ResumenEl presente trabajo tiene como objetivo investigar la eficiencia de dos coagulantes, el sulfato de aluminio y semillas de Moringa oleifera, para remoción de turbiedad en muestras del agua provenientes de la Laguna de Jiqui, estado del Rio Grande do Norte, Natal-Brasil. Las dosificaciones y pH de los coagulantes fueron variados entre límites establecidos. Se realizaron pruebas, en tubos de ensayo Jar-Test y medidas de movilidad electroforética para determinar el potencial Zeta y para determinar los posibles mecanismos involucrados en el proceso de coagulación. Los mecanismos de coagulación con semillas de Moringa oleifera son adsorción y neutralización de cargas y adsorción y formación de puentes. Los resultados sugieren que para aguas de baja turbiedad, las semillas de Moringa oleifera pueden ser un sustituto potencialmente viable al sulfato de aluminio para la clarificación de dichas aguas. Palabras clave: depuración del agua, coagulación, potencial Zeta, coagulantes naturales, Moringa oleifera Comparative Study of Aluminum Sulfate and Moringa oleifera seeds as Coagulants in the Clarification of Water with Low Turbidity AbstractThe objective of the present work is to investigate the efficiency of a coagulant prepared from Moringa oleifera seeds, for clarifying water samples with low turbidity from the Jiqui Lake, in the State of Rio Grande do Norte, Natal-Brazil. The dosages and pH of the coagulants were changed within defined limits. Jar-test essays and measurements of electrophoretic mobility were done to determine the Zeta potential and the possible mechanisms involved in the coagulation process. The mechanisms of coagulation with Moringa oleifera are absorption and neutralization of charges and absorption and bridging. The results suggest that for low turbidity waters, Moringa oleifera seeds represent a potentially viable substitute of aluminum sulfate for water clarification.

The aim of this work is to improve the separation efficiency in the case of liquid−liquid dispersions using a new type of mixer-settler design called MSPI (mixer-settler based on phase inversion) and a so-called solvent assisted method. The phase inversion is used to decrease the distance between the drops of the disperse phase and the interface in spherical decanters called carrier drops, while a solvent injection in the mixer allows for optimal drop diameters and, therefore, for better and easier separation. In this study, a new design method for the mixing zone in a mixer-settler is proposed. It is based on the capacity of the settler to provide high separation efficiency while throughput increases. This separation is of essential importance when residual water of good quality has to be released. A number of correlations are identified that allow reasonable prediction of the D 3,2 of carriers formed using a perforated plate, as well as the drop size distribution and the Sauter mean diameter (d̄ min) of the primary dispersion. They allow predicting the influence of the organic/aqueous phase ratio as well as the contact angle on these parameters. The method is applied to design operating conditions in MSPI devices used in two particular cases, a heavy metal extraction and a crude oil emulsion separation. The results show that it is possible to obtain very good extraction efficiency coupled with good separation efficiency. They make the MSPI a viable alternative in the treatment of residual water contaminated with crude oil as well as in hydrometallurgy. At the same time the study shows that the MSPI is a simple piece of equipment to work with and very easy to maintain. While the results obtained are for some specific cases, the design methodology presented here can allow the rapid evaluation of other separation processes in the MSPI unit.

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Stability of bubble size in the pulp zone and froth control is an important param

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