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Las espectaculares tasas de crecimiento del sector pecuario mundiales en las últimas dos décadas han conformado una auténtica revolución agraria. Los cambios demográficos, la urbanización acelerada y el rápido crecimiento económico de las economías emergentes son los factores que han impulsado esta revolución. En este proceso el sector pecuario ha sufrido una transformación de su estructura productiva, desde los sistemas tradicionales extensivos hacia los sistemas industrializados intensivos. Esta revolución pecuaria, sin embargo, confronta desafíos y oportunidades globales que solo de manera reciente han llamado la atención sobre la necesidad de desarrollar una institucionalidad coherente con los cambios, y unas políticas que permitan regular los grandes retos que comporta el nuevo entorno del sector pecuario. The spectacular growth rates of the global livestock sector in the last two decades have formed an agrarian revolution. Demographic changes, rapid urbanization and fast economic growth in emerging economies are the factors that have driven this revolution. In this process the livestock sector has undergone a transformation of its productive structure, from extensive traditional systems to intensive industrial systems. This livestock revolution, however, confronts a number of global challenges and opportunities, which have only recently drawn attention to the need to develop an institutional framework that is coherent with changes and a series of policies that make it possible to regulate the great challenges involved in the new environment of the livestock sector. As espetaculares taxas de crescimento do setor pecuário mundiais nas últimas duas décadas possibilitaram uma autêntica revolução agrária. As mudanças demográficas, a urbanização acelerada e o rápido crescimento econômico das economias emergentes são os fatores que impulsionaram esta revolução. Neste processo o setor pecuário sofreu uma transformação de sua estrutura produtiva, desde os sistemas tradicionais extensivos rumo aos sistemas industrializados intensivos. Esta revolução pecuária, porém, confronta desafios e oportunidades globais, que só de maneira recente chamaram a atenção sobre a necessidade de desenvolver uma institucionalidade coerente com as mudanças e políticas que permitam regular os grandes desafios que comporta o novo entorno do setor pecuário.

Feedlots have increased in several regions of Argentina, particularly in the Pampas. The absence of adequate treatments of the effluents produced in these establishments creates serious problems to the society. Phytoremediation can be defined as inexpensive and environmentally sustainable strategy used to remove pollutants by plants. The aim of this study was to evaluate the remediation potential of two macrophyte species (Eichhornia crassipes and Hydrocotyle ranunculoides) on a feedlot effluent. This effluent was treated with these species for 31 days. Control and macrophyte treatments decreased dissolved inorganic nitrogen (DIN), Kjeldahl nitrogen (Kj N), biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved salts (TDS), total phosphorus (TP), Pb, Zn and Cr levels. At macrophyte treatments, relatively constant pH levels were kept and decreased EC and TDS values were obtained compared to control, mitigating the release of contaminants and potential greenhouse gases to the atmosphere. Moreover, significant increases in biomass were obtained, being higher in E. crassipes. The results allow concluding that the presence of aquatic plants increases the removal rates of nutrients, organic matter and heavy metals from wastewater in approximately 10-17 days for a feedlot effluent with high organic load. En diversas regiones de la Argentina, en particular en la región Pampeana, se han incrementado los sistemas de engorde a corral (feedlots). La ausencia de tratamientos adecuados de los efluentes producidos por estos establecimientos crea severos problemas para la sociedad. El uso de plantas nativas para la remediación de sistemas contaminados es una tecnología de muy bajo costo y ambientalmente sustentable. El objetivo de este estudio fue evaluar el potencial de remediación de dos especies de plantas acuáticas (Eichhornia crassipes e Hydrocotyle ranunculoides) sobre un efluente de feedlot. Este efluente fue tratado con estas especies durante 31 días. Tanto el tratamiento control como los tratamientos con macrófitas disminuyen los niveles de nitrógeno inorgánico disuelto, nitrógeno Kjeldahl, demanda bioquímica de oxígeno, demanda química de oxígeno, sales totales disueltas (STD), fósforo total, Pb, Zn y Cr. El uso de macrófitas mantuvo relativamente constante los niveles de pH, disminuyendo CE y STD respecto del control, pudiendo mitigar la liberación de contaminantes hacia la atmósfera. Además se alcanzaron incrementos significativos de biomasa, siendo mayores en E. crassipes. Los resultados permiten concluir que la presencia de plantas acuáticas incrementan las tasas de remoción de nutrientes, material orgánico y metales pesados en aproximadamente 10-17 días desde un efluente con alta carga orgánica. Fil: Rizzo, Pedro Federico. Instituto Nacional de Tecnología Agropecuaria (Argentina). Instituto de Microbiología y Zoología Agrícola. Laboratorio de Transformación de Residuos Fil: Arreghini, Silvana. Universidad de Buenos Aires. Facultad de Agronomía Fil: Serafini, Roberto José María. Universidad de Buenos Aires. Facultad de Agronomía Fil: Bres, Patricia Alina. Instituto Nacional de Tecnología Agropecuaria (Argentina). Instituto de Microbiología y Zoología Agrícola. Laboratorio de Transformación de Residuos Fil: Crespo, Diana Elvira. Instituto Nacional de Tecnología Agropecuaria (Argentina). Instituto de Microbiología y Zoología Agrícola. Laboratorio de Transformación de Residuos Fil: Fabrizio de Iorio, Alicia Rosa. Universidad de Buenos Aires. Facultad de Agronomía

47-64 Feedlots have increased in several regions of Argentina, particularly in the Pampas. The absence of adequate treatments of the effluents produced in these establishments creates serious problems to the society. Phytoremediation can be defined as inexpensive and environmentally sustainable strategy used to remove pollutants by plants. The aim of this study was to evaluate the remediation potential of two macrophyte species (Eichhornia crassipes and Hydrocotyle ranunculoides) on a feedlot effluent. This effluent was treated with these species for 31 days. Control and macrophyte treatments decreased dissolved inorganic nitrogen (DIN), Kjeldahl nitrogen (Kj N), biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolved salts (TDS), total phosphorus (TP), Pb, Zn and Cr levels. At macrophyte treatments, relatively constant pH levels were kept and decreased EC and TDS values were obtained compared to control, mitigating the release of contaminants and potential greenhouse gases to the atmosphere. Moreover, significant increases in biomass were obtained, being higher in E. crassipes. The results allow concluding that the presence of aquatic plants increases the removal rates of nutrients, organic matter and heavy metals from wastewater in approximately 10-17 days for a feedlot effluent with high organic load.