, ce résultat est dû à la combinaison de plusieurs facteurs impliquant la texture, la capacité d’échange cationique, la procédure d’irrigation et la rotation des cultures

Caractérisation d'un Système Lagunaire en Zone Tropicale: Cas du lac Nokoué (Bénin)

This survey permitted to make hydrological balance of the lake Nokoué and to know quality physico-chemical of the waters of the lake in order to offer the basis elements for a future ecological modeling of the system. The results of hydrological balance show that the average of the flow of the soft waters received by the lake in period of high waters is 216m3/s essentially brought by the Ouémé stream, the longest stream of Benin that crosses the country from the north to the south. This value falls to 49m3/s in dry season with 86% of the flow brought by the Sô river in dry season. In dry season, the Sô at Ganvié has the most important rate of organic load (53% DBO). For the phosphorus in dry season, the highest rate is gotten at the level of strongest rate is gotten at the level of Ouémé stream at Totchè (42%). In the period of high waters (from August to October) a dilution effect of the contribution is observed. In term of nutrient loads brought by purification systems, the results obtained are 360kg/j-P and 840 kg/j - N for Cotonou and Calavi and 150 kg/j- P and 700 kg/j-N for Ganvié. The contributions of "Acadjas " give 2,3 - 2,9 kg/j P and 29 - 36 N kg/j. The main results obtained for the physico-chemical for characterization are presented as follows: * a very remarkable saline intrusion in dry season, Sô at Ganvié the value passes from 0g/L in period of high waters to 2,5g/L in dry season, * the average pH varies between 6,6 and 7,5 for the waters of the bottom and between 6,9 and 7,8 for the waters of surface of the lake. The pH varies very little between the bottom of the lake and its surface, * the values of nitrogen and phosphorus nutrients are extensively high than the limited values indicated by the system of classification by the Organization of Cooperation and Economic Development (OECD). The waters of the lake are therefore eutropheses. We notice a seasonal evolution of the system. According to the factors of control hyacinths of waters, it is concluded that nutrients control the development of hyacinths when the salinity doesn't inhibit the growth of hyacinths anymore; that means of July to January

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