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DEGRADACIÓN BIOLÓGICA DE FENOL UTILIZANDO TÉCNICAS RESPIROMÉTRICAS

Ingeniería Sanitaria y Ambiental 01/2007; 92:66-71.

ABSTRACT El fenol es un constituyente común de las aguas residuales originarias de varias industrias. Es tóxico aun a bajas concentraciones y es por ello que son necesarios métodos de tratamiento eficientes para reducir la concentración de fenol en las aguas residuales a niveles aceptables. En la provincia de Buenos Aires el límite de descarga en agua superficial es de 0.5 mg/L (Res. N° 287). De los muchos métodos existentes aplicables para la degradación de fenol, el tratamiento biológico es especialmente recomendable porque tiene un potencial capaz de degradar casi completamente el fenol generándose productos finales inocuos.
Los objetivos del presente trabajo fueron analizar la degradación biológica de fenol utilizando barros activados aclimatados y no aclimatados a dicho sustrato y determinar los parámetros cinéticos y estequiométricos correspondientes utilizando medidas respirométricas.
Se utilizaron reactores semi-continuos a escala laboratorio para generar barros activados aclimatados y no aclimatados a fenol. Para evaluar el efecto del fenol sobre la respiración microbiana se utilizó un respirómetro cerrado. Se llenó el reactor con barros (aclimatados o sin aclimatar) previamente lavados y resuspendidos en buffer de pH=7 y se agregaron distintos pulsos de fenol a fin de obtener valores de concentración entre 20 y 4000 mg/L. Se representó la concentración de oxígeno en función del tiempo y de la pendiente se obtuvo el valor de velocidad de respiración. En el caso de la biomasa no aclimatada se observó que el fenol produce un efecto de inhibición sobre los microorganismos a concentraciones mayores a 20mg/L. Para la biomasa aclimatada se observó un rápido ascenso en la velocidad de respiración e inmediatamente una disminución a medida que la concentración de fenol aumentaba. Se ajustaron los datos de velocidad de respiración a la ecuación de Haldane, que contempla inhibición por sustrato, obteniéndose los siguientes valores para las constantes cinéticas: qO2*=0.047mgO2.mgDQO-1.h-1, Ks=14.04mgfenol/L y Ki=1912.09mgfenol/L. Por otra parte se realizaron ensayos utilizando un respirómetro abierto para obtener el coeficiente de oxidación del fenol obteniéndose un valor de YO/S = 0.74mgO2/mgfenol.

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