Principales microorganismos sulfato reductores (MSR) de reactores anaerobios alimentados con efluentes ácidos, una revisión bibliográfica / Main sulfate-reducing microorganisms (SRM) present in anaerobic reactors fed with acid effluents, a review

RESUMEN En esta investigación bibliográfica se encontraron reportes sobre una gran variedad de especies responsables de precipitar a cuatro metales de interés (Cu, Pb, Zn y Fe). En la mayoría de las investigaciones no solamente se considera la precipitación de estos metales, sino también la de otros elementos que están presentes en cada efluente estudiado. Los artículos aquí mencionados tienen una relación directa con el efluente proveniente de la operación unitaria de flotación. Aportan conocimiento acerca del proceso de sulfato-reducción, comprendiendo el mecanismo mediante microorganismos con características específicas, especialmente su versatilidad pues se desarrollan en diferentes ecosistemas. Se muestra que varias especies, como Desulfobacter o Desulfovibrio son comunes pues tienen condiciones relativamente sencillas para desarrollarse. Los microorganismos sulfato reductores (MSR) son eficientes para reducir la acidez del agua (de la operación unitaria de flotación de una mina, de cocinas, de corrientes marinas, etc.). También lo son para precipitar diferentes elementos pues no requieren de algún agente externo salvo en contadas ocasiones donde debe actuar un catalizador. Hay investigaciones sobre los nutrientes que deben adicionarse para incrementar su actividad. Los reportes de investigación revisados identificaron las variables a controlar para obtener buenos resultados en la remoción de metales y menores impactos en el ambiente. Es de gran importancia el desarrollo de proyectos que tomen en cuenta un sistema natural, como la degradación anaerobia, para alcanzar un punto en el cual la tecnología y el ambiente puedan complementarse logrando bienes de consumo necesarios para la población sin causar daños irreparables a la naturaleza.

ABSTRACT In this bibliographical research, reports were found on a great variety of species responsible for precipitating four metals of interest (Cu, Pb, Zn and Fe). In most of the investigations, not only the precipitation of these metals is considered, but also that of other elements that are present in each effluent studied. The items mentioned here have a direct relationship with the effluent from the flotation unit operation. They provide knowledge about the sulfate-reduction process, understanding the mechanism through microorganisms with specific characteristics, especially their versatility as they develop in different ecosystems. It is shown that several species, such as Desulfobacter or Desulfovibrio, are common because they have relatively simple conditions to develop. Sulfate-reducing microorganisms (SRM) are efficient in reducing the acidity of water (from the flotation unit operation of a mine, kitchens, ocean currents, etc.). They are also used to precipitate different elements since they do not require any external agent except on rare occasions when a catalyst must act. There is research on the nutrients that should be added to increase its activity. The research reports reviewed identified the variables to control to obtain good results in the removal of metals and less impact on the environment. The development of projects that take into account a natural system, such as anaerobic degradation, is of great importance in order to reach a point where technology and the environment can complement each other, achieving necessary consumer goods for the population without causing irreparable damage to nature.

Exploration of the ability of Coleus blumei to accumulate aluminum.

In this study, the capacity of an ornamental species (Coleus blumei) to extract and accumulate aluminum was evaluated. The analyzed parameters were amount of soluble aluminum, radical growth, tolerance rate, bioaccumulation factor, and tissues aluminum concentration. The main limiting factor for aluminum accumulation is the availability of the metal. However, Coleus blumei can grow and accumulate up to 1445.7 mg kg(-1) of aluminum dry base. This plant can play an important role in the treatment of polluted water with metals, since it can grow in conditions with a pH of around 4.8. The aluminum tolerance rate showed for this plant ranged between 18.8% and 25%. Therefore, this species behaves as a non-accumulator, even though the bioaccumulation factor was 3098.5 L kg(-1).