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Ismail T.,Center des Recherches et Technologies des Eaux | Toshihiko M.,Hokkaido University
Desalination and Water Treatment

Micro-organisms attached to granular activated carbon (GAC) in a fixed bed reactor were applied to treat synthetic leachate with different ratios of carbon to nitrogen. The leachate treatment reactor used in this study was run in batch operation under control of temperature, circulating flow rate, and oxygen concentration in pore space. The efficiency of a new device was estimated by treating artificial leachate having low levels of C/N ratios (0 to 5) at a temperature of 30°C, flow rate of 40 ml/min and oxygen gas concentration ranging from 1%, 5%, 10%, 15% to 21%. It was found that this device is adequate for the elimination of both dissolved organic carbon and ammoniacal-nitrogen. Even with the absence of external carbon supply, the denitrification process occurred. Partial bio-mass decay is considered the main source that supplies carbon to denitrifying bacteria. The average time needed for the elimination of dissolved organic compound (DOC) and NH4 + - N was 1 and 2 d, respectively. © 2012 Desalination Publications. All rights reserved. Source

Chatti A.,Center des Recherches et Technologies des Eaux | Aloui M.,University of Carthage | Tagourti J.,University of Carthage | Mihoub M.,University of Carthage | Landoulsi A.,University of Carthage
Polish Journal of Microbiology

This study was carried out to determine the effects of novobiocin, a gyrase inhibitor, on the growth, survival, motility and whole cell proteins of S. Typhimurium dam and/or seqA strains. Our results showed that the dam and seqA/dam mutants are the most sensitive to novobiocin, compared to wild type and seqA strains. Surprisingly, the motility of seqA mutants increased after exposure to novobiocin only in stationary phase cells. All the other strains showed a significant decrease in their motility. The analysis of protein profiles of all strains demonstrated several modifications as manifested by the alteration of the expression levels of certain bands. Our work is therefore of great interest in understanding the effects of novobiocin on S. Typhimurium and the involvement of DNA methylation. Source

Ben Salah Sayadi I.,Center des Recherches et Technologies des Eaux | Sistat P.,Montpellier University | Tlili M.M.,Center des Recherches et Technologies des Eaux
Chemical Engineering and Processing: Process Intensification

In electrodialysis (ED) desalination plants, calcium carbonate is the main component of meted scales. To prevent its formation several treatments were proposed. For more efficiency, treatments must be assessed at experimental conditions close to real ones. Thus, this work is a contribution to understand and evaluate three anti-calcareous physical treatments for ED desalination systems simulating real conditions. Magnetic field (MF) and ultrasonic field (UF) were applied to concentrate solution, compartment where scaling is imminent in the used ED pilot unit. The third treatment was a pulsed electric field (PEF) application. Tested solution was a synthetic brackish water. Results show that magnetic and ultrasonic treatments accelerate the precipitation of CaCO3 by reducing the nucleation time and the metastable domain. It is also shown that pulsed electric treatment accelerates CaCO3 precipitation resulting from desalination improvement comparing to stationary mode. However, all these treatments favor the homogeneous precipitation which prevents scale formation on membrane surfaces. It seems that MF improves the desalination only by preventing membrane scaling. However, UF and PEF application improve desalination by preventing membrane scaling and by improving the ions transfer during desalination; UF application acts on ions mobility or diffusion, while PEF application reduces the concentration polarization layer. © 2014 Elsevier B.V. Source

Mansouri L.,Center des Recherches et Technologies des Eaux | Mohammed H.,University of Swansea | Tizaoui C.,University of Swansea | Bousselmi L.,Center des Recherches et Technologies des Eaux
Desalination and Water Treatment

Diethyl phthalate (DEP) is one of the phthalate esters having wide industrial applications, but its occurrence in the aquatic environment has been linked to disruption of the endocrine system. In this study, the removal of DEP with ozone alone (OA) and heterogeneous catalytic ozonation (HCO) with activated carbon (AC) was investigated. Results show that the addition of AC was effective to achieve almost 100% degradation of DEP in about 30 min using 2.86 g AC/L as compared to over 80 min without AC. It was also found that radical reactions were the main mechanism by which DEP was degraded and adsorption contributed significantly to the removal of DEP by OAC. Indeed, after 60 min, adsorption alone achieved about 75% removal, whilst OA achieved 92% removal. In contrast, as expected molecular ozone reactions were relatively insignificant. The contribution of adsorption and radical reactions to the overall removal of DEP were of similar rates at the beginning of the experiments but the latter declined due to competitive reactions. The notable decrease of DEP removal rate observed in the presence of radical scavenger tert-butanol (tb) indicates that the reaction between DEP and proceeds mainly in the bulk of the aqueous phase. Moreover, the experimental results also revealed that in the absence of tb and after 40 min, almost 100% removal was observed as compared to only 64% when tb was added to the solution. This confirms that radical reactions play an important role in DEP removal by the OAC process. A model taking into account the various reactions in the bulk solution and on the surface of AC was developed and was found to predict well the experimental data. This study proves that HCO was effective to remove DEP and the changes of the contributory mechanisms underpinning the process were determined as function of time. © 2013 © 2013 Balaban Desalination Publications. Source

Boulahlib-Bendaoud Y.,University of Tebessa | Ghizellaoui S.,University of Mentouri Constantine | Tlili M.,Center des Recherches et Technologies des Eaux
Desalination and Water Treatment

The present work examines the effect of two mineral inhibitors on the CaCO3 precipitation in two Algerian ground waters. The main objective was to reduce the scaling power and then to prevent the fouling phenomenon met in the equipments supplied by these waters. It was shown that, for a large rang of temperature, Hamma water is more scale-forming water than the one of Negrine because its lower content in foreign ions to the calcocarbonic system, especially magnesium. Chronoamperometry tests show that the antiscale treatment with mineral phosphates is more efficient for the Hamma than Negrine water. Tested inhibitors affect strongly the nucleation-growth kinetics in the case of Hamma water and only the scale compactness in Negrine water. This was attributed to the difference in the chemical composition of the studied waters. Besides, it was shown that polyphosphate is more efficient as scaling inhibitor than the dihydrogenophosphate ions. © 2012 Desalination Publications. All rights reserved. Source

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