47 research outputs found
Alternatives to the use of synthetic organic coagulant aids in drinking water treatment: improvements in the application of the crude extract of Moringa oleifera seed
[EN] Drinking water treatment is a process based on multiple stages that has a main objective to provide water safe enough to be consumed by humans. Coagulationâflocculation is used to remove colloidal and suspended solids. This process improves the performance of subsequent stages (as sedimentation or filtration) as well as the water quality with a desired end-use. For many years, inorganic and organic synthetic polyelectrolytes have been used in coagulationâflocculation processes. However, its use has been deeply studied recently to determine the potential impact of residual concentration of these substances on human health and the environment. Strict regulations limit the concentration of free residual monomer after the addition of polyacrylamide (PAM) in drinking water treatment and study the effect of interaction of the residues with disinfection products. Therefore, in the last years there has been a resurgence of interest to use natural materials with the same performance that synthetic, but with lower hazard for the environment and humans. This work studies the use of the flocculant extracted from Moringa oleifera seed, in combination with polyaluminum chloride (PAC). The performance is compared with the combination PACâPAM in terms of coagulant activity and physicalâchemical quality of the water treated. Jar test was carried out using two types of natural water (with presence of bentonites) and different combinations of coagulant and flocculants. Results show that coagulant activity of PACâMoringa combination is comparable with the results obtained with PACâPAM, reducing initial turbidity up to 90% in all the tests. With regard to physicalâchemical quality of the treated water, PACâMoringa produces values under the drinking water quality standards for all the parameters analyzed. It is remarkable that the decrease of 50% in the trihalomethanes formation potential rate shown for PACâMoringa combination, observed when treating natural water with presence of bentonites. Therefore, the results obtain in this work encourage the use of Moringa oleifera extract as a natural, low cost, effective, and low-toxicity alternative to the use of synthetic organic polyelectrolytes as polyacrylamide for drinking water treatment.This research has been done in the framework of the project âStudy of synthetic and natural coagulants susceptible of being used in the water treatment plant of âRibarroja del Turiaâ (Valencia) as substitutes for polyacrylamideâ. The authors wish to thank the staff
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Application of Multi-Barrier Membrane Filtration Technologies to Reclaim Municipal Wastewater for Industrial Use
Etude de cas d'élimination de composés organiques dans des usines de production d'eau potable : réalimentations artificielles de nappes, traitements d'eaux de surface et d'eaux souterraines
Trois types de traitements ont été décrits : un traitement d'eau de surface comprenant une préozonation ou une préchloration couplée à une flottation, un procédé de réalimentation artificielle de nappe et un traitement d'eau souterraine avec nitrification, ozonation, filtration sur charbon actif en grains et désinfection par le chlore.
Les analyses spécifiques de matiÚres organiques par chromatographie gazeuse et spectrométrie de masse font appel à des échantillons composites réalisés sur la site par des appareils de prélÚvement ou d'extraction automatiques.
Les filtres de nitrification biologique conduisent à une bonne élimination des solvants chlorés par aération, tandis que la combinaison ozone-charbon permet d'éliminer de nombreux composés toxiques ou indésirables. Des phénomÚnes de relargage sur les filtres de nitrification biologique ou de charbon actif ont été également mis en évidence
Les nouvelles espÚces oxydantes en désinfection : efficacité des radicaux hydroxyles et de l'oxygÚne singulet
Les combinaisons de l'ozone avec le peroxyde d'hydrogÚne ou les ultraviolets sont des techniques prometteuses pour l'élimination de composés indésirables réfractaires à l'ozone. L'efficacité de la désinfection par ces combinaisons n'est pas bien connue à l'heure actuelle. Cette étude réalisée avec Bacillus cereus montre que ces combinaisons ont un pouvoir désinfectant important. Toutefois, l'efficacité est inférieure d'environ 1,5 log par rapport à celle de l'ozonation seule.
Les essais de dĂ©sinfection avec le couplage du chlore avec le peroxyde d'hydrogĂšne qui produit de l'oxygĂšne singulet se traduisent par les mĂȘmes conclusions Ă savoir bonne efficacitĂ© dĂ©sinfectante mais infĂ©rieure Ă celle du chlore seul dans les mĂȘmes conditions