Comportamiento de un reactor de biopelícula para tratamiento de agua residual a diferentes velocidades de flujo

Membrane–attached biofilm reactor under different flow rate conditions in the treatment of a synthetic wastewater

M. González–Brambila¹* y F. López–Isunza²

¹ Departamento de Ciencias Básicas, Universidad Autónoma Metropolitana–Azcapotzalco, Av. San Pablo # 180. Col. Reynosa Tamaulipas, México 02200, D.F. * Autor para la correspondencia. E–mail: mmgb@correo.azc.uam.mx Tel. (55)5904–4956, Fax (55)5804–4900

² Departamento de lngeniería de Procesos e Hidráulica, Universidad Autónoma Metropolitana–lztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, lztapalapa. Apdo. Postal 55–534, México 09340, D.F.

Recibido 10 de Abril 2008
Aceptado 10 de Noviembre 2008

Resumen

En este trabajo se estudia el efecto de la velocidad superficial de flujo de un agua residual modelo en un reactor de membrana con biopelícula adherida (RMBA) para su tratamiento. Se comparan tres diferentes flujos de recirculación en el reactor para evaluar el impacto del transporte de masa interfacial sobre el consumo de acetato de sodio. El sistema de estudio es un RMBA conectado a un tanque agitado que contiene al agua residual. El consumo de sustrato y la concentración de oxígeno disuelto se analizaron a la salida del reactor durante experimentos por lote, variando la velocidad de flujo de recirculación en cada experimento. Se utiliza un modelo dinámico para predecir las observaciones experimentales de consumo de sustrato y oxígeno disuelto. El modelo toma en cuenta el transporte de masa difusivo y la biorreacción dentro de la biopelícula, así como el transporte de masa interfacial. Se estiman los coeficientes de transferencia de masa interfacial para cada una de las diferentes velocidades, y se comparan con los valores calculados con expresiones empíricas, derivadas de solución de Blasius a las ecuaciones de la capa límite. El modelo predice satisfactoriamente las concentraciones medidas experimentalmente para los tres diferentes flujos, y permite la predicción de los perfiles de concentración y reacción a interior de la biopelícula.

Palabras clave: reactor de biopelícula, transporte de masa, estimación de parámetros.

Abstract

This work studies about the effect of the flow mass velocity on a model wastewater in a membrane attached biofilm reactor, for its treatment. Three different mass flow recirculation rates in the reactor are compared to assess the impact of interfacial mass transfer on the sodium acetate consumption. The system used was a single–tube membrane attached biofilm reactor, connected to a reservoir with the model waste water. The substrate and oxygen dissolved concentrations in the liquid, were measure at the exit of the reactor. The decreases of substrate and oxygen concentration were measured along batch operation, using different recirculation flow rates. A dynamic model was employed to predict the observed evolution of substrate and oxygen dissolved in the tank. The model accounts for the counter–diffusion of substrate and oxygen as well as for the bioreaction within the biofilm, and the external mass transfer. The interfacial mass transport coefficients were estimated specifically for each one of the different flow rates used and they were compared to those calculated from the Blasius' solution to the boundary layer equations. The model successfully predicted concentration measurements for the different sets of experiments, and it was able to predict the concentration profiles and reaction profiles inside the biofilm.

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