La teoría de Florentino Ameghino y el Plan Maestro Integral Cuenca del Río Salado en el tramo de la desembocadura en la Bahía de Samborombón : Propuesta de construcción de un dique de retención

The Theory of Florentino Ameghino and the Plan Maestro Integral Cuenca del Río Salado at the mouth in the Samborombón Bay. A retention dam building proposal. Florentino Ameghino established that the Buenos Aires Province needs retention structures and not drainage ones in order to prevent drought and flood events. In the lower Salado River drainage basin, Channel Aliviador and Channel 15, that reach the Samborombón Bay, were built with the purpose of control water excess during flooded periods. But Channel 15 was made wider and deeper during 1997, then almost all the water coming from the river goes directly to the Samborombón Bay and this causes a lesser supply of freshwater, that promotes a change in the ecological and socioeconomic conditions in that region. As a consequence, the government taking into account the results of the project Plan Maestro Integral Cuenca del Río Salado (PMI), decided to build threshold bottom dams in the two channels. On the other way, near the mouth of Samborombón Bay, it is located the rock shell littoral chain, which generates an aquifer of a low salinity water. At present, hydrochemical studies indicate that the absence of the river makes the water of the aquifer goes to the bed of the river, which reaches the bay in the moment of low tide and, on the contrary, during high tide a mix with high salinity water coming from the bay takes place. In both cases a loss of freshwater occurs. So in order to minimize this effect, the construction of a retention dam was suggested in a previous work. Since, once the dams of the PMI will be concluded, still a probability of a lack of water may persist in case of drought event as well as for the intensive use of water in the rest of the drainage basin, then the aim of the present work is to maintain the proposal of the construction of the retention dam to assure a source of freshwater in the region and to preserve the rock shell littoral chain aquifer.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

La teoría de Florentino Ameghino y el Plan Maestro Integral Cuenca del Río Salado en el tramo de la desembocadura en la Bahía de Samborombón : Propuesta de construcción de un dique de retención

The Theory of Florentino Ameghino and the Plan Maestro Integral Cuenca del Río Salado at the mouth in the Samborombón Bay. A retention dam building proposal. Florentino Ameghino established that the Buenos Aires Province needs retention structures and not drainage ones in order to prevent drought and flood events. In the lower Salado River drainage basin, Channel Aliviador and Channel 15, that reach the Samborombón Bay, were built with the purpose of control water excess during flooded periods. But Channel 15 was made wider and deeper during 1997, then almost all the water coming from the river goes directly to the Samborombón Bay and this causes a lesser supply of freshwater, that promotes a change in the ecological and socioeconomic conditions in that region. As a consequence, the government taking into account the results of the project Plan Maestro Integral Cuenca del Río Salado (PMI), decided to build threshold bottom dams in the two channels. On the other way, near the mouth of Samborombón Bay, it is located the rock shell littoral chain, which generates an aquifer of a low salinity water. At present, hydrochemical studies indicate that the absence of the river makes the water of the aquifer goes to the bed of the river, which reaches the bay in the moment of low tide and, on the contrary, during high tide a mix with high salinity water coming from the bay takes place. In both cases a loss of freshwater occurs. So in order to minimize this effect, the construction of a retention dam was suggested in a previous work. Since, once the dams of the PMI will be concluded, still a probability of a lack of water may persist in case of drought event as well as for the intensive use of water in the rest of the drainage basin, then the aim of the present work is to maintain the proposal of the construction of the retention dam to assure a source of freshwater in the region and to preserve the rock shell littoral chain aquifer.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

La teoría de Florentino Ameghino y el Plan Maestro Integral Cuenca del Río Salado en el tramo de la desembocadura en la Bahía de Samborombón : Propuesta de construcción de un dique de retención

The Theory of Florentino Ameghino and the Plan Maestro Integral Cuenca del Río Salado at the mouth in the Samborombón Bay. A retention dam building proposal. Florentino Ameghino established that the Buenos Aires Province needs retention structures and not drainage ones in order to prevent drought and flood events. In the lower Salado River drainage basin, Channel Aliviador and Channel 15, that reach the Samborombón Bay, were built with the purpose of control water excess during flooded periods. But Channel 15 was made wider and deeper during 1997, then almost all the water coming from the river goes directly to the Samborombón Bay and this causes a lesser supply of freshwater, that promotes a change in the ecological and socioeconomic conditions in that region. As a consequence, the government taking into account the results of the project Plan Maestro Integral Cuenca del Río Salado (PMI), decided to build threshold bottom dams in the two channels. On the other way, near the mouth of Samborombón Bay, it is located the rock shell littoral chain, which generates an aquifer of a low salinity water. At present, hydrochemical studies indicate that the absence of the river makes the water of the aquifer goes to the bed of the river, which reaches the bay in the moment of low tide and, on the contrary, during high tide a mix with high salinity water coming from the bay takes place. In both cases a loss of freshwater occurs. So in order to minimize this effect, the construction of a retention dam was suggested in a previous work. Since, once the dams of the PMI will be concluded, still a probability of a lack of water may persist in case of drought event as well as for the intensive use of water in the rest of the drainage basin, then the aim of the present work is to maintain the proposal of the construction of the retention dam to assure a source of freshwater in the region and to preserve the rock shell littoral chain aquifer.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

Chromium(III) biosorption onto spent grains residual from brewing industry : equilibrium, kinetics and column studies

The use of industrial wastes for wastewater treatment as a strategy to their re-use and valorisation may provide important advances toward sustainability. The present work gives new insights into heavy metal biosorption onto low-cost biosorbents, studying chromium(III) biosorption onto spent grains residual from a Portuguese brewing industry both in batch and expanded bed column systems. Experimental studies involved unmodified spent grains and spent grains treated with NaOH. Metal uptake followed a rapid initial step, well described by the pseudo-second-order kinetic model up to 27 h, indicating chemisorption to be the rate-limiting step. Beyond this period intraparticle diffusion assumed an important role in the uptake global kinetics. The best fit for equilibrium data was obtained using the Langmuir model, with unmodified spent grains having the higher maximum uptake capacity (q max = 16.7 mg g1). In open system studies, using expanded bed columns, the best performance was also achieved with unmodified spent grains: Breakthrough time (C/C i = 0.25) and total saturation time (C/C i = 0.99) occurred after 58 and 199 h of operation, corresponding to the accumulation of 390 mg of chromium(III), 43.3 % of the total amount entering the column. These results suggest that alkali treatment does not improve spent grains uptake performance. Changes in biomass composition determined by Fourier transform infrared spectroscopy suggested hydroxyl groups and proteins to have an important role in chromium(III) biosorption. This study points out that unmodified spent grains can be successfully used as low-cost biosorbent for trivalent chromium.The authors would like to thank the Portuguese brewing industry UNICER for all the support and FCT (Fundacao para a Ciencia e a Tecnologia) financial support through the Grant PRAXIS XXI/BD/15945/98