Effect of initial substrate/inoculum ratio on cell yield in the removal of hydrophobic vocs in fungal biofilters

Efecto de la razón sustrato/inóculo sobre el rendimiento celular en la remoción de covs hidrofóbicos en biofiltros fúngicos

A. Vergara-Fernández¹*, J. San Martín-Davison³, L.A. Díaz-Robles², O. Soto-Sánchez³

¹ Facultad de Ingeniería y Ciencias Aplicadas, Universidad de los Andes, Mons. Álvaro del Portillo 12455, Las Condes. Santiago, 7620001 Chile * Corresponding author. E-mail: aovergara@miuandes.cl telephone/fax: 56-02-2618 1000.

³ Escuela de Ingeniería Ambiental, Facultad de Ingeniería, Universidad Católica de Temuco.

Received September 30, 2013.
Accepted June 19, 2014.

Abstract

Different kinetic models have been proposed to describe the elimination of hydrophobic volatile organic compounds (VOCs) by fungal biofiltration. In this process the ratio of the initial substrate concentration (C^p_b0) to the initial biomass (X₀) has been shown to influence the cell yield. This papers presents a study of the efect of the C^p_b0/X₀ ratio on observed cell yield (Y_obs) in a fixed bed batch system (microcosm) using a gaseous carbon source, as an approximation to its application in the fungal biofiltration of hydrophobic VOCs. Essays were carried out in fixed-bed microcosms using the filamentous fungus Fusarium solani as a biological agent and n-pentane as a carbon and energy source. The results indicated that Y_obs in the gas phase is inversely proportional to the C^p_b0/X₀ ratio, with values of 0.9 to 0.35 g_biomass g^-1_pentane being obtained when the C^p_b0/X₀ ratio is changed from 0.1 to 1.0 g_pentane g^-1_biomass. The results indicate that more than 60% of n-pentane was consumed due to energy spilling, and that strong dissociation of catabolism from anabolism occurred at higher C_b0/X₀ ratios.

Keywords: hydrophobic VOCs, fungal biofiltration, substrate/inoculum ratio, growth yield.

Diferentes modelos cinéticos han sido propuestos para describir la eliminación de compuestos orgánicos volátiles hidrofóbicos (COVs) en biofiltros fúngicos. En este proceso la razón de la concentración inicial de sustrato (C^p_b0) a la biomasa inicial (X₀) ha mostrado influir en el rendimiento celular. Este artículo presenta el estudio del efecto de la razón C^p_b0/X₀ en el rendimiento celular observado (Y_obs) en un sistema por lote de lecho fijo (microcosmo) utilizando una fuente de carbono gaseosa, como una aproximación a su aplicación en la biofiltración fúngica de COVs hidrofóbicos. Los ensayos fueron realizados en microcosmos de lecho fijo utilizando el hongo filamentoso Fusarium solani como agente biológico y n-pentano como fuente de carbono y energía. Los resultados indican que Y_obs en la fase gaseosa es inversamente proporcional a la razón C^p_b0/X₀, con valores de 0.9 a 0.35 g_biomasa g^-1_pentano siendo obtenido cuando la razón C^p_b0/X₀ es cambiada desde 0.1 a 1.0 g_pentano g^-1_biomasa. Los resultados indican que más del 60% del n-pentano fue consumido debido a pérdida de energía, y que una fuerte disociación del catabolismo y anabolismo ocurre para altas razones C^p_b0/X₀.

Palabras clave: COVs hidrofóbicos, biofiltración fúngica, razón sustrato/inoculo, rendimiento de crecimiento.

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Acknowledgements

The present research was financed by the CONICYT (National Commission for Scientific and Technological Research) (FONDECYT Project N°11080036).

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